Patent Application
20130209506
Chickenpox is caused by acute infection with varicella-zoster virus (VZV). The virus spreads throughout the body and enters cells of the nervous system. Latent infection occurs and the virus establishes itself in dorsal root and cranial nerve ganglia. The latent virus subsequently can reactivate and present as zoster (shingles). Researchers and pharmaceutical companies have developed chickenpox vaccines but the side effect of shingles due to the live virus establishing a latent infection is still of concern. The ability of a live virus vaccine to enter and maintain a latent infection phase therefore can compromise the safety of live viral vaccines. Any change to the virus that decreases the probability of establishing or maintaining a latent infection can bring significant public health benefits.
Live vaccines are very popular despite the possibility of latent infection. For example, the live attenuated VZV vaccine based on the “Oka virus” (see, U.S. Pat. No. 3,985,615) prevents chickenpox but the virus used in this vaccine can enter a latent infection phase in vaccinated individuals and later cause zoster (Sharrar et al. Vaccine 19:916 (2000), Wise et al. JAMA 284:1271 (2000)) The Oka virus is attenuated. However the reason for this attenuation and its significance to the latency problem is unknown.
During latency of VZV a limited repertoire of viral genes are expressed including open reading frames (ORFs) 4, 21, 29, 62, 63, and 66. ORF29 transcripts have been detected in human and rodent ganglia by in situ hybridization and reverse-transcription followed by PCR. (Cohrs et al, J. Vir. 74:11464 (2000); Kennedy et al., Virology 289:218 (2000). ORF29 encodes a 130 kDa protein that binds to single-stranded DNA and localizes predominantly to the nucleus of virus-infected cells in vitro (Kinchington et al, J. Virol. 62:802 (1988)). ORF29 contains a nuclear localization signal within amino acids 9 to 154 and transport to the nucleus requires Ran and karyopherins (Stallings et al., J. Virol. 79:10370 (2005)). While ORF29 protein is present in the nucleus of lytically infected cells, the protein is in the cytoplasm of neurons from human ganglia (Grinfeld et al, virus Genes 29:317 (2004); Lungu et al, PNAS 95:7080 (1998)). ORF29 protein localizes to the cytoplasm of guinea pig enteric ganglia neurons and in an astrocyte-like cell line (Chen et al, J. Med. Virology (Suppl. 1):S71 (2003); Stallings et al., J. Virol. 80:1497 (2006)). Treatment with a proteosome inhibitor or expression of HSV-1ICPO or VZV ORF61 results in translocation of ORF29 protein to the nucleus in both guinea pig enteric ganglia neurons and the astrocyte-like cell line.
ORF29 protein is secreted from VZV-infected fibroblasts and is endocytosed by human neurons in vitro (Annunziato et al., J. Virology 74:2005 (2000)). The protein is present in endothelial and epithelial cells in the skin of patients with varicella zoster; the protein is also located in nerves in the dermis of patients with varicella. ORF29 protein is not present in virions (Kinchington et al, J. Virology 66:359 (1992). The relationship of ORF 29 protein and latency has not been established.
Improved vaccines both for humans and for veterinary care, are needed that comprise altered viruses that present less risk of establishing or maintaining a latent infection and therefore are less likely to reactivate.
The disclosure provides recombinant herpes virus with diminished latency. In embodiments, the recombinant herpes virus comprises a latency gene or transcript linked to a heterologous promoter or a modified promoter. The disclosure also provides compositions and methods for inducing immunity in animals using the recombinant herpes viruses.
In one aspect, a recombinant virus includes all or a portion of a herpes virus genome, wherein the genome has the promoter for a latency gene or transcript altered or modified so that the gene or transcript is expressed during virus replication, but not expressed or poorly expressed during latency. In embodiments, a recombinant virus has the promoter for a latency gene or transcript replaced by a heterologous promoter. In other embodiments, a recombinant virus has a deletion in a latency gene or transcript at its native location, and the latency gene or transcript is located at different location in the viral genome and is expressed from a heterologous promoter. The recombinant virus as described herein can replicate but has an impaired ability to establish latency. In embodiments, the recombinant virus is attenuated.
Any herpes virus can be altered or modified as described herein. In some embodiments, the herpes virus is selected from the group consisting of herpes simplex virus, varicella-zoster virus (VZV), Marek's disease virus, pseudorabies virus, or cytomegalovirus. In other embodiments, the herpes virus is selected from the group consisting of simian varicella virus, feline herpes 1, equine herpes 1, equine herpes 4, pseudorabies virus, canine herpes 1, bovine herpes 1, Marek's disease virus (of chicken), Laryngotracheitis virus, Meleagrid herpes virus 1, and herpes simplex virus.
Genes or transcripts expressed during a latent herpesvirus infection can be identified. In embodiments, the herpes virus is VZV and the latency gene is selected from the group consisting of genes that correspond to ORF4, ORF21, ORF29, ORF62, ORF63, ORF66 of VZV and combinations thereof. In other embodiments, the gene is homologous to a latency gene or transcript, such as VZV ORF29.
In some embodiments, the promoter associated with a latency gene or transcript is modified or altered to provide for expression during replication but is not expressed or poorly expressed during latency. In other embodiments, the latency gene or transcript is linked to a heterologous promoter. In embodiments, the heterologous promoter can be from the same virus, from a different virus, or from a nonviral source.
In some cases, the recombinant virus has a modified latency gene at its native location, wherein all or a portion of the latency gene or flanking sequences thereof are deleted. In an embodiment, a recombinant virus substantially lacks a DNA binding protein encoding gene at its native location, the gene being encoded by a nucleic acid sequence that hybridizes to a nucleic acid sequence that encodes an ORF29 protein of varicella zoster virus. In other embodiments, the nucleic acid encoding the major DNA binding protein has a deletion of a nucleic acid that encodes at least 10 amino acids. For example, a nucleic acid encoding amino acids corresponding to amino acids 22-957 of an ORF29 having the amino acid sequence of SEQ ID NO:3 is deleted.
In embodiments, where the latency gene or transcript is located at a non native location, the latency gene or transcript is located between other genes, especially those not required for replication, so as not disrupt viral replication.
Another aspect of the disclosure provides immunogenic compositions and methods of using immunogenic compositions. As described herein an immunogenic composition includes a recombinant herpesvirus as described herein and a carrier. The immunogenic composition may further include an adjuvant or a live vaccine stabilizer. The immunogenic compositions are useful in methods of preventing, diminishing herpes viral infection and/or establishment or maintenance of latency.
The term “attenuated” as used herein refers to a virus that is weakened or impaired for virulence.
The term “antibody” is used in the broadest sense and specifically includes, for example, single monoclonal antibodies, antibody compositions with polyepitopic specificity, single chain antibodies, and fragments of antibodies. The term “monoclonal antibody” as used herein refers to an antibody obtained from a population of substantially homogeneous antibodies, i.e., the individual antibodies comprising the population are identical except for possible naturally-occurring mutations that may be present in minor amounts.
“Antibody fragments” comprise a portion of an intact antibody, preferably the antigen binding or variable region of the intact antibody. Examples of antibody fragments include Fab, Fab′, F(ab′)2, and Fv fragments; diabodies; linear antibodies (Zapata et al., 1995, Protein Eng., 8:1057-1062); single-chain antibody molecules; and multispecific antibodies formed from antibody fragments.
The term “binds specifically” refers to an antibody that binds VZV and does not substantially bind other herpes viruses.
“Carriers” as used herein include pharmaceutically acceptable carriers, excipients, or stabilizers, which are nontoxic to the cell or mammal being exposed thereto at the dosages and concentrations, employed. Often the physiologically acceptable carrier is an aqueous pH buffered solution. Examples of physiologically acceptable carriers include buffers such as phosphate, citrate, and other organic acids; antioxidants including ascorbic acid; low molecular weight (less than about 10 residues) polypeptide; proteins, such as serum albumin, gelatin, or immunoglobulins; hydrophilic polymers such as polyvinylpyrrolidone; amino acids such as glycine, glutamine, asparagine, arginine or lysine; monosaccharides, disaccharides, and other carbohydrates including glucose, mannose, or dextrins; chelating agents such as EDTA; sugar alcohols such as mannitol or sorbitol; salt-forming counterions such as sodium; and/or nonionic surfactants such as TWEEN™, polyethylene glycol (PEG), and PLURONICS™
The term “VZV” as used herein refers to an isolate, strain, or recombinant varicella zoster virus. In embodiments, the genome is about 125-kbp long and includes terminal repeat (TR), unique long (UL) repeat, internal repeat (IR), and unique short repeat (US) DNA domains. VZV can be isolated from infected humans and propagated in cell lines, such as human embryonic lung cells. An attenuated vaccine strain has been described in Gomi et al, Journal of Virology 76:11447 (2002). The complete sequences of VZV Oka strain and vaccine strain have accession nos. AB097932(gI 26665420) and AB097933(gI 26665422), respectively. A reference sequence in the Genbank data base is found at NC—001348 (gI 9625875) or X04370 (gI 59989;strain Dumas). Numbering of the nucleotides of the sequences presented herein is in reference to the VZV, strain Dumas as exemplified in X04370.
The term “immunogenic effective amount” of a recombinant virus or component thereof refers to an amount of a recombinant virus or component thereof that induces an immune response in an animal. The immune response may be determined by measuring a T or B cell response. Typically, the induction of an immune response is determined by the detection of antibodies specific for the recombinant virus or component thereof.
An “isolated” antibody is an antibody that has been identified and separated and/or recovered from a component of its natural environment. Contaminant components of its natural environment are materials that would interfere with diagnostic or therapeutic uses for the antibody, and may include enzymes, hormones, and other proteinaceous or nonproteinaceous solutes. Isolated antibody includes the antibody in situ within recombinant cells since at least one component of the antibody's natural environment will not be present. Ordinarily, however, isolated antibody will be prepared by at least one purification step.
An “isolated” nucleic acid molecule is a nucleic acid molecule that is identified and separated from at least one contaminant nucleic acid molecule with which it is ordinarily associated in the natural source. Preferably, the isolated nucleic is free of association with all components with which it is naturally associated. An isolated nucleic acid molecule is other than in the form or setting in which it is found in nature.
“Percent (%) nucleic acid sequence identity” with respect to the nucleic acid sequences identified herein is defined as the percentage of nucleotides in a candidate sequence that are identical with the nucleotides in a reference herpesvirus nucleic acid sequence, after aligning the sequences and introducing gaps, if necessary, to achieve the maximum percent sequence identity. In some embodiments, the reference VZV nucleic acid sequence is that of SEQ ID NO:1 or SEQ ID NO:11. Alignment for purposes of determining percent nucleic acid sequence identity can be achieved in various ways that are within the skill in the art, for instance, using publicly available computer software such as BLAST, BLAST-2, ALIGN, ALIGN-2 or Megalign (DNASTAR) software. Those skilled in the art can determine appropriate parameters for measuring alignment, including any algorithms needed to achieve maximal alignment over the full-length of the sequences being compared.
For purposes herein, the % nucleic acid sequence identity of a given nucleic acid sequence A to, with, or against a given nucleic acid sequence B (which can alternatively be phrased as a given nucleic acid sequence A that has or comprises a certain % nucleic acid sequence identity to, with, or against a given nucleic acid sequence B) is calculated as follows:
100 times the fraction W/Z
where W is the number of nucleotides scored as identical matches by the sequence alignment program in that program's alignment of A and B, and where Z is the total number of nucleotides in B. It will be appreciated that where the length of nucleic acid sequence A is not equal to the length of nucleic acid sequence B, the % nucleic acid sequence identity of A to B will not equal the % nucleic acid sequence identity of B to A.
“Recombinant” refers to a polynucleotide that has been isolated and/or altered by the hand of man. A DNA sequence encoding all or a portion of a herpesvirus viral genome may be isolated and altered or modified as described herein.
“Percent (%) amino acid sequence identity” with respect to the herpesvirus polypeptide sequences identified herein is defined as the percentage of amino acid residues in a candidate sequence that are identical with the amino acid residues in a herpesvirus polypeptide reference sequence, after aligning the sequences and introducing gaps, if necessary, to achieve the maximum percent sequence identity, and not considering any conservative substitutions as part of the sequence identity. Alignment for purposes of determining percent amino acid sequence identity can be achieved in various ways that are within the skill in the art, for instance, using publicly available computer software such as BLAST, BLAST-2, ALIGN, clustal V (DNASTAR) or Megalign (DNASTAR) software. Those skilled in the art can determine appropriate parameters for measuring alignment, including any algorithms needed to achieve maximal alignment over the full-length of the sequences being compared. Alignments of ORF from different VZV strains, variants and isolates can be determined using sequences known or readily determined by those of skill in the art. A reference sequence for ORF 29 is that of a polypeptide comprising the amino acid sequence of SEQ ID NO:3 or SEQ ID NO:10.
For purposes herein, the % amino acid sequence identity of a given amino acid sequence A to, with, or against a given amino acid sequence B (which can alternatively be phrased as a given amino acid sequence A that has or comprises a certain % amino acid sequence identity to, with, or against a given amino acid sequence B) is calculated as follows:
100 times the fraction X/Y
where X is the number of amino acid residues scored as identical matches by the sequence alignment program in that program's alignment of A and B, and where Y is the total number of amino acid residues in B. It will be appreciated that where the length of amino acid sequence A is not equal to the length of amino acid sequence B, the % amino acid sequence identity of A to B will not equal the % amino acid sequence identity of B to A. In an embodiment, the B amino acid sequence is that of SEQ ID NO:3 or SEQ ID NO:10.
“ORF29 polypeptide variant” refers to an ORF29 polypeptide that differs in amino acid sequence from a particular ORF29 polypeptide reference sequence. In an embodiment, the ORF29 polypeptide reference sequence comprises an amino acid sequence of SEQ ID NO:3 or SEQ ID NO:10. The variants may include deletions and additions of amino acids, as well as amino acid substitutions as described herein.
An ORF29 polypeptide variant has at least about any number of % sequence identity from 70% to 100% sequence identity to a full-length mature ORF29 polypeptide reference sequence. An ORF29 variant has at least about 70% sequence identity, more preferably at least about 75% sequence identity, more preferably at least about 80% sequence identity, more preferably at least about 85% sequence identity, more preferably at least about 90% sequence identity, more preferably at least about 95% sequence identity and even 100% sequence identity to an ORF29 polypeptide reference sequence such as that of SEQ ID NO: 3 or SEQ ID NO:10.
An ORF29 polypeptide variant has at least about any amount of % deleted amino acids from 0.2% to 100% of a full-length mature ORF29 polypeptide reference sequence, such as SEQ ID NO:3 or SEQ ID NO:10. An ORF29 variant has at least about 0.2% deleted, more preferably at least about 4% amino acids deleted, more preferably at least about 10%, more preferably at least about 15%, more preferably at least about 20%, and more preferably at least about 25% amino acids deleted.
The disclosure also includes variants of nucleic acid molecules encoding ORF29 polypeptides. In one embodiment, the disclosure includes polynucleotides encoding a polypeptide having at least about any number of sequence identity from 70% to 100% sequence identity to the reference polypeptide for ORF29, more preferably about 70% sequence identity, more preferably about 75% sequence identity, more preferably about 80% sequence identity, more preferably about 85% sequence identity, more preferably about 90% sequence identity, more preferably about 95% sequence identity, and even up to 100% sequence identity to a reference ORF29, such as that having an amino acid sequence of SEQ ID NO:3 or SEQ ID NO:10. The variants may include deletions and additions of nucleotides, as well as nucleotide substitutions as described herein. A reference sequence for a nucleic acid sequence encoding an ORF29 polypeptide is that comprising sequence of SEQ ID NO:1 or SEQ ID NO:11.
An ORF29 nucleic acid variant has at least about any amount of % deleted nucleotides from 0.2% to 100% of a full-length mature ORF29 nucleic acid reference sequence, such as SEQ ID NO:1 or SEQ ID NO:11. An ORF29 variant has at least about 0.2% deleted, more preferably at least about 4% nucleotides deleted, more preferably at least about 10%, more preferably at least about 15%, more preferably at least about 20%, and more preferably at least about 25% nucleotides deleted.
“Stringent conditions” or “high stringency conditions”, as defined herein, may be identified by those that: (1) employ low ionic strength and high temperature for washing, for example 0.015 M sodium chloride/0.0015 M sodium citrate/0.1% sodium dodecyl sulfate at 50° C.; (2) employ during hybridization a denaturing agent, such as formamide, for example, 50% (v/v) formamide with 0.1% bovine serum albumin/0.1% Ficoll/0.1% polyvinylpyrrolidone/50 mM sodium phosphate buffer at pH 6.5 with 750 mM sodium chloride, 75 mM sodium citrate at 42° C.; or (3) employ 50% formamide, 5×SSC (0.75 M NaCl, 0.075 M sodium citrate), 50 mM sodium phosphate (pH 6.8), 0.1% sodium pyrophosphate, 5×Denhardt's solution, sonicated salmon sperm DNA (50 g/ml), 0.1% SDS, and 10% dextran sulfate at 42° C., with washes at 42° C. in 0.2×SW (sodium chloride/sodium citrate) and 50% formamide at 55° C., followed by a high-stringency wash consisting of 0.1×SSC containing EDTA at 55° C.
“Moderately stringent conditions” may be identified as described by Sambrook et al., Molecular Cloning: A Laboratory Manual, New York: Cold Spring Harbor Press, 1989, and include the use of washing solution and hybridization conditions (e.g., temperature, ionic strength and % SDS) less stringent that those described above. An example of moderately stringent conditions is overnight incubation at 37° C. in a solution comprising: 20% formamide, 5×SSC (150 mM NaCl, 15 mM trisodium citrate), 50 mM sodium phosphate (pH 7.6), 5×Denhardt's solution, 10% dextran sulfate, and 20 mg/ml denatured sheared salmon sperm DNA, followed by washing the filters in 1×SSC at about 37-50° C. The skilled artisan will recognize how to adjust the temperature, ionic strength, in etc. as necessary to accommodate factors such as probe length and the like.
Recombinant Herpesvirus
The disclosure provides recombinant herpes virus for use in immunogenic compositions and for attenuated live virus compositions. These compositions are useful, interalia, in a vaccine composition in order to provide immunity against herpesvirus infection while diminishing the establishment or maintenance of latency.
Herpesviridae is the name of a family of enveloped, double-stranded DNA viruses with relatively large complex genomes. They replicate in the nucleus of a wide range of vertebrate hosts, including eight varieties isolated in humans, several each in horses, cattle, mice, pigs, chickens, turtles, lizards, fish, and even in some invertebrates, such as oysters. All herpesvirus virions have four structural elements. The core contains of a single linear molecule of dsDNA in the form of a torus. Surrounding the core is an icosahedral capsid with a 100 nm diameter constructed of 162 capsomeres. Between the capsid and envelope is an amorphous, sometimes asymmetrical, feature named the tegument. It contains viral enzymes, some of which are needed to take control of the cell's chemical processes and subvert them to virion production, some of which defend against the host cell's immediate responses. The envelope is the outer layer of the virion and is composed of altered host membrane and a dozen unique viral glycoproteins.
Herpesvirus genomes range in length from 120 to 230 kbp with base composition from 31% to 75% G+C content and contain 60 to 120 genes. Because replication takes place inside the nucleus, herpesviruses can use both the host's transcription machinery and DNA repair enzymes to support a large genome with complex arrays of genes. Herpesvirus genes, like the genes of their eukaryotic hosts, are not arranged in operons and in most cases have individual promoters. Essential genes regulate transcription and are needed to construct the virion. Dispensable genes for the most part function to enhance the cellular environment for virus production, to defend the virus from the host immune system and to promote cell to cell spread. All herpesvirus genomes contain lengthy terminal repeats both direct and inverted. Herpes viruses include subfamilies Alphaherpesvirinae, Betaherpesvirinae, and Gammaherpesvirinae.
Members of the subfamily Alphaherpesvirinae are neurotropic (infect nervous system tissue), have a short reproductive cycle (˜18 hr.) with efficient cell destruction and variable host range. The human Alphaherpesvirinae with their commom name and the disease they cause are: Herpes simplex virus 1; facial, labial and ocular lesions; Herpes simplex virus 2; genital lesions; and Varicella Zoster (Human herpesvirus 3) chicken pox and shingles.
Members of Betaherpesvirinae are lymphotropic, have a long reproductive cycle, restricted host range and infected cells become enlarged (cytomegalo). Human Betaherpesvirinae include: Human cytomegalovirus (Human herpesvirus 5), human herpes virus 6, and human herpesvirus 7.
Gammaherpesvirinae herpesviruses are also lymphotropic and specific for either T or B lymphocytes. Members of this subfamily isolated in humans are: Epstein Barr virus (human herpes 4) and Karposi's sarcoma herpes virus (human herpes 8).
Pseudorabies virus, a non-human pathogen, is an alphaherpesvirus model, both in cell biology and pathogenesis. In addition, the PRV genome provides a close, almost one to one, correspondence of genes to HSV-1, a sexually transmitted infection, and VZV, a common childhood infection causing chicken pox.
It was discovered that modification of a gene encoding a protein expressed during latency or a transcript expressed during latency creates an altered herpesvirus virus that can replicate in vitro but has markedly diminished ability to establish a latent infection. Moreover, immunogenic compositions that contain such modified virus should be safer than regular unmodified live virus vaccines.
In embodiments, the gene or transcript expressed during latency is modified at its native location by altering or replacing the promoter linked with that gene or transcript in the virus. Some herpes viruses may encode latency transcripts which do not encode proteins, such as herpes simplex and pseudorabies virus.
In embodiments, the promoter is altered or replaced with a promoter that is a heterologous promoter, that is, a promoter different from the promoter normally linked to the gene or transcript in the virus. In some embodiments, the promoter is a non latency promoter from the same virus. A latency promoter is a promoter that provides for expression of a gene or transcript that is expressed during latency of a viral infection, in particular, a herpes virus infection. A non latency promoter is any other promoter that can provide for expression of the viral gene or transcript but does not provide for expression of a gene or transcript during latent infection.
The heterologous promoter can be a non latency promoter obtained from the same virus, a promoter (latency or nonlatency) from a different herpesvirus or a different virus, or a promoter from a non viral source. In embodiments, the non latency VZV promoter is a promoter from a VZV strain that provides for expression of gene that is not expressed during latency including, but not limited to, VZV ORF10, VZV ORF14, or VZV ORF67. In other embodiments, the promoter is obtained from a gene of a different herpesvirus than the type of herpesvirus being altered and may be a promoter linked to a gene not expressed during latency or expressed during latency. For example, when the virus being altered is VZV, the promoter may be obtained from another herpesvirus, such as a cytomegalovirus (CMV). In other embodiments, the promoter is obtained from a gene from a virus that is not a herpesvirus. Suitable promoters include, without limitation, CMV IE promoter, Herpes simplex virus ICP4 protein promoter, and SV40 early promoter. In embodiments, the promoter is the human CMV IE promoter.
In other embodiments, the native promoter linked with the latency gene or latency transcript in the virus can be altered to provide for expression of the gene or transcript during replication but reduced or no expression during latency. The sequences of promoters associated with latency genes or latency transcripts of herpesviruses are known to those of skill in the art and may be available in publicly available databases such as the eukaryotic promoter database. Alterations to the sequence of a promoter can be made and the altered virus can then be introduced into a host cell or animal to determine the effect of the alteration on viral replication and on expression during latency. Methods for detecting viral replication and expression of viral transcripts during latency are described herein and are known to those of skill in the art.
Some genes or transcripts that are expressed during latency of a herpes virus infection are known to those of skill in the art and include ORFs 4, 21, 29, 62, 63, and 66 of VZV. Genes or transcripts of other herpes virus expressed during latency are known to those of skill in the art and are readily identifiable. A reference describing the genes of herpesvirus is Fields Virology Knipe D M, Howley P M, et al. Philadelphia, Lipincott, Williams & Wilkins, 2007.
Genes that encode latent proteins of VZV, include ORF4, 21, 29, 62, 63, and 66. Exemplary protein and nucleic acid sequences for these genes and the flanking sequences are known to those of skill in the art and are readily identifiable. For example, sequences for ORF4 post transcriptional regulation of gene expression factor protein are described at CAA27887; P09269 (gI 59993); for ORF21 tegument protein are described at CAA27912; P09277(gI 60010); for ORF 29 major single stranded DNA binding protein are described at CAA27912; P09246 (gI 60018); for ORF62 transcription regulator are described at CAA27945; P09310(gI60051); for ORF63 host range factor are described at CAA27946; P09255(gI 60052); and for ORF66 serine threonine protein kinase are described at CAA27949; P09251(gI60055).
Sequences of the genomes of other herpes viruses and of genes or transcripts expressed during latency are known and can be identified in publicly available databases. The sequences of viral (non latency and latency) promoters and other heterologous promoters are known to those of skill in the art and can be obtained from the eukaryotic promoter database at epd.isb-sib.ch/epd.; or readily determined from nucleic acid sequence using available tools such as the local alignment promoter predictor tool (LAPP).
In embodiments, the latency gene is homologous to the varicella zoster virus and is found in simian varicella virus, feline herpes 1, equine herpes 1, equine herpes 4, pseudorabies virus, canine herpes 1, bovine herpes 1, Marek's disease virus (of chickens), Laryngotracheitis virus, Meleagrid herpes virus 1, or herpes simplex virus. Each such gene can be identified as having sequence similarity to the latency gene, such as the ORF29, of varicella zoster virus and are particularly contemplated for embodiments. Examples of the sequences homologous to ORF29 of varicella zoster virus are shown in Table 6. Examples of sequences of other genes or transcripts expressed during latent infection can be obtained from publicly available data bases in a similar manner.
In some embodiments, the latency gene is a nucleic acid encoding the major DNA binding protein. In an embodiment, the nucleic acid encoding the major DNA binding protein is modified at its native location in the viral genome by replacing the native promoter with a heterologous promoter. In embodiments, the heterologous promoter is another viral promoter and is nonlatency promoter. Sequences of the major DNA binding protein of herpes viruses are available as described in the table below.
In a desirable embodiment, the latency gene or latency transcript is selected by examination of homology with a conserved region of a varicella zoster virus ORF29 gene product. Advantageously, the region is at least 10%, 25%, 27%, 28%, 40%, 45%, 50%, 60%, 70%, 80%, 90% or at least 100% identical to the conserved region of the compared gene product. For example, corresponding major DNA binding proteins of HSV-1, HSV-2, and pseudorabies virus have about 50% overall amino acid sequence identity, and about the same sequence identity in the DNA binding domain. In addition, such genes or nucleic acids can be identified by hybridization to a nucleic acid sequence encoding an ORF29 protein such as that of SEQ ID NO:1 or SEQ ID NO:10 under stringent or moderately stringent conditions as described herein.
In embodiments, the DNA binding protein gene is homologous to the varicella zoster virus ORF29 gene or protein and is found in simian varicella virus, feline herpes 1, equine herpes 1, equine herpes 4, pseudorabies virus, canine herpes 1, bovine herpes 1, Marek's disease virus (of chickens), Laryngotracheitis virus, Meleagrid herpes virus 1, or herpes simplex virus. Examples of the sequences homologous to ORF29 of varicella zoster virus are shown in Table 6.
In some embodiments, the nucleic acid encoding the DNA binding protein linked to the heterologous promoter, located at the native location, has one or more modifications. In some embodiments, the modifications include one or more substitutions or deletions of nucleic acid sequence encoding the nuclear localization signal. For example, in VZV the nuclear localization signal is located at about amino acids 9 to 154. In some embodiments, substitutions or deletions are selected that diminish translocation of the protein to the nucleus. Some deletions of the DNA binding protein include deletions of amino acids 1 to 345; deletion of amino acids 1 to 155, deletion of amino acids 1 to 9; and deletion of amino acids 9 to 154. Substitutions at amino acid positions include positions A35P, F58I, A63V, V93A, S104P, L109H, F122L, G146A, C142R, C169Y, H182Y, C236S and combinations thereof.
In some embodiments, all or a portion of the nucleic acid encoding the gene or transcript expressed during latent infection in its native location is deleted and a nucleic acid encoding the latency protein or comprising the latency transcript is relocated or moved in the viral genome to another location. In embodiments, the latency gene or latency transcript located in the new location is under control of or linked to a heterologous promoter. In other embodiments, the latency gene or transcript located in the new location is linked to its native promoter that has been altered to provide for expression during viral replication but diminished expression during latency.
In embodiments, a nucleic acid encoding a gene or transcript expressed during a latent infection is located in the genome of the recombinant virus at a position different from that of the native location. The native location is the location of the gene or transcript found in the viral genome before any alterations or modification are made in the viral genome or by reference to a reference virus of the same type of virus. The native locations of genes or transcripts involved in latency can readily be determined by reference to the genomic sequences of herpes viruses that are publicly available.
For example, the native location of a gene expressed during latency of VZV can be determined based on a reference virus, such as VZV, strain Dumas. In embodiments, ORF29 in a reference VZV is located at nucleotides 50857 to 54471 of the viral genome of VZV (numbering corresponding to VZV strain Dumas; SEQ ID NO:10). The location of genes encoding major DNA binding proteins of other herpes viruses is readily determined by referring to the viral genome sequences available in publicly available databases, and or by alignment with a reference sequence as described in Table 6.
The genome of herpes viruses is large so that the gene encoding the DNA binding protein may be located at any other location different than the native location but preferably between other known coding sequences that do not interfere with gene expression of the adjacent sequences or do not interfere with sequences important for virus replication. In some embodiments, the gene encoding the DNA binding protein is located in a region of the genome that has restriction sites that provide for ease of insertion of the sequence. In some embodiments, the gene is inserted between ORF 65 and ORF 66 of VZV.
It is desirable for the nucleic acid encoding a gene or transcript expressed during latency, located at a non native location, to be under the control of or linked to a heterologous promoter. As discussed above, in some embodiments, the heterologous promoter is from the same virus, another virus, or a nonviral source. Suitable heterologous promoters include, without limitation, CMV IE promoter, Herpes simplex virus ICP4 protein promoter, and SV40 early promoter. In embodiments, the promoter is the human CMV IE promoter.
In addition, to heterologous promoters, other transcriptional or translational control elements may be incorporated in the nucleic acid. Other regulatory elements, such as termination signals may also optionally be included, such as the SV 40 polyadenylation signal.
It was also discovered that modification, particularly by deletion, of all or a portion of a gene encoding a protein or a transcript expressed during latency, creates an altered virus that can replicate in vitro but has markedly diminished ability to establish a latent infection. In embodiments, the virus is modified both by the presence of a gene encoding a protein or transcript expressed during latency at a non native location linked to a heterologous promoter, and by modification, particularly by deletion, of all or part of the same gene or flanking sequence of the same gene at its native location in the virus.
In some embodiments, substantially all (at least 1%, 10%, 20%, 30%, 40%, 50%, 75%, 85%, 90% or 100% and particularly at least 25%) of the protein coding sequence of all copies of the gene encoding a protein expressed during latency at the native location used in the virus or virus vaccine is deleted. Desirably, the amount of the gene or transcript to be deleted is enough to diminish the function of the protein encoded by the gene or transcript while still providing for expression of a protein (in the case of a gene) that may stimulate an immune response. In other embodiments, the flanking regions of the gene are modified to decrease expression levels during latency. In some embodiments, the latency promoter is deleted or modified.
With respect to VZV ORF29, embodiments include a deletion of at least a nucleic acid encoding at least 10 amino acids. In an embodiment, codons 22 to 957 of the coding sequence of the nucleic acid sequence, such as SEQ ID NO:1 or SEQ ID NO:11 are deleted. Other embodiments, include a deletion of nucleic acids encoding the nuclear localization signal. In VZV ORF29, the nuclear localization signal is at about amino acids 9 to 154.
The recombinant virus with a latency gene or latency transcript linked to an altered or heterologous promoter, the recombinant virus with a latency gene or latency transcript linked to a altered or heterologous promoter at a non native location, and/or the recombinant virus with a latency gene or latency transcript linked to an altered or heterologous promoter at a non native location and that has a deletion of all or part of the latency gene or latency transcript at the native location, has certain properties.
In some embodiments, the recombinant virus has reduced capability to produce proteins expressed late in infection, such as glycoprotein E. Glycoprotein E functions as a low affinity receptor for antibody aggregates and is expressed late during the infection. In embodiments, the recombinant virus has little or no effect on the expression of early and/or intermediate early gene expression of genes, such as IE62, IE63, IE4, viral thymidine kinase, and combinations thereof. In contrast, a gene expressed late in infection such as glycoprotein E is reduced at least 2 fold. The expression of proteins during infection can be determined by methods known to those of skill in the art including a western blot. In embodiments of the recombinant virus described herein, it is desirable to maintain expression and replication of the virus at least to some extent in order to stimulate an immune response when administered to a subject.
In embodiments, a recombinant virus as described herein, has an increased capacity to produce ORF29. In embodiments, a recombinant virus produces at least 1.5 fold to 5 fold more of ORF29 in cell culture.
In embodiments, the recombinant virus can infect dorsal root ganglia during an acute infection. The presence of VZV DNA in dorsal root ganglia of an animal infected with recombinant or wild type virus can be determined using methods known to those of skill in the art, including PCR as described herein.
In embodiments, the recombinant virus has markedly diminished ability to establish a latent infection but is able to replicate. In some cases, the recombinant virus can replicate to a level sufficient to establish an acute infection. Desirably, the recombinant virus can replicate to an amount that is within a log or half a log of the amount of replication of the unaltered virus or a reference virus. In other embodiments, the recombinant virus replicates to an amount comparable to the replication of the virus when unaltered or comparable to a reference virus. In embodiments, a recombinant virus has a decreased ability to cause a latent infection as measured by the presence of nucleic acid known to be associated with latency of herpes viruses, such as ORF63. In some embodiments, latency is impaired by at least 50% as compared to a wild type virus or vaccine strain virus, such as Oka.
Exemplary methods for making recombinant viruses are described herein and are known to those of skill in the art.
Recombinant Herpesvirus/Other Sequences
In an embodiment when one or more deletions are made, one or more protein antigen encoding genetic sequences are added in that location. In a related embodiment a selected viral gene is at least partly deleted and replaced with sequence(s) that encodes one or more epitopes of another viral protein. A viral protein that is synthesized to a high level and that is packaged into the virus, is particularly desired for this embodiment. For example, enough of a protein that forms a viral capsid (or envelope glycoprotein) may be added in place of the deleted portion in-frame with a promoter and initiation codon to allow expression. A skilled artisan may engineer or select a protein that becomes packaged in the regular capsid (or viral envelope). In a related embodiment, a promoter or other regulatory sequence is chosen to allow low enough expression as to avoid formation of unstable virus structures.
In yet another embodiment, a cytokine gene is inserted into the site of deletion of a viral genome or even elsewhere in the genome of the recombinant virus to improve the immunogenicity of the virus. Such replacement and the effects on immunogenicity are known and readily carried out. Advantageously one or more cytokine genes replace one or more deletions of a virus used to make a live virus vaccine.
Immunogenic Compositions and Methods of Use
Another aspect of the disclosure provides immunogenic compositions comprising the recombinant herpesviruses as described herein. In embodiments, the composition comprises a live attenuated recombinant virus having a diminished ability to establish latency, such as, a recombinant virus having a latency gene or latency transcript linked to an altered or heterologous promoter. In other embodiments, a recombinant virus has a latency gene or latency transcript linked to an altered or heterologous promoter at a non native location, and/or a recombinant virus has a latency gene or latency transcript linked to an altered or heterologous promoter at a non native location and has a deletion of all or part of the latency gene or latency transcript at the native location. In embodiments, the composition comprises an adjuvant or a live virus vaccine stabilizer. Other attenuated live herpes virus vaccines may also form part of the composition.
In some embodiments, the immunogenic compositions of the invention comprise an immunogenic effective amount of the recombinant live virus as described herein. An immunogenic effective amount is an amount of live virus that induces an immune response when administered to a host, for example an animal. In embodiments, the composition includes attenuated live recombinant virus that can replicate to an amount that is within one log or 0.5 log of the amount of viral replication of the wild type or a reference virus. The amount of virus in a live attenuated virus vaccine composition can readily be determined based on known vaccine compositions.
The actual amount of the immunogenic composition may vary depending on the animal to be immunized, the route of administration and adjuvants. Immunogenic dosages can be determined by those of skill in the art. The immune response can be humoral, cellular, or both. Generally, the immune response inhibits the herpesvirus viral levels in the immunized host compared to herpesvirus levels in non-immunized hosts. The immunogenic composition optionally includes a pharmaceutically acceptable excipient or carrier.
An embodiment provides an immunogenic composition according to the present disclosure also including immunomodulators such as cytokines or chemokines. In some embodiments, the recombinant virus encodes the immunomodulator or adjuvant. Immunomodulators refers to substances that potentiate an immune response including, but not limited to cytokines and chemokines Examples of cytokines include but are not limited to IL-2, IL-15, IL-12, or GM-CSF.
An embodiment provides an immunogenic composition further comprising an adjuvant. Such adjuvants may include ganglioside receptor-binding toxins (cholera toxin, LT enterotoxin, their B subunits and mutants); surface immunoglobulin binding complex CTA1-DD; TLR4 binding lipopolysaccharide; TLR2-binding muramyl dipeptide; mannose receptor-binding mannan; dectin-1-binding ss 1,3/1,6 glucans; TLR9-binding CpG-oligodeoxynucleotides; cytokines and chemokines; antigen-presenting cell targeting ISCOMATRIX and ISCOM. Adjuvants such as lipids (fatty acids, phospholipids, Freund's incomplete adjuvant in particular), Vaxfectin, polaxomer, anionic copolymers, CpG units, etc. may be added to the composition. In some embodiments, the adjuvant may be encoded or expressed by the recombinant virus used herein.
An important factor in vaccine formulation is the stabilizer, as vaccine potency may be adversely affected by concentration and storage conditions. Stabilizers often used for live vaccines of viruses such of measles, rubella and mumps generally include one or more saccharides, amino acids, sugar alcohols, gelatin and gelatin derivatives, to stabilize the virus and, in many cases keep the virus from denaturing during a concentration step. In an advantageous embodiment a recombinant virus described herein may by formulated into a vaccine using a stabilizer or other additive that includes native or recombinant serum albumin for this purpose. U.S. Pat. No. 6,210,683 provides representative conditions for this embodiment of the invention. U.S. Pat. Nos. 5,728,386, 6,051,238, 6,039,958 and 6,258,362 also contain details for stabilizers and methods for more gentle treatment of live virus vaccines. Each of these disclosures, and particularly those portions that describe stabilizer compositions and stabilizing methods are specifically incorporated by reference in their entireties.
Another aspect of the disclosure provides for a method for producing a live recombinant virus in amounts sufficient for a vaccine composition. A method for making an attenuated live virus having impaired ability to establish latency, comprises introducing the recombinant virus as described herein into a host cell to produce an amount of the recombinant virus suitable for a vaccine; and recovering the recombinant virus. Suitable host cells for production of the recombinant virus as described herein include human diploid cells, such as MRC5 cells, or Vero cells.
Generally, preparation of a stabilized live virus vaccine begins with centrifugation of a cell culture extract, to obtain a more purified virus fraction. Generally a vaccine stabilizer is then added to the virus fraction, and the mixture diluted. The final desired virus concentration typically will be about 10 to 100,000 PFU (plaque-forming units) and more typically 100 to 10,000 PFU or more of virus content per dose of the stabilized live vaccine. Aliquots of the thus prepared live vaccine may be tested for safety, effectiveness and homogeneity, to confirm eligibility as a vaccine.
After preparation with a stabilizer, the vaccine may be, for example, stored as a lyophilized vaccine, a lyophilized mixed vaccine, a liquid vaccine or a liquid mixed vaccine. Methods for forming these are known. Typically, a lyophilized vaccine is prepared by lyophilizing the vaccine in a vial or an ampule having a volume of about 3 to 30 ml, tightly sealing and storing at a temperature of 5 degrees Centigrade or less. The stored preparation vaccine typically is used according to instructions attached thereto, as a product insert or a notice on the vial or other container. In many cases, a lyophilized vaccine is re-constituted by addition of sterile distilled water before use, and the resultant solution is inoculated by hypodermic injection in an amount, for example, of 0.5 ml per dose. In another embodiment, the vaccine is provided orally.
In an embodiment a modified virus prepared as described herein might be less stable than the wild type from which the virus is derived and a more gentle stabilizer is used. For example, a modified virus that contains one or more added genes that encode other antigens may have a larger amount of genetic material than usual and may be more sensitive to denaturation. In one related embodiment the free divalent cation concentration of the stabilizer or final vaccine formulation is reduced, for example, by the addition of EDTA to counteract this instability. U.S. Pat. No. 6,039,958 for example provides instructions for lowering the concentration of calcium and magnesium in preparations of live virus vaccines. Other techniques described in the literature that alleviate instability and/or facilitate combinations of multiple viruses in the same formulation may of course be used and are contemplated.
The immunogenic compositions of the invention can be in the form of sterile injectable preparations, such as sterile injectable aqueous or oleagenous suspensions. For administration as injectable solutions or suspensions, the immunogenic compositions can be formulated according to techniques well-known in the art, using suitable dispersing or wetting and suspending agents, such as sterile oils, including synthetic mono- or diglycerides, and fatty acids, including oleic acid.
The present disclosure is also directed to uses and methods for immunizing an animal, including a human, other mammals and birds, with the immunogenic compositions of the disclosure to inhibit, control, or prevent herpes virus infection, to inhibit or reduce establishment or maintenance of latency, and/or to inhibit, control, or prevent reactivation of the virus and establishment of a latent infection. Methods for measuring viral replication and for determining the presence of a latent infection are known to those of skill in the art and are described herein. Animals include humans, cats, cows, monkeys, mice, chickens, turkeys, horses, and pigs.
In an embodiment, an animal is immunized with an immunogenic composition of the invention and then boosted one or more times with the immunogenic composition. In an embodiment, the animal is boosted about 2 to about 4 weeks after the initial administration of the immunogenic composition. If the animal is to be boosted more than once, there is about a 2 to 12 week interval between boosts. In an embodiment, the animal is boosted at about 12 weeks and about 36 weeks after the initial administration of the immunogenic composition. The dose used to boost the immune response can include one more cytokines, chemokines, or immunomodulators not present in the priming dose of the immunogenic composition.
The immunogenic compositions of the invention can be administered by intramuscular (i.m.), subcutaneous (s.c.), or intrapulmonary route in dosage unit formulations containing conventional non-toxic pharmaceutically acceptable carriers, adjuvants, or vehicles. Other suitable routes of administration include, but are not limited to intratracheal, transdermal, intraocular, intranasal, inhalation, intracavity, and intravenous (i.v.) administration. Transdermal delivery includes, but is not limited to intradermal, transdermal, and transmucosal administration. Intracavity administration includes, but is not limited to administration into oral or nasal cavities. The immunogenic compositions can be coated onto particles or nanofibers for delivery or formulated in liposomes.
The following examples are provided for illustrative purposes only, and are in no way intended to limit the scope of the present disclosure.
Materials and Methods
Cells and viruses. VZV was propagated in human melanoma (MeWo) cells. Recombinant VZV was constructed using cosmids derived from the Oka vaccine strain. The herpes simplex virus type 1 (HSV-1) ICP8 deletion mutant 301 and V827 Vero cells that express HSV-1 ICP8 and ICP27 proteins were gifts from David Knipe. (Gao, M. J. et al., Virol. 63:5258-5267; Da Costa et al., 2001, Virology 288:256-63).
Baculovirus was grown in Sf9 (Spodoptera fhigiperda) insect cells using TNM-FH media (PharMingen, San Diego, Calif.). Baculoviruses expressing ORF29 were constructed by cotransfecting Sf9 cells with BaculoGo Id-linearized baculovirus DNA (PharMingen) and either plasmid pAc-CMV29StuI or pAc-CMV 29EcoRV to produce viruses Baculo 29 and Baculo 29EcoRV, respectively. The recombinant baculoviruses were plaque purified on Sf9 cells, concentrated by centrifugation at 8,800×g for 2 hr, and resuspended in phosphate-buffered saline with 1% fetal bovine serum.
Plasmids and cosmids. Plasmid pCI-29 was constructed by performing PCR on VZV cosmid Mstll B with primers GCCTAGCTAGCCAAAATGGAAAATACTCAGAAGACTGTG (SEQ. ID NO:4) and GTCAGAATGCGGCCGCGGGAGGTTAAATCATTTCCATTG (SEQ ID NO:5) that amplify the ORF29 open reading frame, cutting the PCR product with NheI and NotI, and inserting the fragment into the corresponding sites of pCI (Promega, Madison, Wis.). Plasmid pAc-CMV contains the human cytomegalovirus (CMV) immediate early (1E) promoter inserted into the XhoI-EcoRI site of pAcSG2 (PharMingen). Plasmids pAc-CMV29StuI and pAc-CMV29EcoRV were constructed to produce baculoviruses expressing ORF29. Plasmid pCI-29 was cut with NheI, blunted with the Klenow fragment of E, coli DNA polymerase, cut with BamHI and the fragment containing ORF29 and the simian virus 40 (SV40) polyadenylation sequence was inserted into the Stul-Bglll site of pAc-CMV to create plasmid pAc-CMV29StuI. This plasmid is predicted to express ORF29 from both the baculo virus polyhedron promoter and the human immediate-early (1E) CMV promoter. Plasmid pCI-29 was cut with Bglll, blunted with Klenow, cut with BamHI, and the fragment containing ORF29 driven by the human CMV IE promoter and followed by the SV40 polyadenylation sequence was inserted into the EcoRV-Bglll site of pAc-CMV to create plasmid pAc-CMV29EcoRV. This plasmid is predicted to express ORF29 from only the human IE CMV promoter.
VZV cosmids NotI A, NotI B, Mstll A, and Mstll B encompass the VZV genome (
ORF29 was inserted into cosmid Mstll A to construct a virus expressing ORF29 at a normative site. VZV cosmid Mstll A was digested with Avrll, which cuts at nucleotide 112,853 (between VZV ORFs 65 and 66), and the ends of the cosmid were blunted with Klenow. The Bglll-BamHI fragment containing ORF29 from pCI-29 was blunted with Klenow and inserted into the Avrll site of cosmid Mstll A. The resulting cosmid Mstll A-29 contains the ORF29 gene driven by the human CMV promoter and followed by an SV40 polyadenylation signal (
Transfections, Southern blotting, immunoblotting, and virus growth studies. VZV cosmids were linearized with NotI or Bsu36I and transfected along with plasmid pCMV62 into human melanoma cells using the calcium phosphate procedure. Cells were passaged each week by treatment with trypsin, and cytopathic effects were noted.
Virion DNA was isolated from nucleocapsids, digested with restriction enzymes, fractionated on 1% agarose gels, transferred to nylon membranes, and probed with a radio-labeled fragment containing ORF29.
Lysates of baculovirus or VZV-infected cells were fractionated on SDS-PAGE gels, transferred to nylon membranes and incubated with rabbit antibody to VZV ORF29 protein, thymidine kinase (a gift from Christine Talarico), IE4, IE63, or IE62, or mouse monoclonal antibody to glycoprotein E (gE) (Chemicon, Temucla, Calif.). (Kinchington, 1988, 1992 cited supra; Moriuchi, H. et al., 1995, Virology 208:376-382; Ng et al., 1994, J. Virol. 68:1350-1359). The blots were incubated with horseradish peroxidase-conjugated anti-rabbit or anti-mouse antibodies and developed with enhanced chemiluminescence (Pierce Chemical Company, Rockford, Ill.).
Flasks of melanoma cells were infected with 200 PFU of VZV recombinants and on days 1 to 5 after infection, the cells were treated with trypsin and serial dilutions were titered on melanoma cells. VZV deleted for ORF29 was titered on melanoma cells that had been infected with Baculo 29 the day before. One week after infection, the cells were fixed and stained with crystal violet and plaques were counted.
Four- to 6-week-old female cotton rats were inoculated intramuscularly along the sides of the spine with virus-infected melanoma cells containing 1.75×105 PFU of recombinant VZV. For analysis of acute infection, animals were sacrificed 3 days after infection; for latent infection, animals were sacrificed 5 to 6 weeks after infection. Dorsal root ganglia from the left thoracic and lumbar spine were pooled, DNA was isolated, and PCR was performed using 500 ng of ganglia DNA from infected animals, or serial dilutions of cosmid NotI A in 500 ng of ganglia DNA from uninfected animals (to generate a standard curve), and primers corresponding to ORF21(Brunell et al., 1999, J. Med. Virol. 58:286-290). The PCR products were fractionated by electropheresis on agarose gels, transferred to nylon membranes, probed with a radio labeled ORF21 probe, and copy numbers were determined using a phosphorimager. The lower limit of reliable detection was 10 copies per 500 ng of ganglia DNA. PCR was also performed using 500 ng of ganglia DNA and ORF29 primers CATTTGACCCTGCCAACAAC (SEQ ID NO:8) and TAGTGCGTGCTCCAGAAACC (SEQ ID NO:9) (the latter sequence is located within the region absent from the ORF29 deletion mutant). Southern blotting was performed, and the membrane was hybridized to a radio labeled ORF29 probe.
RNA from dorsal root ganglia was isolated using Trizol (Invitrogen, Carlsbad, Calif.), treated with DNase I, heated to inactivate DNAse, and cDNA was prepared using oligo(dT) 12-18 and reverse transcriptase. PCR was performed using ORF63 primers (35), and Southern blotting of the amplified DNA was performed using a radiolabeled ORF63 probe.
Results
VZV ORF29 is required for virus replication. Cosmid Mstll B-29D was constructed which is deleted for codons 22 to 957 of ORF29. Transfection of melanoma cells with VZV cosmids NotI A, NotI B, Mstll A, and Mstll B yielded infectious virus (termed VZV ROka) 7 days after infection. However, transfection of cells with cosmids NotI A, NotI B, Mstll A, and Mstll B-29D failed to yield VZV.
To complement a VZV ORF29 deletion mutant, we produced baculovirus expressing ORF29. Infection of Sf9 insect cells with Baculo 29 followed by immunoblotting with antibody to ORF29 protein yielded a 130 kDa band (
Sodium butyrate is a histone deacetylase inhibitor that enhances expression of foreign genes in mammalian cells when expressed by baculovirus (Condreay J. P. et al., 1999, Proc Natl Acad Sci USA. 96:127-32). Therefore, we treated baculo virus-infected melanoma cells with 5 mM sodium butyrate 1 day before preparing lysates of infected cells. Immunoblotting of Baculo 29-infected cells treated with sodium butyrate showed a band of 130 kDa (
To construct VZV deleted for ORF29, we infected melanoma cells with Baculo 29 or Baculo 29EcoRV and one hour later transfected the cells with cosmids NotI A, NotI B, Mstll A, and Mstll B-29D. One week after transfection, the cells were treated with trypsin and additional baculovirus was added to the cells. CPE was detected in melanoma cells 10 days after cosmid transfection of Baculo 29-infected cells and 12 days after transfection of Baculo 29EcoRV-infected cells. Virus obtained from Baculo 29-infected cells was used for all subsequent experiments and was termed VZV ROka29D.
To verify that the deletion in ORF29 did not significantly affect expression of the genes adjacent to ORF29, we constructed cosmid Mstll A-29 which contains the ORF29 gene driven by the human CMV promoter. Transfection of cells with cosmids NotI A, NotI B, Mstll A-29, and Mstll B-29D yielded infectious virus 7 days after transfection. This virus was termed ROka29DR.
To verify that VZV ROka29D and ROka29DR had the expected genomic structures, Southern blotting was performed. Virion DNA was digested with EcoRI and Pad and hybridized with a radio labeled probe to ORF29. Virion DNA from cells infected with VZV ROka showed a band of 6.5 kb, while cells infected with ROka29D had a band of 3.7 due to the 2.8 kb deletion in ORF29 (
Reduced or excessive expression of ORF29 reduces late, but not immediate-early or putative early gene expression. Lysates were prepared from cells infected with ROka, ROka29DR, ROka29D and Baculo 29, or from ROka29D that had been passaged once in cells without Baculo 29, and immunoblotting was performed with several VZV antibodies (
Expression of VZV IE62, IE63, IE4 and viral thymidine kinase, a putative early gene, were similar in cells infected with ROka, ROka29DR, or ROka29D either in the presence or absence of added Baculo 29. In contrast, expression of VZV gE was reduced in cells infected with ROka29DR or ROka29D passaged once in cells in the absence of Baculo 29, compared with cells infected with ROka. These experiments indicate that appropriate levels of ORF29 protein are required for optimal expression of gE, but not for VZV IE or putative early proteins.
Growth of VZV ORF29 deletion and repaired virus in cell culture. To study the growth of the ORF29 mutants in cell culture, melanoma cells were infected with the viruses and titers were measured for five consecutive days. VZV deleted for ORF29 was unable to grow in melanoma cells (
VZV ORF29 cannot complement HSVICP8, and ICP8 cannot substitute for VZV ORF29. VZV ORF29 is the homolog of HSV-1ICP8 and both genes encode single stranded DNA binding proteins. To determine if ORF29 protein can complement HSV-1 ICP8, melanoma cells were infected with Baculo 29, and the following day the cells were infected with HSV d301, which is deleted for ICP8. After incubation for 3 days, no plaques were detected (Table 7). In contrast, wild-type HSV-1 produced plaques on these cells.
aVero, V827 cells (Vero cells expressing ICP8 and ICP27), or Me Wo cells were infected at an MOI of 0.03 and incubated at 37° C. for 3 days. VZV-infected cells were treated with trypsin and cell-associated virus was titered. The titer of VZV ROka29D was determined on Me Wo cells infected with Baculo 29 and the titer of ROka was determined on MeWo cells. HSV-infected cells were scraped, freeze-thawed, and media and cell lysates were pooled and titered. The titer of HSV d301 (HSV-1 deleted for ICP8) was determined on V827 cells.
To determine if HSV-1 ICP8 can complement VZV ORF29, Vero cells and Vero cells expressing ICP8 (V827) were infected with VZV deleted for ORF29 and parental virus. While parental virus grew to similar titers on both cell lines, VZV deleted for ORF29 could not grow on either cell line (Table 7). As expected, HSV-1 deleted for ICP8 (HSV-1 d301) grew on V827 cells, but not on Vero cells. The experiment was performed with two different titers of inocula, 0.3×104 PFU (data not shown) and 2.2×104 PFU (data not shown), with similar results.
VZV deleted for ORF29 can infect ganglia. To determine whether VZV ORF29 is required for acute infection of ganglia, cotton rats were infected with ROka29D or ROka and three days later the animals were sacrificed and dorsal root ganglia were obtained and assayed for VZV DNA. All animals infected with VZV ROka29D or ROka had viral DNA in their ganglia. The geometric mean number of VZV genomes in animals acutely infected with ROka29D was 339 copies, and for those infected with ROka the geometric mean number of VZV genomes was 115 copies. (data not shown)
VZV ORF29 is critical for latent infection. To determine if VZV ORF29 is required for establishment of latent infection, cotton rats were inoculated with ROka29D, ROka29DR, or ROka,- and 5 to 6 weeks later the animals were sacrificed, DNA was isolated from dorsal root ganglia, and PCR was performed with primers for ORF21 followed by Southern blotting. In the first experiment, 1 of 10 animals infected with VZV ROka29D, 3 of 11 animals infected with ROka 29DR, and 6 of 10 animals infected with ROka had viral DNA in ganglia (
To verify that animals were latently infected with the ORF29 mutants, RNA was isolated from ganglia on the opposite side of the spinal cord from which DNA had been isolated. cDNA was prepared from the RNA and PCR was performed using primers for ORF63, a gene known to be expressed in VZV latently infected rodent ganglia, followed by Southern blotting. ORF63 RNA was detected in 2 of 8 ganglia from animals infected with ROka29D, 1 of 6 animals with ROka29DR, and 2 of 3 animals infected with ROka (
The inoculum used to infect animals with ROka29D was prepared by passaging Baculo 29-infected cells that had subsequently been infected with VZV ROka29D, onto uninfected melanoma cells. Therefore, it was possible that recombination might have occurred between Baculo 29 and ROka29D. PCR and Southern blotting for ORF29 using DNA from rodent ganglia showed that 1 of 8 ganglia from animals infected with ROka29D was positive for ORF29, while 5 of 8 animals infected with ROka were positive for ORF29 (
Discussion
We have shown that ORF29, the major DNA binding protein, is required for replication in cell culture and that the protein cannot complement its HSV-1 homolog. Furthermore, we have found that cells infected with VZV mutants either deleted for ORF29, or that overexpress the protein, are impaired for late gene expression and for establishment of latency in rodents.
ORF29 protein shares a number of features with its HSV-1 ICP8 homolog. The two proteins show 65% homology and 49% identity at the amino acid level. Both proteins bind to single stranded DNA and localize to punctate regions within the nucleus (Cohrs, R. J. et al., 2002, J. Virol. 76:7228-38; Kinchington et al, cited supra). ICP8 and ORF29 are essential for replication of HSV and VZV, respectively. (Gao et al., cited supra) However, there are a number of differences between ORF29 protein and ICP8. While ICP8 is a phosphoprotein, ORF29 protein is not phosphorylated. Although HSV ICP8 interacts with UL37 protein, VZV ORF29 protein does not interact with ORF21 protein, its HSV UL37 homolog. VZV ORF29 cannot substitute for ICP8 in an in vitro replication assay using an HSV or VZV origin of replication (Webster, C. B. et al., 1995, Virology 206:655-660). We found that VZV ORF29 protein could not complement the growth of an HSV-1 ICP8 deletion mutant, and that ICP8 could not allow a VZV ORF29 deletion mutant to grow in cell culture. In contrast, HSV-1 ICP8 can complement the growth of an HSV-2 replication defective ICP8 mutant (Da Costa X. J. et al., 1997, Virology 232:1-12). Thus, despite the high degree of homology in their amino acid sequences and their ability to bind to single stranded DNA, VZV ORF29 protein and HSVICP8 are functionally distinct.
Cells infected with VZV deleted for ORF29 expressed similar levels of IE or putative early proteins as cells infected with parental virus, but the level of gE was reduced. Previous studies showed that ORF29 protein has no significant effect on the ability of IE62 to activate the ORF20 or ORF21 promoters and only a modest effect on the ORF28 promoter (Cohrs, 2002, cited supra). While ORF29 protein alone cannot upregulate expression from the gl promoter, ORF29 enhances the ability of ORF62 protein to transactivate the gl promoter (He, H. et al., 2001, Arch. Virol. Suppl. 17:57-60). Our studies show that in the context of the virus, ORF29 protein is important for expression of a late gene, gE. Metabolic labeling studies with an HSV-2 ICP8 replication defective mutant virus showed that proteins of all kinetic classes were expressed at levels similar to or slightly less than parental virus; gB and gD were expressed at lower levels than wild-type virus on immunoblot (Da Costa et al, 1997, cite supra). Surprisingly, we found that overexpression of ORF29 protein during virus infection also resulted in reduced expression of gE. Thus, the level of ORF29 protein must be properly regulated for optimal late gene, but not necessarily immediate-early or early gene expression.
ORF29 is one of six proteins that are expressed during latency in human sensory or cranial nerve ganglia. Previously we showed that ORFs 21 and 66 are not required for establishment of latency, while ORFs 4 and 63 have a critical role in latency (Sato, H., L. et al., 2002, J. Virol. 76:3575-3578; Xia, D. et al., 2003, J. Virol. 77: 1211-1218; Cohen, J. I., et al., 2004, J. Virol. 78:11833-11840; Cohen, J. I. et al., 2005, J. Virol. 79:6969-6975). Here we show that while ORF29 is not required for VZV to enter ganglia, ORF29 is important for efficient establishment of latency in rodents. Similar studies with HSV-2 showed that an ICP8 null mutant was markedly impaired for latency in mice (Jones et al., 2000, Virology 278:137-150).
Overexpression of ORF29 protein, as exemplified by the ROka29DR mutant, was also associated with a significant impairment of VZV latency in rodents. ORF29 protein is present in the nucleus of lytically infected cells, but in the cytoplasm of human neurons during latency (Grinfeld et al, cited supra; Lungu et al., cited supra). Interestingly, when an astrocytoma-derived cell line is infected with adenovirus which expresses ORF29, the protein is expressed in the cytoplasm; however, when these cells are treated with a proteosome inhibitor, the half-life of ORF29 protein is increased and the protein migrates to the nucleus (Stallings et al., 2006, cited supra). Thus, it is possible that overexpression of ORF29 protein in ROka29DR-infected neurons could result in both cytoplasmic and nuclear expression of the protein in the cells and thereby impair latency.
VZV mutants of ORF29 can serve as useful vaccine candidates. Inoculation of mice with the HSV-1 d301 ICP8 deletion mutant virus induces HSV-specific T cell proliferation and protects animals from lethal infection with wild-type virus (Morrison L. A. et al., 1994, J. Virol. 68:689-696; Nguyen, L. H. et al., 1992., J. Virol. 66:7067-7072). Similarly, inoculation of animals with an HSV-21PC8 null mutant reduces acute and latent infection with a challenge virus and protects the animals from death by a challenge virus (Da Costa et al., 2001, cited supra; Jones, C. A. et al., 2000, Virology 278:137-150.). A VZV ORF29 deletion mutant might be useful as a replication defective VZV vaccine, providing that a mutant is made that cannot recombine with the complementing cell line. ROka29DR, which overexpresses the ORF29 protein, and is also impaired for latency, also is a vaccine candidate. This virus is impaired for latency, but has the advantage that none of the viral proteins are deleted and all can be presented to the immune system, albeit at higher or lower levels than with wild-type virus.
It should be noted that, as used in this specification and the appended claims, the singular forms “a”, “an” and “the” include plural referents unless the content clearly dictates otherwise. It should also be noted that the term “or” is generally employed in its sense including “and/or” unless the content clearly dictates otherwise.
All publications and patent applications in this specification are indicative of the level of ordinary skill in the art to which this disclosure pertains. All publications and patent applications are herein incorporated by reference to the same extent as if each individual publication or patent application was specifically and individually indicated by reference.
The disclosure has been described with reference to various specific and preferred embodiments and techniques. However, it should be understood that many variations and modifications may be made while remaining within the spirit and scope of the disclosure.
Kennedy, P. GE., E. Grinfeld, and J. W. Gow. 1999. Latent varicella-zoster virus in human dorsal root ganglia. Virology 258:451-454.
Each of the above references as well as PCT/US05/021788 is incorporated by reference.
This application is being filed on Nov. 9, 2007, as a PCT International Patent application in the name of THE GOVERNMENT OF THE UNITED STATES OF AMERICA, AS REPRESENTED BY THE SECRETARY, DEPARTMENT OF HEALTH AND HUMAN SERVICES et al. U.S. national corporation, applicant for the designation of all countries except the US, and Jeffrey I. Cohen and Lesley M. Pesnicak both citizens of the U.S., applicants for the designation of the US only, and claims priority to U.S. Provisional patent application Ser. No. 60/857,766, filed Nov. 9, 2006.
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/US07/84331 | 11/9/2007 | WO | 00 | 12/21/2012 |
| Number | Date | Country | |
|---|---|---|---|
| 60857766 | Nov 2006 | US |
