Patent Application
20110117126
1. Technical Field
The present invention relates to the field of animal health and in particular to attenuated pestiviruses such as classical swine fever virus (CSFV), bovine viral diarrhea virus (BVDV) or border disease virus (BDV).
2. Background Information
Pestiviruses are causative agents of economically important diseases of animals in many countries worldwide. Presently known virus isolates have been grouped into four different species which together form one genus within the family Flaviviridae.
I/II Bovine viral diarrhea virus (BVDV) type 1 (BVDV-1) and type 2 (BVDV-2) cause bovine viral diarrhea (BVD) and mucosal disease (MD) in cattle (Baker, 1987; Moennig and Plagemann, 1992; Thiel et al., 1996). The division of BVDV into 2 species is based on significant differences at the level of genomic sequences (summarized in Heinz et al., 2000) which are also obvious from limited cross neutralizing antibody reactions (Ridpath et al. 1994).
III Classical swine fever virus (CSFV), formerly named hog cholera virus, is responsible for classical swine fever (CSF) or hog cholera (HC) (Moennig and Plagemann, 1992; Thiel et al., 1996).
IV Border disease virus (BDV) is typically found in sheep and causes border disease (BD). After intrauterine infection of lambs with BDV persistently infected lambs can be born that are weak and show different abnormalities among which the ‘hairy shaker’ syndrome is best known (Moennig and Plagemann, 1992; Thiel et al., 1996).
Pestiviruses are small enveloped viruses with a single stranded RNA genome of positive polarity lacking both 5′ cap and 3′ poly(A) sequences. The viral genome codes for a polyprotein of about 4000 amino acids giving rise to final cleavage products by co- and posttranslational processing involving cellular and viral proteases. The viral proteins are arranged in the polyprotein in the order NH2-NPpro-C-Ems-E1-E2-p7-NS2-NS3-NS4A-NS4B-NS5A-NS5B-COOH (Lindenbach and Rice, 2001). Protein C (=core- or capsidprotein) and the glycoproteins Ems, E1 and E2 represent structural components of the pestivirus virion as demonstrated for CSFV (Thiel et al., 1991). This also holds true for BVDV. E2 and to a lesser extent Ems were found to be targets for antibody neutralization (Donis et al., 1988; Paton et al., 1992; van Rijn et al., 1993; Weiland et al., 1990, 1992). Ems lacks a typical membrane anchor and is secreted in considerable amounts from the infected cells; this protein has been reported to exhibit RNase activity (Hulst et al., 1994; Schneider et al., 1993; Windisch et al., 1996). The function of this enzymatic activity for the viral life cycle is presently unknown. The enzymatic activity depends on the presence of two stretches of amino acids conserved between the pestivirus Ems and different known RNases of plant and fungal origin. Both of these conserved sequences contain a histidine residue (Schneider et al., 1993). Inactivation of the RNase activity residing within the Ems results in an attenuated apathogenic pestivirus which is capable to be used as a modified live vaccine (WO 99/64604).
The pestivirus glycoprotein Ems is expressed on the surface of virions and in infected cells as a disulfide-linked homodimer. The most C-terminal cysteine residue forms the intermolecular disulfide bond between two Ems monomers, resulting in the Ems homodimer (Schneider et al., 1993). Recently it has been reported for CSFV that a substitution of the most C-terminal cysteine against serine results in a viable CSFV, which, however, lacks the ability to form any Ems homodimers (van Gennip et al., 2005).
Npro represents the first protein encoded by the long open reading frame in the pestivirus RNA. NPpro represents a nonstructural protein that has protease activity and cleaves itself of the nascent polyprotein (Stark et al., 1993; Wiskerchen et al., 1991) presumably already during translation. NPpro is a cysteine protease (Rümenapf et al., 1998) that is not essential for virus replication (Tratschin et al., 1998). Recently, it was shown that NPpro somehow interferes with the cellular antiviral defense so that it can be hypothesized to modulate the immune system within an infected host (Rüggli et al., 2003). Mayer and coworkers presented indications for an attenuation of CSFV in consequence of a deletion of the Npro gene (Mayer et al., 2004).
Present BVDV vaccines for the prevention and treatment of BVDV infections still have drawbacks (Oirschot et al. 1999). Vaccines against the classical BVDV-1 provide only partial protection from BVDV-2 infection, and vaccinated dams may produce calves that are persistently infected with virulent BVDV-2 (Bolin et al., 1991, Ridpath et al., 1994). This problem is probably due to the great antigenic diversity between type 1 and type 2 strains which is most pronounced in the glycoprotein E2, the major antigen for virus neutralization (Tijssen et al., 1996). Most monoclonal antibodies against type 1 strains fail to bind to type 2 viruses (Ridpath et al., 1994).
Vaccines comprising attenuated or killed viruses or viral proteins expressed in heterologous expression systems have been generated for CSFV and BVDV and are presently used. Conventional BVDV life vaccines are typically generated by cell culture passages resulting in viruses with attenuated virulence in the target species. The structural basis of the attenuation of BVDV used as life vaccines is not known. Therefore it is not possible to assess the molecular stability of the attenuation process. These vaccines, although attenuated, are most often associated with safety problems regarding use in breeding animals. The vaccine viruses may cross the placenta of pregnant animals, e.g. cows and lead to clinical manifestations in the fetus and/or the induction of persistently infected calves. The international patent application WO2005/111201 provides a new generation of a modified live pestivirus vaccine, which comprises a multiple modified pestivirus, having at least one mutation in the coding sequence for glycoprotein Ems and at least another mutation in the coding sequence for Npro, wherein said mutation in the coding sequence for glycoprotein Ems leads to inactivation of RNase activity residing in Ems and/or said mutation in the coding sequence for NPpro leads to inactivation of said NPpro.
However, in view of the importance of an effective and safe as well as detectable prophylaxis and treatment of pestiviral infections, there is a strong need for attenuated pestiviruses, such as BVDV, with a high potential for induction of immunity as well as a defined basis of attenuation which can also be distinguished from pathogenic pestiviruses, such as BVDV, as well as compositions and vaccines comprising said attenuated pestiviruses, such as BVDV.
Therefore, the technical problem underlying the present invention is to provide new attenuated pestiviruses, referably an attenuated BVDV for use as live attenuated vaccines. Such improved attenuated pestivirus, preferably BVDV, should especially (i) not cross the placenta themselves and (ii) induce an immunity that prevents viral transmission across the placenta and thereby prevents pregnancy problems like abortion of the fetus or birth of persistently calves from infected host animals in the case of BVDV infection.
All subsequent Sequences are depicting the deleted regions with dashes (_d), which are also numbered, whereas the sequences in the sequence listing attached hereto are continuously numbered without the deleted regions or amino acid codons.
It has surprisingly been found that a modification in the coding region of the Ems glycoprotein of a pestivirus, which results in the lack of homodimer formation of the Ems glycoprotein, leads to an attenuated pestivirus. Such attenuated pestiviruses can be used as modified live vaccine for the prophylaxis and/or treatment of pestivirus infections. Hence, one aspect of the present patent application relates to a recombinant attenuated pestivirus, wherein said recombinant attenuated pestivirus does not produce a dimeric Ems glycoprotein. Preferably, that pestivirus is selected from the group consisting of CSFV, BVDV and BDV, including any subtype of any of these pestiviruses.
It is known from the international patent application WO2005/111201 that pestiviruses attenuated by a modification within the Ems glycoprotein as well as in the Npro protein show a higher safety level in terms of the prevention of fetal infections by the vaccine virus. Therefore, according to a further aspect, the present invention also relates to attenuated pestiviruses, wherein said attenuated pestiviruses do not produce a dimeric Ems glycoprotein and having at least a mutation in the Npro protein, wherein said mutation in the Npro protein leads to inactivation of said Npro protein. Preferably, that pestivirus is selected from the group consisting of CSFV, BVDV and BDV, including any subtype of any of these pestiviruses.
Any of the attenuated pestiviruses mentioned above are suitable vaccine candidates for developing a modified live vaccine for the prophylaxis and/or treatment of pestivirus infections. Thus, according to a further aspect, the present invention relates to an immunogenic composition comprising an attenuated pestivirus, wherein said attenuated pestivirus does not produce a dimeric Ems glycoprotein. Preferably, that pestivirus has at least a further mutation in the NPpro protein, wherein said mutation in the NPpro protein leads to inactivation of said NPpro protein. Preferred pestiviruses are selected from the group consisting of CSFV, BVDV and BDV, including any subtype of any of these pestiviruses.
According to a further aspect, the present invention also relates to a method for attenuating a pestivirus, comprising modifications in the Ems glycoprotein of said pestivirus in such that said attenuated pestivirus does not produce a dimeric Ems glycoprotein. Preferably, that pestivirus is selected from the group consisting of CSFV, BVDV and BDV, including any subtype of any of these pestiviruses.
Before the embodiments of the present invention it must be noted that as used herein and in the appended claims, the singular forms “a”, “an”, and “the” include plural reference unless the context clearly dictates otherwise. Thus, for example, reference to “a BVDV” includes a plurality of such BVDV, reference to the “cell” is a reference to one or more cells and equivalents thereof known to those skilled in the art, and so forth. Unless defined otherwise, all technical and scientific terms used herein have the same meanings as commonly understood by one of ordinary skill in the art to which this invention belongs. Although any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present invention, the preferred methods, devices, and materials are now described. All publications mentioned herein are incorporated herein by reference for the purpose of describing and disclosing the cell lines, vectors, and methodologies as reported in the publications which might be used in connection with the invention. Nothing herein is to be construed as an admission that the invention is not entitled to antedate such disclosure by virtue of prior invention.
The term “pestivirus” as used herein refers to all members of the genus Pestivirus, including BVDV, CSFV and BDV, within the family Flaviviridae.
The term “CSFV” as used herein refers to all viruses belonging to species of classical swine fever virus (CSFV) in the genus Pestivirus within the family Flaviviridae.
The term “BVDV” as used herein refers to all viruses belonging to species bovine viral diarrhea virus (BVDV) type 1 (BVDV-1) and BVDV type 2 (BVDV-2) in the genus Pestivirus within the family Flaviviridae (Heinz et al., 2000). The more classical BVDV type 1 strains and the more recently recognized BVDV type 2 strains display some limited but distinctive differences in nucleotide and amino acid sequences.
The term “Npro” as understood herein relates to the first protein encoded by the viral open reading frame and cleaves itself from the rest of the synthesized polyprotein (Stark, et al., J. Virol. 67:7088-7093 (1993); Wiskerchen, et al., Virol. 65:4508-4514 (1991)). Said term, depending on the context, may also relate to the remaining “Npro” amino acids after mutation of the encoding nucleotide sequence or to the coding nucleotide sequence for said protein itself. “Protease activity residing in Npro” relates to the polypeptide cleavage activity of said “Npro”.
“Ems” as used herein relates to the glycoprotein Ems which represents a structural component of the pestivirus virion (Thiel et al., 1991). Ems lacks a typical membrane anchor and is secreted in considerable amounts from the infected cells; this protein has been reported to exhibit RNase activity (Hulst et al., 1994; Schneider et al., 1993; Windisch et al., 1996). It should be noted that the term glycoprotein E0 is often used synonymously to glycoprotein Ems in publications. Said term, depending on the context, may also relate to the mutated “Ems” protein after mutation of the encoding nucleotide sequence or to the coding nucleotide sequence for said protein itself. “RNase activity residing in glycoprotein Ems” relates to the RNA cleavage activity of said glycoprotein, i.e. the ability of the glycoprotein Ems to hydrolyze RNA. The term “inactivation of the RNase activity residing in said glycoprotein” refers to the inability or reduced capability of a modified glycoprotein Ems to hydrolyze RNA as compared to the unmodified wild type of said glycoprotein Ems.
Attenuation: “An attenuated pestivirus or BVDV particle” as used herein means that there is a statistically significant difference between the virulence of attenuated pestivirus or BVDV particles of the present invention, wherein said attenuated viral particles being attenuated by a method described herein, and wild-type pestivirus or BVDV isolates from which said attenuated pestivirus or BVDV particles have been derived, for the predominant clinical parameters, in case of BVDV for diarrhea, pyrexia and lethality in animals infected with the same dose, preferably 6×106 TCID50. Thus, said attenuated BVDV particles do not cause diarrhea, pyrexia and lethality and thus may be used in a vaccine.
Inactivation of Ems as used herein means RNase activity not significantly above the level measured for noninfected control cells in an RNase assay as described in Meyers et al., 1999. “Not significantly above the level measured for noninfected control cells in an RNase assay as described in Meyers et al., 1999, means for example, that the RNase activity is less than 150% compared to the noninfected control cells.
Inactivation of Npro as used herein means the prevention or considerable reduction of the probable immunemodulating activity of Npro by mutation. In a preferred embodiment this mutation prevents or considerably reduces the interference of Npro with the induction of an interferon response by the infected cells as described by Rüggli et al., (2003). In this case, the inactivation of Npro would allow the cell to mount a normal interferon response.
The “dimeric Ems glycoproteins” means a homodimer of two monomers of Ems glycoproteins. It should be noted that the two monomers of the Ems glycoprotein which build the homodimer may comprise a certain level of sequence diversity within their amino acid sequence. In this context, “a certain level of sequence diversity” shall mean that the monomers forming the homodimer show at least 80%, preferably 90%, more preferably 95%, even more preferably 98% sequence homology in respect to the amino acid sequence of the Ems gene region.
The term “non-dimeric Ems glycoprotein” shall mean, but is not limited to an Ems glycoprotein that is not capable to form a detectable amount of homodimer with a second Ems glycoprotein. Preferably, the term “non-dimeric Ems glycoprotein” shall mean, but is not limited to an Ems glycoprotein that is not capable to any homodimer with a second Ems glycoprotein
“Processing signal” as used herein relates to a substance that ensures the generation of a functional N-terminal of the C protein of the pestivirus, preferably of BVDV, in particular a substance selected from the group of ubiquitin, LC3, SUMO-1, NEDD8, GATE-16 and GABA(A)RAP. Also proteases selected from the group of Intein, picornavirus 3C, caridovirus 2A, and p15 of rabbit hemorrhagic disease virus are understood as “processing signals” as used herein. Similarly, 2A proteins of aphtoviruses or related sequences that promote the expression of two separate proteins by translational discontinuity are included in the term “Processing signal”. Any other similar processing signal known to the skilled person that ensures the generation of a functional N-terminal of the C protein shall also be comprised in the term “processing signal”.
“Protein C” or “C protein” or “C-protein” as used herein relates to a structural component of the pestivirus virion (Thiel et al., 1991). “Protein C” is the capsid or core protein of pestiviruses. Said term, depending on the context, may also relate to the “Protein C” with one or several amino acids exchanges resulting from mutation of the encoding nucleotide sequence.
A “fragment” according to the invention is any subunit of a polynucleotide molecule according to the invention, i.e. any subset. For DNA, said fragment is characterized in that it is shorter than the DNA covering the full length viral genome.
A “functional variant” of the nucleotide molecule according to the invention is a nucleotide molecule which possesses a biological activity (either functional or structural) that is substantially similar to the nucleotide molecule according to the invention. The term “functional variant” also includes “a fragment”, “a functional variant”, “variant based on the degenerative nucleic acid code” or “chemical derivative”. Such a “functional variant” e.g. may carry one or several nucleotide exchanges, deletions or insertions. Said functional variant at least partially retains its biological activity, e.g. function as an infectious clone or a vaccine strain, or even exhibits improved biological activity. “Possess a biological activity that is substantially similar” means with respect to the pestiviruses provided herewith, for example, that said pestivirus is attenuated in a manner described herein and result in a non-pathogenic virus suitable for the production of live attenuated virus, which loss ability to pass the placenta but mediates an immune response after vaccination.
A “variant based on the degenerative nature of the genetic code” is a variant resulting from the fact that a certain amino acid may be encoded by several different nucleotide triplets. Said variant at least partially retains its biological activity, or even exhibits improved biological activity.
A molecule is “substantially similar” to another molecule if both molecules have substantially similar nucleotide sequences or biological activity. Thus, provided that two molecules possess a similar activity, they are considered variants as that term is used herein if the nucleotide sequence is not identical, and two molecules which have a similar nucleotide sequence are considered variants as that term is used herein even if their biological activity is not identical.
A mutation as used herein relates to modifications in the nucleic acid molecules encoding the proteins/amino acids according to the invention. Said mutations relate to, but are not limited to, substitutions (replacement of one or several nucleotides/base pairs), deletions (removal of one or several nucleotides/base pairs), and/or insertions (addition of one or several nucleotides/base pairs). As used herein, mutation may be a single mutation or several mutations, therefore, often the term “mutation(s)” is used and relates to both a single mutation and several mutations. Said mutations include, but are not limited to point mutations (single nucleotide mutations) or larger mutations wherein e.g. parts of the encoding nucleic acid molecules are deleted, substituted and/or additional coding nucleic acid is inserted. Said mutations may result in a modified expressed polypeptide due to the change in the coding sequence. Such modified polypeptides are desired, as set out in the disclosure of the invention as set out below.
The term “vaccine” as used herein refers to a pharmaceutical composition comprising at least one immunologically active component that induces an immunological response in an animal and possibly but not necessarily one or more additional components that enhance the immunological activity of said active component. A vaccine may additionally comprise further components typical to pharmaceutical compostions. The immunologically active component of a vaccine may comprise complete virus particles in either their original form or as attenuated particles in a so called modified live vaccine (MLV) or particles inactivated by appropriate methods in a so called killed vaccine (KV). In another form the immunologically active component of a vaccine may comprise appropriate elements of said organisms (subunit vaccines) whereby these elements are generated either by destroying the whole particle or the growth cultures containing such particles and optionally subsequent purification steps yielding the desired structure(s), or by synthetic processes including an appropriate manipulation by use of a suitable system based on, for example, bacteria, insects, mammalian other species plus optionally subsequent isolation and purification procedures, or by induction of said synthetic processes in the animal needing a vaccine by direct incorporation of genetic material using suitable pharmaceutical compositions (polynucleotide vaccination). A vaccine may comprise one or simultaneously more than one of the elements described above. The term “vaccine” as understood herein is a vaccine for veterinary use comprising antigenic substances and is administered for the purpose of inducing a specific and active immunity against a disease provoked by a pestivirus infection, preferably by a BVDV infection. The attenuated pestivirus, in particular the attenuated BVDV as described herein, confer active immunity that may be transferred passively via maternal antibodies against the immunogens it contains and sometimes also against antigenically related organisms. A vaccine of the invention refers to a vaccine as defined above, wherein one immunologically active component is a BVDV or of pestiviral origin or derived from a nucleotide sequence that is more than 70% homologous to any known pestivirus sequence (sense or antisense).
The term “live vaccine” refers to a vaccine comprising a living, in particular, a living viral active component.
Additional components to enhance the immune response are constituents commonly referred to as “adjuvants”, like e.g. aluminiumhydroxide, mineral or other oils or ancillary molecules added to the vaccine or generated by the body after the respective induction by such additional components, like but not restricted to interferons, interleukins or growth factors.
A “pharmaceutical composition” essentially consists of one or more ingredients capable of modifying physiological e.g. immunological functions of the organism it is administered to, or of organisms living in or on the organism. The term includes, but is not restricted to, antibiotics or antiparasitics, as well as other constituents commonly used to achieve certain other objectives like, but not limited to, processing traits, sterility, stability, feasibility to administer the composition via enteral or parenteral routes such as oral, intranasal, intravenous, intramuscular, subcutaneous, intradermal or other suitable route, tolerance after administration, controlled release properties. One non-limiting example of such a pharmaceutical composition, solely given for demonstration purposes, could be prepared as follows: Cell culture supernatant of an infected cell culture is mixed with a stabilizer (e.g. spermidine and/or BSA (bovine serum albumin)) and the mixture is subsequently lyophilized dehydrated by other methods. Prior to vaccination, said mixture is then rehydrated in aqueous (e.g. saline, PBS (phosphate buffered saline)) or non-aqueous solutions (e.g. oil emulsion, aluminum-based adjuvant).
The solution to the above technical problem is achieved by the description and the embodiments characterized in the claims.
As mentioned above, at least for the CSFV it has been shown that the last C-terminal cystein of the Ems glycoprotein is involved in the homodimer formation of two monomers of Ems glycoprotein. A substitution of this last C-terminal cystein against serine (cystein/serine substitution) results in a pestivirus that is not longer capable to form homodimers of the Ems glycoprotein (van Gennip et al., 2005). Now it has been surprisingly found that a pestivirus lacking the ability to form homodimers of the Ems glycoprotein is also apathogenic for its host. Consequently, pestiviruses lacking the ability to form homodimers of the Ems glycoprotein are well attenuated and suitable candidates for a modified live vaccine for the prophylaxis and/or treatment of animals against a pestivirus infection (see example section for more details). Hence, one aspect of the present patent application relates to an attenuated pestivirus, wherein said attenuated pestivirus does not produce a dimeric Ems glycoprotein. Preferably, that pestivirus is selected from the group consisting of CSFV, BVDV and BDV, including any subtype of any of these pestiviruses.
According to the further aspect, the pestivirus lacking the ability to form homodimers of the Ems glycoprotein can be established by recombinant bioengineering techniques. For instances, a deletion or substitution at least of the cystein at amino acid position 438 of the CSFV pestivirus (according to SEQ ID NO:1 as shown in an exemplarily manner) results in such a recombinant attenuated CSFV pestivirus lacking the ability to form Ems homodimers, because such Ems glycoprotein is not longer able to form intermolecular disulfide bonds between to Ems monomers. With regard to the BVDV pestivirus (type 1 and/or 2), a deletion or substitution of at least the cystein at amino acid position 441 of the BVDV pestivirus (according to SEQ ID NO:4 (BVDV-1) or SEQ ID NO:7 (BVDV type 2) as shown in an exemplarily manner) results in such a recombinant attenuated BVDV pestivirus lacking the ability to form Ems homodimers. In respect to BDV, a deletion or substitution of at least the cystein at amino acid position 439 of the BDV pestivirus (according to SEQ ID NO:10 as shown in an exemplarily manner) results in such a recombinant attenuated BDV pestivirus lacking the ability to form Ems homodimers. Preferred substitutions are cystein/serine substitutions. However, any other substitutions of the last C-terminal cystein within the Ems glycoprotein (e.g. Cys438 of CSFV, Cys441 of BVDV type 1 or 2, Cys439 of BDV) are also within the meaning of the present invention.
The key element of the present invention is to provide a pestivirus that is not longer able to form homodimers of the Ems glycoprotein. Homodimer formation can be prevented by a deletion or substitution of at least the last C-terminal cystein within the Ems glycoprotein as described above, because any such pestiviruses are not longer capable to form intermolecular disulfide bonds between two Ems glycoprotein monomers. Beside the deletion or substitution of the last C-terminal cystein of the Ems glycoprotein, homodimerisation between two monomers of the Ems glycoprotein can also be inhibited by a modification of the amino acid environment of the last C-terminal cystein of the Ems glycoprotein, if this modification leads, for instance, to a change of the charge and/or conformation of the direct environment of the last C-terminal cystein in a manner that the intermolecular disulfide bonds can not be formed any more. For instance, an insertion, deletion or substitution of prolin close to that last C-terminal cystein may change the conformation of the Ems glycoprotein in such that the last C-terminal cystein of the Ems glycoprotein is not longer exposed in a manner that it can form intermolecular disulfide bonds with a second Ems glycoprotein. Moreover, modifications of the cystein environment with result in a strong positive or negative polarity of such environment (e.g by insertion of or substitution by positive charged amino acids such as argnin, lysine and/or histidine; by insertion of or substitution by negative charged amino acids such as aspratate or glutamate) could also inhibit the formation of intermolecular disulfide bonds between two Ems glycoproteins. Thus, the present invention does not only relate to recombinant attenuated pestiviruses, wherein the last C-terminal cystein of such Ems glycoprotein is deleted or substituted by a non-cystein residue, it also relates to any modified attenuated pestivirus, wherein the formation of homodimers of the Ems glycoprotein of said pestivirus is (in general) inhibited by a deletion, insertion or modification. Preferably, such modification is introduced closely to the last C-terminal cystein of the Ems glycoprotein, preferably such modification affects the amino acids between the amino acid positions 410 to 470, preferably 420 to 460. A skilled person in the art is able to modify the coding sequence of a pestivirus in such that the pestivirus may not longer form any Ems glycoprotein dimers by routine work. The publication of van Gennip et al., (2005) teaches a person skilled in the art how he can estimate dimerization of the Ems glycoprotein.
Thus, one aspect of the present invention relates to a recombinant attenuated pestivirus, wherein said attenuated pestivirus does not produce a dimeric Ems glycoprotein.
According to further aspect, the carboxy-terminus of the Ems glycoprotein of said attenuated pestivirus is modified by a deletion, insertion or substitution.
According to further aspect, at least the last C-terminal Cystein-residue of the Ems glyoprotein of said attenuated pestivirus is deleted or substituted by non-Cys amino acid residue.
According to further aspect, at least the most last Cystein-residue in the Ems glycoprotein of said attenuated pestivirus is deleted.
According to further aspect, said attenuated pestivirus selected from the group consisting of CSFV, BVDV type 1 and/or 2, and BDV.
According to further aspect, said attenuated pestivirus is a CSF pestivirus.
According to a further aspect, at least the Cystein-residue at amino acid position 438 according to SEQ ID NO: 1 of the Ems glyoprotein of said attenuated CSFV is deleted or substituted by a non Cystein-residue.
According to further aspect, said attenunated pestivirus is a BVD type 1 and/or 2 pestivirus.
According to a further aspect, at least the Cystein-residue at amino acid position 441 according to SEQ ID NO: 4 (BVDV type 1) or SEQ ID NO:7 (BVDV type 2) of the Ems glyoprotein of said attenuated BVDV is deleted or substituted by a non Cystein-residue.
According to further aspect, said attenunated pestivirus is a BDV pestivirus.
According to a further aspect, at least the Cystein-residue at amino acid position 439 according to SEQ ID NO: 10 of the Ems glyoprotein of said attenuated BDV is deleted or substituted by a non Cystein-residue.
In WO 99/64604 it is described that the inactivation of the RNAse activity residing within the Ems also results in an attenuated apathogenic pestivirus, which is capable to be used as a modified live vaccine. According to a further aspect of the present invention, both modifications can be combined which would result in an attenuated pestivirus, wherein the RNAse activity residing within the Ems is inactivated by a deletion, insertion or substitution and which is not capable to form any Ems dimers. Suitable modifications of the glycoprotein Ems which result in RNase negative Ems glycoproteins are for example, the single substitutions/deletions: S298G, H300K, H300L, H300R, H300del, W303G, P304del, E305A, C308G, R343G, E345del, W346G, K348A, H349K, H349L, H349del, H349Q, H349SV (mutation H349S and insertion of V), K348R, W351P, W351G, W351L, W351K, W351H; the double substitutions/deletions: H300L/H349L, K348del/H349del, H349del/G350del, E345del/H349del, W303G/E305A, H300K/H349K, H300K/H349L and the triple deletions: L299del/H300del/G300del, K348del/H349del/G350del. Numbering is according to the published amino acid sequence of BVDV CP7 for all the mutants listed above (the given numbers minus 3 would correspond to the equivalent residues of the CSFV Alfort/Tübingen amino acid sequence). All the above-listed mutants were at least tested as respective CSFV or BVDV mutants. Suitable mutants of the pestiviral glycoprotein Ems are provided, for example, by WO 99/64604, which is incorporated herein at its whole.
The putative active site of the RNase is represented by the conserved Ems sequences SLHGIWPEKICTG and/or LQRHEWNKHGWCNWFHIEPW (sequence of the BVDV-2 New York '93 protein given here in an exemplary manner; minor changes can possibly be found in other pestivirus sequences but the identity of the motif will always be obvious for an expert in the field. As an example, the corresponding amino acid sequences of BVDV-1 CP7 would be SLHGIWPEKICTG and/or LQRHEWNKHGWCNWYNIEPW and that of CSFV Alfort/Tübingen SLHGIWPEKICKG and/or LQRHEWNKHGWCNWYNIDPW). Thus, preferably, the invention further relates to a BVDV according to the invention, wherein said RNase negative mutation(s) in the coding sequence for glycoprotein Ems are located in the nucleotide sequence coding for the conserved Ems sequence SLHGIWPEKICTG and/or LQRHEWNKHGWCNWFHIEPW. These sequences are representing the putative active site of the RNase. The sequences SLHGIWPEKIC and RHEWNKHGWCNW of the putative Ems active site are even more conserved across pestiviruses.
It is known from the international patent application WO2005/111201 that pestiviruses attenuated by a modification within the Ems glycoprotein as well as in the Npro protein show a higher safety level in terms of the prevention of fetal infections. Therefore, according to a further aspect, the present invention also relates to attenuated pestiviruses, wherein said attenuated pestiviruses do not produce a dimeric ERNS glycoprotein and having at least a mutation in the Npro protein, wherein said mutation in the Npro protein leads to inactivation of said Npro protein. Preferably, that pestivirus is selected from the group consisting of CSFV, BVDV and BDV, including any subtype of any of these pestiviruses.
Inactivation of the Npro is achieved in pestiviruses, in particular BVDV of the specified formula described more in detail below, wherein between 0 and all amino acids of Npro are present; ubiquitin or LC3 or another sequence serving as processing signal (e.g. SUMO-1, NEDD8, GATE-16, GABA(A)RAP, or proteases like e.g. Intein, picornavirus 3C, caridovirus 2A, or p15 of rabbit hemorrhagic disease virus, or sequences like aphtovirus 2A that lead to discontinuous translation) is present or absent. In case a processing signal is present, the coding sequence of the processing signal is inserted at or close to the C-terminal end of the (remaining part of the) Npro-protein. Only in the case that a processing signal is present, any number of amino acids coding for Npro (=Npro amino acids) may be present. In case no processing signal sequence is inserted, a maximum of 12 amino acids, preferably aminoterminal amino acids, of Npro may be present, the remaining amino acids have to be deleted. Furthermore, other than the Ems mutations as disclosed above (at least one of which has to be present in the pestivirus, in particular in BVDV according to the invention), the remaining sequences of the pestivirus, in particular BVDV may remain unchanged, i.e. are not mutated, or may also have mutations close to the N-terminal end of the C-protein. A number of more specific embodiments as disclosed below exemplify this.
Thus, the invention relates to a pestivirus, in particular to BVDV according to the invention, wherein said mutation(s) in the coding sequence for Npro lead to an encoded polyprotein as characterized by the following formula:
[Npro]x-[PS]y-[C-term]
Also more preferably, the invention relates to a pestivirus, in particular to BVDV according to the invention, wherein said mutation(s) in the coding sequence for Npro lead to an encoded polyprotein as characterized by the following formula:
[Npro]1-[PS]0-[C-term]
A specific example thereof is disclosed below, wherein the N-terminal methionine is followed by the C-protein and any other protein present in the polyprotein including the carboxyterminal NS5B. Hence, most preferably, the invention relates to a pestivirus, in particular BVDV according to the invention, wherein said mutation(s) in the coding sequence for Npro lead to an encoded polyprotein as characterized by the following formula:
M[C-term].
Also more preferably, the invention relates to a pestivirus, in particular to BVDV according to the invention, wherein said mutation(s) in the coding sequence for Npro lead to an encoded polyprotein as characterized by the following formula:
[Npro]3-[PS]0-[C-term]
A specific example of BVDV is disclosed below, wherein the N-terminal methionine is followed by the Npro sequence EL and the C-protein and any other protein present in the polyprotein including the carboxyterminal NS5B. Hence, most preferably, the invention relates to a BVDV according to the invention, wherein said mutation(s) in the coding sequence for Npro lead to an encoded polyprotein as characterized by the following formula:
MEL-[C-term]
Also more preferably, the invention relates to a pestivirus, in particular to BVDV according to the invention, wherein said mutation(s) in the coding sequence for Npro lead to an encoded polyprotein as characterized by the following formula:
[Npro]4-[PS]0-[C-term]
A specific example of BVDV is disclosed below, wherein the N-terminal methionine is followed by the Npro sequence ELF and the C-protein and any other protein present in the polyprotein including the carboxyterminal NS5B. Hence, most preferably, the invention relates to a BVDV according to the invention, wherein said mutation(s) in the coding sequence for Npro lead to an encoded polyprotein as characterized by the following formula:
MELF-[C-term].
Also more preferably, the invention relates to pestivirus, in particular to BVDV according to the invention, wherein said mutation(s) in the coding sequence for Npro lead to an encoded polyprotein as characterized by the following formula:
[Npro]6-[PS]0-[C-term]
and wherein the definitions are as defined above.
A specific example of BVDV is disclosed below, wherein the N-terminal methionine is followed by the Npro sequence ELFSN and the C-protein and any other protein present in the polyprotein including the carboxyterminal NS5B. Hence, most preferably, the invention relates to a BVDV according to the invention, wherein said mutation(s) in the coding sequence for Npro lead to an encoded polyprotein as characterized by the following formula:
MELFSN-[C-term].
Also more preferably, the invention relates to a pestivirus, in particular to BVDV according to the invention, wherein said mutation(s) in the coding sequence for Npro lead to an encoded polyprotein as characterized by the following formula:
[Npro]4-[PS]0-[C-term*]
A specific example of BVDV is disclosed below, wherein the N-terminal methionine is followed by the Npro sequence ELF and in the C-protein sequence, the amino acid at position 2 is changed from D to N. Therefore, the aminoterminal C-protein sequence is SNEGSK . . . instead of SDEGSK. Hence, most preferably, the invention relates to a BVDV according to the invention, wherein said mutation(s) in the coding sequence for Npro lead to an encoded polyprotein as characterized by the following formula:
MELF-[C-term*],
Also more preferably, the invention relates to a pestivirus, in particular BVDV according to the invention, wherein said mutation(s) in the coding sequence for Npro lead to an encoded polyprotein as characterized by the following formula:
[Npro]x-[PS]1-[C-term],
A specific example of BVDV is disclosed below, wherein the N-terminal methionine is followed by any 21 or 28 Npro amino acids, ubiquitin or LC3 and the C-protein. Hence most preferably, the invention relates to a BVDV according to the invention, wherein said mutation(s) in the coding sequence for Npro lead to an encoded polyprotein as characterized by the following formula:
[Npro]22-[PS]1-[C-term],wherein preferably,the PS is ubiquitin or LC3 or
[Npro]29-[PS]1-[C-term],wherein preferably,the PS is ubiquitin or LC3.
Ubiquitin is a well known highly conserved cellular protein of 76 amino acids. Among other functions, ubiquitin is a key player in protein catabolism since conjugation with ubiquitin can mark a protein for degradation via the proteasome. Ubiquitin conjugated with or fused to other proteins via the carboxyterminal glycin can be cleaved off by cellular ubiquitin-specific proteases. Thus, fusion of a protein to the carboxyterminus of ubiquitin will usually result in defined proteolytic cleavage of the fusion protein into its components when expressed within a cell.
LC3 (light chain 3 of microtubule associated proteins) represents a cellular protein of 125 amino acids that serves a variety of functions (length given for bovine LC3). Recently, a fundamental role of the protein in autophagy has been defined. During this process, LC3 is activated by carboxyterminal cleavage. Thereby, a new carboxyterminus is generated that consists of glycine. LC3 is then conjugated via the carboxyterminal glycine to phosphatidylethanolamine present in the membranes of autophagic vesicles. Because of this process, a protein fused to the carboxyterminus of LC3 will be cleaved off by a cellular protease at a defined position.
Also more preferably, the invention relates to a pestivirus, preferably to BVDV according to the invention, wherein said mutation(s) in the coding sequence for Npro lead to an encoded polyprotein as characterized by the following formula selected from the group of:
According to a further aspect, the invention relates to a pestivirus, preferably to BVDV according to the invention, wherein said mutation(s) in the coding sequence for Npro lead to an encoded polyprotein as characterized by the following formula selected from the group of:
According to a further aspect, the invention relates to a pestivirus, preferably to BVDV according to the invention, wherein said mutation(s) in the coding sequence for Npro lead to an encoded polyprotein as characterized by the following formula selected from the group of:
According to a further aspect, the invention relates to a pestivirus, preferably to BVDV according to the invention, wherein said mutation(s) in the coding sequence for Npro lead to an encoded polyprotein as characterized by the following formula selected from the group of:
Another important aspect of the invention described herein are immunogenic compositions comprising a pestivirus, in particular a BVDV according to the invention, and a solution. The skilled person knows additional components which may be comprised in said composition (see also Remington's Pharmaceutical Sciences. (1990). 18th ed. Mack Publ., Easton). The expert may use known injectable, physiologically acceptable sterile solutions. For preparing a ready-to-use solution for parenteral injection or infusion, aqueous isotonic solutions, such as e.g. saline or corresponding plasma protein solutions are readily available. The pharmaceutical compositions may be present as lyophylisates or dry preparations, which can be reconstituted with a known injectable solution directly before use under sterile conditions, e.g. as a kit of parts.
The final preparation of the immunogenic compositions of the present invention are prepared for e.g. injection by mixing said pestivirus, preferably BVDV according to the invention with a sterile physiologically acceptable solution, that may be supplemented with known carrier substances or/and additives (e.g. serum albumin, dextrose, sodium bisulfite, EDTA). Said solution may be based on a physiologically acceptable solvent, e.g. an aqueous solution between pH 7 and 8. The pH may be stabilised by a pharmaceutically acceptable buffer. The solution may also contain further stabilising agents like a detergent like Tween 20, serum albumin such as BSA (bovine serum albumin), ascorbic acid, and/or spermidine. The composition may also comprise adjuvants, e.g. aluminiumhydroxide, mineral or other oils or ancillary molecules added to the vaccine or generated by the body after the respective induction by such additional components, like but not restricted to interferons, interleukins or growth factors.
For example, in an immunogenic composition according to the invention, the pestivirus, in particular BVDV may be solved in:
If the immunogenic composition is first lyophilized or dehydrated by other methods, then, prior to vaccination, said composition is rehydrated in aqueous (e.g. saline, PBS (phosphate buffered saline)) or non-aqueous solutions (e.g. oil emulsion (mineral oil, or vegetable/metabolizable oil based/single or double emulsion based), aluminum-based, carbomer based adjuvant).
The immunogenic composition according to the invention is capable to induce an immunological response in an animal. More preferred, the immunogenic composition according to the invention is a vaccine. A vaccine as understood herein comprises a pestivirus, in particular BVDV according to the invention and is defined above (section “definitions”)
Most preferred, the immunogenic composition according to the invention further comprises a pharmaceutically acceptable carrier or excipient. Several carriers or excipients are disclosed above. The composition may comprise, if aimed at injections or infusion, substances for preparing isotonic solutions, preservatives such as p-hydroxybenzoates, stabilizers, such as alkalisalts of ethylendiamintetracetic acid, possibly also containing emulsifying and/or dispersing.
The immunogenic composition according to the invention may be applied intradermally, intratracheally, or intravaginally. The composition preferably may be applied intramuscularly or intranasally. In an animal body, it can prove advantageous to apply the immunogenic compositions as described above via an intravenous or by direct injection into target tissues. For systemic application, the intravenous, intravascular, intramuscular, intranasal, intraarterial, intraperitoneal, oral, or intrathecal routes are preferred. A more local application can be effected subcutaneously, intradermally, intracutaneously, intracardially, intralobally, intramedullarly, intrapulmonarily or directly in or near the tissue to be treated (connective-, bone-, muscle-, nerve-, epithelial tissue). Depending on the desired duration and effectiveness of the treatment, the immunogenic compositions according to the invention may be administered once or several times, also intermittently, for instance on a daily basis for several days, weeks or months and in different dosages.
The invention also relates to the use of a pestivirus, in particular BVDV according to the invention in the manufacture of a vaccine for the prophylaxis and treatment of pestiviral infections, in particular of BVDV infections.
Another important part of the invention is a polynucleotide molecule comprising the nucleic acid coding for a pestivirus, in particular for a BVDV according to the invention, or a fragment, functional variant, variant based on the degenerative nucleic acid code, fusion molecule or a chemical derivative thereof. Preferably, said polynucleotide molecule is DNA. Also preferably, said polynucleotide molecule is RNA. In a more preferred embodiment, said polynucleotide molecule also comprises the nucleotide sequence of a functional 5′- and/or 3′-non-translated region of a pestivirus, in particular of BVDV.
There are several nucleotide sequences known in the art, which represents the basis for the production of a polynucleotide molecule coding for a pestivirus attenuated according to the present invention. Examples of nuclecic acid sequences of wild-type sequences of several members of pestiviruses are listed below:
The mutations/modifications according to the invention relating to the coding sequence of Npro and Ems are described above more in detail. Having this information, a person skilled in the art is able to realize the manufacture of any polynucleotide/polynucleic acid coding for a pestivirus according to the present invention. Furthermore, this person is able to manufacture an attenuated pestivirus according to the invention. Molecular method for introducing a mutation into a polynucleotide sequence, cloning and amplification of said mutated polynucleotide are for example provided by Sambrook et 1989 or Ausubel et al. 1994.
Another important aspect of the invention is a method for attenuating a pestivirus which results in a pestivirus according to the invention, comprising modifying the Ems glycoprotein of said pestivirus in such that said attenuated pestivirus does not produce a dimeric Ems glycoprotein. According to further aspect, the carboxy-terminus of the Ems glycoprotein of said pestivirus is modified by a deletion, insertion or substitution. According to further aspect, at least the last C-terminal Cystein-residue of the Ems glyoprotein of said pestivirus is deleted or substituted by a non-Cys amino acid residue. According to further aspect, at least the last C-terminal Cystein-residue in the Ems glycoprotein of said pestivirus is deleted. According to further aspect, said pestivirus selected from the group consisting of CSFV, BVDV type 1 and/or 2, and BDV. According to further aspect, said attenunated pestivirus is a CSF pestivirus. According to a further aspect, at least the Cystein-residue at amino acid position 438 according to SEQ ID NO: 1 of the Ems glyoprotein of said CSFV pestivirus is deleted or is substituted by a non Cystein-residue. According to further aspect, said pestivirus is a BVD type 1 and/or 2 pestivirus. According to a further aspect, at least the Cystein-residue at amino acid position 441 according to SEQ ID NO: 4 (BVDV type 1) or SEQ ID NO:7 (BVDV type 2) of the Ems glyoprotein of said BVDV is deleted or substituted by a non Cystein-residue. According to further aspect, said pestivirus is a BD pestivirus. According to a further aspect, at least the Cystein-residue at amino acid position 439 according to SEQ ID NO: 10 of the Ems glyoprotein of said BDV is deleted or is substituted by a non Cystein-residue.
According to a further aspect the present invention provides a method for attenuating a pestivirus, characterized in that the glycoprotein Ems is modified in such that the RNAse activity residing within the Ems is inactivated by a deletion, insertion or substitution, and in such that said pestivirus is not capable to form any Ems dimer. According to a preferred embodiment, said pestivirus is selected from the group consisting of CSFV, BVDV, and BDV, including any subtypes thereof.
According to a further aspect, the present invention provides a method for attenuating a pestivirus, characterized in that glycoprotein Ems is modified by a deletion, insertion or substitution in such that said pestivirus is not capable to form any Ems dimer and by modifying the Npro protein by a deletion, insertion or substitution in such that the Npro protein is inactivated.
According to a further aspect, said method comprises the steps:
Yet another important embodiment of the invention is a method of treatment of disease caused by a pestivirus, wherein a pestivirus according to the invention or a composition according to the invention is administered to an animal in need thereof at a suitable dosis as known to the skilled person and the reduction of symptoms of said pestivirus infection.
Yet another important embodiment of the invention is a method of treatment of disease caused by BVDV, wherein a BVDV according to the invention or a composition according to the invention is administered to an animal in need thereof at a suitable dosis as known to the skilled person and the reduction of symptoms of BVDV infection such as viremia and leukopenia and/or pyrexia and/or diarrhea is monitored.
The following examples serve to further illustrate the present invention; but the same should not be construed as limiting the scope of the invention disclosed herein.
The objective of the study TV#26 was to define the outcome of clinical signs after infection of pigs with a CSFV Alfort/Tübingen mutant exhibiting a deletion of the cysteine codon at position 438 in the polypeptide (171 in the Ems sequence). This mutation prevents Ems dimerization (EP #82(4)). As controls an RNase negative variant of CSFV Alfort/Tübingen with mutation H297K and wt virus were used.
In this study, 12 animals with weight of about 20 kg were split in three groups of four animals each. The CSFV mutants (first group: TF #283(1)/second group: EP #82(4)) and CSFV wild type virus (third group: EP #98(1)) were applied via the intramuscular and intranasal route on day 0 (0 dpi). Each animal received 106 KID50 virus in 1.5 ml DMEM. After infection, animals were monitored for 22 days and rectal temperatures were recorded daily or every second day. A clinical score was determined according to Mittelholzer with modifications.
1. TF #283 (1): CSFV Alfort/Tübingen, RNase negative
2. EP#82(4): CSFV Alfort/Tübingen, incompetent for Ems dimerization
3. EP#98(1): CSFV Alfort/Tübingen, wild type virus.
The mutants show only a slightly reduced growth rate between 24 to 70 h p.i. in cell culture compared to the parental strain. It will have to be tested in further experiments whether this difference is significant (
The CSFV mutants (first group: TF #283(1)/second group: EP #82 (4)) and CSFV wild type virus (EP #98(1)) were applied intramuscularly and intranasally on day 0 (0 dpi). Each animal received 106 KID50 virus in 1.5 ml DMEM. Two-thirds of the suspension were applied intranasally (0.5 ml per nostril). For better i.m. application the last 0.5 ml of virus was filled up to 2 ml with DMEM and were injected in the muscle brachiocephalicus.
For titre confirmation of challenge virus 1 ml virus suspension was collected after different dilution and transport steps:
Blood was taken from the jugular vein for BC isolation, leukocyte counting, plasma isolation, FACS analysis and serum preparation according to table 3. After infection, animals were monitored for 22 days and rectal temperatures were recorded daily or, in the late stage of the experiment, every second day.
Twelve animals with an average weight of 20 kg arrived at the institute on Mar. 28, 2008. The pigs were divided into three different groups of 4 animals. After six days of acclimatisation the animals were infected with the mutant and wild type viruses.
Pigs were observed daily for general health status. The animals of group #3 challenged with the wild type virus had to be killed prematurely on day 9 p.i. because of considerable signs of CSF. In groups infected with the RNase negative mutant and the dimerization incompetent mutant all animals showed signs of disease typical for CSF. In comparison with the wild type infected animals (group 3) the severity of symptoms in group 1 and 2 were significantly less distinctive.
A clinical score according to Mittelholzer (with the following modifications: defecation: soft feces, normal amount=0; Reduced amount of feces, dry/thin feces=1; only small amount of dry, fibrin-covered feces, or diarrhea=2; no feces, mucus in rectum, or watery or bloody diarrhea=3) was recorded to evaluate the pathological signs.
Rectal temperatures were recorded on −3 and −2 dpi and daily or every second day from 0 dpi up to 20 dpi. In group 1 and 2 every animal reached the critical temperature of 40° C. on 4/5 or 6 days post infection. The temperature recovered in all animals of these groups to normal values till 10 dpi or 11 dpi. In the wild type virus infected group body temperature increased from day 4 post infection and no descent was detectable until euthanasia.
Detection of viremia through virus isolation in Buffy coat preparations has not been finished yet.
WBC counts were determined in a haemocytometer, “Neubauer chamber”, by standard laboratory procedure. For all animals a reduction of WBC was detectable during the study. The surviving animals showed an increase to almost normal values until study termination.
Determination of antibody titers has not been finished yet.
Serum neutralisation assays will be performed using SP50 as test virus on day −1 before infection, 9 days post infection for group 3 and 22 dpi for group 1 and 2.
It is obvious that the deletion of cysteine #438 and thereby the prevention of Ems dimer formation (biochemical data available) leads to attenuation of CSFV. This attenuation can hardly be due to a general growth retardation of the virus mutant since only marginal differences between the growth rates of the mutant and wt viruses were observed. The development and intensity of the clinical scores and fever as well as the degree of the WBC number reduction are very similar between the virus mutant lacking the Ems RNase activity and the variant with the deletion preventing Ems dimer formation. Since the dimerization has been found to be crucial for the biological functions but not enzymatic activity of other RNases, it can be hypothesized that the attenuation of CSFV in consequence of the prevention of Ems dimer formation and the abrogation of the RNase activity rely on the same principles of the virus host interaction, namely the blockage of the Ems RNase effect. Thus, the prevention of dimer formation is most likely equivalent to blocking the RNase activity, even though the virus is able to express an active RNase.
| Number | Date | Country | Kind |
|---|---|---|---|
| 08159009.3 | Jun 2008 | EP | regional |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/EP2009/057911 | 6/24/2009 | WO | 00 | 1/21/2011 |
