Patent Grant
9409973
The disclosure relates generally to biotechnology and medicine and more particularly to a vaccine against Respiratory Syncytial Virus (RSV). More specifically, it relates to a recombinant subunit vaccine comprising the ectodomain of the RSV-encoded Small Hydrophobic (SH) protein. The ectodomain of SH is referred to as SHe. The ectodomain may be presented as an oligomer, even more preferably, as a pentamer. The disclosure relates further to antibodies, raised against the ectodomain or specific for the ectodomain, and their use for protecting a subject against RSV infection and/or for treatment of an infected subject.
RSV infection is the leading cause of infant hospitalization in industrialized countries. Following primary RSV infection, which generally occurs under the age of 2 years, immunity to RSV remains incomplete, and reinfection can occur. Furthermore, RSV can cause serious disease in the elderly and is, in general, associated with higher mortality than influenza A in non-pandemic years (Falsey et al., 1995). The WHO-estimated global annual infection rate in the human population is estimated at 64 million cases, with a mortality figure of 160000; in the US alone, from 85000 to 144000 infants are hospitalized each year as a consequence of RSV infection (on the World Wide Web at who.int/vaccine_research/diseases/ari/en/index2.html update 2009).
RSV belongs to the family Paramyxoviridae, subfamily Pneumovirinae, genus Pneumovirus; in human, there are two subgroups, A and B. Apart from the human RSV, there is a bovine variant. The genome of human RSV is approximately 15200 nucleotides long and is a negative-sense RNA molecule. The RSV genome encodes 11 known proteins: Glycoprotein (G), Fusion protein (F), Small hydrophobic protein (SH), Nucleoprotein (N), Phosphoprotein (P), Large protein (L), Matrix protein (M), M2 ORF-1 protein (M2-1), M2 ORF-2 protein (M2-2), Nonstructural protein 1 (NS1) and Nonstructural protein 2 (NS2). G, F and SH are transmembrane surface proteins; N, P, L, M, M2-1 are nucleocapsid associated proteins; and NS1 and NS2 are non-structural proteins. The status of M2-2 as a structural or nonstructural protein is unknown. (Hacking and Hull, 2002.) The RSV subgroups show differences in the antigenic properties of the G, F, N and P proteins (Ogra, 2004).
RSV infection is followed by the formation of specific IgG and IgA antibodies detectable in the serum and some other body fluids. Several studies have demonstrated that antibody responses are mainly directed to the major RSV transmembrane proteins F and G; only F- and G-specific antibodies are known to have in vitro RSV-neutralizing activity. Antibody responses to the F protein are often cross-reactive between the A and B subgroups, whereas antibody responses to the G protein are subgroup specific (Orga, 2004). Contrary to F and G, the transmembrane protein SH is considered as non-immunogenic (Gimenez et al., 1987; Tsutsumi et al., 1989) and in some vaccine candidates, SH has even been deleted in order to obtain a non-revertible attenuated vaccine (Karron et al., 2005).
Development of vaccines to prevent RSV infection has been complicated by the fact that host immune responses appear to play a significant role in the pathogenesis of the disease. Early attempts at vaccinating children with formalin-inactivated RSV showed that vaccinated children experienced a more severe disease on subsequent exposure to the virus as compared to the unvaccinated controls (Kapikian et al., 1969). Live attenuated vaccines have been tested, but show often over- or underattenuation in clinical studies (Murata, 2009).
Subunit vaccines using one immunogenic protein or a combination of immunogenic proteins are considered safer, because they are unable to revert or mutate to a virulent virus. Candidate vaccines based on purified F protein have been developed and were tested in rodents, cotton rats, and humans, and were shown to be safe, but only moderately immunogenic (Falsey and Walsh, 1996; Falsey and Walsh, 1997; Groothuis et al., 1998). In a similar vein, clinical trials with a mixture of F-, G- and M-proteins have been discontinued in phase II (ADISinsight Clinical database). An alternative approach consisted of a recombinant genetic fusion of the antigenic domain of human RSV G protein to the C-terminal end of the albumin-binding domain of the streptococcal G protein (BBG2Na; Power et al., 2001). BBG2Na was investigated up to a phase III clinical trial in healthy volunteers, but the trial had to be stopped due to the appearance of unexpected type 3 hypersensitivity side effects (purpura) in some immunized volunteers (Meyer et al., 2008).
A recent development is the use of chimeric recombinant viruses as vector for RSV antigens. A chimeric recombinant bovine/human parainfluenzavirus type 3 (rB/HPIV-3) was engineered by substituting in a BPIV-3 genome the F and HN genes by the homologous genes from HPIBV-3. The resulting chimeric rB/HPIV-3 strain was then used to express the HRSV F and G genes (Schmidt et al., 2002). This vaccine is currently under clinical investigation.
Only a limited number of prevention and treatment options are available for the severe disease caused by RSV. The most widely used intervention is based on passive immunoprophylaxis with a humanized monoclonal antibody that is derived from mouse monoclonal antibody 1129 (Beeler and van Wyke Coelingh, 1989). This antibody is specific for RSV F protein and neutralizes subgroup A and B viruses. The recombinant humanized antibody 1129 is known as palivizumab (also known as Synagis) and is used for prophylactic therapy of infants that are at high risk of developing complications upon RSV infection. The antibody is administered intramuscularly on a monthly basis in order to lower the risk of RSV infection in infants at risk due to prematurity, chronic lung disease, or hemodynamically significant congenital heart disease (Bocchini et al., 2009). Some studies have reported acceptable cost-effectiveness ratios for RSV prophylaxis with palivizumab (Prescott et al., 2010).
As there is no approved vaccine on the market, there is still an unmet need for development and availability of a safe and efficient RSV vaccine. Surprisingly, we found that the extracellular part (ectodomain) of the small hydrophobic protein SH, referred to as SHe, can be used safely for vaccination against RSV infection, especially when it is presented on a carrier as an oligomer, such as a pentamer. Furthermore, polyclonal or monoclonal antibodies, directed against SHe, can also be used prophylactically or therapeutically for prevention or treatment of RSV infection, respectively.
Described is an immunogenic composition comprising the ectodomain of the small hydrophobic (SH) protein of a Respiratory Syncytial Virus (RSV), and a carrier. In one embodiment, RSV is either a human subgroup A or a human subgroup B strain; in another embodiment, RSV is bovine RSV. The SH protein is known to the person skilled in the art, and contains 64 (RSV subgroup A), 65 (RSV subgroup B) amino acid residues or 81, 77 or 72 amino acid residues for bovine RSV. In one embodiment, the ectodomain of SH(SHe) consists of the 23 carboxy terminal amino acids for subgroup A (SEQ ID NO:1), and of the 24 carboxy terminal amino acids for subgroup B (SEQ ID NO:2). The sequence of the ectodomain may be selected from the group consisting of SEQ ID NO:1 (ectodomain subgroup A) and SEQ ID N° 2 (ectodomain subgroup B), or a variant thereof. A “variant,” as used herein, means that the sequence can carry one or more mutations, such as deletions, insertions or substitutions. In certain embodiments, the mutations are substitutions. Even more preferably, the variant has 80% identities, preferably 85% identities, even more preferably, 90% identities, most preferably 95% identities, as measured in a BLASTp alignment (Altschul et al., 1997). Preferably, the variant comprises the sequence NKL C/S E Y/H K/N XF (SEQ ID NO:3). Preferred variants are listed in SEQ ID NO:4-SEQ ID NO:16. In another preferred embodiment, the ectodomain consists of SEQ ID NO:17 (ectodomain of Bovine RSV SH) or a variant thereof, as defined above. Preferably, the variant comprises the sequence NKLCXXXXXHTNSL (SEQ ID NO:18). Preferred variants are listed in SEQ ID NOS:19-30.
A carrier molecule is a molecule that is heterologous to the SH protein; a carrier can be any carrier known to the person skilled in the art as suitable for the presentation of an antigen and includes, but is not limited to, virus-like particles such as HBcore (Whitacre et al., 2009), and other VLPs derived from assembling virus capsid or coat proteins. Any other molecular construct can also be used, provided it can efficiently present antigens to the immune system, such as the pentameric Cartilage Oligomeric Matrix Protein (comp; McFarlane et al., 2009), Thromobospondins 3 and 4 (Malashkevich et al., 1996), the B subunit of bacterial AB5 type toxins (e.g., subunit of Cholera toxin or E. coli heat labile toxin; Williams et al., 2006), a pentameric tryptophan-zipper (Liu et al., 2004), a pentameric phenylalanine-zipper (Liu et al., 2006) or a tetrameric GCN4-derived leuzine zipper (tGCN4, De Filette et al., 2008) and Lpp-56 (Shu et al., 2000). The carrier can be of a proteinaceous nature, as well as of a non-proteinaceous nature. Examples of non-proteinaceous nature carriers are, as a non-limiting example, liposomes, CLIPS™ constructs (Timmerman et al., 2007) and trimethyl chitosan (Sliitter et al., 2010). Preferably, the carrier presents the SHe as an oligomer, even more preferably, as a pentamer, by presenting multiple SHe molecules on one scaffold, by presenting one SHe on a multimerizing scaffold, or by a combination of both. The SHe oligomer may be presented as a linear repeated structure, or as individual SHe units forming an oligomeric complex, or as a combination of both. The carrier may be an oligomeric carrier (dimeric, up to decameric) or a pentameric carrier. In one specific embodiment, the transmembrane domain of SH, which may be without the cytoplasmic domain, can be used as oligomerizing domain, optionally further fused or linked to a carrier.
Not all carrier molecules should be loaded by SHe. Indeed, as a non-limiting example, one can imagine that only 5 units of a hexameric carrier are loaded with SHe, thereby presenting a pentameric SHe complex on a hexameric carrier complex. The ectodomain can be genetically linked to the carrier, aiming a fusion protein; both domains may be directly fused, or they may be linked by a hinge sequence or a spacer sequence. As used here, in a genetically fused construct, a hinge sequence is an amino acid sequence that links two domains together; the sequence links the two domains in a flexible way; the hinge sequence is shorter than 150 amino acids, even more preferably, shorter than 100 amino acids, even more preferably, shorter than 50 amino acids, most preferably, shorter than 20 amino acids. A “spacer,” as used herein, indicates a short hinge sequence shorter than 15 amino acids. In one embodiment, a hinge sequence comprises the sequence (Gly-Ser)n with n equal to one, 2, 3, . . . 20. In another embodiment, the hinge of immunoglobulin genes, such as the hinge region of human IgG1, is used as a hinge sequence. In the case of a genetic linkage, the linkage may occur at the amino terminal end of the SHe, as well as at the carboxy terminal end.
Alternatively, the ectodomain is chemically linked to the carrier. Chemical linkage is known to the person skilled in the art, and includes, but is not limited to, peptides that are conjugated to the carrier by covalently joining peptides to reactive sites on the surface of the carrier. The resulting structure is a conjugate. A reactive site on the surface of the carrier is a site that is chemically active or that can be activated and is sterically accessible for covalent joining with a peptide. A preferred reactive site is the epsilon nitrogen of the amino acid lysine. Covalently joined refers to the presence of a covalent linkage that is stable to hydrolysis under physiological conditions. The covalent linkage may be stable to other reactions that may occur under physiological conditions including adduct formation, oxidation, and reduction. Often, the linkage of an antigenic peptide to a carrier is achieved using bifunctional reagents (Hermanson, 1996). Any suitable residue in the SHe may be used for linkage to the chemical carrier; preferably, SHe is linked to the carrier by its amino terminal or carboxy terminal end.
In still another embodiment, the ectodomain is linked to the carrier by a non-covalent interaction, such as, but not limited to, hydrophobic interactions, cooperative H-bond interactions, or Van der Waals interactions.
Also described is the use of an immunogenic composition hereof as a vaccine. Still further described is the use of an immunogenic composition hereof for the preparation of a vaccine for the protection against RSV infection. The RSV may be selected from the group consisting of RSV subgroup A and RSV subgroup B. The vaccine can be administrated to the subject to be treated by any route known to the person skilled in the art including, but not limited to, intranasal, intraperitoneal, intramuscular and intradermal administration. Preferably, there is no enhancement of the disease symptoms upon RSV infection after vaccination. The vaccine can be for animal or for human use. A preferred animal use is for protection of cattle or other Bovidae by vaccination against bovine respiratory viruses related to human RSV, such as, but not limited to, Bovine RSV. Protection against RSV infection covers both prophylactic and therapeutic uses. More particularly, a preferred use of the vaccine is for prophylactic purposes. “Preparation of a vaccine,” as used herein, means that the immunogenic composition hereof may be optimized by addition of suitable excipients, or it may be formulated for, as a non-limiting example, increasing the shelf life or improving the pharmaceutical characteristics of the vaccine.
Described is a vaccine comprising an immunogenic composition hereof, or a combination of immunogenic compositions hereof. Indeed, as a non-limiting example, immunogenic compositions comprising SHe of RSV subgroup A and SHe of RSV subgroup B may be mixed to obtain a vaccine with a broader specificity. The vaccine can be for human or for veterinary use. Apart from the immunogenic composition, the vaccine may comprise one or more other compounds, such as an adjuvant. The vaccine may be a vaccine for the protection of humans against RSV infection or, in animals, against animal respiratory viruses related to human RSV, such as, but not limited to, bovine RSV.
Described is the use of an immunogenic composition hereof for the detection and/or purification of antibodies, directed against the ectodomain of RSV. Such antibodies may be isolated after vaccinating a subject with the immunogenic composition of the invention; alternatively, similar antibodies and/or antibody-producing cells can also be obtained from an RSV-infected human or animal subject, and, after proper development known in the art, used for production of SHe-specific antibodies, preferably human-type antibodies that can be used for prophylactic or therapeutic purposes as described above.
Described is a method for the production of blood, plasma and/or serum from an animal, the blood, plasma and/or serum comprising one or more antibodies or cells producing antibodies against the SHe domain of RSV, the method comprising (a) delivering an immunogenic composition hereof to the animal and (b) obtaining blood, plasma and/or serum from the animal, wherein the blood, plasma and/or serum comprises one or more antibodies or cells producing antibodies against the SHe domain of RSV, or cells producing the antibodies. Preferably, the animal is a non-human animal. As used herein, “plasma” is the liquid fraction of the blood after removal of the blood cells; serum is plasma after removal of fibrinogen and other blood clotting factors. As indicated above, specific anti-SHe antibodies may be isolated using the immunogenic composition hereof.
Described is the use of blood, plasma and/or serum containing RSV-antibodies and obtained with the method hereof for protection against RSV infection and/or treatment of RSV infection. As mentioned above, protection against RSV infection covers both the prophylactic and therapeutic use. Indeed, the antibody-comprising serum can be administered to a human or an animal, thereby providing passive immunity against the RSV infection. The serum may be part of a pharmaceutical composition comprising the serum, wherein the serum is formulated and/or mixed with a suitable excipient. Described is a pharmaceutical composition comprising a serum obtained with the method hereof.
Described is an RSV-inhibiting monoclonal antibody, directed against the ectodomain of the RSV SH-protein. “RSV-inhibiting,” as used herein, means that, upon infection, the lung virus titer is lower in treated animals compared to the non-treated animals, as measured in a suitable animal model. Preferably, the monoclonal antibody is a human or humanized monoclonal antibody.
Described is a pharmaceutical composition comprising a monoclonal antibody directed against the ectodomain of the RSV SH-protein, hereof. Indeed, an organ of an immunized non-human animal, preferably the spleen of the animal, or a blood sample from an immunized animal or human subject, can be used as starting material for the production of monoclonal antibodies and derivatives such as, but not limited to, single-chain antibodies, multivalent antibodies, or antibodies linked to antiviral compounds. The monoclonal antibodies and derivatives are used for passive immunization or for treatment of RSV infection.
Cloning and Plasmid Construction
Construction of the pLT32 Flag-COMPcc-SHe Expression Plasmid.
A plasmid containing the coding sequence of Flag-COMPcc-SHe (
Construction of the pCAGGS-Etag-SH Expression Vector.
Total RNA of RSV A2-infected Hep-2 cells was prepared using the High Pure RNA tissue kit (Roche, Mannheim) according to the manufacturer's instructions. After cDNA synthesis, the RSV A2 SH coding sequence was amplified using the following forward and reverse primers (5′ATAAGAAAGCGGCCGCTATGGAAAATACATCCATAACAATAG3′ (SEQ ID NO:36); 5′GAAGATCTCTATGTGTTGACTCGAGCTCTTGGTAACTCAAA3′ (SEQ ID NO:37)). The PCR product was digested with NotI and BglII and ligated in a NotI/BglII opened pCAGGS-PTB-Etag expression vector (Cornelis et al., 2005). The resulting vector pLT32-Flag-COMPcc-SHe was deposited under the Budapest treaty at BCCM (BCCM/LMBP: Technologiepark 927, 9052 Zwijnaarde, Belgium) under deposit number LMBP 6817 on 8 Nov. 2010.
The construction of the pCAGGS-Luc expression vector was described earlier (Schepens et al., 2005; referred as pCAGGS-HIF-RLuc).
Construction of the pLT32 mHBc Expression Vector.
The coding sequence of mHBc, as described earlier by Jegerlehner et al., as part of the “abi” plasmid, was ordered at Geneart (SEQ ID NO:32) (De Filette et al., 2005; Jegerlehner et al., 2002). This coding sequence was cloned as a NdeI/NotI fragment in a NdeI/NotI opened pLT32H bacterial expression vector.
Construction of the pLT32 SHe-tGCN4-Flag Expression Vector.
To construct pLT32 SHe-tGCN4, the SHe coding sequence was fused to the tGCN4-Flag coding sequence by fusion per. The SHe fragment for fusion per was amplified using the primers: 5′GGAATTCCATATGAACAAGTTATGTGAGTACAACG3′ (SEQ ID NO:38) and 5′GATTTGTTTTAAACCTCCTGTATTTACTCGTGCCCGAGGCAA3′ (SEQ ID NO:39) and a template plasmid that was ordered at Geneart (SEQ ID NO:33) and that contains the coding sequence of the RSV A2 SH ectodomain (NKLCEYNVFHNKTFELPRARVNT) (SEQ ID NO:40). The GCN4 fragment for fusion PCR was amplified using the primers 5′CCCAAGCTTCTAACATTGAGATTCCCGAGATTGAGA3′ (SEQ ID NO:41) and 5′TATTAACCCTCACTAAAGGGAAGG3′ (SEQ ID NO:42) and a template plasmid that contains the tGCN4 coding sequence, C-terminally fused to the coding sequence of three successive Flag-tag sequences (SEQ ID NO:34; De Filette et al., 2008). The two PCR fragments were fused using the primers: 5′GGAATTCCATATGAACAAGTTATGTGAGTACAACG3′ (SEQ ID NO:43) and 5′TATTAACCCTCACTAAAGGGAAGG3′ (SEQ ID NO:44). This fusion PCR product was cloned as a NdeI/HindIII fragment in a NdeI/HindIII opened pLT32H bacterial expression vector. The resulting pLT32 SHe-tGCN4-Flag was deposited under the Budapest treaty at BCCM (BCCM/LMBP: Technologiepark 927, 9052 Zwijnaarde, Belgium) under deposit number LMBP 6818 on 8 Nov. 2010.
The construction of the PLT32 M2e-tGCN4 expression vector was described earlier (De Filette et al., 2008).
Construction of the pLH36-HisDEVD-LPP(5)-SHe Expression Plasmid.
A plasmid containing the coding sequence of the LPP(5) tryptophan-zipper fused to the coding sequence of the SH ectodomain separated by the coding sequence of a GlyGly linker was ordered at Genscript. This coding sequence was amplified using the following forward and reverse primers (5′GCGAAATGGGATCAGTGGAGCAGC-3′ (SEQ ID NO:53); 5′AATATAGGATCCCTAGGTCGCCCAGTTATCCCAGCG-3′ (SEQ ID NO:54)), phosphorylated and digested with BamHI. The pLH36-HisDEVD-LPP-SHe was constructed by a three-point ligation using the described PCR fragment, BamHI/PstI-digested pLT32 plasmid fragment and EcoRV/PstI-digested pLH36 fragment. The sequence of the constructed pLH36-HisDEVD-LPP(5)-SHe plasmid is displayed in SEQ ID NO:49.
Expression and Purification of SHe-tGCN4, M2e-tGCN4, Flag-COMPcc-SHe, mHBc and LPP(5)-SHe
A 30-ml preculture of pLT32SHe-tGCN4-transformed E. coli was grown at 28° C. in Luria broth and used to inoculate 1 liter of fresh medium. At an A600 of 0.6-0.8, the cells were treated with 1 mm isopropyl 1-thio-β-d-galactopyranoside, incubated for another four hours, and then collected by centrifugation (6000×g, 20 minutes, 4° C.). The bacterial pellet was resuspended in 20 ml Tris-HCl buffer (50 mM Tris-Hcl, 50 mM NaCl and 1 mM EDTA), pH 8, and sonicated. Bacterial debris was pelleted by centrifugation (20,000×g, one hour, 4° C.). The supernatant was applied to a DEAE Sepharose column pre-equilibrated with Tris-HCl buffer containing 50 mM NaCl (buffer A). After washing, the bound proteins were eluted by a two-step gradient going from 0-40% buffer B (50 mM Tris-Hcl, 1 M NaCl) and 40-100% buffer B. Fractions containing SHe-tGCN4 were pooled, adjusted to 25% ammonium sulfate saturation, and applied to a phenyl-Sepharose column pre-equilibrated with 25% ammonium sulfate, 50 mm Tris-HCl, pH 8. Bound proteins were eluted with a two-step gradient. The two-step elution was performed with 0-40% and 40-100% 50 mM Tris-HCl buffer, pH 8 (buffer A). The fractions containing SHe-tGCN4 were loaded on a Superdex 75 column. Gel filtration was performed in phosphate-buffered saline (PBS), and the fractions containing SHe-tGCN4 were pooled and stored at −70° C.
Expression and purification of flag-COMPcc-SHe was identical to SHe-tGCN4 apart from the use of a Q Sepharose column for anion exchange chromatography instead of a DEAE Sepharose column.
The expression and purification of M2e-tGCN4 was described before (De Filette et al., 2008).
Expression and purification of mHBc was identical to SHe-tGCN4 apart from the use of a Sephacryl S400 column for gel filtration chromatography instead of Superdex 75 column.
Expression and Purification of LPP(5)-SHe.
A 30-ml preculture of pLH36-HisDEVD-LPP(5)-SHe-transformed E. coli cells was grown at 28° C. in Luria broth with ampicillin and used to inoculate 3 liters of fresh medium. At an A600 of 0.6-0.8, the cells were treated with 1 mM isopropyl 1-thio-β-d-galactopyranoside, incubated for another four hours, and then collected by centrifugation (6000×g, 20 minutes, 4° C.). The bacterial pellet was resuspended in 300 ml buffer containing 20 mM NaH2PO4/Na2HPO4, 300 mM NaCl and 5 mM imidazole, pH 7.5 and sonicated. Bacterial debris was pelleted by centrifugation (20,000×g, one hour, 4° C.). The supernatant was loaded on a Nickel-Sepharose column pre-equilibrated with buffer containing 5 mM Imidazole. After washing, the bound proteins were eluted by a step-wise (50 mM, 100 mM, 200 mM and 400 mM) imidazole gradient. Fractions containing LPP(5)-SHe were pooled, desalted and further purified on a Q-sepharose column. The sample was applied to a DEAE Sepharose column pre-equilibrated with Tris-HCl buffer containing 50 mM NaCl (buffer A). After washing, the bound proteins were eluted by a two-step gradient going from 0-40% buffer B (50 mM Tris-Hcl, 1 M NaCl) and 40-100% buffer. The fractions containing LPP(5)-SHe were loaded on a Superdex 75 column. Gel filtration was performed in phosphate-buffered saline (PBS) and the fractions containing LPP(5)-SHe.
Adjuvants
A detoxified mutant of heat-labile E. coli enterotoxin, LTR192G, was used for intranasal (i.n.) administration; this preparation was generously provided by Dr. J. Clements (Department of Microbiology and Immunology, Tulane University Medical Center, New Orleans, La., USA) (Norton et al., 2010).
Chemical Linking and Characterization of SHe-HBc Particles
SHe(cc4s), a chemically synthesized, HPLC-purified SHe peptide in which the naturally occurring cysteine was replaced by a serine and to which a cysteine was added at the N-terminus was ordered at Pepscan (Pepscan, Lelystad). The SHe(cc4s) peptide was via its N-terminal cysteine residue fused to a Lysine in the immunodominant loop of mHBc on the surface of HBc VLPs by chemical linkage using the heterobifuctional sulfo-MBS (Pierce), according to the manufacturer's instructions. In short, 400 μg mHBc, dissolved in 200 μl PBS, was incubated with Sulfo-MBS (at a final concentration of 1 mg/ml) for one hour. After removal of unbound Sulfo-MBS molecules by size exclusion chromatography, sulfo-MBS-linked mHBc VLPs were diluted in 2 ml H2O, Subsequently, 100 μl SHe(cc4s) peptide (dissolved in 100 ml PBS) was added and incubated for one hour at room temperature to allow cross-linking of the peptide to the mHBc VLPs. Finally, free SHe(cc4s) peptide was removed by size exclusion chromatography. The purity and cross-linking efficacy was tested via SDS-PAGE followed by Coomassie staining.
Cells
Hep-2 cells (ATCC, CCL-23), Vero cells (ATCC, CCL-81), HEK293T cells (a gift from Dr. M. Hall) and A549 cells (ATCC, CCL-185) were grown in DMEM medium supplemented with 10% heat-inactivated fetal calf serum (FCS), 1% penicillin, 1% streptomycin, 2 mM L-glutamine, non-essential amino acids (Invitrogen, Carlsbad, Calif.), and 1 mM sodium pyruvate.
Mice and Viruses
Specific pathogen-free, female BALB/c mice were obtained from Charles River (Charles River Wiga, Sulzfeld, Germany). The animals were housed in a temperature-controlled environment with 12-hour light/dark cycles; food and water were delivered ad libitum. Mice were immunized at 8 weeks of age after one week adaptation in the animal room.
The animal facility operates under the Flemish Government License Number LA1400091. All experiments were done under conditions specified by law (European Directive and Belgian Royal Decree of Nov. 14, 1993) and authorized by the Institutional Ethical Committee on Experimental Animals.
RSV A2, an A subtype of RSV (ATCC, Rockville), was propagated by infecting monolayers of Vero cells, with 0.1 MOI in the presence of growth medium containing 1% FCS. Five to seven days after infection, the cells and growth medium were collected, pooled and clarified by centrifugation (450×g). To concentrate the virus, the clarified supernatant was incubated for four hours at 4° C. in the presence of 10% polyethylene glycol (PEG6000). After centrifugation (30 minutes at 3000×g), the pellet was resuspended in Hank's balanced salt solution (HBSS), containing 20% sucrose, aliquoted and stored at −80° C.
Intranasal Immunizations and Infections
For intranasal immunization or infection, the mice were slightly anesthetized by isofluorane. The final volume used for administration of vaccine+adjuvant or virus was 50 μl (25 μl per nostril). Vaccines+adjuvant were formulated in PBS, whereas the viral inoculum was formulated in HBSS.
Determination of Lung Viral Titer by Plaque Assay
Three or four days post-challenge, the mice were sacrificed. The mouse lungs were removed aseptically and homogenized with a Heidolph RZR 2020 homogenizer for 30 seconds in 1 ml HBSS containing 10% sucrose. Lung homogenates were subsequently cleared by centrifugation at 4° C. and used for virus titration on Hep-2 cells. Monolayers of Hep-2 cells were infected with 50 μl of serial 1:3 dilutions of the lung homogenates in a 96-well plate in serum-free OPTI-MEM® medium (Invitrogen) supplemented with penicillin and streptomycin. Four hours later, the cells were washed twice with DMEM medium containing 2% FCS and incubated for five days at 37° C. in 50 μl overlay medium (completed DMEM medium containing 1% FCS, 0.5% agarose). The cells were fixed by adding 50 μl of a 4% paraformaldehyde solution on top of the agarose overlay. After overnight fixation at 4° C., the overlay medium and paraformaldehyde solution were removed, the cells were washed twice with PBS and blocked with PBS containing 1% BSA (PBS/BSA). Subsequently, polyclonal goat anti-RSV serum (AB1128, Chemicon International) was added (1/4000). After washing three times with PBS/BSA, the cells were incubated with hrp-conjugated anti-goat IgG antibodies (SC2020, Santa Cruz) for 30 minutes. Non-binding antibodies were removed by washing four times with PBS/BSA containing 0.01% TRITON® X-100 and once with PBS. Finally, the plaques were visualized by the use of TrueBlue peroxidase substrate (KPL, Gaithersburg). The plaques of different dilutions were counted and, for each dilution, the number of PFU per lung (1 ml) was calculated as: number of plaques present in the dilution×the dilution×20 (=1000 μl total supernatant volume/50 μl of the volume of supernatant used to infect the first well of the dilution series). The number of PFU/lung was then calculated as the average number of PFU/lung calculated for the different dilutions. As each supernatant of the homogenized lungs was tested in duplicate, the final number of PFU/lung was calculated as the average of these duplicates.
Determination of Lung Viral Titer by qRT-PCR
To determine the lung RSV load by qRT-PCR, lung homogenates were prepared and clarified as described above. Total RNA from these lung homogenates was prepared by the use of the High Pure RNA tissue kit (Roche, Mannheim) according to the manufacturer's instructions. cDNA was prepared by the use of hexamer primers and the Transcriptor First Strand cDNA synthesis kit (Roche, Mannheim). The relative levels of genomic RSV M cDNA were determined by the use of qRT-PCR using primers specific for the genomic RNA of the RSV A2 M-gene (5′TCACGAAGGCTCCACATACA3′ (SEQ ID NO:45) and 5′GCAGGGTCATCGTCTTTTTC3′ (SEQ ID NO:46)) and a nucleotide probe (#150 Universal Probe Library, Roche) labeled with fluorescein (FAM) at the 5′-end and with a dark quencher dye near the −3′ end. The relative amount of GADPH mRNA was determined by qRT-PCR using primers specific for mouse GADPH (5′TGAAGCAGGCATCTGAGGG3′ (SEQ ID NO:47) and 5′CGAAGGTGGAAGAGTGGGAG3′ (SEQ ID NO:48) and LIGHTCYCLER® 480 SYBR® Green I Master Mix (Roche). The relative amount of genomic RSV RNA per lung homogenate was calculated as the ratio between the relative amount of RSV M-gene RNA and the relative amount of mouse GADPH mRNA.
Peptide ELISA
Two weeks after each immunization, blood samples were collected from the lateral tail vein. The final bleeding was performed by cardiac puncture of animals anesthetized with avertin. Blood was allowed to clot for 30 minutes at 37° C., and serum was obtained by taking the supernatant from two subsequent centrifugations.
Serum antibody titers were determined by ELISA using pooled sera from the group. To determine M2e or SHe-specific antibody titers, microtiter plates (type II F96 MaxiSorp, Nunc) were coated with, respectively, 50 μl of a 2 μg/ml M2e-peptide solution or 2 μg/ml SHe-peptide solution in 50 mM sodium bicarbonate buffer, pH 9.7, and incubated overnight at 37° C. After washing, the plates were blocked for one hour with 200 μl of 1% BSA in PBS. After a one-hour incubation, the plates were washed again. A series of 1/3 dilutions of the different serum samples, starting with a 1/100 dilution, were loaded on the peptide-coated plates. The bound antibodies were detected with a peroxidase-labeled antibody directed against mouse isotypes IgG1 or IgG2a (Southern Biotechnology Associates, Inc., Birmingham, Ala., USA) and diluted 1/6000 in PBS+1% BSA+0.05% TWEEN® 20. After washing, the microtiter plates were incubated for five minutes with TMB substrate (Tetramethylbenzidine, Sigma-Aldrich). The reaction was stopped by addition of an equal volume 1 M H3PO4 and the absorbance at 450 nm was measured. Endpoint titers are defined as the highest dilution producing an O.D. value twice that of background (pre-immune serum).
Flow Cytometric Analysis
Hek293T cells were transfected with the indicated expression vectors. Twenty-four hours later, the cells were detached using enzyme-free dissociation buffer (Invitrogen, Carslbad, Calif.), washed once with PBS and incubated for one hour in PBS containing 1% BSA (PBS/BSA). Subsequently, the cells were incubated with the indicated serum or antibodies at the indicated concentrations. One hour later, the cells were washed three times with PBS/BSA and incubated with the anti-mouse IgG alexa 633 secondary antibodies for 30 minutes. After washing the cells four times with PBS/BSA and once with PBS, the cells were analyzed using a Becton Dickinson LSR II flow cytometer. Single GFP-expressing cells were selected based on the peak surface of the sideward scatter signal, the peak surface and peak height of the forward scatter signal and the peak surface of the green fluorescence signal. Finally, of these GFP-positive single cells, the alexa 633 fluorescence signal was measured.
Immunostaining
Vero cells were either mock infected or infected with 0.5 MOI of RSV A2 in the presence of serum-free medium. Four hours later, the free virus was washed away and the cells were incubated in growth medium containing 1% FCS. Sixteen hours later, the cells were washed once with PBS and fixed with 2% paraformaldehyde for 20 minutes. Subsequently, the cells were washed twice with PBS and permeabilized with 0.2% TRITON® X-100 detergent for five minutes. After washing once with PBS, the cells were blocked in PBS/BSA. One hour later, SHe-specific 3G8 monoclonal antibody or isotype control antibody was added at a final concentration of 5 μg/ml. After washing the cells twice with PBS/BSA, polyclonal anti-RSV goat serum was added. One hour later, the cells were washed three times with PBS/BSA. The binding of the indicated antibodies to the cells was analyzed by the use of anti-mouse and anti-goat IgG antibodies labeled with, respectively, alexa 488 and alexa 568 fluorescent dyes. Confocal images of the stained cells were recorded with a Zeiss confocal microscope.
Generation of SHe mAb Producing Hybridomas
Stable hybridomas cells producing SHe-specific monoclonal antibodies (mAb) were generated by hybridoma technology (Kohler and Milstein 1975). Briefly, SHe-specific hybridomas were derived from individual mice that were immunized i.p. three times at three-week intervals with 10 μg of SHe-tGCN4 vaccine adjuvanted with ALHYDROGEL® (Brenntag Biosector). Three days before fusion, mice were boosted an additional time with the same formulation and splenocytes were isolated then fused to SP2/0-Ag14 myeloma cells in the presence of PEG 1500 (Roche Diagnostics GmbH, Germany). Fused cells were grown in RPMI 1640 medium supplemented with 10% Fetal bovine serum, 10% BM Condimed H1 (Roche Diagnostics GmbH, Germany), 2 mM L-glutamine, and 24 μM beta-mercaptoethanol and 1×HAT supplement (Invitrogen, Carlsbad, Calif.). Hybrids secreting SHe-specific antibodies were identified by SHe peptide ELISA screening and monoclonal antibodies producing hybrids were obtained after two rounds of sub-cloning by limiting dilution procedure. Monoclonal antibodies were purified on a protein A-Sepharose column (electrical engineering biosciences).
The resulting hybridomas were deposited under the Budapest treaty at BCCM (BCCM/LMBP: Technologiepark 927, 9052 Zwijnaarde, Belgium) under deposit numbers LMBP 7795CB for 3G8 on 8 Nov. 2010 and LMBP 7796CB for 3D11 on 10 Nov. 2010, respectively.
The SH protein is expressed at the surface of RSV virions and the plasma membrane of RSV-infected cells as a pentamer. The pentameric organization of SH is organized by the SH transmembrane domain, which oligomerizes as a coiled coil of five parallel alpha-helices. In order to present the C-terminal SH ectodomain (SHe) of RSV A as a pentamer that mimics its natural conformation, SHe was genetically fused to the short pentameric coiled coil domain of the rat cartilage oligomeric matrix protein (COMPcc), which is also composed of five parallel alpha-helices (Malashkevich et al., 1996;
To test if vaccination with Flag-COMPcc-SHe could evoke protection against RSV infection, we used a BALB/c mouse RSV infection model. BALB/c mice were immunized three times intranasally with 25 μg of Flag-COMPcc-SHe in combination with 1 μg E. coli heat-labile enterotoxin LTR192G adjuvant. PBS and the Influenza A M2 ectodomain fused to a tetrameric GNC4 scaffold (M2e-tGNC4) (De Filette et al., 2008) were used as negative controls. Immunizations were performed every fortnight. A single RSV infection (5×105 PFU) was used as positive control. Between the first and the second week after each immunization, blood was collected to investigate the induction of SHe-specific IgG antibodies. The presence of SHe-specific antibodies was first tested by SHe peptide ELISA. M2e peptide ELISA was used as negative control.
Next, we investigated if SHe-specific antibodies present in the Flag-COMPcc-SHe immune serum could bind to cells expressing the RSV-SH protein at their surface by flow cytometry. HEK-293T cells were transfected with a GFP expression vector, in combination with either a SH expression vector (pCAGGS-Etag-SH) or a Luciferase expression vector (pCAGGS-Luc) as negative control. Twenty-four hours after transfection, the cells were detached, stained with different dilutions of Flag-COMPcc-SHe or M2e-tGCN4 immune serum and analyzed by flow cytometry.
To test if Flag-COMPcc-SHe/LTR192G vaccination can elicit protection against RSV infection, the mice were challenged with 1×106 PFU RSV A2 nine weeks after the last immunization. Four days after infection, the mice were sacrificed to determine the viral lung titer by plaque assay.
Vaccination with formalin-inactivated virus or the RSV G protein can induce enhancement of disease upon infection, resulting in significant morbidity, by the induction of an unbalanced Th2 immune response (Prince et al., 1986). To test if Flag-COMPcc-SHe vaccination might also induce enhancement of disease, we monitored the body weight before and after RSV challenge (
The Hepatitis B virus core protein (HBc) virus-like particle (VLP) can present antigens as a dense array. In this way, HBc-VLPs can induce a strong humoral immune response toward the presented antigen (Boisgerault et al., 2002). Therefore, as an alternative to presenting SHe as a pentamer, the SH ectodomain was presented in the immunodominant region loop of mHBc-VLPs. HBc-SHe-VLPs were obtained by chemical linkage of SHe peptides to mHBc, a mutant of HBc in which a lysine was introduced in the top of the HBc immunodominant region (De Filette et al., 2005). To enable chemical linking, a cysteine residue was added to the N-terminus of SHe. In addition, the cysteine residue, present at position 4 of the SHe peptide, was replaced by a serine residue. This peptide was called SHe-CC4S. After purification of the mHBc-SHe-VLPs, by size exclusion chromatography, the degree of cross-linking was examined by SDS PAGE.
Next to presenting the SHe peptide at the surface of mHBc VLPs, SHe was also fused to tGCN4, which is known to induce a strong humoral response toward fused peptides (Ref marina GCN4). SHe and a Flag-tag were genetically linked to, respectively, the 5′-end and the −3′ end of the tGCN4 coding sequence and cloned into a PLT32 expression vector. After expression in E. coli, recombinant SHe-tGCN4-Flag was purified by anion exchange, hydrophobic interaction and gel filtration chromatography (
To test if vaccination with mHBc-SHe(CC4S) and SHe-tGCN4 can evoke protection against RSV infections, Balb/c mice were vaccinated three times intranasally with 10 mHBc-SHe(CC4S) and SHe-tGCN4 in combination with 1 μg LTR192G adjuvant. PBS and empty mHBc, the latter in combination with 1 μg LTR192G, were used as negative controls. Immunizations were performed every three weeks. A single RSV infection (5×105 PFU) was used as positive control. Between the second and the third week after each immunization, blood was collected to investigate the induction of SHe-specific IgG antibodies. The presence of SHe-specific antibodies was tested by SHe peptide ELISA.
To test if vaccination with mHBc-SHe(CC4S) or SHe-tGCN4 can hamper RSV infection, the mice were challenged with 5×106 PFU RSV A2 three weeks after the last boost immunization. Three days after challenge, the mice were sacrificed to determine the pulmonary RSV A2 levels by QPCR.
To investigate if SHe-specific antibodies that can interact with infected cells can provide protection against RSV infections, we developed RSV SHe-specific monoclonal antibodies based on SHe-TGCN4 immunized mice. One IgG1 (3D11) and one IgG2a (3G8) subtype hybridoma that produced antibodies that efficiently bound to SHe peptide in an ELISA were selected, subcloned and used for antibody production. The 3D11 and 3G8 were purified via protein A affinity chromatography and tested for binding efficacy to SHe via an ELISA.
As antibodies can protect against viral infections via recognition and killing of infected cells by (ADCC) or CDC, we investigated if the SHe-specific mAbs 3D11 and 3G8 can recognize SH at the surface of cells. Therefore, Hek293T cells were transfected with an RSV SH expression vector or with a control Firefly luciferase vector (Schepens et al., 2005), both in combination with a GFP expression vector. Twenty-four hours after transfection, live cells were stained with different concentrations of the SHe-specific monoclonal antibodies (3D11 and 3G8) or isotype matched Influenza M2e-specific antibodies (14C2 IgG1 and a IG2a M2e-specific mAb). Polyclonal serum from Flag-COMPcc-SHe-immunized mice was used as positive control.
During infection, the RSV SH protein is mainly expressed at the ER, golgi and cell membrane. In order to more directly investigate whether the RSV SH-specific antibodies can recognize infected cells via SH expressed at the surface of these cells, we performed immunostaining of RSV-infected and mock-infected cells. Human A594 lung epithelial cells were either infected with 0.05 MOI of RSV or mock infected. Twenty-four hours after infection, the cells were fixed and stained with the SHe-specific mAbs 3D11 or 3G8 in combination with polyclonal anti-RSV immune serum.
To test if SHe-specific antibodies can reduce RSV replication in vivo, mice were passively immunized with SHe-specific monoclonal antibodies. SHe-specific 3G8 monoclonal antibodies, isotype control antibodies or PBS were intranasally administered to mice one day before and one day after RSV Challenge. Three days after RSV challenge, blood was collected to test for the presence of mAbs in the serum of the treated mice. Four days after RSV challenge, the mice were sacrificed to determine the viral titer in the lungs. Peptide ELISA demonstrated the presence of low concentrations of SHe-specific and isotype control antibodies in the serum of mice treated with the respective antibodies (data not shown).
To test if SHe-based vaccines can also protect against RSV infections when this vaccine is administered via an alternative route with an alternative adjuvant and with a different carrier, the vaccine was tested intraperitoneally, with keyhole limpet hemocyanin (KLH) as a carrier. Maleimide-activated KLH (Pierce) was chemically linked to the peptide (CGGGSNKLSEYNVFHNKTFELPRARVNT (SEQ ID NO:50); the sequence corresponding to the RSV A SH ectodomain (SHe) is underlined) corresponding to the RSV A SH ectodomain. To promote directional chemical linking, a CysGlyGlyGlySer (SEQ ID NO:55) linker was added to the N-terminus of the RSV A SHe peptide. In addition, the cysteine residue present in the natural RSV A SHe was substituted by a serine residue. Chemical linkage was performed according to the manufacturer's instructions (Pierce). Cross-linked KLH-SHe proteins were isolated by size exclusion chromatography.
To test if intraperitoneal (I.P.) vaccination with a SHe-based vaccine can evoke protection against RSV infections, Balb/c mice (six mice per group) were vaccinated three times intraperitoneally with 20 μg of KLH-SHe or KLH, each in combination with 50 μl of Freund's Incomplete Adjuvant (Millipore). PBS vaccination without adjuvant was used as an additional negative control. Between the second and third week after vaccination, blood was collected to determine the induction of SHe-specific IgG antibodies. The presence of SHe-specific antibodies was determined and quantified by SHe peptide ELISA.
To test whether intraperitoneal KLH-SHe vaccination can reduce RSV infection, the vaccinated mice were infected with 1×106 PFU of RSV A2 four weeks after the last vaccination. Five days after challenge, the mice were sacrificed to determine the pulmonary RSV A2 titer by plaque assay.
To test if intranasal vaccination with KLH-SHe can evoke protection against RSV infections, Balb/c mice (six mice per group) were vaccinated three times intranasally with 20 μg of KLH-SHe or KLH, each in combination with 1 μg of LTR192G adjuvant. PBS vaccination without adjuvant was used as an additional negative control. Between the second and third week after vaccination, blood was collected to investigate the induction of SHe-specific IgG antibodies. The presence of SHe-specific antibodies was tested by SHe peptide ELISA.
To test whether intraperitoneal KLH-SHe vaccination can reduce RSV infection, the vaccinated mice were infected with 1×106 PFU of RSV A2 nine weeks after the last vaccination. Five days after challenge, the mice were sacrificed to collect BAL (Broncho Alveolar Lavage) fluid (3 ml). The RSV A2 titer in the collected BAL fluids was determined by plaque assay.
To further investigate if the reduction in RSV replication in mice that have been vaccinated with a SHe-based vaccine can be mediated by RSV SHe-specific antibodies, passive transfer experiments were performed. Balb/c mice were vaccinated intraperitoneally with 20 μg of either KLH-SHe or KLH, both in combination with 75 μl of Freund's Incomplete Adjuvant. As an additional negative control, mice were vaccinated with PBS without adjuvant. SHe peptide ELISA illustrated that the sera of all mice that had been vaccinated with KLH-SHe contains high levels of SHe-specific IgG antibodies. After final bleeding, the sera of the mice of each group were pooled and heat inactivated at 56° C. for 30 minutes. To test if KLH-SHe sera can protect against RSV infections, 40 μl of KLH or KLH-SHe sera were administered to mice intranasally one day before (day −1) and one day after (day 1) RSV challenge (2×105 PFU) (day 0). Mice that were treated with PBS were included as additional controls. The weight of all mice was monitored daily (
Although highly conserved within their subtype, the SHe amino acid sequences of RSV B viruses differs from that of the RSV A subtype viruses. Therefore, to protect against RSV B viruses, a SHe-based vaccine most likely needs to include the RSV B SHe amino acid sequence.
A RSV B SHe vaccine was constructed by chemically linking the consensus RSV B SHe peptide (SHeB: CGGGSNKLSEHKTFSNKTLEQGQMYQINT (SEQ ID NO:51) to the mHBc virus-like particles. To promote chemical linking, a CysGlyGlyGlySer (SEQ ID NO:55) linker was added to the N-terminus of the RSV B SHe peptide. In addition, the cysteine residue present in the natural RSV B SHe was substituted by a serine residue. The immunogen resulting from chemical linkage of the RSV B SHe peptide to mHBc was named mHBc-SHeB. After purification of the mHBc-SHeB VLPs by size exclusion chromatography, the degree of cross-linking was analyzed by SDS-PAGE gel electrophoresis and Coomassie staining.
To test whether mHBc-SHeB VLPs were immunogenic, one BALB/c mouse was immunized three times subcutaneously with 20 μg of mHBc-SHeB combined with 50 TITERMAX® (Sigma). The three immunizations were performed with two-week intervals. Bleedings were performed one day before each immunization and two weeks after the final immunization. To test whether mHBc-SHeB immune serum can recognize RSV B SH proteins expressed on the surface of infected cells, Vero cells were either mock infected or infected with a clinical isolate of RSV B virus (kindly provided by Dr. Marc van Ranst, University of Leuven, Leuven, Belgium). Seventy-two hours after infection, the cells were fixed and either permeabilized using 0.2% TRITON® X-100 or not permeabilized. The cells were then stained with either mHBc-SHeB immune serum (1/100 dilution) or control immune serum (1/100 dilution) derived from BALB/c mice that had been vaccinated with KLH (KLH serum) in combination with Freund's Incomplete Adjuvant. The samples were analyzed by immunofluorescent microscopy or flow cytometry.
To test whether mHBc-SHeB vaccination can protect mice from RSV B infection, two groups of six mice were immunized with mHBc or mHBc-SHeB VLPs, adjuvanted with 50 μl of Freund's Incomplete Adjuvant. As additional controls, six mice were vaccinated with PBS. Vaccinations were performed intraperitoneally, three times with three-week intervals. Bleedings were performed two weeks after each immunization. The induction of SHe-specific antibodies was determined by peptide ELISA using SHeA or SHeB as coating peptides. This analysis demonstrated that in all mice, three successive mHBc-SHeB immunizations induced high titers of RSV B SHe-specific IgG antibodies of both IgG1 and IgG2a subtype (
Previous experiments in our and other laboratories have illustrated that no or very little replicating virus can be rescued from RSV B-infected mice. Nevertheless, we could observe that infections with clinical RSV β isolates induce pulmonary inflammation and weight loss in BALB/c mice (data not shown). Therefore, we tested whether mHBc-SHeB vaccination could protect mice from RSV B-induced pulmonary inflammation. Six days after intranasal challenge of mice with 2×106 PFU of an RSV B clinical isolate, Broncho Alveolar Lavage (BAL) was performed. Mock-infected mice were used as negative control for analysis of BAL cell infiltration. The BAL fluid was analyzed for immune cell infiltration by flow cytometry as described in Bogaert et al., 2011.
As an alternative protein scaffold to present SHe as a pentamer, we used the pentameric tryptophan-zipper described by Liu et. al. (LPP(5)), which is derived from the E. coli LPP-56 lipoprotein (Liu et al., 2004). The coding sequence of the LPP(5) tryptophan-zipper was genetically fused to the SHe coding sequence and cloned into an E. coli expression vector (pLH36) containing a hexahistidine peptide and a caspase cleavage site as described by Mertens et al., 1995. This expression plasmid was named pLH36-HisDEVD-LPP-SHe (SEQ ID NO:49). Expression from this plasmid renders the chimeric LPP(5)-SHe protein (SEQ ID NO:52) (MHHHHHHPGGSDEVDAKWDQWSSDWQTWNAKWDQWSNDWNAWRSDWQAWK DDWARWNQRWDNWATGGNKLCEYNVFHNKTFELPRARVNT (SEQ ID NO:52), His-tag sequence is underlined, linkers are in italic, DEVD caspase cleavage site is in italic+underlined, pentameric LPP tryptophan-zipper is in bold and the RSV A SH ectodomain is in bold+italic). After induction of expression in E. coli, the LPP(5)-SHe protein was purified by subsequent Nickel affinity, anion-exchange and gel filtration chromatography.
In order to prove the efficacy of the vaccine in an independent animal model, cotton rats are used. Cotton rats (Sigmondon hispidus) are susceptible to RSV infection (Prince et al., 1978). Five groups of six cotton rats each are used. Two groups of animals are immunized intraperitoneally (i.p.) with 100 μg of KLH (vehicle control) or 100 μg of KLH-SHe (i.e., a chemical conjugate of SHe peptide derived from RSV-A with KLH as a carrier). KLH and KLH-SHe vaccine antigens are formulated with Freund's Incomplete Adjuvant and used to immunize cotton rats on days 0, 21, and 42. A third group of animals is immunized intramuscularly with formalin-inactivated RSV (FI-RSV) in the presence of alum adjuvant. The latter group serves as a positive control for the induction of vaccine-enhanced disease that becomes apparent upon subsequent challenge with RSV. A fourth group is infected with 2.04×105 plaque forming units per cotton rat of RSV-Tracy on day 0 and serves as positive control for protection against subsequent challenge. A fifth group of cotton rats remains untreated until the day of challenge and served as control for the challenge with RSV. The schedule of the vaccination is shown in
Sera are collected before each immunization and on the day of challenge. On day 63, cotton rats are challenged intranasally with 2.04×105 plaque forming units of RSV-Tracy. The challenge virus is administered intranasally in a volume of 100 microliters while the animals are lightly anesthetized with isofluorane. On day 68, serum is collected and all animals are sacrificed to collect lungs for virus titration and histopathological analysis. Each lung is divided in two to perform histopathological analysis and virus titration. The left lungs are tied off and used for histopathological analysis. The lobes of the right lung are lavaged using 3 ml of Iscove's media with 15% glycerin. The lavage fluid is stored on ice until titration. In addition, nasal lavages are prepared with 2 ml (1 ml for each nare) in the same medium.
The viral load in the lung and nasal lavages is determined by plaque assay on HEp2 cells. Cells are infected for 90 minutes with a serial dilution of the lavage samples. After removal of the inoculum, the cells are overlaid with 2% methylcellulose in MEM-containing antibiotics. After six days of incubation at 37° C. in a CO2-incubator, plaques are counterstained with 0.1% crystal violet/10% formalin solution and left at room temperature for 24 hours.
For histopathological analysis, the left lung is perfused with 10% neutral buffered formalin. Fixed lung tissue is subsequently processed with a microtome to produce sections that are stained with hematoxilin and eosin and scored for the degree of histopathological lesions.
Serum samples are assayed for the presence of anti-SHe- and anti-RSV-neutralizing antibodies by peptide ELISA and by a microneutralization assay. For peptide ELISA, plates are coated overnight at 37° C. with 2 μg of SHe-peptide in 50 μl of 0.1 M carbonate buffer pH 9.6. After coating, plates are blocked with 3% (w/v) milk powder in PBS, followed by application of three-fold serial dilutions on cotton rat sera. Retained SHe-specific cotton rat IgG are detected using horseradish peroxidase conjugated secondary antibodies and tetramethylbenzidine substrate. The endpoint anti-SHe peptide IgG titer in the samples is defined as the highest dilution for which the absorbance is at least twice as high as that of the pre-immune serum.
Neutralizing antibody titers are determined for RSV-A and -B in 96-well microtiter plates with HEp2 cells. Serial dilutions of serum samples are mixed with a fixed amount of inoculum virus. The neutralizing antibody titer is defined as the serum dilution at which >50% reduction is cytopathic effect is observed. This cytopathic effect refers to the destruction of cells and is determined visually after the cells are fixed with 10% neutral buffered formalin and stained with crystal violet. The results show that the animals, vaccinated with KLH-SHe in Freund's Adjuvant develop neutralizing antibodies and are clearly protected, whereas the vehicle control shows no protection at all.
| Number | Date | Country | Kind |
|---|---|---|---|
| 1019240.9 | Nov 2010 | GB | national |
This application is a national phase entry under 35 U.S.C. §371 of International Patent Application PCT/EP2011/070161, filed Nov. 15, 2011, designating the United States of America and published in English as International Patent Publication WO 2012/065997 A1 on May 24, 2012, which claims the benefit under Article 8 of the Patent Cooperation Treaty to Great Britain Patent Application Serial No. 1019240.9, filed Nov. 15, 2010, and under Article 8 of the Patent Cooperation Treaty and under 35 U.S.C. §119(e) to U.S. Provisional Patent Application Ser. No. 61/458,012, filed Nov. 15, 2010.
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/EP2011/070161 | 11/15/2011 | WO | 00 | 8/7/2013 |
| Publishing Document | Publishing Date | Country | Kind |
|---|---|---|---|
| WO2012/065997 | 5/24/2012 | WO | A |
| Number | Name | Date | Kind |
|---|---|---|---|
| 7510863 | Samal et al. | Mar 2009 | B2 |
| 20070184069 | Buchholz et al. | Aug 2007 | A1 |
| 20090285853 | Cheng et al. | Nov 2009 | A1 |
| Number | Date | Country |
|---|---|---|
| 2008106980 | Sep 2008 | WO |
| 2008133663 | Nov 2008 | WO |
| 2009092113 | Jul 2009 | WO |
| WO 2012-065997 | May 2012 | WO |
| Entry |
|---|
| Collins et al., J Gen Virol 1993 vol. 74, pp. 1445-1450. |
| Pringle C R et al: Immunogenicity and Pathogenicity of a Triple Temperature-Sensitive Modified Respiratory Syncytial Virus in Adult Volunteers, Vaccine. Elsevier Ltd. GB, vol. 11, No. 4. Mar. 1, 1993, pp. 473-478. |
| Power U F et al: Induction of Protective Immunity in Rodents by Vaccination with a Prokaryotically Expressed Recombinant Fusion Protein Containing a Respiratory Syncytial Virus G Protein Fragment, Virology. Academic Press. Orlando. US, vol. 230, No. 2. Apr. 14, 1997, pp. 155-166. |
| Bastien N et al: Complete protection of mice from respiratory syncytial virus infection following mucosal delivery of synthetic peptide vaccines, Vaccine. Elsevier Ltd. GB, vol. 17, No. 7-8. Feb. 26, 1999, pp. 832-836. |
| Singh et al: Immunogenicity and efficacy of recombinant RSV-F vaccine in a mouse model, Vaccine. Elsevier Ltd. GB, vol. 25. No. 33. Jul. 24, 2007, pp. 6211-6223. |
| Edward E. Walsh: Respiratory Syncytial Virus Vaccine, Encyclopedia of Molecular Cell Biology and Molecular Medicine. 2nd Edition, vol. 12, 2005, pp. 297-322. |
| Woo W-P et al: Hepatitis B Surface Antigen Vector Delivers Protective Cytotoxic T-Lymphocyte Responses to Disease-Relevant Foreign Epitopes, Journal of Virology. The American Society for Microbiology. US, vol. 80, No. 8. Apr. 1, 2006, pp. 3975-3984. |
| Schmidt A C et al: Mucosal immunization of Rhesus monkeys against respiratory syncytial virus subgroups A and B and human parainfluenza virus type 3 by using a live eDNA-derived vaccine based on a host range-attenuated bovine parainfluenza virus type 3 vector backbone, Journal of Virology. The American Society for Microbiology. US, vol. 76, No. 3. Feb. 1, 2002, pp. 1089-1099. |
| Yoshihiko Murata: Respiratory Syncytial Virus Vaccine Development, Clinics in Laboratory Medicine, vol. 29, No. 4, Dec. 1, 2009, pp. 725-739. |
| Initiative for Vaccine Research (IVR), Acute Respiratory infections (Update Sep. 2009) available at http://www.who.int/vaccine—research/diseases/ari/en/index2.html, printed May 14, 2013. |
| PCT International Search Report, PCT/EP2011/070161, dated Mar. 9, 2012. |
| Fuentes et al. (2007) “Function of the Respiratory Syncytial Virus Small Hydrophobic Protein,” Journal of Virology. 81(15):8361-8366. |
| Office Action corresponding to Japanese Patent Application No. 2013-538235, mailed Sep. 29, 2015—with English translation. |
| Gan et al. (2008) “Structure and Ion Channel Activity of the Human Respiratory Syncytial Virus (hRSV) Small Hydrophobic Protein Transmembrane Domain,” Protein Science. 17:813-820. |
| Olmsted et al. (1989) “The 1A protein of respiratory syncytial virus is an integral membrane protein present as multiple, structurally distinct species,” J. Virol. 63(5):2019-2029. |
| Rixon et al. (2004) “The small hydrophobic (SH) protein accumulates within lipid-raft structures of the Golgi complex luring respiratory syncytial virus infection,” J. Gen. Virol. 85:1153-1165. |
| Rixon et al. (2005) “The respiratory syncytial virus small hydrophobic protein is phosphorylated via a mitogen-activated protein kinase p38-dependent tyrosine kinase activity during virus infection,” J. Gen. Virol. 86:375-384. |
| Examination Report corresponding to Australian Patent Application No. 2011331251, issued Apr. 15, 2016. |
| Number | Date | Country | |
|---|---|---|---|
| 20130315916 A1 | Nov 2013 | US |
| Number | Date | Country | |
|---|---|---|---|
| 61458012 | Nov 2010 | US |
