RSV F/G CHIMERIC VACCINE

Abstract

A novel vaccine antigen for prevention of Respiratory Syncytial Virus (RSV) infection is created which surpasses conventional vaccines comprising as an antigen RSV F protein alone in view of efficacy and/or safety. A vaccine is prepared which comprises as an antigen a RSV F/G chimeric protein wherein a portion of RSV F protein as a basic structure is replaced with a whole or a portion of Conserved Central Domain sequence of RSV G protein or wherein a whole or a portion of Conserved Central Domain sequence of RSV G is added to the basic structure. As a result of assessment of both efficacy and safety, a vaccine comprising as an antigen the F/G chimeric protein of the present invention confirmed to be more excellent than a vaccine comprising as an antigen RSV F protein alone in view of efficacy and/or safety.

Claims

1. A chimeric protein (RSV F/G protein) of Respiratory Syncytial Virus (RSV) F protein and G protein wherein a portion of RSV F protein as a basic structure is replaced with a whole or a portion of CCD sequence of RSV G protein or wherein a whole or a portion of CCD sequence of RSV G is added to the basic structure.

2. The chimeric protein of claim 1 wherein an amino acid sequence of the F protein comprises a sequence having a homology of 90% or more to the amino acid sequence of SEQ ID NO: 1.

3-25. (canceled)

26. The chimeric protein of claim 2 wherein a portion of the basic structure is replaced with a whole or a portion of RSV G protein at positions 158 to 199 of SEQ ID NO: 2 or wherein a whole or a portion of RSV G at positions 158 to 199 is added to the basic structure.

27. The chimeric protein of claim 2 wherein a portion of the basic structure is replaced with RSV G protein at positions 162 to 171 of SEQ ID NO: 2 or wherein RSV G at positions 162 to 171 is added to the basic structure.

28. The chimeric protein of claim 2 wherein a portion of FP domain of the RSV F protein is replaced with RSV G protein at positions 162 to 171 of SEQ ID NO: 2.

29. The chimeric protein of claim 1 wherein the sequence of RSV F protein corresponding to the amino acid sequence at positions 137 to 146 of SEQ ID NO: 1 is replaced with RSV G protein at positions 162 to 171 of SEQ ID NO: 2.

30. The chimeric protein of claim 2 wherein RSV G protein at positions 162 to 171 of SEQ ID NO: 2 is added to the C-terminal of the RSV F protein.

31. The chimeric protein of claim 2 wherein a portion of the basic structure is replaced with RSV G protein at positions 187 to 197 of SEQ ID NO: 2 or wherein RSV G at positions 187 to 197 is added to the basic structure.

32. The chimeric protein of claim 2 wherein a portion of FP domain of the RSV F protein is replaced with RSV G protein at positions 187 to 197 of SEQ ID NO: 2.

33. The chimeric protein of claim 1 wherein the sequence of RSV F protein corresponding to the amino acid sequence at positions 137 to 146 of SEQ ID NO: 1 is replaced with RSV G protein at positions 187 to 197 of SEQ ID NO: 2.

34. The chimeric protein of claim 2 wherein RSV G protein at positions 187 to 197 of SEQ ID NO: 2 is added to the C-terminal of the RSV F protein.

35. The chimeric protein of claim 2 wherein a portion of FP domain of the RSV F protein is replaced with a sequence consisting of the sequences of RSV G protein at positions 162 to 172 and 187 to 199 of SEQ ID NO: 2 linked to each other via a linker.

36. The chimeric protein of claim 2 wherein a portion of FP domain of the RSV F protein is replaced with a sequence consisting of the sequences of RSV G protein at positions 162 to 172 and 187 to 199 of SEQ ID NO: 2 linked to each other via a linker of GGGGS (SEQ ID NO: 5) or EAAAK (SEQ ID NO: 6).

37. The chimeric protein of claim 2 wherein a sequence consisting of the sequences of RSV G protein at positions 162 to 172 and 187 to 199 of SEQ ID NO: 2 linked to each other via a linker is added to the C-terminal the RSV F protein.

38. The chimeric protein of claim 2 wherein a sequence consisting of the sequences of RSV G protein at positions 162 to 172 and 187 to 199 of SEQ ID NO: 2 linked to each other via a linker of GGGGS (SEQ ID NO: 5) or EAAAK (SEQ ID NO: 6) is added to the C-terminal of the RSV F protein.

39. The chimeric protein of claim 1 wherein a portion of FP domain of the RSV F protein comprising the amino acid sequence of SEQ ID NO: 1 is replaced with a sequence consisting of the sequences of RSV G protein at positions 162 to 172 and 187 to 199 of SEQ ID NO: 2 linked to each other.

40. The chimeric protein of claim 1 wherein a sequence consisting of the sequences of RSV G protein at positions 162 to 172 and 187 to 199 of SEQ ID NO: 2 linked to each other is added to the C-terminal of the RSV F protein comprising the amino acid sequence of SEQ ID NO: 1.

41. The chimeric protein of claim 1 wherein the sequence of RSV F protein corresponding to the sequence at positions 137 to 146 of SEQ ID NO: 1 is replaced with RSV G protein at positions 162 to 171 and wherein amino acid modifications of K419N, K421T, and G430T are made.

42. The chimeric protein of claim 1 wherein the sequence of RSV F protein corresponding to the sequence at positions 137 to 146 of SEQ ID NO: 1 is replaced with RSV G protein at positions 162 to 171 and wherein amino acid modifications of K419N, K421T, and T434N and S436T are made.

43. The chimeric protein of claim 1 wherein an amino acid sequence of a whole or a portion of the CCD sequence comprises a sequence selected from the group consisting of the sequences at positions 158 to 199, 162 to 197, 164 to 190, 164 to 186, 164 to 176, 173 to 197, 187 to 197, 173 to 186, and 162 to 171 of SEQ ID NO: 2, a sequence consisting of the sequences at positions 162 to 172 and 187 to 199 of SEQ ID NO: 2 linked to each other, a sequence consisting of the sequences at positions 164 to 172 and 187 to 197 of SEQ ID NO: 2 linked to each other, a sequence consisting of the sequences at positions 162 to 172, 187 to 199 and 162 to 172 of SEQ ID NO: 2 linked to each other, and a sequence consisting of two or three of the sequences at position 162 to 172 of SEQ ID NO: 2 linked to each other.

44. The chimeric protein of claim 1 wherein a glycosylation site is introduced into the vicinity of siteIV of the F protein, i.e. at positions 419 to 468 of SEQ ID NO: 1.

45. The chimeric protein of claim 44 wherein an amino acid modification for introduction of the glycosylation site of siteIV is any one of the following (1) to (7): (1) G430T/S (2) K419N, and K421T/S (3) K427N, and R429T/S (4) T434N, and S436T/S (5) K419N, K421T/S, and G430T/S (6) K419N, K421T/S, and K427N and R429T/S (7) K419N, K421T/S, and T434N and S436T/S.

46. An RSV vaccine comprising as an antigen the chimeric protein of claim 1.

47. The RSV vaccine of claim 46 wherein the vaccine has a lower exacerbation tendency of RSV infection than RSV F protein.

48. The chimeric protein of claim 44 wherein an amino acid modification for introduction of the glycosylation site of siteIV of the F protein is the following (1) or (2): (1) K419N, K421T, and G430T (2) K419N, K421T, and T434N and S436T.

49. The chimeric protein of claim 44 wherein an amino acid modification for introduction of the glycosylation site of siteIV of the F protein is K419N, K421T, and G430T.

50. The chimeric protein of claim 44 wherein an amino acid modification for introduction of the glycosylation site of siteIV of the F protein is K419N, K421T, and T434N and S436T.

51. The RSV vaccine of claim 46 wherein the vaccine has a higher complement-dependent neutralization titer than that of RSV F protein.

52. A fragment DNA coding for the chimeric protein of claim 1.

53. An expression vector comprising the fragment DNA of claim 52.

54. A cell transfected with the fragment DNA of claim 52.

55. A cell transfected with the expression vector of claim 53.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0054] FIG. 1 shows schematic diagrams of RSV F/G chimeric protein sequences.

[0055] FIG. 2 shows schematic diagrams of RSV G protein sequences (Nos. 1 to 9) to be a portion of the RSV F/G chimeric protein.

[0056] FIG. 3 shows schematic diagrams of RSV G protein sequences (Nos. 10 to 14) to be a portion of the RSV F/G chimeric protein.

[0057] FIG. 4 shows schematic diagrams of RSV G protein sequences (Nos. 15 to 18) to be a portion of the RSV F/G chimeric protein.

[0058] FIG. 5 is a list of expression levels of RSV F/G chimeric proteins.

[0059] FIG. 6 is a list of expression levels of RSV F/G chimeric proteins.

[0060] FIG. 7 shows the results of SDS-PAGE of RSV F/G chimeric proteins.

[0061] FIG. 8 shows the results of SDS-PAGE of RSV F/G chimeric proteins.

[0062] FIG. 9 shows the results of SDS-PAGE of RSV F/G chimeric proteins.

[0063] FIG. 10 shows the results of SDS-PAGE of RSV F/G chimeric proteins.

[0064] FIG. 11 shows the results of SDS-PAGE of RSV F/G chimeric proteins.

[0065] FIG. 12 shows the results of SDS-PAGE of RSV F/G chimeric proteins.

[0066] FIG. 13 shows the results of SDS-PAGE of RSV F/G chimeric proteins.

[0067] FIG. 14 shows the results of SDS-PAGE of RSV F/G chimeric proteins.

[0068] FIG. 15 shows the results of Western blot of RSV F/G chimeric proteins.

[0069] FIG. 16 shows electron microscopic images of RSV F/G chimeric proteins.

[0070] FIG. 17 shows the results of ELISA test of RSV F/G chimeric proteins.

[0071] FIG. 18 shows the results of ELISA test of RSV F/G chimeric proteins.

[0072] FIG. 19 shows the results of neutralization test of RSV F/G chimeric protein immune sera.

[0073] FIG. 20 shows the results of complement-dependent neutralization test of RSV F/G chimeric protein immune sera.

[0074] FIG. 21 shows the results of subclass analysis of anti-RSV F protein antibodies contained in RSV F/G chimeric protein immune sera.

[0075] FIG. 22 shows an evaluation of an anti-RSV G protein antibody induced by immunization with RSV F/G chimeric proteins.

[0076] FIG. 23 shows the results of test in protection against infection of RSV F/G chimeric vaccines.

[0077] FIG. 24 shows the results of test in protection against infection of RSV F/G chimeric vaccines.

[0078] FIG. 25 shows the results of test in protection against infection of RSV F/G chimeric vaccines.

[0079] FIG. 26 shows the results of evaluating infection suppressing ratios of RSV F/G chimeric vaccines.

[0080] FIG. 27 shows the results of SDS-PAGE of RSV F/G chimeric proteins.

[0081] FIG. 28 shows the results of SDS-PAGE of RSV F/G chimeric proteins.

[0082] FIG. 29 shows the results of SDS-PAGE of RSV F/G chimeric proteins.

[0083] FIG. 30 shows the results of SDS-PAGE of RSV F/G chimeric proteins.

[0084] FIG. 31 shows the results of SDS-PAGE of RSV F/G chimeric proteins.

[0085] FIG. 32 shows the results of SDS-PAGE of RSV F/G chimeric proteins.

[0086] FIG. 33 shows the results of SDS-PAGE of RSV F/G chimeric proteins.

[0087] FIG. 34 shows the results of SDS-PAGE of RSV F/G chimeric proteins.

[0088] FIG. 35 shows the results of SDS-PAGE of RSV F/G chimeric proteins.

[0089] FIG. 36 shows the results of SDS-PAGE of RSV F/G chimeric proteins.

[0090] FIG. 37 shows the results of SDS-PAGE of RSV F/G chimeric proteins.

[0091] FIG. 38 shows the results of SDS-PAGE of RSV F/G chimeric proteins.

[0092] FIG. 39 shows the results of SDS-PAGE of RSV F/G chimeric proteins.

[0093] FIG. 40 shows the results of ELISA test of RSV F/G chimeric proteins.

[0094] FIG. 41 shows the results of ELISA test of RSV F/G chimeric proteins.

[0095] FIG. 42 shows the results of complement-dependent neutralization test of RSV F/G chimeric protein immune sera.

[0096] FIG. 43 shows the results of evaluating infection enhancement of RSV F/G chimeric vaccines.

BEST MODE FOR CARRYING OUT THE INVENTION

Definitions

[0097] As used herein, the term “enhancement of infection” refers to an increase in infectivity titer or viral copy number when an antigen is immunized and then infected with RSV as compared with a control group infected with RSV without immunizing the antigen.

[0098] As used herein, the term “RSV F/G-W-X-Y Z” is a name based on characteristics of RSV F/G chimeric protein. “W” represents a substitution position with G protein or an addition position of G protein in RSV F protein (basic structure) by alphabets A to D (FIG. 1). In the case of two letters of the alphabet, it means that there are substitutions with G protein or additions of G protein at two positions. For example, the case of “AD” means that there are substitutions or additions at positions of A and D. “X” represents an RSV G protein sequence substituting the basic structure or added to the basic structure with the number of 1 to 18 (FIGS. 2 to 4). When there are two numbers, it means that there are substitutions or additions in two corresponding G protein sequences. For example, the case of “RSV F/G-AD-9/7” means that there are substitutions with, or additions of, “9 at position A” and “7 at position D”. When there is no substitution with G protein or addition of G protein, it is represented by 0. “Y” represents amino acid modification of RSV F protein accompanied by a sugar chain modification, by the number 0 to 4, and specifically means “0: no modification, 1: K419N, K421T and G430T, 2: K419N, K421T, T434N and S436T, 3: K421N and G430T, 4: K419N, K421T, K427N, and R429T”. Here, for example, the notation “K419N” indicates that lysine (K) at position 419 of the RSV F protein is substituted with asparagine (N). Also, for example, the notation “K421T/S” indicates that lysine (K) at position 421 is substituted with threonine (T) or serine (S). Note that “Z” represents other modifications or the number and type of linkers. Specifically, as other modifications, one obtained by deleting 136 amino acids of RSV F protein is denoted by Δ136aa, and one obtained by substituting arginine at position 136 with glutamine is denoted by R136Q. The number of linkers is shown as “0: 0, 1: 1, 2: 2, 3: 3, 4: 4”, and the number of linkers is shown in order from the left side of three linker insertion positions of Nos. 12 and 13 in FIG. 3. For example, when the numbers of linkers are 0, 4, and 0, it is indicated as “040”. In addition, the type of linker is shown as “GGGGS linker: G, EAAAK linker: E”, and is shown in order from the left side of three or four linker insertion positions of No. 14 in FIG. 3 and Nos. 17 and 18 in FIG. 4, and a separator between the linker and the G protein sequence is represented using “/” to show the type of linker. Then, when there is an amino acid mutation at the end of the name, for example, the notation “N191S”, it indicates that N at position 191 of SEQ ID NO: 1 is substituted with S. Moreover, “Seq11” at the end of the name indicates a G protein sequence of SEQ ID NO: 11.

[0099] Hereinafter, preferred embodiments of the present invention will be described in detail. However, the present invention is not limited to the following embodiments.

(RSV F/G Chimeric Vaccine)

[0100] The vaccine (RSV F/G chimeric vaccine) according to the present embodiment is a formulation using a recombinant RSV F/G chimeric protein obtained by using RSV F protein as a basic structure, and substituting a portion of the basic structure with a whole or a portion of a CCD sequence of RSV G protein, or adding a whole or a portion of the CCD sequence to the basic structure, as an antigen. Here, “adding” includes the meaning of “inserting”, and “substituting” or “adding” may be via a linker with the basic structure. An example of the amino acid sequence of the linker includes GGGGS (SEQ ID NO: 5) or EAAAK (SEQ ID NO: 6).

[0101] Examples of a substitution position with the G protein or an addition position of the G protein in the RSV F protein (basic structure) include an FP domain of the F protein, an FP domain and a p27 domain of the F protein (RSV F/G-A in FIG. 1), specifically, positions 137 to 146 of the F protein, an F1 domain of the F protein, specifically, positions 382 to 393 (RSV F/G-B in FIG. 1) or positions 425 to 436 of the F protein (RSV F/G-C in FIG. 1), and the C-terminus of the F protein (RSV F/G-D in FIG. 1). In addition, the substitution position with the G protein or the addition position of the G protein in the RSV F protein (basic structure) may be a position away from a known epitope on the three-dimensional structure of the protein, and examples thereof include RSV F/G-A, RSV F/G-D, and the like. Alternatively, it may be a conspicuous position (known epitope or the like) as a protein antigen, for example, RSV F/G-B (position of antigenic siteI), RSV F/G-C (position of antigenic siteIV), or the like. The substitutions of RSV F/G-B and RSV F/G-C may be a whole or a portion of amino acid residues 382 to 393 and 425 to 436 shown in FIG. 1.

[0102] The RSV F/G chimeric vaccine has excellent infection protective ability as compared with that of a vaccine using the post F protein as an antigen, and has infection protective ability equal to or higher than that of a vaccine using the pre F protein as an antigen. Surprisingly, the RSV F/G chimeric protein vaccine suppresses enhancement of RSV infection after vaccination, as compared with a vaccine using the post F protein and the pre F protein as antigens.

[0103] Examples of sequences of the RSV F protein used as the basic structure include sequences derived from known wild-type RSV strains or clinical isolates. For example, the sequence may be a sequence registered in databases of GenBank, European Bioinformatics Institute (EBI), and DNA Data Bank of Japan (DDBJ). Examples of representative sequences of the RSV F protein include a sequence set forth in SEQ ID NO: 1. The RSV F protein is generally composed of sites called an SP domain, an F2 domain, a p27 domain, an FP domain, an F1 domain, a TM domain, and a CT domain, in order from the N-terminus.

[0104] Examples of sequences of the RSV G protein to be a portion of the RSV F/G chimeric protein include sequences derived from known wild-type RSV strains or clinical isolates. For example, the sequence may be a sequence registered in databases of GenBank, European Bioinformatics Institute (EBI), and DNA Data Bank of Japan (DDBJ). Examples of representative sequences of the RSV G protein include a sequence set forth in SEQ ID NO: 2 (Human respiratory syncytial virus A2, UniProtKB/Swiss-Prot: Accession No. P03423). In addition, as a representative sequence of G-protein CCD of an RSV B strain, there are a sequence set forth in SEQ ID NO: 11 (Human respiratory syncytial virus B (strain B1), UniProtKB/Swiss-Prot: Accession No. 036633), and the like.

[0105] The RSV F/G chimeric protein according to the present invention is prepared by substituting a portion of the RSV F protein with a whole or a portion of the CCD sequence of the RSV G protein, or adding a whole or a portion of the CCD sequence to the RSV F protein. Here, a whole or a portion of the CCD sequence of the RSV G protein substituted or added may be a sequence derived from a region including a central conserved region (CCR) (amino acid residues 164 to 176 of the RSV G protein) that are sequence regions particularly highly conserved in a sequence of CCD of the RSV G protein (amino acid residues 158 to 199 of the RSV G protein) highly conserved among RSV strains, or a CX3C motif (amino acid residues 182 to 186 of the RSV G protein), for example, a sequence derived from amino acid residues 158 to 199 of the RSV G protein. More specifically, in the present invention, a whole or a portion of the CCD sequence may include, for example, a sequence at positions 158 to 199 of SEQ ID NO: 2, a sequence at positions 162 to 197, a sequence at positions 164 to 190, a sequence at positions 164 to 186, a sequence at positions 164 to 176, a sequence at positions 173 to 197, a sequence at positions 187 to 197, a sequence at positions 173 to 186, a sequence at positions 162 to 171, one in which a sequence at positions 162 to 172 and a sequence at positions 187 to 199 are linked, one in which a sequence at positions 164 to 172 and a sequence at positions 187 to 197 are linked, or one in which two to three sequences at positions 162 to 172 are linked (FIGS. 2 to 4). In the present invention, a whole or a portion of the CCD sequence may have a homology of 75% or more, preferably 85% or more, and more preferably 90% or more with a sequence comprising each of the sequences. The sequence of the F protein may be different from that of SEQ ID NO: 1 by about 90% depending on a known wild-type strain. In addition, although the CCD sequence of the G protein is conserved among virus strains, a portion of the CCD sequence excluding the CCR sequence may be different between known wild strains and clinical isolates by about 75% as compared with SEQ ID NO: 2. In addition, the RSV F protein is generally composed of sites called an SP domain, an F2 domain, a p27 domain, an FP domain, an F1 domain, a TM domain, and a CT domain, in order from the N-terminus, but the TM and CT domains on the C-terminal side are regions that do not go out of the cell, and thus may not comprise these domains.

[0106] The RSV F/G chimeric protein according to the present invention can also improve expression level by modifying glycosylation of the RSV F protein. The modification of glycosylation may be one in which an N-type sugar chain is added to an amino acid residue N (Asn) and an O-type sugar chain is added to an amino acid residue T (Thr)/S (Ser). Modification (mutation) can be added to the RSV F protein for the modification of glycosylation, and the amino acid sequence after modification may comprise an amino acid sequence motif of N (Asn)-α (amino acid other than Pro)-T (Thr) or N (Asn)-α (amino acid other than Pro)-S (Ser).

[0107] The position where a modification (mutation) is added to the RSV F protein for modification of glycosylation is preferably around positions 422 to 468 (Non-Patent Documents 21, 22, and 24) of the RSV F protein called siteIV span to which monoclonal antibody 101F or the like to the RSV F protein specifically binds, that is, positions 419 to 468 of the RSV F protein, and a more preferable position is an amino acid residue at any of positions 419 to 436 of the RSV F protein. Specifically, it is preferable to add modification (mutation) to any of the following amino acid residues (1) to (7).

(1) G430T/S

(2) K419N and K421T/S

(3) K427N and R429T/S

(4) T434N and S436T/S

(5) K419N, K421T/S, and G430T/S

(6) K419N, K421T/S, and K427N and R429T/S

(7) K419N, K421T/S, and T434N and S436T/S

[0108] In particular, it is preferable to add modification of glycosylation by mutagenesis of “K419N, K421T, K427N and R429T”, “K419N, K421T and G430T”, and “K419N, K421T, T434N and S436T”.

[0109] The RSV F/G chimeric vaccine comprises a protein derived from an expression system using E. coli, lactic acid bacteria, yeast, plant cells, insect cells or animal cells as a host. For example, the protein may be a protein derived from an expression system using E. coli (Escherichia coli), budding yeast (Saccharomyces cerevisiae), Pichia yeast (Pichia pastoris), fission yeast (Schizosaccharomyces pombe), Sf9 cells, Hi-5 cells, Chinese Hamster Ovary (CHO) cells, Baby hamster kidney (BHK) cells, C127 cells, NS0 cells, SP2 cells, MDCK cells, EB66 cells, Vero cells, GL-37 cells, HT-1080 cells, HEK293 cells, human lymphoblasts or human normal diploid fibroblast cells as a host.

[0110] The RSV F/G chimeric vaccine can also comprise an adjuvant. The adjuvant may be, for example, poly(I:C), MPL, RC529, GLA, E6020, flagellin, imiquimod, R848, CpG ODN, QS21, TDB, α-Galactosylceramide, aluminum hydroxide, aluminum phosphate, MF59, AS03, AF03, SE, bilosome, AS01, AS02, AS04, AS15, GLA-SE, IC31, CAF01, ISCOMs, or a combination thereof.

[0111] The RSV F/G chimeric vaccine can also comprise an additive. The additive may be, for example, an amino acid, saccharides, a surfactant, or a combination thereof.

[0112] Dosage form of the RSV F/G chimeric vaccine may be, for example, a liquid form, a powder form (lyophilized powder, dried powder), a capsule form, a tablet, or a frozen state, but is not limited thereto.

[0113] The RSV F/G chimeric vaccine can also comprise a pharmaceutically acceptable carrier. Such a carrier may be, for example, saline, buffered saline, dextrose, water, glycerol, isotonic aqueous buffer, emulsifier, pH adjuster, or a combination thereof.

[0114] A method for administering the RSV F/G chimeric vaccine may be a method of administering by a syringe, a transdermal patch, a microneedle, an implantable sustained release device, a syringe with a microneedle, a needleless device, a nasal spray, or oral or sublingual route.

[0115] Examples of mammals to be inoculated with the RSV F/G chimeric vaccine include mouse, rat, guinea pig, hamster, rabbit, cat, dog, sheep, pig, cow, horse, goat, monkey, human, and the like. The RSV F/G chimeric vaccine of the present invention is most preferably used for a human, and can also be used for pregnant women, infants, children under the age of 5, and adults over the age of 65, in addition to persons of the age of 5 to 64 regardless of gender.

[0116] The number of administrations of the RSV F/G chimeric vaccine of the present invention varies depending on the purpose of administration, administration method, and situation of the administration target (gender, age, weight, medical condition), and when administered to a human, the RSV F/G chimeric vaccine may be administered once, twice, or three times.

[0117] Hereinafter, the present invention will be described in detail with reference to examples, but the present invention is not limited to these examples at all.

(Materials and Methods of Examples)

1. Cloning, Construction of Plasmids and Expression Vectors

[0118] A DNA fragment encoding a sequence comprising amino acid residues 1 to 524 of RSV F protein, a flag tag and a his tag was prepared by outsourcing. Using this fragment DNA as a template, assembly PCR was performed using a mutagenesis primer or an oligo DNA synthesis product, and fragment DNAs encoding a sequence comprising each of RSV WT F (prepared using RSV F protein 1-513 amino acid residues among an amino acid sequence (CAA26143) of hRSV F protein reported in Non-Patent Document 18; SEQ ID NO: 1), RSV post F protein (prepared using RSV F protein 1-513 amino acid residues among an amino acid sequence of SEC ID No. 1 described in Patent Document 4; SEQ ID NO: 3), and RSV pre F protein (prepared using RSV F protein 1-513 amino acid residues among an amino acid sequence of SEC ID No. 383 described in Patent Document 4; SEQ ID NO: 4. The RSV pre F was a sequence comprising a trimerization sequence, a his tag sequence, and a Strep tag sequence contained in the sequence described in the same patent document. Note that a sequence comprising a flag tag and a his tag is not contained.) and the RSV F/G chimeric protein were prepared (the RSV F protein was substituted or added to the CCD of SEQ ID NO: 2 or SEQ ID NO: 11 of the RSV G protein, using SEQ ID NO: 1 as a structure. And the RSV F protein was substituted or added to a partial variant of the CCD of SEQ ID NO: 2 of the RSV G protein, using SEQ ID NO: 1 as a structure). The fragment DNA and a pCAGGS1.dhfr.neo vector cleaved by SalI (Patent Document 8, KM Biologics Co., Ltd.) were linked using In-Fusion® HD Cloning Kit (Takara Bio Inc.) to prepare an animal cell expression vector. Plasmid DNA preparation was carried out by cloning using E. coli JM109 competent cell (Toyobo Co., Ltd.).

TABLE-US-00001 TABLE 1 RSV WT F MELLILKANAITTILTAVTFCFASGQNITEEFYQSTCS SEQ ID NO. AVSKGYLSALRTGWYTSVITIELSNIKENKCNGTDAKV 1 KLIKQELDKYKNAVTELQLLMQSTPATNNRARRELPRF MNYTLNNAKKTNVTLSKKRKRRFLGFLLGVGSAIASGV AVSKVLHLEGEVNKIKSALLSTNKAVVSLSNGVSVLTS KVLDLKNYIDKQLLPIVNKQSCSISNIETVIEFQQKNN RLLEITREFSVNAGVTTPVSTYMLTNSELLSLINDMPI TNDQKKLMSNNVQIVRQQSYSIMSIIKEEVLAYVVQLP LYGVIDTPCWKLHTSPLCTTNTKEGSNICLTRTDRGWF CDNAGSVSFFPQAETCKVQSNRVFCDTMNSLTLPSEVN LCNVDIFNPKYDCKIMTSKTDVSSSVITSLGAIVSCYG KTKCTASNKNRGIIKTFSNGCDYVSNKGVDTVSVGNTL YYVNKQEGKSLYVKGEPIINFYDPLVFPSDEFDASISQ VNEKINQSLAFIRKSDELL RSV G MSKNKDQRTAKTLERTWDTLNHLLFISSCLYKLNLKSV SEQ ID NO. AQITLSILAMIISTSLIIAAIIFIASANHKVTPTTAII 2 QDATSQIKNTTPTYLTQNPQLGISPSNPSEITSQITTI LASTTPGVKSTLQSTTVKTKNTTTTQTQPSKPTTKQRQ NKPPSKPNNDFHFEVFNFVPCSICSNNPTCWAICKRIP NKKPGKKTTTKPTKKPTLKTTKKDPKPQTTKSKEVPTT KPTEEPTINTTKTNIITTLLTSNTTGNPELTSQMETFH STSSEGNPSPSQVSTTSEYPSQPSSPPNTPRQ RSV post F MELLILKANAITTILTAVTFCFASGQNITEEFYQSTCS SEQ ID NO. AVSKGYLSALRTGWYTSVITIELSNIKKNKCNGTDAKV 3 KLIKQELDKYKNAVTELQLLMQSTPATNNRARRELPRF MNYTLNNAKKTNVTLSKKRKRRFLGFLLGVGSAIASGV AVSKVLHLEGEVNKIKSALLSTNKAVVSLSNGVSVLTS KVLDLKNYIDKQLLPIVNKQSCSISNIETVIEFQQKNN RLLEITREFSVNAGVTTPVSTYMLTNSELLSLINDMPI TNDQKKLMSNNVQIVRQQSYSIMSIIKEEVLAYVVQLP LYGVIDTPCWKLHTSPLCTTNTKEGSNICLTRTDRGWY CDNAGSVSFFPQAETCKVQSNRVFCDTMNSLTLPSEVN LCNVDIFNPKYDCKIMTSKTDVSSSVITSLGAIVSCYG KTKCTASNKNRGIIKTFSNGCDYVSNKGVDTVSVGNTL YYVNKQEGKSLYVKGEPIINFYDPLVFPSDEFDASISQ VNEKINQSLAFIRKSDELL RSV pre F MELLILKANAITTILTAVTFCFASGQNITEEFYQSTCS SEQ ID NO. AVSKGYLSALRTGWYTSVITIELSNIKENKCNGTDAKV 4 KLIKQELDKYKNAVTELQLLMQSTPATNNRARRELPRF MNYTLNNAKKTNVTLSKKRKRRFLGFLLGVGSAIASGV AVCKVLHLEGEVNKIKSALLSTNKAVVSLSNGVSVLTF KVLDLKNYIDKQLLPILNKQSCSISNIETVIEFQQKNN RLLEITREFSVNAGVTTPVSTYMLTNSELLSLINDMPI TNDQKKLMSNNVQIVRQQSYSIMCIIKEEVLAYVVQLP LYGVIDTPCWKLHTSPLCTTNTKEGSNICLTRTDRGWY CDNAGSVSFFPQAETCKVQSNRVFCDTMNSLTLPSEVN LCNVDIFNPKYDCKIMTSKTDVSSSVITSLGAIVSCYG KTKCTASNKNRGIIKTFSNGCDYVSNKGVDTVSVGNTL YYVNKQEGKSLYVKGEPIINFYDPLVFPSDEFDASISQ VNEKINQSLAFIRKSDELL GGGGS GGGGS SEQ ID NO. Linker 5 EAAAK EAAAK SEQ ID NO. Linker 6 RSVB G KPKDDYHFEVFNFVPCSICGNNQLCKSICKTIPSNKPK SEQ ID NO. (158-199) KKPT 11

2. Expression and Purification

2-1. Transfection

[0119] Expi293 cells (Thermo Fisher Scientific) were prepared into a tube so as to be 7.5×10.sup.7 viable cells, and centrifuged (1000 rpm, 5 min, RT). After removal of the supernatant, the cells were suspended in 25.5 mL of previously warmed Expi293 Expression Medium and transferred to a 125 mL flask. A solution in which 30 μg of plasmid DNA was added to OPTI-MEM and mixed by pipetting and a solution in which 80 μL of ExpiFectamine 293 solution was added to Opti-MEM and incubated at room temperature for 5 minutes were mixed and incubated at room temperature for 20 to 30 minutes. The DNA-Expi293 complex was added dropwise to the flask into which the Expi293 cells were transferred. The mixture was stirred and cultured using a CO2 incubator (Thermo Fisher Scientific) under conditions of 37° C., CO.sub.2 8%, and 125 rpm. Sixteen to eighteen hours after transfection, 150 μL of Transfection Enhancer 1 and 1.5 mL of Transfection Enhancer 2 were added thereto, and the mixture was stirred and cultured using a CO2 incubator under the conditions of 37° C., CO.sub.2 8%, and 125 rpm. After culturing for 2 to 7 days, the cells were harvested, centrifuged (2500 rpm, 5 min, 4° C.) and then filtered to 0.22 μm, and the supernatant was collected.

2-2. Affinity Purification

[0120] Ni-NTA Agarose (Qiagen) was dispensed in 1 mL, and the mixture was washed three times with 5 mL of D-PBS (Wako Pure Chemical Industries, Ltd.). A sample was added to the pretreated Ni-NTA Agarose and collected in a 50 mL tube. The mixture was rotated at 4° C. for 16 to 18 hours and transferred to columns, and washed with D-PBS and Wash buffer 2 (50 mM Tris-HCl (pH 7.4), 500 mM NaCl, 25 mM imidazole). Thereafter, an elution buffer (50 mM Tris-HCl (pH 7.4), 500 mM NaCl, 25 to 500 mM imidazole) was added to collect the eluted fraction. The protein concentration was measured, and the protein elution peak sample was dialyzed with D-PBS. After dialysis and recovery, filtration was performed with a 0.22 μm filter.

3. Adjuvant

[0121] Adju-Phos® (BRENNTAG), an aluminum phosphate gel, was prepared so as to be 6 μg/mouse and used.

4. Cells

[0122] Vero cells, Hep-2 cells (CCL-23, ATCC), and Expi293 cells (Expi293F™, Thermo Fisher Scientific) were passaged by the manufacturer's recommended method, and used for each test and antigen preparation.

5. Mice

[0123] Female BALB/c mice with SPF (Japan SLC, Inc.) were conditioned for about one week, and then used for an immunogenicity test, a test in protection against infection, and the like.

6. Viruses

[0124] RSV A2 (VR-1540, ATCC) was propagated by the manufacturer's recommended method. The prepared virus was stored at −80° C. for a period of time until use.

7. SDS-PAGE and Western Blot

7-1. SDS-PAGE

[0125] A specimen was added to a mixed liquid of sample buffer and DTT, and after heat treatment (96° C., 3 to 5 min), SDS-PAGE was performed using SDS-PAGE mini (TEFCO) or Bolt®Bis-Tris gel (Thermo Fisher Scientific). After electrophoresis, they were stained with Bullet CBB Stain One (Nacalai) and moderately decolorized with deionized water. The gel was photographed with LAS-3000 (FUJIFILM Corporation) or WSE-6100 LuminoGraph I (Atto).

7-2. Western Blot

[0126] After electrophoresis was performed by the above method, a membrane was treated with methanol, and blotting was performed using a semi-dry blotting apparatus. The extracted membrane was blocked with 5% skim milk for 30 minutes. After washing with PBST, a diluted anti-RSV F antibody and the membrane were reacted for 1 hour. After washing with PBST, a diluted anti-mouse IgG antibody (Thermo Fisher Scientific) and the membrane were reacted for 1 hour. After washing with PBST, Western BLoT Ultra Sensitive HRP Substrate (Takara Bio Inc.) and the membrane were reacted. The membranes subjected to the above treatment were photographed with LAS-3000 (FUJIFILM Corporation).

8. Gel Filtration Chromatography (GFC)

[0127] Particle diameter was measured using size exclusion chromatography. A specimen diluted with D-PBS and then filtered through a 0.22 μm filter was measured using a system of Agilent 1200 Series (Agilent Technologies) and a column of Superdex® 200 Increase 5/150 GL (GE Healthcare). The molecular weight was analyzed using Gel Filtration Standard (Bio-Rad) as a standard.

9. Particle Size Measurement by Dynamic Light Scattering (DLS)

[0128] Particle sizes of various proteins were measured using a Zetasizer Nano (Malvern Panalytical). The measurement was performed according to manufacturer's instruction.

10. Electron Microscope

[0129] Observation was performed using TecnaiG2 12 TWIN (FEI Company) by negative staining method with saturated uranium acetate and 2% PTA (phosphotungstic acid).

11. ELISA

11-1. Sandwich ELISA

[0130] An anti-RSV F antibody diluted with D-PBS was applied to a 96 well MAXSORP plate (Thermo Fisher Scientific), and the plate was allowed to stand at 2 to 8° C. overnight or at 37° C. for 1 hour. The antibody diluent was removed from the plate on which the anti-RSV F antibody had been immobilized, then the plate was washed with PBS, 1% BSA was applied, and the plate was allowed to stand for 1 hour. The blocking liquid was removed, the specimen was applied and sealed, and then the plate was allowed to stand at 37° C. for 1 hour. After removing the specimen, the plate was washed with PBST, a biotinylated anti-RSV F antibody diluted with 1% BSA was applied and sealed, and then the plate was allowed to stand at 37° C. for 1 hour. After removing the biotinylated anti-RSV F antibody solution, the plate was washed with PBST, diluted HRP-labeled streptavidin (VECTOR Laboratories) was applied and sealed, and then the plate was allowed to stand at 37° C. for 1 hour. After removing the HRP-labeled streptavidin solution, the plate was washed with PBST, 3,3′,5,5′-Tetramethylbenzidine Liquid Substrate, Supersensitive, for ELISA-ready to use solution (Sigma-Aldrich) was applied, and the plate was allowed to stand at room temperature for 30 minutes. 1 N H.sub.2SO.sub.4 was applied to the plate to stop color development, and then measurement was made with SPECTRAMAX190 (Thermo Fisher Scientific).

11-2. Indirect ELISA

[0131] RSV F protein diluted with D-PBS was applied to well Pierce Nickel Coated Plate (Thermo Fisher Scientific), and the plate was allowed to stand at 2 to 8° C. overnight or at 37° C. for 1 hour. After removing the RSV F protein diluent, the plate was washed with PBS, 1% BSA was applied, and the plate was allowed to stand for 1 hour. The blocking liquid was removed, the specimen was applied and sealed, and then the plate was allowed to stand at 37° C. for 1 hour. After removing the specimen, the plate was washed with PBST, and an anti-mouse IgG HRP-labeled antibody or an anti-human IgG HRP-labeled antibody diluted with 1% BSA was applied and sealed, and then the plate was allowed to stand at 37° C. for 1 hour. After removing the HRP-labeled antibody diluent, the plate was washed with PBST, 3,3′,5,5′-Tetramethylbenzidine Liquid Substrate, Supersensitive, for ELISA-ready to use solution (Sigma-Aldrich) was applied, and the plate was allowed to stand at room temperature for 30 minutes. 1 N H.sub.2SO.sub.4 was applied to the plate to stop color development, and then measurement was made with SPECTRAMAX190 (Thermo Fisher Scientific).

12. Real-Time PCR

[0132] 12-1. RNA Extraction and cDNA Synthesis

[0133] BALF (bronchoalveolar lavage fluid) collected in the infection protection test was centrifuged (300 g or 1500 rpm), and then the supernatant was collected. Viral RNA was separated from 150 μL of the supernatant using NucleoSpin® RNA Virus (MACHEREY-NAGEL). The protocol was performed by the manufacturer's recommended method. cDNA synthesis was performed from RNA extracted using High-Capacity cDNA Reverse Transcription Kit (Applied Biosystems). The protocol was performed by the manufacturer's recommended method.

12-2. PCR

[0134] A sense primer (RSVf-F, SEQ ID NO: 7), an antisense primer (RSVf-R, SEQ ID NO: 8), an MGB probe (RSVfA-TaqPf-FAM, SEQ ID NO: 9 with modifications of [FAM] and [MGBEQ]), a Distilled Water (NIPPON GENE CO., LTD.) and a specimen were mixed to prepare a specimen solution, and standard DNA (SEQ ID NO: 10) was used to have 10.sup.2 to 10.sup.7 copies to prepare a standard solution. The primer, probe, and standard DNA were prepared by outsourcing with reference to Non-Patent Document 20. Real-time PCR was performed by <50° C., 2 min> followed by cycles of <95° C., 10 min>.fwdarw.<95° C., 30 sec>.fwdarw.<60° C., 1 min>50 times. A calibration curve was prepared from an amplification curve of the standard solution, and viral copy number of the specimen was calculated.

TABLE-US-00002 TABLE 2 sense CARCAAAGTTAYTCTATCATGTC SEQ ID primer NO. 7 (RSVf-F) antisense GATCCTGCATTRTCACARTACCA SEQ ID primer NO. 8 (RSVf-R) MGB probe TGTAGTACAATTRCCACT SEQ ID (RSVfA- NO. 9 TaqPf-FAM) standard TGTCCAACAATGTTCAAATAGTTAGACAGCAA SEQ ID DNA AGTTACTCTATCATGTCCATAATAAAAGAGGA NO. 10 AGTCTTAGCATATGTAGTACAATTACCACTAT ATGGTGTTATAGATACACCCTGTTGGAAACTA CACACATCCCCTCTATGTACAACCAACACAAA AGAAGGGTCCAACATCTGTTTAACAAGAACTG ACAGAGGATGGTACTGTGACAATGCAGGATCA GTATCTTTCTTCCCACAAGCTGAAACATGTA DNA sequences are described in 5′ .fwdarw. 3′ direction. Y represents a mixed nucleotide of “C or T” and R represents “G or A”. Note that a labeled fluorescent dye [FAM] is modified on the 5′ side of the MGB probe (SEQ ID NO: 9), and Minor Groove Binder (MGB) and Eclipse quencher (EQ) [MGBEQ] are modified on the 3′ side.

13. Immunogenicity Test

[0135] Specimens prepared so as to be 5 μg/mouse were intramuscularly administered to female BALB/c aged 6 to 7 weeks twice at intervals of 3 weeks, and after 3 weeks, whole blood was collected under isoflurane anesthesia. Serum was separated to collect serum, immunogenicity was evaluated by indirect ELISA, neutralizing capacity was evaluated by a neutralization test, and complement-dependent neutralizing capacity was evaluated by a complement-dependent neutralization test.

14. Neutralization Test

[0136] Hep-2 Cells were seeded at 2×10.sup.5 cells/mL in a 96 well plate, and cultured under conditions of 37° C., 5% CO.sub.2 for 1 day. The serum diluted with a medium and an RSV diluent were mixed in equal amounts, and the mixture was allowed to stand under the conditions of 37° C., 5% CO.sub.2 for 1 hour. After removing the culture supernatant of the plate, the serum-RSV reaction solution was added, and cultured under the conditions of 37° C., 5% CO.sub.2 for 3 to 5 days. After removing the reaction solution, the plate was washed with PBS, methanol was added thereto, and the plate was allowed to stand at room temperature for 30 minutes. After methanol was removed and the plate was air dried, the plate was washed with PBS, an anti-RSV F antibody diluent was applied, and then the plate was allowed to stand at 37° C. for 1 hour. After removing the anti-RSV F antibody diluent, an anti-mouse IgG Alexa 488 labeled antibody (Abcam) diluent was applied, and the plate was allowed to stand at 37° C. for 1 hour. After removing the anti-mouse IgG Alexa 488 labeled antibody (Abcam) diluent, the plate was washed with PBS, a diluted Hoechst 33342 solution (DOJINDO LABORATORIES) was applied, and the plate was allowed to stand in the dark for 10 minutes. After removing a nuclear stain and washing with PBS, PBS was applied to the plate and analyzed with an image analyzer. Based on infection rates of the serum dilution series, curve fitting was performed using GraphPad Prism 7 (GraphPad Software) according to fitting guide using an infection rate of the well to which only RSV was applied as a reference, and a neutralizing antibody titer (IC50) was calculated.

15. Complement-Dependent Neutralization Test

[0137] Cells were prepared as in the neutralization test. A medium comprising 1/50 amount of rabbit serum complement (Cedarlane) was used for RSV dilution. The serum diluted with a medium and an RSV diluent were mixed in equal amounts, and the mixture was allowed to stand under the conditions of 37° C., 5% CO.sub.2 for 1 hour. The serum-RSV reaction solution was added, and cultured under the conditions of 37° C., 5% CO.sub.2 for 1 hour. Thereafter, the serum-RSV reaction solution was removed, the plate was washed with PBS, a complement-free medium was added, and the mixture was cultured under the conditions of 37° C., 5% CO.sub.2 for 3 to 5 days. Other operations and analysis were performed according to the method of the neutralization test.

16. Subclass Analysis

[0138] The same procedure as in the indirect ELISA method was carried out except that an anti-mouse IgG1 HRP-labeled antibody (Abcam) and an anti-mouse IgG2a HRP-labeled antibody (Abcam) were used as secondary antibodies.

17. Test in Protection Against Infection

[0139] A specimen prepared to be 0.005 to 15 μg/mouse was intramuscularly administered to female BALB/c aged 6 to 7 weeks twice at intervals of 3 weeks, and then after 3 weeks, 1×10.sup.5 pfu/mouse of RSV was intranasally inoculated under isoflurane anesthesia. Three to four days after infection, BALF was collected after euthanization with nitrogen gas. RNA was extracted from BALF to synthesize cDNA, and viral copy number was detected by real-time PCR.

18. Evaluation of Infection Enhancement

[0140] Enhancement of infection or infection suppressing ratio was evaluated with reference to a geometric mean of viral copy numbers in BALF of a group immunized with physiological saline and challenged with RSV. In addition, the geometric mean of viral copy numbers in the lung of the RSV-challenged group was evaluated with reference to a group into which a serum obtained by immunization with physiological saline was transferred. The serum transfer was performed by intraperitoneal administration at 400 uL/mouse, using various sera diluted by 10{circumflex over ( )}8, in which exacerbation confirmed by preparing a dilution series in advance becomes a peak. One day after serum transfer, 1×10.sup.5 pfu/mouse of RSV was intranasally inoculated under isoflurane anesthesia. Three to four days after infection, lungs were collected after euthanization with nitrogen gas. RNA was extracted from the lungs to synthesize cDNA, and the viral copy number was detected by real-time PCR.

19. Statistical Analysis

[0141] Statistical analysis was performed using GraphPad Prism 7 (GraphPad Software).

Example 1

Preparation of RSV F/G Chimeric Proteins

[0142] Various RSV F/G chimeric proteins shown in FIGS. 1 to 4 were expressed in Expi293 cells and then purified with an affinity column. Each protein yield was shown in FIGS. 5 and 6. A protein to which mutation was added so as to add a sugar chain to a specific position tended to have a high expression level as compared with a protein to which a sugar chain was not added. Specifically, the expression levels of the F/G chimeric proteins to which a sugar chain was added by mutagenesis in “K419N, K421T and G430T”, “K419N, K421T, T434N and S436T”, and “K419N, K421T, K427N and R429T” increased.

Example 2

Evaluation of Physical Properties

1. SDS-PAGE and Western Blot

[0143] The results of analyzing each protein by SDS-PAGE and Western blot are shown in FIGS. 7 to 15, and 27 to 39. By comparing the results of SDS-PAGE and Western blot, it was confirmed that a main band was an RSV F/G chimeric protein.

[0144] The results of SDS-PAGE of RSV F/G-A-9-1 and RSV F/G-A-9-2 substituted with 10-amino acid sequence (162 to 171; No. 9 in FIG. 2) of RSV G protein comprising a region (164 to 171) that is a particularly highly conserved region and does not comprise Cysteine noose (characteristic structure formed by disulfide bonds between cysteine residues 173 to 186 and between 176 to 182) among sequences of region CCD having high homology between virus strains, among the RSV F/G chimeric proteins, are shown in FIG. 7. Wild-type RSV F protein (593 aa) was 62 kDa, and it was confirmed that main bands of RSV WT F protein (513 aa) and RSV post F protein (513 aa), which are glycoproteins, were observed at positions higher than around estimated molecular weight. Also, the fact that a main band of the RSV F/G chimeric protein (513 aa) is located at a higher position than the WT and post F proteins is suggested to be due to an effect of glycosylation by mutagenesis.

[0145] The results of SDS-PAGE (non-reduced) of various RSV F/G proteins are shown in FIGS. 8 to 14. For Sample in which the application amount is less than 1 μg/Lane due to a small expression level, Lane No. and Sample are shown in gray. Among the RSV F/G chimeric proteins to which mutation to add a sugar chain to the position shown in FIG. 1 was not added, RSV F/G-A-1-0, RSV F/G-A-2-0, RSV F/G-A-3-0, RSV F/G-A-4-0, RSV F/G-A-8-0, RSV F/G-A-5-0, RSV F/G-A-10-0, RSV F/G-A-11-0, and RSV F/G-A-11/11-0 resulted in that a main band could not be confirmed, intensity was low, or the expression level was low. In addition, main bands and high expression levels could be confirmed for RSV F/G-A-1-1, RSV F/G-A-1-2, RSV F/G-A-2-1, RSV F/G-A-2-2, RSV

[0146] F/G-A-3-1, RSV F/G-A-3-2, RSV F/G-A-6-1, RSV F/G-A-6-2, RSV F/G-A-7-1, RSV F/G-A-7-2, RSV F/G-A-8-1, RSV F/G-A-8-2, RSV F/G-A-5-1, RSV F/G-A-5-2, RSV F/G-A-9-1, RSV F/G-A-9-2, RSV F/G-A-10-1, RSV F/G-A-10-2, RSV F/G-A-11-1 and RSV F/G-A-11-2 to which the mutation of “K419N, K421T and G430T” and the glycosylation mutation of “K419N, K421T, T434N and S436T” were added, whereas RSV F/G-A-1-3, RSV F/G-A-2-3 and RSV F/G-A-9-3 to which the glycosylation mutation of “K421T and G430T” was added had low main band intensities or low expression levels as compared with the mutation of “K419N, K421T and G430T” and the glycosylation mutation of “K419N, K421T, T434N and S436T”.

2. Gel Filtration Chromatography Analysis (GFC)

[0147] Size analysis of each protein was performed using gel filtration chromatography. The results of GFC are shown in Table 3. It was found that the RSV F/G-A-9-1 and the RSV F/G-A-9-2 had a protein with a size of 670 kDa or more (extrapolated value is shown when the size is 670 kDa or more) as a main peak and a protein with a size of about 120 kDa as a second peak. The wild-type RSV F protein is known to form a trimer as a natural structure, and when the RSV F/G-A-9-1 and the RSV F/G-A-9-2 are assumed to similarly form a trimer, it was suggested that the RSV F/G-A-9-1 and the RSV F/G-A-9-2 similarly form a trimer because they have molecular weights close to that of the second peak. In addition, it is suggested that the main peak showed a size of 670 kDa or more because the trimers of RSV F/G-A-9-1 and RSV F/G-A-9-2 form a rosette-like structure as in the electron microscope image described later.

TABLE-US-00003 TABLE 3-1 List of GFC results Sample main peak (Mw.) second peak RSV pre F 307,507 1,086,954 RSV post F 1,219,027 — RSV WT F 1,327,282 — RSV F/G-A-1-0 1,150,389 — RSV F/G-A-1-1 1,123,751 159,575

TABLE-US-00004 TABLE 3-2 RSV F/G-A-1-2 1,116,844 163,157 RSV F/G-A-1-3 1,170,420 — RSV F/G-A-2-0 1,199,642 103,643 RSV F/G-A-2-1 1,211,534 140,716 RSV F/G-A-2-2 1,213,029 163,560 RSV F/G-A-2-3 1,141,909 137,627 RSV F/G-A-3-0 1,231,111 102,625 RSV F/G-A-3-1 1,238,725 — RSV F/G-A-3-2 1,235,674 — RSV F/G-A-3-3 1,205,574 135,606 RSV F/G-A-4-0 1,164,661 1,244 RSV F/G-A-4-1 1,170,420 1,118 RSV F/G-A-4-2 1,166,098 1,234 RSV F/G-A-6-0 1,070,990 112,291 RSV F/G-A-6-1 1,048,773 153,970 RSV F/G-A-6-2 1,055,259 151,896 RSV F/G-A-7-0 1,008,197 — RSV F/G-A-7-1 1,076,285 139,163 RSV F/G-A-7-2 1,107,245 — RSV F/G-A-8-0 1,156,077 2,204 RSV F/G-A-8-1 1,108,612 158,790 RSV F/G-A-8-2 1,119,601 158,595 RSV F/G-A-5-1 1,157,503 136,109 RSV F/G-A-5-2 1,151,808 138,821 RSV F/G-A-5-3 1,163,226 131,977 RSV F/G-A-9-0 1,177,658 122,263 Δ136aa RSV F/G-A-9-4 1,168,977 149,112 Δ136aa RSV F/G-A-9-1 1,147,555 166,202 Δ136aa RSV F/G-A-9-2 1,144,729 165,181 Δ136aa RSV F/G-A-9-3 1,158,931 157,620 Δ136aa RSV WT F-R136Q 1,158,931 127,184 RSV post F-R136Q 1,105,881 128,287 RSV F/G-A-9-0-R136Q 1,139,097 459,085 RSV F/G-A-9-0 1,182,022 100,126 RSV F/G-A-9-4 1,146,141 129,399 RSV F/G-A-9-3 1,176,207 139,507 RSV F/G-A-9-1 1,179,111 139,679 RSV F/G-A-9-2 1,167,537 139,335

3. Particle Size Measurement by Dynamic Light Scattering (DLS)

[0148] Particle diameter of each protein was measured by dynamic light scattering. Average particle diameter of each protein is shown in Table 4.

TABLE-US-00005 TABLE 4 List of DLS results Diameter Volume Sample Peak (nm) (%) RSV pre F 1 13.94 99.6 2 491.5 0.2 3 4668 0.2 RSV post F 1 37.31 99.0 2 717.6 0.6 3 4011 0.4 RSV F/G-A-9-1 1 29.81 99.7 2 4013 0.3 3 0.000 0.0 RSV F/G-A-9-2 1 29.58 99.8 2 4190 0.2 3 0.000 0.0

4. Analysis by Electron Microscope

[0149] Shape of the RSV F/G chimeric protein was observed with an electron microscope. Electron microscope images of RSV F/G-A-9-1, RSV F/G-A-9-2, RSV post F, and RSV pre F are shown in FIG. 16. It was suggested that the RSV F/G-A-9-1 and the RSV F/G-A-9-2 formed a rosette-like structure similar to that of the RSV post F.

Example 3

[0150] Analysis of Reactivity with Anti-RSV F Antibody

[0151] Reactivity (indicated by absorbance) between each protein and an anti-RSV F antibody was analyzed by indirect ELISA method. The results of analysis of RSV F protein with anti-RSV F antibodies specific to each site of siteφ, siteI, siteII, siteIII, and siteIV (Non-Patent Document 23) are shown in FIG. 17, FIG. 18, FIG. 40, and FIG. 41. A difference in reactivity with various antibodies was observed, depending on the substituted RSV G protein sequence and the glycosylation mutation. Among the proteins to which glycosylation mutation was added around siteIV, reduced reactivity with the anti-RSV F siteIV antibody was observed. Coincidentally, a plurality of RSV F/G chimeric proteins substituted with RSV G protein that had increased reactivity with an RSV pre F-specific antibody as compared with the RSV WT F were observed.

Example 4

Neutralization Test

[0152] Each protein was immunized to obtain serum, and a neutralization test was carried out. The neutralization test was performed by setting an administration group using Adju-Phos® (BRENNTAG) which is an alum phosphate adjuvant and a group without adjuvant. The results of the neutralization test are shown in FIG. 19. The neutralizing antibody titer (IC50, geometric mean) tended to be high in the RSV F/G-A-9-1 and RSV F/G-A-9-2 comprising the RSV G protein sequence as compared with RSV F/G-A-0-1 and RSV F/G-A-0-2 that are different only in comprising no RSV G protein sequence. In addition, the neutralizing antibody titer (IC50, geometric mean) was the highest in RSV pre F, followed by RSV F/G-A-9-2 and WT in this order. The neutralizing antibody titer of the RSV F/G-A-9-1 was comparable to that of the RSV WT F, and the RSV F/G-A-0-1 and the RSV F/G-A-0-2 showed neutralizing antibody titers (IC50, geometric mean) below the RSV WT F.

Example 5

Complement-Dependent Neutralization Test

[0153] Serum of the administration group using Adju-Phos® was obtained in the same manner as in Example 4, and a complement-dependent neutralization test was carried out. As shown in FIG. 19, the neutralizing antibody titer (IC50, geometric mean) of RSV pre F tends to be high as compared with that of RSV F/G-A-9-1 and RSV F/G-A-9-2, but the neutralizing antibody titer (IC50, geometric mean) in the presence of complement shown in FIG. 20 resulted in higher in the RSV F/G-A-9-1 and the RSV F/G-A-9-2 than in the RSV pre F. (Dunn's multiple comparison test, *: p<0.05, n=) In addition, as shown in FIG. 42, a large number of RSV F/G chimeric proteins having a high neutralizing antibody titer as compared with the RSV pre F were observed.

Example 6

Subclass Analysis

[0154] Serum of the administration group using Adju-Phos® was obtained in the same manner as in Example 4 and Example 5, and subclass analysis of anti-RSV F antibodies present in the RSV pre F, RSV F/G-A-9-1, RSV F/G-A-9-2, and Saline immune serum was performed. The results of the subclass analysis are shown in FIG. 21. It was found that the RSV F/G-A-9-1 and the RSV F/G-A-9-2 had high inducibility of IgG2a with high complement-binding ability, whereas the RSV pre F had high inducibility of IgG1 without complement-binding ability.

Example 7

Evaluation of Inducibility of Anti-RSV G Antibody

[0155] Serum of the administration group using Adju-Phos® was obtained in the same manner as in Example 4, Example 5 and Example 6, and inducibility of anti-RSV G antibody present in the RSV pre F, RSV F/G-A-9-1, RSV F/G-A-9-2, and Saline immune serum was evaluated. The evaluation results of inducibility of the anti-RSV G antibody are shown in FIG. 22. It was shown that an antibody having high reactivity with the RSV G protein was present in the RSV F/G-A-9-1 and RSV F/G-A-9-2 immune sera as compared with the RSV pre F immune serum, and it was suggested that the anti-RSV G antibody was induced by the RSV F/G-A-9-1 and the RSV F/G-A-9-2.

Example 8

Test in Protection Against Infection

[0156] Each protein was prepared to 5 μg/mouse/time (no adjuvant), and 6-week-old female BALB/c mice were immunized twice at intervals of 3 weeks, and infected with RSV after weeks. Three days after RSV inoculation, BALF was collected, RNA extraction and cDNA synthesis were performed, and viral copy number (geometric mean) was quantified using real-time PCR. The results of infection protection test of RSV pre F, RSV WT F, RSV F/G-A-0-1 and RSV F/G-A-0-2, and RSV F/G-A-9-1 and RSV F/G-A-9-2 are shown in FIG. 23. Since the RSV F/G-A-9-1 and the RSV F/G-A-9-2 showed viral copy number comparable to that of the RSV pre F, it was suggested that they had infection protective ability comparable to that of the RSV pre F. In addition, it was suggested that the copy numbers of the RSV F/G-A-9-1 and the RSV F/G-A-9-2 were low as compared with those of the RSV WT F, RSV F/G-A-0-1, and RSV F/G-A-0-2 comprising no RSV G protein sequence, and the infection protective ability tends to be high (vs RSV pre F; Dunn's multiple comparison test, ***: p<0.002, *: p<0.05, n=14 to 16). A comparison result with RSV post F is shown in FIG. 24 (left), and a comparison result with FI-RSV is shown in FIG. 24 (right). In comparison with RSV post F, the test was performed under an immune condition of 15 μg/mouse/time, and significant reduction in viral copy number was observed in the RSV F/G-A-9-1 and the RSV F/G-A-9-2 as compared with the RSV post F (Dunn's multiple comparison test, ***: p<0.002, *: p<0.05, n=8). In comparison with FI-RSV, the test was performed under an immune condition of 5 μg/mouse/time, and significant reduction in viral copy number was observed in the RSV F/G-A-9-1 and the RSV F/G-A-9-2 as compared with the FI-RSV (Dunn's multiple comparison test, **: p<0.01, *: p<0.05, n=7 to 8).

Example 9

[0157] In order to confirm dose dependence, viral copy number (geometric mean) in BALF was measured by setting immune conditions of RSV post F, RSV F/G-A-9-1, and RSV F/G-A-9-2 to 5 doses of 15, 5, 0.5, 0.05, and 0.005 μg/mouse, in the same manner as in Example 8 for other conditions, and the results are shown in FIG. 25. It was shown that the viral copy number of the RSV post F did not change at 5 μg/mouse and 15 μg/mouse, the viral copy numbers of the RSV F/G-A-9-1 and the RSV F/G-A-9-2 were lower than that of the RSV post F in the high dose range (15 μg/mouse), the infection protective ability exceeded that of the RSV post F, and the infection protective ability of the RSV F/G-A-9-1 and the RSV F/G-A-9-2 exceeded that of the RSV post F also in the low dose range (0.05, 0.005 μg/mouse). Therefore, it was suggested that maximum efficacy of the RSV F/G-A-9-1 and the RSV F/G-A-9-2 exceeded that of the RSV post F, and efficacy at minimum dose also exceeded that of the RSV post F (error bar: 95% confidence interval, n=8).

Example 10

Evaluation of Infection Suppressing Ratio

[0158] From the results of test in protection against infection, infection suppressing ratios of RSV F/G-A-9-1, RSV F/G-A-9-2, RSV post F, and RSV pre F were calculated based on the viral copy number (geometric mean) of the Saline group (control group not immunized with antigen) (performed under immune conditions of RSV F/G-A-9-1, RSV F/G-A-9-2 and RSV post F at 5 doses of 15, 5, 0.5, 0.05 and 0.005 μg/mouse, and immune conditions of RSV pre F at 3 doses of 0.5, 0.08 and 0.008 μg/mouse). The calculation results of infection suppressing ratio are shown in FIG. 26. When a low dose immunization group was set to confirm exacerbation tendency, as compared with the viral copy number of Saline, a high viral copy number was detected at 0.08 μg/mouse or less in the RSV pre F and 0.005 μg/mouse in the RSV post F was detected, and enhancement of infection tendency was shown. On the other hand, in the RSV F/G-A-9-1 and the RSV F/G-A-9-2, no enhancement of infection tendency was observed. (error bar: 95% confidence interval, n=4 to 8)

Example 11

Evaluation of Infection Enhancement

[0159] Immune sera were transferred to evaluate enhancement of infection after passive immunization. As shown in FIG. 43, enhancement of infection was significantly observed in the RSV preF, but enhancement of infection was not observed in the RSV F/G-A-9-2. (Dunn's multiple comparison test, *: p<0.05, error bars: 95% confidence interval, n=13).

INDUSTRIAL APPLICABILITY

[0160] The present invention is useful in the field of pharmaceuticals, particularly in the field of vaccines.