title: A novel vaccine against Streptococcus equi ssp. zooepidemicus infections: the recombinant swinepox virus expressing M-like protein.
abstract: To develop a safer, more immunogenic and efficacious vaccine against Streptococcus equi ssp. zooepidemicus (SEZ) infections, the gene of M-like protein (SzP) was placed under the strong vaccinia virus promoter P28 and then inserted into swinepox virus (SPV) genome. The recombinant swinepox virus (rSPV-szp) was isolated in a non-selective medium by the co-expression of Escherichia coli LacZ gene and verified by PCR, western blotting and immunofluorescence assays. To evaluate the immunogenicity of this rSPV-szp, ICR mice were immunized with the rSPV-szp, inactivated SEZ vaccine (positive control), wild type SPV (negative control), or PBS (challenge control). All mice were intraperitoneally challenged with 5 LD(50) of homogenous ATCC 35246 strain 14 days post-vaccination. The results showed that at least 70% mice in rSPV-szp-vaccinated group were protected against homogenous ATCC 35246 challenge, the survival rate was significantly higher compared with mice in the negative control group and the challenge control group (P<0.001). The antibody titers of the rSPV-szp-vaccinated group were significantly higher (P<0.05) than the other three groups. Passive immune protection assays showed that the hyperimmune sera against M-like protein could provide mice with complete protection against challenge of ATCC 35246. Semi-quantitative RT-PCR analysis showed a marked increased in levels of IL-4 and IFN-γ mRNA in immunized mice. The results suggested that the recombinant rSPV-szp provided mice with significant protection from the SEZ infections. It is a promising candidate for the vaccine development against SEZ infections.
authors.affiliation: College of Veterinary Medicine, Nanjing Agricultural University, Nanjing 210095, China.
authors.forename: Hui-xing
authors.initials: HX
authors.lastname: Lin
authors.forename: Dong-yan
authors.initials: DY
authors.lastname: Huang
authors.forename: Ye
authors.initials: Y
authors.lastname: Wang
authors.forename: Cheng-ping
authors.initials: CP
authors.lastname: Lu
authors.forename: Hong-jie
authors.initials: HJ
authors.lastname: Fan
mesh_terms: D000818:Animals; D000907:Antibodies, Bacterial / Q000276:immunology; D000942:Antigens, Bacterial / Q000276:immunology*; D001425:Bacterial Outer Membrane Proteins / Q000276:immunology*; D002352:Carrier Proteins / Q000276:immunology*; D002478:Cells, Cultured; D004926:Escherichia coli / Q000235:genetics; D005260:Female; D007111:Immunity, Cellular / Q000276:immunology; D007116:Immunization, Passive / Q000379:methods; D007371:Interferon-gamma / Q000235:genetics / Q000276:immunology; D015847:Interleukin-4 / Q000235:genetics / Q000276:immunology; D051379:Mice; D008813:Mice, Inbred ICR; D010957:Plasmids / Q000235:genetics; D011401:Promoter Regions, Genetic; D013209:Staphylococcal Vaccines / Q000235:genetics* / Q000276:immunology* / Q000494:pharmacology; D013290:Streptococcal Infections / Q000276:immunology* / Q000517:prevention & control*; D018502:Streptococcus equi / Q000276:immunology*; D018148:Suipoxvirus / Q000235:genetics / Q000276:immunology*; D013552:Swine; D014614:Vaccines, Synthetic / Q000235:genetics / Q000276:immunology / Q000494:pharmacology; D014616:Vaccinia virus / Q000235:genetics / Q000276:immunology; D014764:Viral Proteins / Q000235:genetics / Q000276:immunology
chemical_list: D000907:Antibodies, Bacterial; D000942:Antigens, Bacterial; D001425:Bacterial Outer Membrane Proteins; D002352:Carrier Proteins; D013209:Staphylococcal Vaccines; D014614:Vaccines, Synthetic; D014764:Viral Proteins; C014689:streptococcal M protein; D015847:Interleukin-4; D007371:Interferon-gamma