title: DNA vaccines co-expressing GP5 and M proteins of porcine reproductive and respiratory syndrome virus (PRRSV) display enhanced immunogenicity.
abstract: The two major membrane-associated proteins of porcine reproductive and respiratory syndrome virus (PRRSV), GP5 and M (encoded by ORF5 and ORF6 genes, respectively), are associated as disulfide-linked heterodimers (GP5/M) in the virus particle. In the present study, three different DNA vaccine constructs, expressing GP5 alone (pCI-ORF5), M alone (pCI-ORF6) or GP5 and M proteins simultaneously (pCI-ORF5/ORF6), were constructed. In vitro, the co-expressed GP5 and M proteins could form heterodimeric complexes in transfected cells and heterodimerization altered the subcellular localization of GP5. The immunogenicities of these DNA vaccine constructs were firstly investigated in a mouse model. Mice inoculated with pCI-ORF5/ORF6 developed PRRSV-specific neutralizing antibodies at 6 and 8 weeks after primary immunization. However, only some mice developed low levels of neutralizing antibodies in groups immunized with pCI-ORF5 or pCI-ORF6. The highest lymphocyte proliferation responses were also observed in mice immunized with pCI-ORF5/ORF6. Interestingly, significantly enhanced GP5-specific ELISA antibody could be detected in mice immunized with pCI-ORF5/ORF6 compared to mice immunized with pCI-ORF5. The immunogenicities of pCI-ORF5/ORF6 were further evaluated in piglets (the natural host) and all immunized piglets developed neutralizing antibodies at 10 weeks after primary immunization, whereas there was no detectable neutralizing antibodies in piglets immunized with pCI-ORF5. These results indicate that the formation of GP5/M heterodimers may be involved in post-translational modification and transport of GP5 and may play an important role in immune responses against PRRSV infection. More importantly, co-expression of GP5 and M protein in heterodimers can significantly improve the potency of DNA vaccination and could be used as a strategy to develop a new generation of vaccines against PRRSV.
authors.affiliation: Laboratory of Animal Virology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan 430070, Hubei, PR China.
authors.forename: Yunbo
authors.initials: Y
authors.lastname: Jiang
authors.forename: Shaobo
authors.initials: S
authors.lastname: Xiao
authors.forename: Liurong
authors.initials: L
authors.lastname: Fang
authors.forename: Xiaolan
authors.initials: X
authors.lastname: Yu
authors.forename: Yunfeng
authors.initials: Y
authors.lastname: Song
authors.forename: Chuanshuang
authors.initials: C
authors.lastname: Niu
authors.forename: Huanchun
authors.initials: H
authors.lastname: Chen
mesh_terms: D000818:Animals; D000914:Antibodies, Viral / Q000097:blood; D002460:Cell Line; D006224:Cricetinae; D019281:Dimerization; D049452:Green Fluorescent Proteins / Q000032:analysis / Q000235:genetics; D008164:Luminescent Proteins / Q000032:analysis / Q000235:genetics; D008214:Lymphocytes / Q000276:immunology; D051379:Mice; D008807:Mice, Inbred BALB C; D008856:Microscopy, Fluorescence; D009500:Neutralization Tests; D019318:Porcine Reproductive and Respiratory Syndrome / Q000276:immunology* / Q000517:prevention & control; D019316:Porcine respiratory and reproductive syndrome virus / Q000276:immunology*; D013552:Swine; D019444:Vaccines, DNA / Q000235:genetics / Q000276:immunology*; D014614:Vaccines, Synthetic / Q000008:administration & dosage / Q000276:immunology; D014759:Viral Envelope Proteins / Q000235:genetics / Q000276:immunology*; D014763:Viral Matrix Proteins / Q000235:genetics / Q000276:immunology*; D014765:Viral Vaccines / Q000235:genetics / Q000276:immunology*; D000097573:Red Fluorescent Protein
chemical_list: D000914:Antibodies, Viral; D049452:Green Fluorescent Proteins; D008164:Luminescent Proteins; D019444:Vaccines, DNA; D014614:Vaccines, Synthetic; D014759:Viral Envelope Proteins; D014763:Viral Matrix Proteins; D014765:Viral Vaccines; D000097573:Red Fluorescent Protein; C114789:glycoprotein 5, PRRSV