The immunogenicity of the virus-like particles derived from the VP2 protein of porcine parvovirus

Porcine parvovirus (PPV) is a major cause of the syndrome of sow reproductive failure that can cause economic losses. In this study, we developed a subunit vaccine against porcine parvovirus (PPV), composed of virus-like particles (VLPs) derived from a prokaryotic system, and evaluated its potential against PPV infection. The soluble recombinant VP2 protein was expressed in E. coli Transetta(DE3) cells using a pCold II prokaryotic expression vector at a low temperature of 15 degrees C. After expression and purification, the recombinant VP2 protein was successfully assembled into VLPs with a similar shape of PPV viron and also hemagglutination activity. PPV VLPs formulated in a water-in-oil-in-water adjuvant evoked high hemagglutination inhibition antibody and neutralization antibody titres in both guinea pigs, used as reference model, and target species, pigs. Immunization with VLPs vaccine stimulated high hemagglutination inhibition antibody and neutralization antibody responses in guinea pigs, used as reference, and target species, weaned pigs, and primiparous gilts. PPV VLPs from E. coli yielded complete fetal protection against PPV infection in primiparous gilts immunized with a single-dose vaccine. PPV VLPs inhibited the replication and spread of PPV in primiparous gilts, which was confirmed by the detection of PPV DNA and infectious PPV in nasal and rectal swabs of challenged sows. These results suggest that VLPs-based PPV vaccine is a promising PPV vaccine candidate.