Valuation of protective efficacy of PRRS attenuated vaccine and inactivated mutant PRRSV strains.

In this study,healthy piglets were immunized with porcine reproductive and respiratory syndrome(PRRS) CH-1R attenuated vaccine and inactivated PRRS vaccine,respectively,and challenged with PRRS virus(PRRSV) HuN-4 virulent strains 4 weeks after vaccination.All piglets were slaughtered on 21 day post-inoculation and tissue samples from main organs collected for H.E and immunohistochemistry staining to identify the distribution of the virus antigen.The results showed that the pathological change and the virus antigen distribution of the group immunized with inactivated vaccine were significantly higher than those of the group immunized with attenuated vaccine.Immunopathology studies indicated the immune protection of CH-1R attenuated vaccine was better than inactivated vaccine.