Immune responses of recombinant adenovirus co-expressing VP1 of foot-and-mouth disease virus and porcine interferon alpha in mice and guinea pigs

Foot-and-mouth disease (FMD) is a highly contagious and economically devastating vesicular disease of cloven-hoofed animals. In this study, we constructed and characterized the immune responses and vaccine efficacy conferred by the recombinant adenovirus co-expressing VP1 of FMDV and porcine interferon alpha as fusion protein (rAd-pIFNalpha-VP1). Six groups of female BALB/c mice each with 18 were inoculated subcutaneously twice 2-week intervals with the recombinant adenoviruses. The results showed that the levels of humoral and cell-mediated immune responses in the group inoculated with rAd-pIFNalpha-VP1 were significantly higher than those in the group inoculated with rAd-VP1+rAd-pIFNalpha (P<0.05). Then four groups of guinea pigs each with six were inoculated two times at 2-week intervals intramuscularly with rAd-pIFNalpha-VP1, commercial inactivated FMD vaccine, wild-type adenovirus (wtAd) or PBS, and the protective efficacy of rAd-pIFNalpha-VP1 was determined. The results indicated that all the guinea pigs vaccinated with rAd-pIFNalpha-VP1 as well as inactivated FMD vaccine were protected from FMDV challenge, even though the levels of neutralizing antibodies (1:32-1:40) of the animals vaccinated with rAd-pIFNalpha-VP1 was lower than that in the group inoculated with inactivated FMD vaccine (1:64-1:128). It demonstrated that the newly recombinant adenovirus rAd-pIFNalpha-VP1 might further be an attractive candidate vaccine for preventing FMDV infection in swine.