Mucosal Immune Response Induced By Recombinant Adenoviruses Expressing The Major Epitopes Of Capsid Protein Of Porcine Circovirus Type2

Porcine circovirus type2(PCV2) is the primary causative agent ofpost-weaning multi-systemic wasting syndrome (PMWS). We studied the immuneresponses induced by recombinant adenoviruses expressing the major epitopes ofcapsid protein of porcine circovirus2(rAd/Cap/518) in mice model. BLAB/c micewere immunized with rAd/Cap/518through intranasal, intramuscular or oral route.Mice immunized with rAd/Cap/518through intranasal and oral routes can induceserum IgG Abs and high titers of mucosal IgA Abs in saliva, bronchoalveolar lavagefluid and intestinal lavage fluid. Strong serum IgG Abs responses were induced byintramuscular immunization with rAd/Cap/518, and weak mucosal IgA Abs weredetermined from mucosal secretions. The Cap-specific CD3+, CD4+and CD8+Tcellwere significantly increased in rAd/Cap/518vaccination mice. High levels of IFN-γwere detected in the lymphocytes from the spleen and mesenteric lymph nodes ofmice immunization with rAd/Cap/518through intranasal route, but IL-4was notdetected in any group. Real-time PCR analysis confirmed that only low viral DNAloads in rAd/Cap/518immunized mice. These results indicated that intranasaladministration of rAd/Cap/518could stimulate both humoral and Th1-type cellularimmune responses in systemic and mucosal immune compartments.Due to one single immune induced mucosal immune responses are usually weakand of short duration, therefore, the rAd/Cap/518combine with mucosal adjuvantsmaybe enhance the immune response effect. This study, we studied the immuneresponses induced by rAd/Cap/518combined with unmethylated CpG motifs(CpGODN), cholera actinomycin B unit(CTB) or multiple polycytidylic acidPoly(I:C),respectively. The results showed that rAd/Cap/518combined with CpG ODN or CTBrespectively can induced higher level of sera IgG antibodides and local mucosal sitesof IgA antibodies than the level induced by immunization with rAd/Cap/518alone.The rAd/Cap/518combined with Poly(I:C) did not increase the level of humoralimmune responses. RAd/Cap/518combined with CpG ODN, CTB or Poly(I:C) respectively can significantly increase the T cell subsets, and the content of IL-2inCD4+T cell and IFN-γ in CD8+T cell.In this study, our data demonstrate that a single intranasal administration ofrAd/Cap/518could stimulate both humoral and Th1-type cellular immune responsesin systemic and mucosal immune compartments. RAd/Cap/518combined with CpGODN or CTB respectively can significantly increase the PCV2specific humoral andcellular immune responses, while rAd/Cap/518combined with Poly（I:C）onlysignificantly increase the PCV2specific cellular immune responses.