Immune response to caprine arthritis-encephalitis virus surface protein induced by coimmunization with recombinant vaccinia viruses expressing the caprine arthritis-encephalitis virus envelope gene and caprine interleukin-12

Abstract

The objective of this study was to determine if interleukin (IL)-12 can focus an antigen specific type 1 immune response characterized by activation of Th1 lymphocytes and production of IgG2 antibodies in vivo. Saanen goats co-immunized with recombinant vaccinia viruses expressing caprine IL-12 (rRB-IL12) and the caprine arthritis-encephalitis virus (CAEV) envelope (env) gene (rWR-63) were evaluated for development of immune responses to the CAEV env encoded surface glycoprotein (SU). Immune responses were defined by: (i) SU antibody titers; (ii) the ratio of SU IgG1 and IgG2 antibodies; (iii) interferon gamma (IFNgamma) and IL-4 gene expression and proliferative response of SU stimulated lymph node mononuclear cells (LNMC). Apart from enhancement of IFNgamma and IL-4 gene expression in SU stimulated LNMC, rRB-IL12 did not affect the immune response to rWR-63 encoded SU. Thus, localized production of exogenous species specific IL-12 at the site of immunization did not focus initial priming of antigen reactive Th lymphocytes. These results are in contrast to previous studies using inbred mice and raise questions regarding the use of cytokine adjuvants to focus immune responses in outbred animals.