Plasmid DNA encoding caprine interferon gamma inhibits antibody response to caprine arthritis-encephalitis virus (CAEV) surface protein encoded by a co-administered plasmid expressing CAEV env and tat genes

This study characterized immune responses of Saanen goats co-immunized with pUC18 based plasmids expressing caprine arthritis-encephalitis virus (CAEV) rev-env (pENV) or tat-rev-env (pTAT-ENV) and a second plasmid encoding caprine interferon gamma (IFN gamma). A previous study reported that immunization with pENV or pTAT-ENV induces IgG2 biased antibody responses to plasmid encoded CAEV surface envelope protein (SU). We show here that regional lymph nodes (LN) of pENV and pTAT-ENV immunized goats contain a dominant subset of SU activated IFN gamma (+) Th1 lymphocytes. Go-immunization with pENV or pTAT-ENV and a caprine IFN gamma cDNA expression plasmid (pcIFN gamma) did not potentiate activation of SU responsive Th1 lymphocytes. However, the antibody response to SU encoded by pTAT-ENV was inhibited by co-immunization with pcIFN gamma. Results indicate that synergistic effects of CAEV Tar and IFN gamma suppress the: primary adaptive B cell response to plasmid encoded SU. (C) 2001 Elsevier Science Ltd. All rights reserved.