Enhancement of primary and secondary immune responses by interferon-gamma

We have investigated the effects of interferon-gamma (IFN-gamma) administered with "G" glycoprotein of vesicular stomatitis virus (VSV), on the neutralizing antibody response. Treatment of mice or cattle with recombinant DNA-derived IFN-gamma at the time of primary immunization with "G" glycoprotein enhanced the secondary virus-neutralizing antibody response that followed a booster administration of the same antigen without IFN-gamma treatment. Enhancement was statistically significant, and occurred at relatively low doses of IFN-gamma in the absence of any additional adjuvants. Cattle treated with IFN-gamma at the time of primary immunization were also more resistant to VSV challenge than those immunized without IFN-gamma treatment. Such treatment in conjunction with primary immunization may therefore provide a practical means of enhancing protection from viral challenge without inflammatory adjuvants or boosters.