EFFECT OF POSTEXPOSURE VACCINATION IN A CHIMPANZEE MODEL OF HEPATITIS-A VIRUS-INFECTION

Passive transfer of antibodies to hepatitis A virus (HAV) in immune gl obulin (IG) effectively prevents hepatitis A when given after exposure , but does not provide lasting protection from infection. Hepatitis A vaccines have been shown to generate quickly levels of antibody equiva lent to those found after IG administration. The effect of hepatitis A vaccine in preventing infection following fecal-oral exposure was eva luated in a chimpanzee model of HAV infection. Two animals were vaccin ated 1 and 3 days, respectively following inoculation and two inoculat ed animals served as unprotected controls. Of the two immunized animal s, one had no evidence of HAV infection, while the other had an attenu ated infection with no evidence of virus shedding. These results sugge st that while postexposure hepatitis A vaccination may be infection pe rmissive, it attenuates disease expression and prevents virus shedding . (C) 1994 Wiley-Liss, Inc.