[A trial of a hepatitis A cultured inactivated vaccine on rhesus macaques]

In this work experimental model of hepatitis A virus (HAV) infection in macaques rhesus was used. In 6 seronegative monkeys immunized with the inactivated vaccine (3 injections of 0.3 micrograms of viral protein each at an interval of 1 month) pronounced antibody response was observed. The dynamics and titers of anti-HAV antibodies were similar to those in 5 rhesus macaques which received the active virus. But, in contrast to the latter, no IgM antibodies were detected in the immunized animals. Three months after the end of immunization the monkeys were resistant to challenge with a HAV strain pathogenic for humans (10(3) - 10(4) ID50). The monkeys had no morphological changes in the liver and no rise in the serum alanine-amino transferase activity, but exhibited transient excretion of the virus in feces, as well as stimulation of anti-HAV antibodies (in the absence of IgM antibodies). The vaccine under test proved to be safe, immunogenic and produced a protective effect.