FURTHER EVALUATION OF A LIVE HEPATITIS-A VACCINE IN MARMOSETS

Live, attenuated F' hepatitis A vaccine virus was studied in vivo in Saguinus labiatus marmosets for possible reversion to virulence, for possible establishment of persistent infection and for its capacity as a parenterally administered vaccine to induce immunity to oral infection. Serial transmission of the virus in S. labiatus, using infectious stool extracts for the second and third passages, produced no evidence of reversion of the F' vaccine virus to virulence. Monitoring for live HAV in stools over a 135-day period post-inoculation of marmosets with the F' vaccine revealed no evidence of persistent infection. Vaccinated animals were also shown to be resistant to infection on challenge by the oral route as well as by the previously demonstrated parenteral route.