A simian strain of hepatitis A virus, AGM-27, functions as an attenuated vaccine for chimpanzees.

The AGM-27 strain OF hepatitis A virus (HAV) was originally isolated from an African green monkey with hepatitis and appears to represent a true simian strain. The virus caused acute hepatitis after intravenous inoculation into African green monkeys, rhesus monkeys, and marmosets. Cynomolgus monkeys inoculated with the virus did not develop hepatitis, probably because of prior exposure to HAV. Chimpanzees inoculated with a high dose of the virus did not develop signs of hepatitis, although the virus replicated and the animals seroconverted. Marmosets and chimpanzees convalescent from infection with the AGM-27 strain of HAV were rechallenged with the virulent HM-175 strain of human HAV. They were partially or totally protected from disease.