ABSTRACT

At least four distinct viruses causing human hepatitis have been distinguished to date on the basis of their biologic, physiochemical, and antigenic characteristics (Table 1).

Hepatitis A virus (HAV) belongs to the picornavirus group. The virus is approximately 27 nm in diameter and appears to have cubic symmetry. Degradative analysis has revealed four capsid polypeptides as well as the presence of a genome of linear single-stranded RNA. The polypeptides have molecular weights similar to three of the four polypeptides of enteroviruses. HAV is stable in the presence of ether at acid pH. Compared with the other picornaviruses, HAV is more resistant to heat. HAV exposed to temperatures of 60° C for up to 12 hours does not completely inactivate the virus. Survival of the virus in marine sediment, soil, water, and especially in seafood such as shellfish for weeks has been reported. In 1969, Holmes and Deinhardt succeeded in transmitting HAV to marmoset monkeys. The subsequent detection of hepatitis A antigen (HAAg) in the serum and liver of infected marmoset monkeys, by Hilleman and associates, paved the way for the development of the current tests for hepatitis A antibody (anti-HAV).