Propagation of human hepatitis A virus in African green monkey kidney cell culture: primary isolation and serial passage.

Human hepatitis A virus (HAV) was propagated in primary African Green Monkey (Cercopithecus aethiops) kidney (AGMK) cell cultures. Three strains of HAV were used: MS-1, SD-11, and HM-175. Cells were inoculated with marmoset-passaged material or human clinical specimens and were stained by direct immunofluorescence to establish the identity of the virus. Both clinical samples and marmoset-passaged material produced immunofluorescence. HAV antigen was found scattered throughout the cytoplasm of inoculated cultures. The HM-175 strain produced the most intense immunofluorescence. This strain of HAV had been serially passaged in cell culture seven times. Blocking experiments with paired human sera from naturally acquired HAV infections and hyperimmune chimpanzee serum from an experimentally infected animal established that the immunofluorescence was specific. The viral antigen was found to be exclusively intracellular. The interval to maximum HAV antigen expression was decreased by serial passage. The HAV strain described herein, which was recovered directly from the stool specimen of a patient with HAV in primary AGMK cell culture, may prove useful as a source of antigen for serological tests and as a candidate vaccine strain.