Hepatitis A virus in cell culture. II. Growth characteristics of hepatitis A virus in Frhk-4/R cells.

The propagation of hepatitis A virus (HAV) is shown in a rapidly growing fetal rhesus monkey kidney cell line (Frhk-4/R). In the course of ten passages through Frhk-4/R cells the HAV, which was released in the supernatants of the cell cultures, was adapted to these cells. In the tenth passage 6 days after infection, it was possible to detect low amounts of HAV in the supernatants by radioimmunoassay (RIA). With indirect immunofluorescence 3 days after infection, a specific granular fluorescence was demonstrated in the cytoplasm of cells infected with HAV from the tenth passage. A persistent infection of Frhk-4/R cells appeared with a main peak at a density of 1.32 g/cm(3) in CsCl density gradients. In the 1.32 g/cm(3) fractions, typical HAV particles are shown by electron microscopy. Furthermore the HAV produced in Frhk-4/R cells is shown to be a useful antigen for diagnostic tests.