Continuous production of hepatitis A virus in PLC/PRF/5 cell cultures: use of antigen for serology.

The strain CF53 of hepatitis A virus (HAV) previously adapted to growth in PLC/PRF/5 cells was grown in 175 cm2 flasks, at different passages. After infection, cells were incubated at 32 degrees C in RPMI 1640 medium supplemented with 2.5% foetal calf serum (FCS) for 6-12 months. HAV which was released continuously in the culture medium was harvested weekly. Hepatitis A virus antigen (HAAg) and infectious virus production was stable during each passage. The antigen titre, determined by radioimmunoassay, was about 50 for each passage whereas the infectious virus titre increased from 10(3.7) (passage 7) to 10(6.0) TCID50/ml (passage 13). Virus production was not influenced by the FCS concentration (0-2.5%) in the maintenance medium. The cell culture produced HAAg was used for detection of total anti-HAV antibodies, anti-HAV titration and IgM antibody capture assay and the results were identical to those obtained with commercial kits. HAAg produced by this practical and cheap method could easily replace primate derived antigen for the detection of anti-HAV antibodies.