Replication Kinetics and Cytopathic Effect of Hepatitis A Virus

The replication kinetics and c.p.e. of hepatitis A virus (HAV) strain HM-175 were shown to depend upon the passage level of the cell line, and the passage level and method of selection of the virus population. Maximum virus production under single-step growth curve conditions occurred as early as 24 to 28 h or as late as 10 days post-infection. Although rapid replication of an isolate of HM-715 (pHM-175) occurred initially in BS-C-1 cells, its most pronounced c.p.e. was induced in FRhK-4 cells. The replication kinetics of pHM-175 in BS-C-1 cells were similar to those in FRhK-4 cells, although a higher yield of virus was obtained in the latter. The HAV that generated c.p.e. in FRhK-4 cells was obtained by two different selection processes: virus passage, or cloning of large focus-forming variants from the radioimmunofocus assay. The c.p.e. and yield of infectious pHM-175 in FRhK-4 cells could be reduced by 3 mM-guanidine. Another HAV isolate, strain MD-1, isolated directly from contaminated ground water in cell culture demonstrated c.p.e. in FRhK-4 cells after passage as persistently infected A-549 cells.