Localization of hepatitis A virus antigen to specific subcellular fractions of hepatitis-A-infected chimpanzee liver cells.

The localization of hepatitis A virus antigen to specific subcellular fractions of infected chimpanzee liver cells was studied by solid-phase radioimmunoassay following a mild subcellular fractionation procedure designed to separate various organelles from the cytosol and the nuclei. Most of the antigenic activity (93%) was evenly divided between the cytosol fraction and the microsomal suspension. Within the microsomal fraction, more than 75% of the detectable antigen was associated with the smooth endoplasmic reticulum. Less than 4% of the total antigenic activity was localized to the nucleus. These data provide additional evidence that replication of hepatitis A virus occurs primarily within the cytoplasm of the host cell in close association with cellular membranes, consistent with that observed for other members of the genus Enterovirus.