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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.

Bacteriophage φX174 when photodynamically inactivated (i.e., when rendered unable to produce plaques as a result of exposure to visible light in air in the presence of proflavine) progressively lost their capacity to bind efficiently with homologous antiserum. Such loss of serum-blocking power was evident with heat-inactivated but not with UV-irradiated phage. The ability of the phages to adsorb to host cells, however, remained practically unaltered even after photodynamic inactivation. It thus appears that photodynamic damages in the so-called “jacket” component of the φX174 coat proteins are partly responsible for the loss of plaque-forming ability, whereas the “spikes” are either poor antigens or insensitive to photodynamic treatment.

Hepatitis A virus (HAV) transmission through blood is a rare but potential cause of posttransfusion hepatitis. We can now document such a case supported by laboratory evidence of HAV in the donor blood. A 10-year-old girl manifested icteric hepatitis A 31 days after receiving a single unit of packed RBCs from a donor who subsequently experienced hepatitis A and died in hepatic failure. Hepatitis A virus antigen was detected in the donor's hepatocytes and in plasma obtained from the original donor unit. The density in cesium chloride of the HAV antigenic activity from the liver and plasma ranged from 1.33 to 1.37 g/cu cm, which is similar to that reported for infectious HAV particles. The implicated donor plasma had normal aminotransferase levels and was negative for antibody to HAV. Inoculation of this plasma into a chimpanzee resulted in the development of hepatitis A 23 days later based on the appearance of fecal HAV antigen, hepatitis, and IgM anti-HAV seroconversion. These data clearly document the presence of HAV in the donor sample that produced posttransfusion hepatitis A. (JAMA1983;250:2313-2317)