Localization and persistence of hepatitis A virus in artificially contaminated oysters

Bivalve molluscan shellfish, such as oysters, clams, and cockles, are well-recognized as vectors that concentrate foodborne pathogens by filter feeding. The objective of this study was to investigate the distribution and persistence of hepatitis A virus (HAV) in experimentally contaminated oysters that were either fed or not fed with algae. Oysters were experimentally contaminated with HAV and maintained in depuration conditions. qRT-PCR, immunohistochemistry (IHC), and in situ hybridization (ISH) were performed on oyster samples collected at 0, 1, 3, 5, and 7 days post-inoculation. When HAV-contaminated oysters were depurated for 7 days, HAV was detected in 91.1-97.8% of the digestive glands and gills. While the high viral load in the digestive glands in oysters did not change significantly regardless of algae-feeding, the viral load of the gills gradually decreased in both groups during the depuration. HAV antigen and RNA were detected in the digestive diverticula and connective tissues by both IHC and ISH. HAV was detected in the stomach, intestine, and gills by only ISH. The distribution of HAV in various oyster tissues may explain the persistence of contamination in oysters during the depuration process.