Occurrence and Molecular Characterization of Human Astrovirus and Hepatitis A Virus in Bivalve Mollusks Marketed in Tourist Cities in Rio de Janeiro, Brazil

This study investigated the prevalence and genetic diversity of human astrovirus (HAstV), hepatitis A virus (HAV), and hepatitis E virus (HEV) in bivalve mollusks (mussels and oysters) marketed in three tourist cities in the State of Rio de Janeiro, Brazil, from January to December 2022. One hundred and thirty-four samples were processed according to the ISO 15216-1:2017 (Microbiology of food a chain—horizontal method for determination of hepatitis A virus and norovirus in food using real-time RTPCR—Part 1: method for quantification, vol 2017. International Organization for Standardization, Geneva, pp 1–48, 2017), and viral screening was performed by the TaqMan real-time RT-qPCR. HAstV RNA was detected in 13.9% (10/72) of the oyster samples and 14.5% (9/62) of the mussel samples. HAV RNA was detected in 8.1% (5/62) of the mussels, while HEV RNA was not detected in any of the analyzed bivalves. The molecular characterization revealed that HAstV strains detected in live oysters belonged to both classical (HAstV-1) and non-classical (MLB-1) genotypes. The HAV-IA genotype was detected in mussel samples and segregated into two subclusters. This study reports the presence of HAstV and HAV in oysters and mussels marketed in Brazil for the first time. The findings indicate local water contamination in the bivalve sampling areas, highlighting the importance of environmental monitoring and surveillance improvements, particularly in shellfish production areas.