Genotyping of hepatitis A virus detected in bivalve shellfish in Galicia (NW Spain).

Hepatitis A virus (HAV) represents a significant public health problem due to its high persistence in the environment and its transmission through contaminated water and food. Bivalve shellfish are filter feeders that can bioaccumulate human pathogens found in contaminated waters, their consumption being a potential cause of hepatitis A outbreaks. In this work, cultured and wild bivalve shellfish from the Ría de Vigo (Galicia, NW Spain) were analysed for the presence and genotyping of HAV. A total of 160 shellfish samples were collected between March 2004 and December 2006, including 68 samples from cultured mussels (Mytilus galloprovincialis), 30 from wild clams (Rupitapes decussatus), 31 from wild cockles (Cerastoderma edule) and 31 from wild mussel. HAV detection, carried out by quantitative RT-PCR, was positive for 29 (42.6%) cultured and 40 (43.5%) wild samples, with levels ranging from 3.1 x 10(2) and 1.4 x 10(10) RNA copies/g of shellfish digestive tissue. The phylogenetic analysis of VP1-P2A and VP3-VP1 regions, separately or as concatenated sequences, revealed that all HAV strains analysed belong to subgenotype IB. These results indicate a high prevalence of this subgenotype in the area studied.