Genetic analysis of HAV strains recovered from patients with acute hepatitis from southern Italy

Southern Italy is an endemic area for HAV infection contributing to the majority of Italian hepatitis A cases. Using molecular analysis, HAV strains have been classified in distinct genotypes and subgenotypes. To characterize HAV wildtype strains circulating in Southern Italy, sequence analysis of VP3-VP1 and VP1/2A junction regions of HAV isolates recovered from 25 patients with acute hepatitis during 2000 and 2001 was carried out. HAV isolates showed a degree of identity, after pairwise comparison with one another, ranging from 91.9-100% in the VP3-VP1 junction region and 89.9-100% in the VP1/2A junction region. All strains belonged to genotype 1, with 84% (21/25) of samples clustering in subgenotype IA and 16% (4/25) in subgenotype IB. Cocirculation of subgenotypes IA and IB was observed among isolates from 2000, whereas all strains from 2001 were subgenotype IA. In addition,the subgenotype IA strains formed different clusters, one of which was related closely to some Cuban strains, showing a percent similarity of 98.8% in the 168-base pair segment encompassing the VP1/2A junction and the same amino acid substitution. The latter finding suggests that this subgenotype variant circulates also in the Mediterranean area. The results of the phylogenetic analysis confirm the genetic heterogeneity among HAV strains in Western Europe.