Genetic variability of hepatitis A virus in South America reveals heterogeneity and co-circulation during epidemic outbreaks. 
Genetic analysis of selected genome regions of hepatitis A virus (HAV) suggested that distinct genotypes of HAV could be found in different geographical regions.  In order to gain insight into the genetic variability and mode of evolution of HAV in South America, an analysis was performed of sequence data obtained from the VP1 amino terminus and the VP1/2A region of HAV strains isolated over a short period of time in Uruguay, Argentina and Chile.  Sequences obtained from 22 distinct HAV isolates were compared with published sequences from 21 different strains isolated all over the world.  Phylogenetic analysis revealed that all strains isolated belong to a unique sub-genotype (IA).  Strains isolated during an outbreak period showed a higher degree of heterogeneity than anticipated previously and the co-circulation of different isolates.  The genetic variability among strains isolated in this region seems to be higher in comparison with strains isolated in other regions of the world.