Typing of European strains of parvovirus B19 by restriction endonuclease analyses and sequencing: Identification of evolutionary lineages and evidence of recombination of markers from different lineages

European isolates of parvovirus B19 were analyzed by restriction enzyme analysis of PCR products of the VP1/2 coding region and sequencing of the same amplified region, five cloned fragments from each PCR product. Two main groupings were found based on three perfectly linked point deviations. On the assumption that identical point deviations causing the various restriction patterns regardless of time and origin of virus isolation were unlikely to emerge independently in different evolutionary lineages, traits of evolutionary lineages were identified, suggesting a clonal population structure of global circulating B19 strains. However, combinations of markers from different evolutionary lineages were also found, particularly in a strain derived from an individual chronically infected with B19 for more than 7 years. As chronically infected individuals might be subject to superinfections due to contacts or possibly due to blood transfusions or the administration of γ-globulin, it is suggested that coexistance of, and recombination between variants of B19 of different phylogenetic origin incidentally occur in such individuals.