Four putative subtypes of human parvovirus B19 based on amino acid polymorphism in the C-terminal region of non-structural protein.

The nucleotide sequence of 10 isolates of human parvovirus B19 (B19) were determined and compared throughout 96.3% of the open reading frames (4145 nucleotides from nt. 509-4653). In the 4145 nucleotides, 122 mutation sites were found, of which 24 were accompanied by amino acid displacement. Furthermore, the polymorphism of the amino acids was seen in about 110 bases near the carboxy terminal of the non-structural protein, ranging from nt. 2011 to 2123, where four amino acid mutation points were found to exist. Based on the amino acid polymorphism of these four mutation sites in this area, 10 isolates of the B19 parvovirus could be divided into 4 subtypes (subtypes A, B, C, and D). The frequency of isolation of the subtypes depended on the time and location of collection of the B19 viremic blood specimens.