Genetic variation of the nucleocapsid genes of waterfowl parvovirus.

Duck parvovirus (DPV) and Goose parvovirus (GPV) isolated from infected waterfowls with Derzsy's disease in the year 1999 were identified by polymerase chain reaction and sequencing. The nucleotide sequences of their viral capsid proteins (VPs) show that they share 77% similarity at the DNA, and 84.6% at the protein level. The most variable region between DPV and GPV resides in the N-terminal of VP2 before the initiation codon of VP3 with 35% (19/54) amino acids divergence. Viral capsid protein sequences diverge 4.1 to 4.4% among 1990-99 isolated strains. Variant amino acids cluster in the common regions of VP3 at residues 203-266 and 482-534 which overlaps with the regions proposed to expose on the outer surfaces of parvoviral particles, implying that selective pressure from host immune system might play a part. These data provide useful information for antigenic epitope prediction. This study also reveal the presence of conserved strain-specific residues in VPs and these residues seldom vary among different viral isolates, suggesting that they might be functionally important and worth further investigation.