Phylogeny and evolution of the NS1 and VP1/VP2 gene sequences from porcine parvovirus

The objective of the present study was to gain new insights on the evolution and phylogeny of the PPV genome, specifically on the NS1 and VP1/VP2 genes. Moreover, two new complete sequences from PPV isolates from China (BQ and ZJ strains) were generated and included in the study. The data set studied contained available NS1 and VP1/VP2 sequences at the GenBank database, plus those corresponding to the mentioned Chinese isolates. PPV sequences were divided into two major groups, with one group separated into two branches. Both phylogenetic groups were homogeneous and several marker aminoacidic changes and synapomorphic positions were identified along both genes. Despite the two genes were satisfactory molecular markers, the absence of selection pressure on the VP1/VP2 fragment makes it a preferential option compared to the NS1 one. Furthermore, NS1 gene showed a biased mutation pattern compared with VP1/VP2 genes, which is compatible with the existence of selection in the first but not in the second gene (as indicated by the negative difference between non-synonymous and synonymous values). No correlation between NS1 and VP1/VP2 phylogenetic groups and/or branches and health status was observed. However, a relationship among virulence and the absence of the 127-bp repeat located downstream the part of ORF2 encoding the structural proteins VP1 and VP2 cannot be excluded.