Genetic analysis of porcine circovirus type 2 (PCV2) strains isolated between 2001 and 2009: genotype PCV2b predominate in postweaning multisystemic wasting syndrome occurrences in eastern China.

Porcine circovirus type 2 (PCV2) is the essential infectious agent of postweaning multisystemic wasting syndrome (PMWS). In the present study, we obtained sequences of 31 PCV2 isolates from different farms of 11 provinces of eastern China and analyzed the genetic characterization of 136 eastern China-derivate PCV2 isolated during 2001-2009. The results showed that these PCV2 isolates could be divided into two groups, PCV2b (108 of 1A/1B, 19 of 1C) and PCV2a (1 of 2A, 2 of 2D, 6 of 2E). Among the 9 PCV2a isolates, eight were found before the year 2005. Meanwhile, three major heterogenic regions were observed in amino acid positions 53-91, 121-151, and 190-210; a few specific substitution patterns were found in each subgroup and several variant or conserved epitopes were also observed in the Cap protein. It indicated that PCV2b predominated in PMWS occurrences in eastern China and a few recombinants of different genotypes existed in nature.