Genetic variation analysis of Chinese strains of porcine circovirus type 2

Forty Chinese PCV2 strains collected between 2004 and 2008 were sequenced and their genetic variations were analyzed together with nine previous PCV2 isolates. Phylogenetic analysis indicated that these Chinese PCV2 strains could be divided into four genotypes (PCV-2a, PCV-2b, PCV-2d and PCV-2e), and the genotype PCV-2c defined in Denmark was not found. PCV-2d and PCV-2e were two genotypes firstly determined in our study. Variation analysis of amino acids of capsid protein revealed that Chinese PCV2 strains clustered within PCV-2d had four amino acid marker positions and the isolates within PCV-2e had seven unique amino acid mutations. Our analysis also showed that PCV-2b became dominating in China in recent years. These data contribute to the understanding of PCV2 molecular epidemiology.