Abstract:

Tissue samples were collected from pig farms of different regions of 11 provinces in China. 812 suspicious samples were detected by ORF2PCR, and 235 samples were PCV2positive. The genotype of 235 ORF2 fragments amplified from positive samples was identified by distinction PCR for PCV2a and PCV2b. The results showed that the isolated rates of PCV2a genotype and PCV2b genotype were 4.2% and 56.6%,respectively. A pair of primers was designed according to documented data in the GenBank, and the complete genomes of 235 PCV2positive template were amplified by PCR. The PCR products of complete genome of PCV2 isolates were cloned and sequenced. The sequences were compared with those of other PCV2 strains in the GenBank, the results indicated that genomic sequences of PCV2 strains tested in this study could be divided into three genotypes，PCV2a，PCV2b and the other genotype that neither PCV2a nor PCV2b(PCV2c?). The results mentioned above also revealed that the epidemic characteristics of genotype of PCV2 in some areas of China were PCV2b ，secondly for little PCV2a as well as neither PCV2a nor PCV2b(PCV2c?).

Key words: porcine circovirus type 2, molecular epidemiology, PCV2a, PCV2b