Analysis and detection of dominant genetic types of porcine circovirus type 2.

The genetic variation of porcine circovirus type 2(PCV2) were studied by analyzing the sequences of 556 PCV2 isolates during 1999 to 2009 in GenBank.The results showed that the dominant genetic type of PCV2 was type A(PCV2A) in 1999 to 2002,and the genetic type B(PCV2B) became the dominant type since 2003,with 95.4% isolated in 2004 and more than 76% in 2007 to 2009.The 287 PCV2 isolates in China in 2003 to 2009,250 strains belonged to PCV2B and 37 belonged to PCV2A,indicating that PCV2B was the dominant genetic type in China at present.The PCR methods were developed for differentiating PCV2A and PCV2B and 70 clinical samples were tested,34.29%(24/70) were detected PCV2 positive,all of which belonged to PCV2B genotype,no PCV2A was detected.Those findings indicated that PCV2B was dominant PCV2 strain in the local swine population.