Molecular Epidemiology Investigation And Detection Of Porcine Bocavirus In Jiangsu Province

Bocaviruses were novel DNA viruses which were discovered from human beings,pigs,cattle,dogs and apes,and suffered from many kind of mammals in recent years.Porcine bocavirus（PBoV）is a single-stranded DNA virus firstly identified in the lymph node of swine with a background of post-weaning multisystemic wasting syndrome in 2009.PBoV is presented at a high prevalence in either health or diseased swine herds around the world,and may be an important cause for the re-outbreak of piglet diarrheal.So it is significant to conduct the research on PBoV.According to the published PBoV nucleotide sequence in GenBank,we designed a pair of specific primers to establish a PCR method that can amplify a variety of PBoV and tested its specificity,sensibility,repeatability and reliability.The results showed that the method had no cross reaction for Pseudo rabies virus（PRV）,porcine circovirus type Ⅱ（PCV2）,porcine parvovirus（PPI）,porcine epidemic diarrhea virus（PEDV）,Transmissible gastroenteritis virus（TGEV）,indicating that its specificity is high.Its sensibility was high,with 6.2×10-9ng/μL,and its repeatablity was good,as the results were consistent in 3 repeative tests.We sequenced the positive products and it was similarity with PBoV published by GenBank,suggesting that the method was reliable.We applied the established method to test 242 pig samples collected in Jiangsu area.Thirty-four samples were shown to contain PBoV,proving that the infection of PBoV existed among fattening pigs in Jiangsu area.In addition,we chose 18 positive PCR products for DNA sequencing discretionarily and then sequences from those PCR products were compared with the sequences of PBoV in the GenBank.The results indicated that positive rate was 14%（34/242）.We made bioinformatics analysis of these 18 samples and it showed that the nucleotide sequence of the genome of 18 strains had 34.6%～100%identities to that of 13 published Bocavirus strains.The phylogenetic tree analysis stated that 31 strains formed four big branches and 18 strains of PBoV in this experiment and NC₀24453 were distributed in one branch.This suggested that infection rate of PBoV was high in Jiangsu and evolution relation was fairly complex.