3Pathogens Detection Of Slaughtered Pigs’ Lymphods And Its PCV2Molecular Epidemiology Investigation In A City Of Guangxi Province

Currently, Classical swine fever(CSF), porcine reproductive and respiratory syndrome(PRRS) and porcine circovirus type2(PCV2) infection have caused huge damage to the pig industry all over the world. These3kinds of virus commenly exsit in our country’s pig industry. Besides,these3pathogens have multiple transmission rutes and media. Secondary infection of other pathogens and co-infections between these3pathogens are not unusual. As the source of pork,slaughtered pig’s health status and its virus infection conditions need more strict check up to prevent the pathogens spreading around by the pork in the markets.In this study,640lymph nodes of slaughtered pigs were collected in a city of GuangXi province.The virus infection rate of CSFV, PRRSV and PCV2was investigated. The results revealed that CSFV, PRRSV and PCV2infection exist in the healthy sloughtered pigs, the positive rate were5.12%,10.27%and43.88%respectively.The PCV2infection in the slaughtered pigs seemed to be the most serious. Among the25co-infection samples,24were related to PCV2infection,only1were CSFV and PRRSV coinfected. Based on the PCV2positive samples, the ORF2gene of PCV2were cloned and sequence analysed.20ORF2of PCV2were obtained in this study,of which15were705bp,4were702bp and1was704bp in length.The sequence analysis showed that the special704bp ORF2isolate had1bp deletion.The homology indentity of the20ORF2in this study with PCV2a, PCV2b and PCV2c standard strain AF055391,AF055393,EU148503were90.5%-93.4%,94.2%-99.3%and89.5%-91.0%respectively. The homology between the domestic strains and the20ORF2sequences in this study was90.0%-99.0%, the GuangDong strain AY035820showed the highest homology and the Beijing strain AY381176showed the lowest. At last, genetic evolutionary tree was constructed, the results showed that the20ORF2isolates in this study belongs to3 subgenotypes:PCV2a, PCV2b and PCV2d, no PCV2c strains were isolated. The218,529,543,202and213isolates in this study with GuangDong strain AY916791, ZheJiang strain AY217743and France classic strain AF055393belonged to the genotype PCV2b. The501,530and532isolates with GuangDong strain AY035820and PCV2a classice strain AF055931belonged to PCV2a. The510,541,544,540,536,507,528,534,548,535,522and538isolates belonged to PCV2d, and showed the highest homology with Hunan strain AY943819.