Serological Investigation Of PCV2 Infection And The Expressoin Of ORF2 Gene Of PCV2 Shaanxi Isolate In E.coli

The infection of porcine circovirus type2(PCV2) is an epidemic of porcine which was recognized in recent years, including postweaning multisystemic wasting syndrome(PMWS), reproductive failure/sow abortion and mortality syndrome (SAMS), porcine respiratory disease syndrome(PRDS), porcine dermatitis and nephropathy syndrom(ePDNS), congenital tremor type A2 (CT), intersticial pneumonia (IP), proliferative and necrotizing pneumonia(PNP),etc. The infection of PCV2 may reduce the immunological ability of porcine , lead to the secondary infection of other pathogens, and the wide prevalence and spreading of this disease posed a serious threat to pig industry and great loss in many nations and regions all over the world, cause more huge indirect loss, and handicap the progress of pig industry badly. PCV2 infection have been reported in many regions of our country,although there is no report about PCV2 infection in Shaanxi province,we got some cases which show PMWS-like clinical appearances in the practice,in order to study the epidemic situation of PCV2 infection in Shaanxi province,the serological investigation of PCV2 infection was done;So far, there is no effective vaccine to be used for the prevention of this disease, and the serological diagnosis techniques become very useful and important。Some ELISA diagnosis kits for PCV2 infection was supplied ,because the performance of these kits is low, and with high costs, these kits cannot be used widely for diagnosis and detection. So the ORF2 gene of PCV2 Shaanxi Isolate was cloned and expressed in E.coli , the result sets basis for the study of diagnosis antigen in serological diagnosis technique for PCV2 infection. This study maybe summarized as follows:1. During January 2004 to June 2005, 237 serum samples were collected from the various pig herds in Yulin, Baoji, Xi'an, Weinan, Hanzhong, Shangluo and Ankang 7 prefectures of Shaanxi province for detection the antibody against Porcine Circovirus type2(PCV2)by means of indirect ELISA, and some serum specimens were detected for the antibody against Porcine Pseudorabies (PRV) gE protein by means of Blocking ELISA . The results showed that the PCV2 antibody positivee rate of unweaned piglets,postweaning piglets,hogs,service boar,replacememt gilts,sows were 0(0/40) ,28.6%(2/7),43.7%(31/71), 7.7%(1/13), 15.6%(7/45), 60.4%(29/48), respectively; 13 serum specimens of 2 to 3 mouth old pigs which show PMWS-like clinical appearances were examined, the positive detectable rate was 61.5%(8/13),the total positive detectable rate reach 32.9%(78/237); the result showed the co-infection rate of PRV and PCV2 reached 21.7%(5/23).2. A pair of primers was designed according to the genomic sequence of PCV2 from GenBank, and the...