Artificial Infection Of Porcine Circovirus 2 And Study On The Recombinant Adenovirus Vaccine

Porcine circovirus 2 (PCV2) is causal agent of postweaning multisystemic wasting syndrome(PMWS). The syndrome mainly affects weaned pigs and is characterized by dyspnea, progressive weight loss, respiratory signs, jaundice and occasionally skin lesions. The disease was first described in Cananda in 1991 and now is considered to be widespread throughout the most important swine production areas of the world.During the period of Jan. 2002 to Dec. 2002, the type 2 porcine circovirus (PCV2) and porcine reproductive and respiratory syndrome virus (PRRSV) were detected by PCR and RT-PCR respectively from 146 piglets samples with postweaning multisystemic wasting syndrome from 100 pig farms in 6 provines in mid-eastern region of China, based on the investigation of the clinical signs and pathological characteristics of piglets. The results showed that 28 samples of 24 pig farms were diagnosed positive with PCV2 infection and 77 samples of 64 pig farms positive with PRRSV infection. In these samples and pig farms, 21 samples of 19 pig farms simultaneously infected with PCV2 and PRRSV. To determine the extent of genetic heterogencity of PCV2, two PCV2 isolates, PCV2-AH and PCV2-SH, were isolated and identified with indirect immunofluorescence assay (IFA).The ORF2 of two isolates were partly amplified by PCR and sequenced with length of 340bp. The results indicated that ORF2 fragments had 92%-99% similarity with others isolated from other countries. To some extent, ORF2 genes of the two isolates vary in their genomic sequence.PCV2-SH isolat had 84% geneic homology with PCV2-AH isolate. It indicated that PCV2-AH isolate was closely related to the Korea isolate KSY-1, and PCV2-SH isolate is similar to the Canadian isolate imp. 1147. The results showed that co-infection of PCV2 and PRRSV existed wildly in China and PCV2 might be original from different geographic regions.24 piglets were distributed in six groups: PCV2 inoculated and KLH immuno-stimulated (n=4), PRRSV and PCV2 inoculated (n=4), PCV2 inoculated (n=4), PRRSV inoculated(n=4), KLH immunostimulated (n=4), and control(n=4),. After challenged, these...