A pair of specific primers were designed and synthesized according to the published sequences of ORF1 gene of PCV 2. The complete DNA fragment of ORF1 gene was obtained by PCR from viral DNA of PCV 2 QD strain.Its nuclectide sequence was determined by the dideoxy mediated chain termination method.The results showed that the complete open reading frame (ORF) of ORF1 gene encoding 314 amino acids was 945 bp in length.A comparison of the nucleotide and amino acid sequences of ORF1 gene with that of other PCV strains showed that the identity of nucleotide with PCV 1 and PCV 2 were 83% and 96 4%～99 2% respectively,and identity of the deduced amino acid with PCV 1 and PCV 2 were 84% and more than 98% respecitively.The DNA fragment of ORF1 gene was subcloned into prokaryotic expression vector pET 28a and pGEX KG;while the specific non fusion and fusion proteins with GST of molecular weight 38 kD and 63 kD were expressed in E.coli BL 21 (DE3).Western blotting assay indicated that the polyclonal antibody against PCV 2 could recognize these two proteins.
PCV1 was isolated from IBRS-2 cells line,and its complete genomic sequence was cloned by PCR.Sequence analysis indicated that this PCV1 strain shares >98% nucleotide identity with the other PCV1 strains in GenBank.Then double copy molecule clone(pSK2PCV1) was constructed and used to transfect PK-15 cell line.The results of indirect immunofluorescence(IIF) and RT-PCR suggested that pSK2PCV1 could form infectious virus after being transfected into PK-15 cells.
