猪Ⅱ型圆环病毒ORF1基因克隆及在E.coli中的表达

猪圆环病毒(porcinecircovirus ,PCV)属圆环病毒科(Circoviridae) ,为单股负链DNA病毒,以滚环方式进行复制,是目前已知的最小的动物病毒之一.PCV有2种基因型即PCV 1和PCV 2 ,两者细胞培养均不引起病变.前者广泛存在于猪源肾细胞中,但并不引起感染猪发病,其基因组为1 75 9bp ;后者首先由Allan等1 ] 从患断奶猪多系统衰弱综合症(postweaningmultisystemicwastingsyndrome ,PMWS)的猪群中分离到,被证明为PMWS的重要病原.PCV 2主要侵害感染猪的免疫系统2 ] ,从而诱发猪体的免疫抑制.PCV 2常和呼吸与繁殖障碍综合征病毒(PRRSV)…

Cloning of ORF1 Gene of Porcine Circovirus Type 2 and Its Expression in E.coli

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.