猪细小病毒SD-68株vp2基因的克隆及序列分析

对猪细小病毒(PPV)SD-68株印2基因进行的克隆和序列测定表明：SD-68株VP2基因全长1740bD，编码579个氨基酸残基组成的多肽；PPVSD-68株与Kresse株、SY-99株、NADL-2(5075)株、NADL-2(4973)株、US-1株的VP2基因比较，核苷酸的同源性在99％以上，氨基酸的同源性在96％以上。进化树分析表明SD-68株与kresse株的亲缘关系最近；在决定毒株组织嗜性的关键氨基酸位点上(378，383及436)，SD-68株与kresse株的差异最小，据此推测SD-68株的组织嗜性与Kresse株相似，即SD-68株属皮炎型PPV；而比较弱毒株NADL-2、SD-68和强毒株kresse VP2的氨基酸差异后发现，215、378和383可能是决定PPV致病性强弱的关键位点。

Cloning and Sequence Analysis of vp2 Gene of Porcine Parvovirus SD-68 Strain

vp2 gene of Porcine parvovirus (PPV) SD-68 strain was cloned and sequenced .The results showed that vp2 gene of Porcine parvovirus (PPV) SD-68 strain was 1740bp and encoded a protein of 579 amino acids. vp2 gene of SD-68 strain exhibited over 99% nucleotide sequence identity and 96% amino acid sequence identity with other PPV strains: Kresse, SY-99, NADL-2(5075), NADL-2(4973), US-1. Phylogenetic tree analysis of vp2 gene showed the closest relationship between SD-68 strain and kresse strain. The difference between SD-68 strain and kresse strain was only on 378, 383 and 436 residues, which decided the tissue tropism of PPV, so the tissue tropism of SD-68 strain suggested more similar with kresse stain, that is to say, SD-68 was a dermatitis strain. Comparison of amino acid residues of virulent strain (kreese) and vaccine strain (NADL-2 and SD-68) suggested that 215, 378 and 383 were important residues that decided the pathogenicity of PPV.