Shangjin Cui, Cortey Martí, Segalés Joaquim
Division of Swine Infectious Diseases, State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute of CAAS, Harbin 15001, China.
Virus Res. 2009 Mar;140(1-2):209-15. doi: 10.1016/j.virusres.2008.11.003. Epub 2008 Dec 16.
The objective of the present study was to gain new insights on the evolution and phylogeny of the PPV genome, specifically on the NS1 and VP1/VP2 genes. Moreover, two new complete sequences from PPV isolates from China (BQ and ZJ strains) were generated and included in the study. The data set studied contained available NS1 and VP1/VP2 sequences at the GenBank database, plus those corresponding to the mentioned Chinese isolates. PPV sequences were divided into two major groups, with one group separated into two branches. Both phylogenetic groups were homogeneous and several marker aminoacidic changes and synapomorphic positions were identified along both genes. Despite the two genes were satisfactory molecular markers, the absence of selection pressure on the VP1/VP2 fragment makes it a preferential option compared to the NS1 one. Furthermore, NS1 gene showed a biased mutation pattern compared with VP1/VP2 genes, which is compatible with the existence of selection in the first but not in the second gene (as indicated by the negative difference between non-synonymous and synonymous values). No correlation between NS1 and VP1/VP2 phylogenetic groups and/or branches and health status was observed. However, a relationship among virulence and the absence of the 127-bp repeat located downstream the part of ORF2 encoding the structural proteins VP1 and VP2 cannot be excluded.
本研究的目的是深入了解猪细小病毒（PPV）基因组的进化和系统发育，特别是NS1和VP1/VP2基因。此外，还获得了来自中国的PPV分离株（BQ和ZJ株）的两个新的完整序列并纳入本研究。所研究的数据集包含GenBank数据库中可用的NS1和VP1/VP2序列，以及上述中国分离株的相应序列。PPV序列分为两个主要组，其中一组又分为两个分支。两个系统发育组均具有同质性，并且在两个基因中均鉴定出了几个标记性氨基酸变化和共衍征位置。尽管这两个基因都是令人满意的分子标记，但VP1/VP2片段不存在选择压力，这使其成为比NS1更优的选择。此外，与VP1/VP2基因相比，NS1基因显示出偏向性的突变模式，这与第一个基因存在选择而第二个基因不存在选择相一致（非同义与同义值之间的负差异表明）。未观察到NS1和VP1/VP2系统发育组和/或分支与健康状况之间的相关性。然而，不能排除毒力与位于编码结构蛋白VP1和VP2的ORF2部分下游的127 bp重复序列缺失之间的关系。
