北京地区新近报道的人Boca病毒VP1、VP2蛋白编码区基因序列分析

目的了解北京地区新近报道的人Boca病毒（human bocavirus，HBoV）主要结构蛋白编码区基因的特征。方法选择已经过初步研究证明为HBoV NP1基因检测为阳性的2份临床标本BJ3064、BJ3722。应用针对HBoV VP1蛋白编码区基因的PCR引物进行扩增，对所获得的PCR扩增产物直接进行核苷酸序列测定。将所测到的序列与GenBank中的基因序列进行比较分析和种系进化分析。结果从标本BJ3064及BJ3722中扩增得到HBoV VP1蛋白编码区全基因的PCR扩增产物为2016bp，编码671个氨基酸。VP2蛋白是在不改变开放性读码框架（ORF）的情况下，由VP1蛋白编码区内起始合成，并与VP1终止于同一终止密码子，长度为1629bp，编码542个氨基酸。与HBoV原型株ST1、ST2株相比较，BJ3064、BJ3722的VP1及VP2蛋白无论是核苷酸水平还是氨基酸水平的同源性均超过98％，但与同属细小病毒的BPV及MVC相应位置的序列相比较，同源性较低，其中核苷酸序列同源性低于60％，而氨基酸序列同源性低于50％。VP1及VP2蛋白的编码区基因进化分析显示。BJ3064、BJ3722与ST2之间进化关系较ST1更密切。在BJ3064、BJ3722的VP1蛋白中，也存在类似于MVC的保守性磷酸酯酶A2特异性位点的活性基序（HDXXY）及Ca^2＋结合位点。结论已得到HBoV的结构蛋白VP1和VP2的全基因，将为儿科急性呼吸道感染中该病毒的病原作用、地位及其在各年龄组人群中的血清学特征的深入研究打下坚实的基础。

Sequences analysis of the VP1 and VP2 coding-region genes of human bocavirus circulating in Beijing

Objective To characterize the major structure proteins VP1 and VP2 of human bocavirus (HBoV) which was identified recently by two scientists in Sweden in September 2005 and related to acute respiratory infections in pediatric patients. Methods The coding-region genes of the VP1 and VP2 of HBoV were amplified from 2 clinical specimens BJ3064, BJ3722 after these samples were determined as HBoV positive by PCR amplification of partial NP1 gene. The PCR amplicons were sequenced and sequence analysis was performed by comparison with the sequences of the prototype strains ST1 and ST2 in GenBank. Results The predicted start of the VP2 locates inside the VP1, which closely resembles that of the other known bocavinises BPV and MVC. The VP1 and VP2 coding-region genes amplified from BJ3064 and BJ3722 were 2016 bp and 1629 bp in length, and the deduced proteins were 671 AA and 542 AA, respectively. The sequences of the coding-region genes and the deduced amino acids of VP1 and VP2 share high homology ( > 98 % ) with those of ST1 and ST2, but show lower homology with BPV and MVC, < 60% in nuceotides and < 50% in amino acids. Phylogenetic analysis of VP1 and VP2 nucleotides showed that BJ3064 and BJ3722 were related to ST2 more closely compared to ST1. The conserved phospholipase A2-specific residues (HDXXY) and the Ca2+ binding loop residues (YXGXG) were in the N-terminal of VP1 of BJ3064 and BJ3722 such as MVC. Conclusion The human bocavirus detected from clinical specimens from children in Beijing is closely related to the prototype strains described by the scientists in Sweden.