中文摘要：

目的分析新疆地区人类免疫缺陷病毒1型（human immunodeficiency virus type 1,HIV-1）感染者中流行的CRF07_BC亚型毒株gag基因的遗传变异特性。方法对75例HIV-1感染者分别于间隔6个月的两个时间点采集标本。抽提标本RNA反转录后用巢式聚合酶链反应扩增gag基因片段,将得到的2次序列进行亚型、同源性、基因离散率和选择压力分析。结果进化树上同一样本的2次序列聚集成一个小分枝,有15大簇分枝的共同特征是每枝上的几个毒株来源的新疆下属地区相同且同源相似性在94.2%-99.4%之间,具有这种特征的标本超过全部标本量的半数;与首次采样的序列相比,6个月后的样本序列组内基因离散率、与标准株间的组间基因离散率均呈现出增加的趋势;基因选择压力分析表明新疆地区的HIV-1毒株正受到正向选择压力。结论进化树上每簇分枝上的几个样本来源的地区相同和序列高度同源提示每簇上的几例标本很有可能是由同一株亲本毒株进化而来的;基因离散率随流行时间的增长而增加和基因选择压力分析结果均表明HIV-1毒株发生着连续的定向突变。

英文摘要：

Objective To analyze the genetic structure of prevalent subtype CRF07_BC of human immunodeficiency virus 1（ HIV-1） infected patients in Xinjiang. Methods Blood samples were collected at two time points from 75 HIV-1 infected patients in Xinjiang. Then HIV-1 RNA was extracted and HIV-1 gag gene was amplified by nested polymerase chain reaction. The gag gene was sequenced and subject to genetic analyses. Results All the samples were identified as CRF07_BC. Phylogenetic tree showed two sequences of the same sample gathered into a small branch. Fifteen framed clusters on the phylogenetic tree equally showed that some strains in the same cluster were highly homologous（ 94. 2%-99. 4%）and from the same subordinate region in Xinjiang. All the viral sequences showed positive selective pressure. The gene distances within different groups at two time points showed an increasing trend. Conclusions Fifteen framed clusters on the phylogenetic tree equally showed that some of the same cluster were highly homologous and from the same subordinate region in Xinjiang. Thus,it may be presumed that each cluster had the same parental strain. The increasing trend of gene distance with the viruses prevailing in Xinjiang over time and the positive selective pressure equally showed that HIV-1 of subtype CRF07_BC in Xinjiang was occurring continuously directed mutagenesis.