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目的:分析我国4个地区的人免疫缺陷病毒1型(HIV-1)主要流行毒株的亚型分布,以及在宿主免疫压力下的基因变异和抗原表位的变化情况,初步探讨这些地区HIV-1gag基因的分子进化特征。方法:从来自河南、广东、四川、北京的HIV-1感染者血浆样本中提取基因组RNA,经逆转录-聚合酶链反应(RT-PCR)扩增部分gag基因,用扩增产物直接进行测序;使用Genotyping Tool软件进行亚型分析,使用MEGA4.1软件绘制系统进化树;用Distance工具计算各个亚型序列的基因离散率;用SNAP程序分析同义替换率与非同义替换率的比值(Ks/Ka),并对各亚型中我国人群中较常见的HLA-Ⅰ型限制的CTL抗原表位的突变情况进行分析。结果:这些地区HIV-1主要流行毒株gag基因亚型主要是B′、CRF07_BC、CRF01_AE、B、CRF08_BC和CRF02_AG。各亚型内的基因离散率不同,由大到小排列为CRF01_AE>B>CRF08_BC>CRF07_BC>B′,Ks/Ka为CRF01_AE>B>CRF08_BC>B′>CRF07_BC。p17区段的CTL抗原表位变异远大于p24区段。各个亚型共享序列中存在的突变位点由多到少排列为CRF01_AE>B>B′>CRF07_BC。结论:我国HIV-1流行毒株的gag基因序列中,CRF01_AE亚型受到的选择压力最大,基因离散率也最大,且CTL抗原表位的变异亦最大,其次是B和B′亚型,CRF07_BC亚型变异最小。各亚型间CTL抗原表位变异的差异明显。
OBJECTIVE: To analyze the distribution of subtypes of the major epidemic strains of human immunodeficiency virus type 1 (HIV-1) in four regions of China, as well as the genetic variation and antigenic epitopes under host immune pressure. Molecular evolution of -1gag gene. METHODS: Genomic RNA was extracted from plasma samples of HIV-1 infected individuals from Henan, Guangdong, Sichuan and Beijing. Some of the gag genes were amplified by reverse transcription-polymerase chain reaction (RT-PCR) and sequenced directly using the amplified products ; Using Genotyping Tool software for subtype analysis, using MEGA4.1 software to draw the phylogenetic tree; using the Distance tool to calculate the genetic divergence rate of each subtype sequence; using SNAP program analysis of synonymous substitution rate and non-synonymous substitution rate ratio Ks / Ka). The mutations of the more common HLA-I restricted CTL epitopes in our subgroups were analyzed. RESULTS: The major subtypes of HIV-1 gag genes in these areas were mainly B ’, CRF07_BC, CRF01_AE, B, CRF08_BC and CRF02_AG. The distribution of genes in different subtypes was different from high to low, which were CRF01_AE> B> CRF08_BC> CRF07_BC> B ’, Ks / Ka were CRF01_AE> B> CRF08_BC> B> CRF07_BC. The CTL epitope variation in p17 was much greater than in p24. Mutations in the shared sequences of each subtype are arranged in ascending order of CRF01_AE> B> B> CRF07_BC. CONCLUSION: Among the gag gene sequences of HIV-1 strains in our country, the CRF01_AE subtypes are under the highest selection pressure, the largest gene dispersion rate and the largest variation of CTL epitopes, followed by B and B ’subtypes, CRF07_BC Subtype variation is the smallest. The differences of CTL epitope variation between subtypes were obvious.