中国人群中HIV-1辅助受体CCR5基因新突变位点及CCR5-894C缺失基因多态性分析

目的：研究中国人群HIV-1辅助受体CCR5基因编码区新的单核苷酸多态性（SNP）位点;分析CCR5-894C缺失等位基因在中国普通人群和HIV-1高危人群中的分布特点和相关意义。方法：针对CCR5编码区用2对引物进行PCR扩增,设计测序引物对45例汉族人样本进行PCR产物直接测序,用DNAstar分析测序结果,寻找SNP位点。采用错配PCR-RFLP法对中国汉族、蒙族、藏族普通人群,性传播疾病和静脉吸毒高危人群及HIV-1携带者,共627份样品进行了CCR5-894C缺失等位基因分型。结果：在45例汉族人CCR5基因编码区共发现6个SNP位点,4个（184A→G、503G→T、668G→A、99G→T）引起氨基酸改变,两个无义突变;此外还发现1个单碱基缺失（894C缺失）,引起移码突变和提前终止。其中184A→G、503G→T、999G→T三个中国汉族人所特有的SNP位点为首次发现,它们的等位基因频率分别为1.11％,21.1%和10.0％;其中503G→T分布明显不符合Hardy-Weinberg平衡。汉、藏、蒙等民族的普通人群CCR5-894C缺失等位基因频率为1.11％,0.53%和0.在汉族HIV-1性传播、静脉吸毒传播的高危人群中,HIV-1阳性个体和阴性个体间CCR5-89C缺失等位基因频率差异无显著意义,与汉族普通人群比较差异也无显著意义。结论：中国人CCR5基因的SNP位点有自己的特点,共发现4个引起氨基酸改变的SNP位点（其中3个为首次发现）,1个引起移码突变的单碱基缺失。汉族人群中存在CCR5-894C缺失突变,但突变频率很低。这些SNP和缺失突变对于HIV-1感染和艾滋病病程的影响值得进一步研究。

Identification of new mutant sites and 894C deletion variant genotyping of HIV-1 coreceptor CCR5 in indigenous Chinese populations

OBJECTIVE: To investigate the new single nucleotide polymorphism (SNP) sites of HIV-1 coreceptor CCR5 gene and conduct genotyping of CCR5-894C deletion allele in Chinese populations. METHODS: The full length fragment of CCR5 gene coding region was amplified by PCR amplification and sequenced in 45 healthy subjects from Han ethnic group. The sequencing data was analyzed by using DNAstar software for identification of new SNP sites. Furthermore, the genotyping of CCR5-894C deletion variant was performed by PCR-RFLP assay in 627 indigenous Chinese individuals including HIV-1 carriers, HIV-1 high risk population of STDs or IDUs as well as normal contrast. RESULTS: Totally six SNPs and one cytosine base deletion at the 894 nucleotide of CCR5 gene coding region were found in forty five Chinese Han subjects. Four SNPs, i.e. 184A-->G, 503G-->T, 668G-->A, 999G-->T, cause alteration of corresponding amino acids in CCR5 protein and two SNPs are nonsense mutations. The 894C deletion mutation results in a frame shift mutation of CCR5 gene. Among the six SNPs identified, the three sites 184A-->G, 503G-->T, 999G-->T were firstly reported only in Chinese people. The allelic frequencies of mutant 184G, 503T and 999T alleles were 1.1%, 21.1% and 10.0% in Han healthy subjects, respectively. PCR-RFLP assay showed the frequencies of CCR5-894C deletion alleles are 1.11%, 0.53% and 0% for Chinese Han, Tibetan and Mongolian healthy individuals, respectively. There was not significant different of the frequencies of CCR5-894C deletion allele among HIV-1 high risk populations, HIV-1 carries and healthy subjects. CONCLUSION: The subjects from Chinese Han group has its own distinctive SNP sites in the HIV-1 coreceptor CCR5 gene, three new SNPs (184A-->G, 503G-->T, 999G-->T) were firstly identified. Taking together, the significance and implication of these distinctive SNP sites and the 894C deletion mutation in the pathogenesis of HIV/AIDS disease need to be further studied.