中国人艾滋病毒感染者及健康人群人类免疫缺陷病毒CCR5开放阅读框架区天然突变的对比研究

Functional analysis of naturally occurring mutations on open reading frames of CCR5 among HIV infected Chinese patients and the healthy

目的研究中国人群CCR5基因开放阅读框架(ORF)区突变并分析其对中国人人类免疫缺陷病毒(HIV)传播和致病的影响。方法研究对象为居住在香港特区的1099名成年中国人,其中785名为HIV阴性健康人,314例为确诊HIV感染的患者。首先对CCR5 ORF进行测序,确定并分析CCR5突变在人群的分布。再对突变G106R、Δ32、R223Q、299(FS)和S3361体外克隆,研究其表达及作为HIV辅助受体功能的改变。结果在CCR5 ORF共检测到10个突变位点。其中7个为有意义突变;突变R223Q是发生频率最高的突变,在正常人是4．7％,在HIV感染者是4．5％;其余CCR5 ORF突变发生频率均＜1％; R223Q位于CCR5膜内区,不影响其作为HIV辅助受体的功能;S336I位于CCR5的C端,同样不影响其功能;突变G106R位于CCR5第3跨膜区,实验显示其辅助受体功能受到明显影响。结论CCR5 ORF突变在中国人群较为常见,一些突变明显影响其作为HIV辅助受体的功能,但在流行病学范围内对HIV感染及致病的影响不明显。

Objective To determine the polymorphism of HIV co-receptor, CC ehemokine receptor 5 （CCR5） in Chinese and its effect on HIV infection.Methods Two groups of adult Chinese residing in Hong Kong were recruited： （ 1 ） 785 HIV - healthy donors and （2） 314 HIV^＋ patients. CCR5 mutations were identified from the study subjects by sequencing. Five most prevalent or significant mutant genes were cloned and their effects on HIV infection were analyzed by a series of in vitro experiments, including detections of their transcription levels, expression levels, conformational changes, and HIV co-receptor function. Results Ten mutants in CCR5 open reading frame （ORF） were identified, seven of which were non-synonymous. Two previously reported mutants, R223Q and 299（FS） were the most prevalent, followed by two novel mutants, S336I and G106R. The frequencies of these alleles did not show significant difference between HIV patients and the healthy controls. However, the heterozygous carriers of G106R, A32and 299（FS） were associated with slower disease progression. In vitro studies demonstrated that G106R and 299（FS） mutants suppressed their HIV co-receptor function by conformation changes in the second extracellular loop （ECL2） and a reduction of surface trafficking respectively. Conclusion R223Q is the most prevalent CCR5 mutant in ethnic Chinese with frequency of 0.046, which however does not affect HIV infection. A novel mutant G106R located in the third trans-membrane domain was identified, which led to a loss of the HIV co-receptor function in vitro through conformation changes in ECL2.