中文摘要：

目的了解广西壮族自治区HIV-1流行毒株gag基因分子进化及遗传变异特征。方法收集2011年10月至2012年3月广西地区HIV-1感染者血液样本158份，采用反转录／套式PCR对HIV-1gag基因片段进行扩增并测序。运用MEGA5．03构建系统进化树，并计算gag区及各编码区段的基因离散率和选择压力（globleω）。两样本基因离散率的比较采用两独立样本t检验，多个样本的基因离散率比较采用单因素方差分析。结果158份样本中获得140条gag基因序列，存在4种亚型：CRF_01AE80份（57．1％），CRF08BC46份（32．9％），CRF07BC10份（7．1％），B（B’）4份（2．9％）。gag基因离散率在CRF01AE亚型为0．036±0．001，CRF08BC亚型为0．031±0．002，CRF07-BC亚型为0．043±0．003，B（B’）亚型为0．102±0．006，差异有统计学意义（F=220．62，P〈0．01）。p17和p24编码区均受到负向选择压力作用，globlem〈1。各亚型p17编码区的globleω值相近，差异无统计学意义（F-0．761，P=0．469），p24编码区的globlem值差异也无统计学意义（F=0．037，P=0．964）。结论广西地区HIV-1亚型以CRF_01AE为主，gag基因各编码区段在进化上相对保守，但HIV-1流行特征的变化可能会影响gag基因的遗传变异，应继续追踪检测。

英文摘要：

Objective To study the phylogenetic evolution and genetic variations of gag gene among the prevalent human immunodeficiency virus （HIV）-1 strains in Guangxi Zhuang Autonomous Region. Methods Plasma samples of 158 HIV-1 infected patients in Guangxi area were collected during October 2011 to March 2012. The gag; gene fragments of HIV-1 were amplified by reverse transcription/nestedpolymerase chain reaction and then sequenced. MEGA 5.03 was utilized to construct phylogenetic tree and to calculate the genetic distances and selection pressures （globle ω） of gag gene and its coding regions. The comparisons between two groups were tested by Student＇s t test, and the comparisons of multiple groups were tested by one-way ANOVA. Results A total of 140 amplification products of gag. gene were obtained from 158 samples. Four subtypes of HIV-1 were found, including CRF01_AE （80, 57. 1%）, CRF08_BC （46, 32.9%）, CRF07_BC （10, 7. 1%）, and subtype B （B＇） （4, 2. 9%）. The genetic distances of gag gene of the above subtypes were 0. 036 ± 0. 001, 0. 031 ± 0. 002, 0. 043 ω0. 003 and 0. 102±0. 006, respectively, with statistical significance （F=220.62 ,P〈0.01）. The p17 and p24 coding regions suffered negative selection pressure （globle ω〈1）. Neither the globle ω in p17 region nor that in p24 region had significant differences among different subtypes （F= 0. 761, P= 0. 469 and F=0. 037, P= 0. 964, respectively）. Conclusion CRF01 AE is the major subtypes of HIV-1 in Guangxi Zhuang Autonomous Region. The coding regions of gag gene are relatively conserved during evolution. Changes of HIV 1 prevalence, however, may affect the genetic variation of gag gene, which should be continuously monitored.