The phylogenetic evolution and genetic variations of gag gene among the prevalent human immunodeficiency virus-1 strains in Guangxi region

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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/nested-polymerase 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±0.003 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. Key words: HIV-1; Genes, gag; Variation (Genetics)