Characterization and primary resistance mutations in gag-pol gene of human immunodeficiency virus-1 CRF07_BC strain in Guangdong Province / 中华传染病杂志

ABSTRACT

Objective To investigate the genetic variations of gag-pol gene in human immunodeficiency virus-1(HIV-1) CRF07_BC strain in Guangdong Province.Methods From February to September in 2015,plasma samples of 78 cases with HIV 1 CRF07_BC infection in Guangdong were collected before antiretroviral treatment.Viral RNA was extracted from plasma.Gene (gag and pol) sequences were amplified by reverse transcriptase and nested-PCR using specific primers.Phylogenetic tree,genic dispersion rate,nucleotide polymorphism,selection pressure and variation characteristics were analyzed.Results The main transmission route of the enrolled patients was homosexual transmission (80.77％,63/78).The gag pol gene phylogenetic tree was divided into two sub-clusters.The strains from different transmission routes were not in cluster.The average genetic dispersion rate and average entropy of gag gene were both higher than those of pol gene.The average genetic dispersion and average entropy of p17 and p6 regions of gag gene were both higher than those of p24.The average genetic dispersion and average entropy of pol gene were higher than those of rt region.The average ds/dn values of gag and pol genes were greater than one.Compared with the common HIV-related antigenic epitopes (A2,A11,B39,B60,Cw1,Cw3,Cw8),the cytotoxic lymphocyte (CTL) epitope mutations in the P17 region were more in the consensus of GAG region than those in the P24 region.The epitope conserved rates were 26.92％,0,1.28％,0,96.15％,82.05％,84.62％ and 98.72％,respectively.The drug resistance rate of pol gene was 2.56％ (2/78).Conclusions The gag and pol genes of CRF07_BC strain in Guangdong are all mutated.Diversity of gag gene is greater than that of pol gene,and gag gene variation is mainly in p17 and p6 regions.gag and pol genes are both affected by negative selection pressure.P17 protein CTL epitope variability is greater than P24 protein epitope.The prevalence of drug resistance mutation is lower than the threshold.It's important to monitor the spread of drug-resistant strains.