RESUMO
Objective@#To analyze the variation characteristics of HIV-1 Gp120 sequences in men who have sex with men (MSM) in Guangzhou.@*Methods@#Plasma samples were collected from HIV-1 infected MSM before antiretroviral treatment. Viral RNA was extracted from plasma. Gp120 gene sequences were amplified by reverse transcription and nested-PCR using specific primers. Phylogenetic tree, length polymorphism, amino acid characteristics of V3 loop, co-receptors and signature amino acids were analyzed.@*Results@#The phylogenetic tree were divided into 4 clusters, and the most prevalent subtypes were CRF07_BC (34/61, 55.74%) and CRF01_AE (24/61, 39.34%). Majority of HIV-1 Gp120 sequences had 496-515 amino acids. Among five hypervariable regions, the V1 region had the highest levels of length polymorphism and V3 region had the lowest. The top four peptide of V3 loop were GPGQ (56/58, 96.55%). Most of the co-receptors HIV-1 strains used was CCR5(50/58, 86.21%)according to four methods of comprehensive prediction. There are four signature amino acids in CRF01_AE subtype strains, and the frequency of occurrence was 0.75-0.83; there are eight signature amino acids in CRF07_BC subtype strains, and the frequency was 0.74-0.94.@*Conclusions@#The length of Gp120 sequences in MSM in Guangzhou has a high polymorphism. The top four peptide of V3 loop, co-receptor and signature amino acid of V3 ring have formed unique patterns.