Variation characteristics of gag gene of human immunodeficiency virus type 1 strain in the main epidemic areas of acquired immunodeficiency syndrome in Yunnan Province / 中华传染病杂志

ABSTRACT

Objective:To analyze the variation characteristics of gag gene sequence of human immunodeficiency virus type 1 (HIV-1) epidemic strains in four major acquired immunodeficiency syndrome (AIDS) endemic areas in Yunnan Province. Methods:A total of 480 human immunodeficiency virus (HIV)/AIDS patients from designated antiviral treatment institutions in Kunming City, Dehong Dai and Jingpo Autonomous Prefecture, Hani-Yi Autonomous Prefecture of Honghe and Lincang City in Yunnan Province from January 2019 to December 2020 were randomly selected. The epidemiological information of the patients was collected. The plasma samples were collected and sent to the Yunnan Provincial Infectious Diseases Hospital for analysis. HIV-1 gag gene was amplified by nested polymerase chain reaction for genotyping.The phylogenetic tree was constructed by MEGA 6.06, and the characteristic amino acids were analyzed by VESPA online analysis tool. The gene distances of gag and matrix protein p17, capsid protein p24, nucleocapsid protein p7 and p6 protein of gag protein were calculated by Distance program. The ratio of synonymous mutation frequnency and non-synonymous mutation frequnency (Ks/Ka) was analyzed by SNAP program. Statistical comparison among multiple groups was performed using analysis of variance. Results:The gag gene sequences were successfully obtained from 404 patients.Most of these patients were men (250 cases, 61.9%), 59.7%(241/404) of patients were aged 40 to 59 years, and the main transmission route was heterosexual transmission (61.4%, 248/404). The main epidemic subtypes of HIV-1 were circulating recombinant form(CRF)08_BC (38.4%, 155/404), CRF01_AE (18.3%, 74/404), unique recombinant form (URF) (12.9%, 52/404), CRF07_BC(9.7%, 39/404), C subtype (8.4%, 34/404), other subtypes (6.9%, 28/404) and B subtype (5.4%, 22/404). Two main spreading clusters were formed by CRF08_BC in the phylogenetic tree, and there were significant differences in the distribution of characteristic amino acids of eight loci between the two spreading clusters, including No.79, 93, 121, 122, 151, 363, 395 and 396. The gag gene distances of CRF01_ AE, CRF07_ BC and CRF08_ BC were 0.090±0.004, 0.088±0.004 and 0.078±0.002, respectively, and the difference was statistically significant ( F=118.33, P<0.001). The Ks/Ka values of gag of the three subtypes were 4.003±1.309, 4.141±0.860 and 4.514±1.215, respectively, and the difference was statistically significant ( F=1.35, P<0.001). The Ks/Ka values of p17 were 2.590±0.186, 2.831±0.496 and 2.936±0.475, respectively, and the difference was statistically significant ( F=1.59, P<0.001). The Ks/Ka values of p24 were 12.579±1.116, 10.185±0.494 and 8.522±0.595, respectively, and the difference was statistically significant ( F=1.61, P<0.001). The Ks/Ka values of p7 were 10.850±0.711, 9.717±0.932 and 8.522±0.026, respectively, and the difference was statistically significant ( F=4.24, P<0.001). The Ks/Ka values of p6 were 3.122±0.134, 3.040±1.498 and 4.841±0.353, respectively, and the difference was statistically significant ( F=10.68, P<0.001). Conclusions:CRF08_ BC is the main subtype in these four areas in Yunnan Province.The different clusters of CRF08_BC result in a different pattern of amino acid composition.The variation degree of different subtype gag gene is different in each section. Surveillance of HIV variant strains should be strengthened to control the epidemics of HIV.