Subtype and sequence analysis of HIV-1 strains in Heilongjiang Province

Background Human immunodeficiency virus （HIV-1） is divided into two types, HIV-1 （groups M, N and O） and HIV-2. Heilongjiang Province located in the northeast of China, and the feature of the subtype distribution and sequence characteristics of HIV-1 strains prevalent in Heilongjiang Province is still uncertain. The aim of this study was to investigate the subtype distribution and genetic characteristics of HIV-1 strains in one hospital in Heilongjiang Province. Methods HIV-1 env gene was amplified by nested-PCR from peripheral blood mononuclear cells （PBMCs） obtained from 19 HIV-1 seropositive individuals in Heilongjiang Province. The C2-V3 region was sequenced. Aligned the nucleotide sequence of 19 samples with CLUSTAL W （BioEdit） software, results were acquired and used for phylogenetic tree analysis after artificial adjustment. Reference sequence, downloaded from Los Alamos HIV Sequence Database, was used to identify the subtype of obtained sequence. Genetic distance between sequences was assessed using the software MEGA 3.1 Kimura 2-parameter, and the Phylogenetic tree was reestablished with Neighbor-Joining method. Results Phylogenetic tree analysis showed that 19 Heilongjiang strains clustered closely to subtype B strain from Thailand and were far from other international subtype reference strains. Statistical test showed no significant discrepancy between the genetic distance of interclass and intra-class （P〉0.05）. The analysis of V3 loop amino sequence of 19 Heilongjiang B strains revealed that V3 tip motif of 10 samples （52.63%） was GPGQ, and of 4 samples （21.53%） was GPGR. Conclusions The subtype of 19 HIV-1 seropositive individuals in Heilongjiang Province is B′, and it is introduced from He＇nan Province. V3 tip motifs of the HIV-1 isolates are mainly GPGQ and GPGR.