[Analysis of HIV-1 seropositive individual infected with different subtypes]

To investigate whether there existed any individuals infected with different subtypes of human immunodeficiency virus type 1 (HIV-1) and to analyze their source of infection.

Membrane protein gene (env) of HIV-1 in uncultured single peripheral blood monocytes (PBMCs) from HIV-1 seropositive individuals found in Shenzhen was amplified by nested polymerase chain reaction (PCR). The C2-V3 region and its adjacent region (360 bp) of them were sequenced and analyzed, and their divergence rate and systematic phylogenetic tree (cladogram) were calculated.

There existed sequences of B and C or B and E strains of HIV-1 subtype in three infected individuals in Shenzhen. Gene divergence rates between different subtypes and corresponding international subtype reference strains Bcon, Ccon and Econ were 5.07%-7.26%, 3.23% and 5.38%-5.99%, respectively, and those between different subtypes strains in the same individual were 23.52%, 20.69% and 28.44%, respectively. GPGR sequence of typical Europe and America subtype B was found in strain sz46-1 from prostitute with intravenous drug abuse, based on their tetra-peptide sequence characteristics in the crown of gp 120 V3 loop, strain sz8-2 was GPGH and other strains were GPGQ sequence characterized by Thai B (B') and E subtypes. Furthermore, phylogenetic tree analysis showed that strains sz1-2, sz8-1 and sz46-1 were clustered with international reference sequence Bcon, strain sz1-1 clustered with Econ, and strains sz1-1 and sz8-2 clustered with Ccon.

These findings suggested that an individual could be simultaneously infected with different HIV-1 subtypes, which could probably be caused by his or her own multiple high-risk behavior.