The epidemiology of HIV-1 subtypes in infected patients from northeastern Thailand

In total, 117 HIV-1 infected patients from several provinces in Northeastern Thailand were analysed. All blood samples collected from individuals were confirmed by EIA and Western blot and partially by HIV-1 gag-, pol- and env-PCR. By serotyping with a V3-peptide ELISA, 108 (92.3%) of the sera samples belonged to subtype E, 9 (7.7%) were serotype B. For 10 Thai HIV-1 infections, the serotype and genotype were determined. The genotype was determined by phylogenetic analysis of directly sequenced PCR amplicons, 8 were subtype E, 2 subtype B. For these patients the serotype did correlate with the genotype. Tracing back the origin of Thai patients, it seems that most were infected within early years of the epidemic and the Thai subtype B infected patients have been imported directly from foreign countries via sexual contact. The findings suggest there are two district subtypes in Thailand with the majority being subtype E. The relatively high prevalence of subtype B in Northeastern Thailand may be due to the increasing intermix of the two strains (subtypes E and B) and the migration for employment from foreign countries. This may lead to public health concerns regarding surveillance of HIV-1 subtypes and the regulation of potentially infected workers returning from abroad to the country.