Background and purpose: There are important questions about epidemiologic transmission patterns as well as the possibility that genetic and phenotypic differences in human immunodeficiency virus type 1 (HIV-1) affect transmissibility, infectivity, pathogenicity, and response to therapy and vaccines. To delinate the genetic heterogeneity of HIV-1 and the association of subtypes with risk factors and location of residence in Taiwan, subtypes of HIV-1 in Taiwanese patients were identified and a phylogenetic study was performed. In addition, the accuracy of peptide-enzyme immunoassay (EIA) using serum samples from Taiwanese patients infected with HIV-1 was investigated.
Methods: Peptide-EIA was used to give a preliminary subtype of HIV-1-positive serum samples collected from different areas of Taiwan. Reverse transcription (RT)-polymerase chain reaction (PCR) and genetic sequencing were used to confirm the peptide-EIA results and to construct a phylogenetic tree.
Results: Among the 149 serum samples, 98 were subtype B (66%), 38 subtype E (25%), two subtype Thai-B (1.3%), one subtype G (0.7%), and one subtype C (0.7%). Comparison of risk factors for HIV-1 infection and subtype revealed that most B subtype infections (59/98) occurred in homosexual or heterosexual patients, whereas 28 of 38 E subtype infections occurred in heterosexual patients. The B/E ratio was significantly different (p < 0.05) in Taipei than in other areas of Taiwan.
Conclusions: These results suggest that the predominant subtype of HIV-1 infection in Taiwan is B, followed by E, and that the distribution of HIV-1 subtypes in Taiwan is similar to that of Thailand, although the genetic sequences are distinct. Homosexuality, heterosexuality, bisexuality, and intravenous drug use behaviors affect the distribution of different subtypes of HIV-1 infection. Peptide-EIA in conjunction with RT-PCR and sequencing can provide accurate subtyping of HIV-1 infection.