Subtype Identification and Drug-Resistant Point Mutation of Human Immunodeficiency Virus Type I in Taiwan
2005 Vol.21 NO.4
Human immunodeficiency virus (HIV) is the agent resulting in acquired immunodeficiency syndrome (AIDS). After its initial isolation in 1983, HIV has spread worldwide and resulted in many deaths in an astonishing rate. In 1996, Dr. Ho Da-I proposed the highly active antiretroviral therapy (HAART), also called the combination therapy. Currently HIV infection is treated with this method worldwide. Nevertheless, treatment failure has been reported. The most important reason for this is the emergence of drug resistant strains. The mechanism of resistance is mainly gene mutation: changes in genes of reverse transcriptase and protease, essential enzymes for HIV replication. Recently, drug-resistant mutations (natural polymorphism) were found in reverse transcriptase and protease genes in HIV infected patients who never take antiretroviral medications, and this will result in mild to severe resistance to HAART. To understand the prevalence of HIV subtype infection and drug resistance-related mutation in recent year, this study selected 440 HIV-I positive specimens in the country from 1996 to 2004 to analyze there subtype and mutations in reverse transcriptase and protease genes. According to primers specifically designed for C2V3, gag, and pol regions, and with the use of reverse transcriptase PCR (RT-PCR), we amplified gene fragments of viral capsule, protease, and reverse transcriptase and analyzed their subtype and drug resistance-related mutation. In subtype analysis, 376 (85.6%) were subtype B, 39 (8.8%) were subtype CRF01_AE, 16 (3.6%) were subtype CRF07_BC, 2 (0.4%) were subtype CRF02_AG, and 7 (1.5%) were subtype C. In protease gene mutation analysis, 304 (73%) had L63 mutation, 173 (42%) had V77 mutation, and 134 (32%) had M36 mutation. As to the gene of reverse transcriptase, 30 (44.7%) had K70 mutation, 12 (17.9%) had S68 mutation, 7 (10.44%) had T215 mutation, and 4 (5.9%) had M184 mutation. from the aspect of drug resistance, the incidence of primary mutation was low in these specimens, and in genes of protease and reverse transcriptase. The other mutations were mainly secondary mutation.