HIV protease and reverse transcriptase variation and therapy outcome in antiretroviral-naïve individuals from a large North American cohort [Alexander CS, et al. AIDS 2001;15:601]: This is a report from the Vancouver cohort with genotypic resistance testing in 479 antiretroviral-naïve patients who started treatment and were then assessed 18 months. The prevalence of baseline mutations that confer resistance were 3.4% for "primary" RT mutations (codons 41, 65, 67, 69, 70, 74, 75, 103, 151, 184, 215, and 219) and 3.8% for "primary" protease mutations (codons 30, 46, 48, 50, 82, 84, and 90). Sixteen patients (3%) had mutations that would be expected to confer clinically significant resistance, such as the RT184 mutation (four patients) and the K103 mutation (one patient). "Secondary" mutations on the protease gene were relatively common. The response to therapy was not altered by the presence of "primary" resistance mutations at baseline, but conclusions are limited because the resistance information was used in the selection of agents.
Comment: The authors demonstrated a low frequency of resistance mutations to HIV in terms of changes that would modify initial drug selection. This supports the current recommendations of the DHHS Guideline Panel on Antiretroviral Therapy, which discourage resistance testing in chronically infected treatment-naïve patients. It should be emphasized that this report does not necessarily indicate a low level of resistance in transmitted HIV strains. It simply means that the predominant virus in untreated patients who are chronically infected does not show a high prevalence of primary resistance mutations.
posted 4/25/2001

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