Low prevalence of antiretroviral drug resistance among HIV-1 seroconverters in London, 1984-1991

Objectives: To examine the prevalence of resistance mutations and natural polymorphisms to reverse transcriptase (RT) and protease inhibitors in a cohort of patients with defined seroconversion dates. Methods: Eligible patients were those attending an HIV centre in North London who seroconverted from HIV negative to positive status between 01/01/85 and 31/12/91 (n = 104). Genotypic resistance analysis was performed on the first positive serum sample after seroconversion and before use of antiretroviral therapy using population-based sequencing of RT-PCR fragments and rule-based sequence interpretation (Vircogen). Results: Protease and RT sequences were successfully amplified from only 37 (35.6%,) of the 104 seroconverters. Only one patient who seroconverted in August 1991 showed any evidence of significant mutations in the RT region, and this was associated with resistance to zidovudine (ZDV) (215Y and 210W). An additional patient who seroconverted in July 1991 had a TOR mutation and was classified as having intermediate resistance to ZDV. No spontaneous mutations were detected in the protease region. Conclusions: Overall only 2 (5%) of these treatment-naive individuals were infected with HIV variants resistant to ZDV. Although the data at present do not support the need for pretreatment genotyping, there is a need for continued surveillance of the frequency of resistance mutations in antiretroviral naive patients since the introduction of highly active antiretroviral therapy. (C) 2002 The British Infection Society.