Antiretroviral drug resistance in HIV-1-infected patients experiencing persistent low-level viremia during first-line therapy.

Population sequencing was performed for persons identified with persistent low-level viremia in 2 clinical trials. Persistent low-level viremia (defined as plasma HIV-1 RNA level >50 and <1000 copies/mL in at least 2 determinations over a 24-week period, after at least 24 weeks of antiretroviral therapy) was observed in 65 (5.6%) of 1158 patients at risk. New resistance mutations were detected during persistent low-level viremia in 37% of the 54 evaluable cases. The most common mutations were M184I/V (14 cases), K103N (9), and M230L (3). Detection of new mutations was associated with higher HIV-1 RNA levels during persistent low-level viremia.