Genotypic Resistance in HIV‐1–Infected Patients with Persistently Detectable Low‐Level Viremia while Receiving Highly Active Antiretroviral Therapy

Abstract

Background. Technical limitations in the sensitivity of commercial genotyping methods may prevent clinicians from determining whether drug-resistant human immunodeficiency virus type 1 (HIV-1) is present in patients with low-level viremia. We performed ultrasensitive HIV-1 genotyping for patients with persistent plasma virus loads of 50–400 copies/mL to better define the prevalence of drug resistance and the most common resistance mutations during persistently detectable low-level viremia. Methods. Genotyping of HIV-1 was performed with an ultrasensitive clonal genotyping method. Results. We studied 21 patients who had persistent, detectable, low-level viremia for a median of 11 months. Nine (43%) of 21 patients had HIV-1 isolates with significant resistance mutations. The most common mutations were M184V, K65R, and M41L/T215Y. Conclusions. The finding that clinically significant resistance mutations were present in some but not all patients with persistent viremia (range, 50–400 copies/mL) highlights the need to improve the sensitivity of current clinical assays for detection of drug resistance.