Ultradeep sequencing of B and non-B HIV-1 subtypes: Viral diversity and drug resistance mutations before and after one month of antiretroviral therapy in naive patients.

Background: Ultradeep pyrosequencing technologies permit an assessment of the genetic diversity and the presence and frequency of minority variants in a viral population. The effect of these parameters on the outcome of highly active antiretroviral therapy (HAART) in HIV-infected patients is poorly understood.

Objectives: The present study used the pyrosequencing Roche 454 prototype assay to determine whether antiretroviral efficacy is correlated with viral diversity and minority drug resistance mutations in HIV-infected treatment-naive patients and to compare assay performance in B and non-B subtypes.

Study Design: The study included 30 HIV-1 infected naive patients (20 with subtype non-B and 10 with subtype B). Ultradeep pyrosequencing of protease and reverse transcriptase genes was performed at baseline and 1 month after HAART initiation. Plasma HIV VL was measured at 0 and after 1, 3, and 6 months of HAART.

Results: Pre-HAART minority drug resistance mutations were observed to NRTI in 4 patients, to NNRTI in 6 patients, and to PI in 1 patient; there was no difference in HAART-induced VL decay between patients. Pre-HAART diversity was significantly correlated with the time elapsed since HIV-1 infection diagnosis, but not with the subtype, VL, or CD4 count. Patients with an undetectable VL after 3 months of HAART had a higher pre-HAART diversity. Pre- and post-HAART diversities were not statistically different. There was no difference in assay performance between subtype B and non-B.

Conclusions: A high pre-HAART viral diversity might have a positive effect on the outcome of HAART. Pre-therapeutic minority drug resistance mutations are uncommon in naive patients.