Continued Slow Decay of the Residual Plasma Viremia Level in HIV-1-Infected Adults Receiving Long-term Antiretroviral Therapy.

UNLABELLED: We measured plasma human immunodeficiency virus type 1 (HIV-1) RNA levels by means of single-copy assay in 334 participants receiving virologically suppressive antiretroviral therapy (ART). A residual viremia load of ≥1 copy/mL after 4 years of ART was predicted by a higher pre-ART HIV-1 RNA level, higher CD8(+) T-cell count during treatment, and a lower ratio of CD4+ T cells to CD8+ T cells during treatment but not by initial ART regimen. In a longitudinal subset of 64 individuals, continued decay of the plasma HIV-1 RNA level was observed, with an average annual decrease of 6% and an estimated half-life of 11.5 years. In contrast to prior reports, the persistent viremia level continues to slowly decline during years 4-12 of suppressive ART. CLINICAL TRIALS REGISTRATION: NCT00001137.

Improved single-copy assays for quantification of persistent HIV-1 viremia in patients on suppressive antiretroviral therapy.

A quantitative real-time PCR (qRT-PCR) assay with single-copy sensitivity targeting HIV-1 gag RNA (the gag single-copy assay [gSCA]) has been used widely to quantify plasma viremia below the limit of detection of clinical assays in patients on effective antiretroviral therapy (ART), but viral RNA in 15 to 30% of samples amplifies inefficiently because of primer/probe mismatches. We sought to develop improved single-copy assays with increased sensitivity by improving nucleic acid recovery, designing qRT-PCR primers and a probe for a highly conserved region of integrase in the HIV-1 pol gene (the integrase single-copy assay [iSCA]), and increasing the plasma volume tested (Mega-iSCA). We evaluated gSCA versus iSCA in paired plasma samples from 10 consecutive patients with viremia of >1,000 copies/ml and 25 consecutive patients on suppressive ART. Three of 10 viremic samples amplified inefficiently with gSCA compared to the Roche Cobas Ampliprep/TaqMan 2.0, whereas all 10 samples amplified efficiently with iSCA. Among 25 samples from patients on suppressive ART, 8 of 12 samples that were negative for HIV-1 RNA by gSCA had detectable HIV-1 RNA by iSCA, and iSCA detected 3-fold or higher HIV-1 RNA levels compared to gSCA in 10 of 25 samples. Large-volume plasma samples (>20 ml) from 7 patients were assayed using Mega-iSCA, and HIV-1 RNA was quantifiable in 6, including 4 of 5 that were negative by standard-volume iSCA. These improved assays with superior sensitivity will be useful for evaluating whether in vivo interventions can reduce plasma viremia and for assessing relationships between residual viremia and other virologic parameters, including the inducible proviral reservoir.