Use of reverse-transcriptase-based HIV-1 viral load assessment to confirm low viral loads in newly diagnosed patients in Switzerland

Abstract

BackgroundTreatment-naïve patients newly diagnosed with HIV occasionally present with low viral RNA of ≤1’000 copies/ml, raising concerns about viral load underestimation. Because falsely low or undetectable viral loads might lead to inadvertent virus transmission or treatment delays, confirmation of such cases by a sequence-independent viral load test is recommended in Switzerland.MethodsHIV-1 RNA ≤1’000 cp/ml by Roche’s or Abbott’s tests in patients newly diagnosed from 2010 to 2012 in Switzerland were subjected to viral load testing by the product-enhanced-reverse transcriptase (PERT) assay. These investigations were complemented with repeat and/or alternative viral RNA measurements.ResultsHIV-1 RNA ≤1’000 cp/ml was observed in 71 of 1814 newly diagnosed patients. The PERT assay suggested clinically relevant viral load underestimation in 7 of 32 cases that could be investigated. In four patients, the PERT viral load was 10-1’000-fold higher; this was confirmed by alternative HIV-1 RNA tests. Six of the 7 underestimates had been obtained with meanwhile outdated versions of Roche’s HIV-1 RNA test. In the seventh patient, follow-up revealed similar results for RNA and PERT based viral loads.ConclusionPERT assay revealed occasional severe viral load underestimation by versions of HIV-1 RNA tests meanwhile outdated. Underestimation by contemporary tests appears rare, however.

Comparison of the New Alere HIV Combo with Alere Determine HIV-1/2 Ag/Ab Combo in Acute Primo and Established HIV Infections

“…Only samples with HIV-1 of clade B gave very weak reactions at the p24-antigen site, whereas non-B clade remained negative, thus missing 50% of our primary infections. B clade strains are prominent in Europe and United States, and non-B clades in Africa and South East Asia [9,10]. Nonetheless, 57% of our samples were of non-B clades, as by others [11], meaning that assays with low affinity to non-B types miss an important amount of infections even in our region.…”