Failure to Quantify Viral Load with Two of the Three Commercial Methods in a Pregnant Woman Harboring an HIV Type 1 Subtype G Strain

Abstract

The level of HIV-1 RNA in plasma has become one of the most important markers in the follow-up of HIV-infected patients. Three techniques are commercially available: both the Amplicor HIV Monitor and the NASBA HIV-1 RNA QT are target amplification methods, whereas the Quantiplex HIV RNA assay is a branched DNA signal amplification technique. Detection in both target amplification techniques is based on a single primer pair and a single probe in the gag region, whereas multiple probes capture the pol region of the viral RNA in the branched DNA assay. We investigated the discrepant observation of an undetectable viral load in an immunodeficient pregnant HIV-1-infected patient of African origin with no prior antiretroviral treatment. Although clinical progression was present in this patient with tuberculosis and a low CD4 cell count, viral load determinations with both the Amplicor Monitor and NASBA assays revealed no detectable RNA levels. The presence of HIV-1 RNA in the plasma of the patient was demonstrated by an in-house RNA-PCR. Subsequent HIV-1 RNA quantification with the branched DNA method revealed a high viremia (460,000 copies/ml). DNA sequence analysis of the gag gene identified a subtype G HIV-1 strain (HIV-1BL). To our knowledge this is the first report of a patient harboring an HIV-1 genotype of the main group with a high viral load as quantified by the branched DNA assay, but undetectable with the two commercial HIV RNA amplification techniques because of genetic divergence. In the case of discrepant low viral loads determined by one amplification technique in patients with advanced clinical stage one should use an alternative quantification technique for confirmation.

Correction of Underquantification of Human Immunodeficiency Virus Type 1 Load with the Second Version of the Roche Cobas AmpliPrep/Cobas TaqMan Assay

“…Eight of these nineteen (42.1%) patients were infected with a subtype B strain. Thus, in contrast to earlier-generation HIV-1 VL assay problems (1,2,4,19), even subtype B strains could be affected by the underquantification issue of the first version of the CAP/CTM test, indicating that the mismatches were not associated with the HIV-1 subtype.…”

“…This high genetic diversity of HIV-1 is a challenge for the quantification of plasma HIV-1 RNA. Indeed, in the past, several studies have reported the failure of commercial assays for viral load monitoring in patients infected with non-B subtypes (1,2,4,19). This finding led Roche Diagnostics, Ltd. (Rotkreuz, Switzerland), the manufacturer of the widely used Cobas Amplicor HIV-1 monitor test version 1.0 assay, to modify this assay in 1997.…”

Ultrasensitive Monitoring of HIV-1 Viral Load by a Low-Cost Real-Time Reverse Transcription-PCR Assay with Internal Control for the 5′ Long Terminal Repeat Domain

“…Unfortunately, current commercial viral-load monitoring assays were designed for use in affluent industrialized countries and are thus optimized to work best on HIV-1 subtype B (13,14,25,26 ).…”

Comparison of LCx with Other Current Viral Load Assays for Detecting and Quantifying Human Immunodeficiency Virus Type 1 RNA in Patients Infected with the Circulating Recombinant Form A/G (CRF02)

“…It has been reported that some commercial assays either underevaluate or fail to detect HIV RNA subtypes A, E, and G and other minor strains (7,8,10,11,14,19). Poor performance of the NucliSens HIV RNA QT assay in quantifying viremia for the circulating recombinant form of HIV-1 A/G (CRF02) has been recently described (3,27 a At the time of blood sampling, all patients were naive for antiviral treatment; three of them were under treatment with two nucleoside analogs or two nucleoside analogs plus a protease inhibitor.…”