FAILURE TO QUANTIFY VIRAL LOAD WITH 2 OF THE 3 COMMERCIAL METHODS IN A PREGNANT WOMAN HARBORING AN HIV TYPE-1 SUBTYPE-G STRAIN

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 ar e 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, Detect ion in both target amplification techniques is based on a single prime r pair and a single probe in the gag region, whereas multiple probes c apture the pal region of the viral RNA in the branched DNA assay, We i nvestigated the discrepant observation of an undetectable viral load i n an immunodeficient pregnant HIV-l-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 coun t, 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, Su bsequent HIV-1 RNA quantification with the branched DNA method reveale d a high viremia (460,000 copies/ml), DNA sequence analysis of the gag gene identified a subtype G HIV-1 strain (HIV-1(BL)). To our knowledg e 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 D NA assay, but undetectable with the two commercial HIV RNA amplificati on 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 quantifica tion technique for confirmation.