Effect of HIV-1 genetic diversity on HIV-1 RNA quantification in plasma: comparative evaluation of three commercial assays.

To the Editor: The rapid rate of HIV-I replication in vivo (10' virions per day), coupled with the poor fidelity of reverse transcription of the HIV-1 genome, results in the production of new virus variants (1). This makes it easy to understand how multiple clades of HIV-1 have emerged throughout the world and explains the development of genetic diversity even within clades (2). Numerous reports describe assays designed for the detection or quantification of HIV-1 genomic RNA in plasma. One such assay is based on a coupled reverse transcription-polymerase chain reaction (RT-PCR) process in which specific oligonucleotides sequence primers are used in conjunction with enzymes to amplify the number of HIV-1 genomes in a specimen (3). Another approach involves the nucleic acid sequence-based amplification (NASBA) procedure, which is founded on isothermal amplification of an HIV-1 RNA target sequence by simultaneous enzymatic activity of three enzymes (4). A third procedure involves direct detection of the genomic nucleic sequences by a series of signal amplification processes using a technology called branched DNA (bDNA)(S). These assay methods have been developed into commercial kits (RT-PCR: Amplicor Monitor by Roche Diagnostics Systems, Neuilly, France; NASBA: HIV-1 RNA QT assay by Organon Teknika, Fresnes, France; bDNA: Quantiplex HIV-1 RNA by Chiron Corporation, Cergy Pontoise, France) and are being used more