Ultrasensitive Quantitation of Human Immunodeficiency Virus Type 1 RNA in Plasma by the AMPLICOR and COBAS AMPLICOR HIV-1 MONITOR Tests

The measurement of plasma human immunodeficiency virus type 1 (HIV-1) RNA levels has become an important tool for identifying individuals likely to benefit from antiretroviral therapy (1 –7 ) as well as monitoring patients on therapy (8 –14 ), and is now regarded as standard medical practice for managing the treatment of HIV-1-infected individuals (15 –21 ). Three commercially available assays for measuring HIV-1 RNA levels are available. The firstgeneration AMPLICOR HIV-1 MONITOR™ Test, which uses reverse transcriptase-polymerase chain reaction (RT-PCR) technology, has a lower limit of quantitation of 400 copies/mL of plasma (22 ,23 ). The NucliSens HIV-1 QT Test (Organon Teknika, Boxtel, Netherlands), a second-generation assay based on the nucleic acid sequence-based amplification technique, has a lower limit of quantitation of 100 HIV-1 RNA copies/mL of plasma (24 ). The Quantiplex HIV-1 Version 2.0 Test (Chiron, Emeryville, CA), which uses the branched-chain DNA signal amplification technique, has a lower limit of quantitation of 500 HIV-1 RNA copies/mL of plasma (25 ,26 ).