Molecular assays for monitoring HIV infection and antiretroviral therapy

Infection with HIV results in lifelong persistence of the virus in the body of infected persons, independent of antiretroviral treatment. Therefore, efficient and meaningful therapy monitoring has been developed since its introduction in the 1980s. Whereas, primarily, the measurement of the CD4 cell count was the most important clinical marker of disease progression, nowadays the estimation of plasma viral load with molecular methods plays a major role as a marker of therapy success. To optimize therapy changes in patients failing on antiretroviral therapy regimen, HIV-1 genotyping has been introduced and is now widely accepted as an additional diagnostic tool. Due to this increase in diagnostic parameters, clinicians and virologists have to cope with many different methods. This review should give a brief overview of the current commercially available assays for detection and quantification of HIV, as well as for HIV-1 genotypic resistance testing. Quantitative reverse transcriptase PCR, real-time PCR, nucleic acid sequence-based amplification and the branched DNA system are described in detail, and the advantages and disadvantages are discussed. In addition, two commercially available HIM genotyping assays are compared. However, a general recommendation to favor one system over the other cannot be given, because the final decision of which system to use should be decided on the individual requirements.