Validation of a quantitative RNA PCR assay for HIV-1 in human plasma

A quantitative human immunodeficiency virus type 1 (HIV-1) RNA polymerase chain reaction assay has been validated analytically and clinically in > 13,000 samples. The assay is highly reproducible with intra- and inter-assay precision of 16% and 19%, respectively. In 1,542 of 1,548 subjects with CD4+ counts of 0-500 cells per mm3, viral RNA levels were quantifiable and ranged from approximately 3,000-52,200,000 copies per milliliter. Median plasma HIV-1 RNA values were inversely proportional to CD4+ counts from 0-400 cells per mm3. When patients were off antiretroviral therapies for approximately 14 days prior to the initial baseline RNA PCR evaluation, the mean variance between the two baseline values was 23% (0.1 log). Of these patients, 95% had a sufficient plasma viral load to quantitate a 10-fold (1 log) diminution in viral load caused by antiviral therapy. In contrast, only 20% and 45% of these subjects had sufficient p24 and ICD p24 levels to detect a 50% diminution in circulating virus. The high precision and reproducibility of this quantitative RNA PCR assay provide an enhanced means of evaluating therapeutic drug regimens for HIV-1.