Application of branched DNA signal amplification to monitor human immunodeficiency virus type 1 burden in human plasma.

A branched DNA (bDNA)-based quantitation of plasma human immunodeficiency virus type 1 (HIV-1) RNA was used to monitor the virologic status of 102 patients (29-906 CD4 cells/mm3) enrolled in clinical trials of antiretroviral and immune-based therapies. Virion-associated RNA was measurable in plasma of 74% of patients tested (10,000-10,000,000 RNA equivalents/mL). Virus levels measured by the bDNA assay exceeded titers obtained by quantitative plasma culture and were inversely correlated (r = -.378; P < .05) with total CD4 cell counts. The assay was used to demonstrate a significant decline (mean, 5-fold; range, 0- to 30-fold), relative to pretreatment, in virus load after beginning antiviral therapy and a transient increase (mean, 15-fold; range, 2- to 50-fold) after treatment with interleukin-2. The decrease in RNA was more dramatic than changes in serum p24 antigen. The bDNA assay yields reproducible results, is relatively easy, and should be useful in measuring HIV-1 RNA in patients in clinical trials.