Quantitation of human immunodeficiency virus type 1 (HIV-1) RNA in cell-free cervicovaginal secretions: comparison of reverse transcription-PCR amplification (AMPLICOR HIV-A MONITOR 1.5) with enhanced-sensitivity branched-DNA assay (Quantiplex 3.0)

Abstract

Two commercially available hypersensitive assays for human immunodeficiency virus type 1 (HIV-1) RNA quantitation, AMPLICOR HIV-1 Monitor Test 1.5 and Quantiplex HIV RNA 3.0, were compared to detect and quantify HIV-1 RNA in the cell-free fraction of cervicovaginal secretions collected by vaginal washing. Three panel specimens were used: pooled cervicovaginal secretions spiked with HIV-1 subtype A or HIV-1 subtype B and cervicovaginal lavages from HIV-positive and HIV-negative women. Compared to the AMPLICOR HIV-1 Monitor Test 1.5 assay, the Quantiplex HIV-1 3.0 assay yielded higher estimates of HIV-1 RNA concentrations in several tested samples spiked with HIV-1 RNA subtype A, as well as subtype B, particularly samples containing low amounts of HIV-1 RNA. The sensitivity and specificity of the AMPLICOR HIV-1 Monitor Test 1.5 assay were 93 and 100%, respectively; the sensitivity and specificity of the Quantiplex HIV RNA 3.0 assay were 97 and 50%, respectively. In conclusion, in quantifying HIV-1 RNA in cervicovaginal secretions, the Quantiplex HIV RNA 3.0 may lack specificity, and the AMPLICOR HIV-1 Monitor Test 1.5 assay, although highly specific, may lack sensitivity.

FIG. 1

Scatter plots of observed versus expected HIV-1 RNA levels, expressed in log copies/milliliter, estimated in parallel by the AMPLICOR HIV-1 Monitor Test 1.5 assay (left) and the Quantiplex HIV RNA 3.0 assay (right) in pooled cervicovaginal lavages obtained from HIV-negative not-at-risk women spiked with known amount of HIV-1 subtype A or subtype B (n = 28). The vertical and horizontal dashed lines indicate the positivity threshold of both assays (1.69 log copies/ml).

FIG. 2

Correlation of HIV-1 RNA levels, expressed in log copies/milliliter, estimated in parallel by the AMPLICOR HIV-1 Monitor Test 1.5 assay and the Quantiplex HIV RNA 3.0 assay in cervicovaginal lavages obtained from 30 HIV-positive women and 30 HIV-negative not-at-risk controls. ●, Cervicovaginal HIV-1 RNA load from HIV-infected women; ▴, cervicovaginal HIV-1 RNA load from HIV-negative women. The vertical and horizontal dashed lines indicate the positivity thresholds of both assays (1.69 log copies/ml).