Signal generation in standard and low volume assays.

<p>The standard assay was run with 3 and 15 h target incubation (140 µL) and the low volume assay was run with 3 h target incubation (80 µL). Identical lots of all components except Lysis Diluent were used on a single instrument for the three conditions. A dilution series of 8E5 in Seracon II at three concentrations (n = 10 for each condition) generated nearly identical average Relative Light Units (RLUs) for standard volume target incubation at 15 h and low volume target incubation volume at 3 h. Signal in negative samples remained unchanged (n = 6 for each condition).</p

Polyanions in target incubation solution.

<p>In this example, addition of 1% (w/V) of polyacrylic acid (PAA), polyantholesulfuric acid (PASA), or polyvinylsulfonic acid (PVSA) to the Lysis Diluent (LD, control) caused different enhancement of signal generation relative to the control condition. An 8E5 sample at 80,000 copies/mL (n = 5 for each condition) was analyzed here on a single plate with 3 h target incubation. Superior signal enhancement by PVSA relative to alternative polyanions was observed throughout our experiments. No polyanion caused discernable increase in signal with negative samples (n = 1 for each condition).</p

Analytical performance summary for the modified HIV-1 bDNA assay.

<p>Analytical performance summary for the modified HIV-1 bDNA assay.</p

Cumulative effect of lower volume and PVSA addition.

<p>Three conditions were compared in this experiment: Versant HIV-1 RNA 3.0 Assay with standard volume target incubation (140 µL), low volume target incubation (80 µL), or low volume target incubation plus PVSA (80 µL, PVSA). Two concentrations of 8E5 (n = 4 for each level of each condition) were analyzed on a single plate with 2 h target incubation. Enhanced signal generation (RLU average) was observed for low volume target incubation, and further improvement was observed upon addition of PVSA to the low volume target incubation. Although signal increased slightly for negative samples (n = 6 for each condition) in the low volume conditions, signal for the low concentration positive samples in the low volume conditions increased more than enough to compensate.</p

Specificity with individual HIV-negative clinical specimens: determination of 29 copies/mL as the negative cutoff and subsequent verification in the modified assay.

<p>Specificity with individual HIV-negative clinical specimens: determination of 29 copies/mL as the negative cutoff and subsequent verification in the modified assay.</p

Bland-Altman plot of method comparison data between the modified bDNA assay and the VERSANT HIV-1 bDNA 3.0 Assay.

<p>No evidence of proportional bias across the linear range of the assay is apparent (regression slope = −0.026; 95% CI from −0.086 to 0.035).</p