Optimizing early infant diagnosis at delivery rooms with HIV-1 Abbott RealTime-PCR using phosphate buffered saline to complement low plasma volumes

Background

Improving the early identification of HIV-1-infected newborns with birth testing is critical to comprehensive early infant diagnosis and care for newborns living with HIV-1. Automated RNA quantification systems are valuable diagnostic tools, but the volume of plasma that viral load platforms require makes their widespread use for young children difficult.

Method

Seventy-nine plasma samples with different viral load ranges were evaluated in parallel with the use of 1x PBS, pH 7.4, to supplement the required volume at dilutions factors from 1:2 to 1:50. Viral load quantification assays were evaluated using ABBOTT Molecular platforms, USA.

Results

Using 1x PBS, at 1:10 dilution (70 µL plasma in 630  µL 1x PBS), a sensitivity of 100% and 100% specificity were obtained for detecting a viremia above 400 copies/mL (Kappa of 0.96, p < 0, 0001) for 1:50 dilution the sensitivity was 96% and the specificity 100% (kappa 0.90, p < 0.0001).

Conclusions

Although with reduced sensitivity, proportional to the dilution factor, the use of plasma does not influence the specificity of the test and allows the diagnosis of HIV-1 infections. Cases with very low viremia, a situation that may occur due to the treatment or prophylaxis of the mother and/or child, may go unnoticed with this procedure, and undiluted testing may be necessary.