Quantitation of HIV-1 RNA viral load using Nucleic Acid Sequence Based Amplification methodology and comparison with other surrogate markers for disease progression

ABSTRACT

In this study, HIV-1 viral load quantitation determined by Nucleic Acid Sequence Based Amplification (NASBA) was compared with other surrogate disease progression markers (antigen p24, CD4/CD8 cell counts and Beta-2 microglubulin) in 540 patients followed up at Säo Paulo, SP, Brazil. HIV-1 RNA detection was statistically associated with the presence of antigen p24, but the viral RNA was also detected in 68 per cent of the antigen p24 negative samples, confirming that NASBA is much more sensitive than the determination of antigen p24. Regarding other surrogate markers, no statistically significant association with the detection of viral RNA was found. The reproducibility of this viral load assay was assessed by 14 runs of the same sample, using different reagents batches. Viral load values in this sample ranged from 5.83 to 6.27 log (CV=36 per cent), less than the range (0.5 log) established to the determination of significant viral load changes.