QUANTITATION OF HIV-1 RNA VIRAL LOAD USING NUCLEIC-ACID SEQUENCE BASED AMPLIFICATION METHODOLOGY AND COMPARISON WITH OTHER SURROGATE MARKERS FOR DISEASE PROGRESSION

In this study, HIV-1 viral load quantitation determined by Nucleic Aci d Sequence Based Amplification (NASBA) was compared with other surroga te disease progression markers (antigen p24, CD4/CD8 cell counts and b eta 2 microglobulin) in 540 patients followed up at Sao Paulo, SP Braz il. HIV-1 RNA detection was statistically associated with the presence of antigen p24, but the viral RNA was also detected in 68% of the ant igen p24 negative samples, confirming that NASBA is much more sensitiv e than the determination of antigen p24. Regarding other surrogate mar kers, no statistically significant association with the detection of v iral RNA was found. The reproducibility of this viral load assay was a ssessed by 14 runs of the same sample, using different reagents batche s. Viral load values in this sample range from 5.83 to 6.27 log (CV = 36%), less than the range (0.5 log) established to the determination o f significant viral loan changes.