DETECTION OF HIV-1 RNA IN PLASMA AND SERUM SAMPLES USING THE NASBA AMPLIFICATION SYSTEM COMPARED TO RNA-PCR

The presence of HIV-1 RNA in the plasma and serum of European and Afri can patients was monitored using RNA-polymerase chain reaction (RNA-PC R) and the new isothermal NASBA nucleic acid amplification system enco mpassing a gel-based detection assay (ELGA). Identical RNA extraction procedures, provided by the NASBA amplification system, were used for both methods. The detection limit for HIV-1 RNA, measured on a 10-fold dilution series of spiked HIVIIIB in negative plasma, was about 0.05 CCID50 per test for both methods. Both NASBA and RNA-PCR were more sen sitive than a p24 assay for the detection of circulating HIV-1 virus i n blood: 17 of the 34 (50%) p24 antigen-tested seropositives were p24- positive while 32 (94%) were positive by NASBA and 30 (88%) by RNA-PCR . Among the 45 seropositives, 34 of which were tested for p24 antigen, 43 (96%) were positive by NASBA and 41 (91%) by RNA-PCR. Almost all s eropositives had a detectable viral load in 100 mu l plasma. Lower vir al loads were only encountered in some healthy seropositives with a hi gher CD4 count. There was no cross-reactivity with HIV-2 or HTLV-I wit h both the RNA-PCR and NASBA. The extraction method used permitted the detection of HIV-1 RNA equally well in serum and in plasma with hepar in or EDTA.