1st International Workshop on HIV Drug Resistance & Treatment Strategies 25-28 June 1997, St. Petersburg, Florida, USA

A COMPARISON OF COMMERCIAL HIV-1 RNA LOAD ASSAYS FOR BASELINE VALUES, PRIOR TO COMMENCING THERAPY IN A CLINIC POPULATION WITH EPIDEMIOLOGICAL EVIDENCE OF NON-CLADE B VIRUS

Antiviral Therapy 1997;2 (Suppl 5):33 (abstract no. 50)

C Loveday¹, H Devereux¹, A Burke¹, L Dann¹ and M Johnson²
Departments of ¹Retrovirology and ²Thoracic Medicine, The Royal Free Hospital School of Medicine, Hampstead, London NW3 2PF, UK

The objective of this study was to establish baseline values for a clinic subpopulation with epidemiological evidence of non-clade B virus, using available commercial plasma HIV-1 RNA assays. Ninety-two clinic patients with HIV-1 infection, and having epidemiological evidence of non-clade B virus required baseline values prior to commencing combination therapy.

Measures were performed using RT-PCR (Roche; cut-off 400 copies/ml) RT-PCR including non-B primers (RT-PCRnb, Roche; cut-off 400 copies/ml), NASBA (Organon; cut-off 2000 copies/ml), and bDNA (Chiron; cut-off 500 copies/ml) assays.

In 49.3% of patients there was >0.3 log increase in values from RT-PCR to RT-PCRnb (mean difference +1.05 log, range +0.31 to +2.01), 45% remained within 0.3 log, no patients showed a decline. Comparison of RT-PCRnb with NASBA showed for the latter, 41% of patients remained within 0.3 log, however, 22.5% were >0.3 log lower (mean difference -0.777 log, range -0.39 to -1.88) and 31% were below assay detectability. Comparison of RT-PCRnb with bDNA showed for the latter, 12.7% of patients were within 0.3 log, 56.3% were >0.3 log lower (Mean difference -0.81 log, range -0.36 to -1.74), and 25.3% were below assay detectability.

In these patients we concluded the RT-PCRnb gave the highest signal and detection rates, however this cross-sectional analysis does not allow comment on evolution of these subtypes with time and thus the reliability of longitudinal measures. Further work is underway to sequence and subtype these patient samples and to follow them over time to identify the best approach for virological follow-up of their antiretroviral therapy.

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1997-06-25
50

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