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13th International AIDS ConferenceDurban, South Africa - July 9-July 14, 2000 |
Int Conf AIDS 2000 Jul 9-14; 13:35 (abstract no.. LbPeA7013)
Casteling A, Martin D, Napier G
Toga Laboratories, Edenvale, South Africa. Fax: +27 11 4535059, E-mail: alisonc@iafrica.com.
BACKGROUND: Increasing access to anti-retroviral therapies in South Africa has prompted the need for viral load measurement technologies to assist in making treatment decisions. The two commonly requested viral load assays are RT-PCR(AMPLICOR) and the branched DNA (QUANTIPLEX) assays. We compared the results generated by Quantiplex version 2.0(Q2), Quantiplex version 3.0(Q3) and AMPLICOR HIV-1 MONITOR version 1.5(HIM1.5) on blood samples from a population where clade C is endemic. Subjects and
METHODS: Blood samples were collected prior to commencing therapy from anti-retroviral-naive, asymptomatic subjects enrolled in a clinical trial. All three viral load tests were performed in parallel on 295 samples following the kit manufacturers instructions. Pairwise comparisons were performed by plotting the difference between the two viral load measurements versus the average of the two measurements. Only those samples that gave results within the dynamic range of the two tests being compared were included in the analysis.
RESULTS: Q2 and Q3 gave essentially identical results for the 262 samples that gave results within the dynamic range of both tests. HIM1.5 titres were approximately 0.5 log higher than those reported by Q2 and Q3 for the 272 and 279 samples, respectively, that gave results within the dynamic range of both tests. For all comparisons, the difference between viral load measurements were similar across the range of concentrations tested.
CONCLUSION: In this population, Q2 and Q3 generated essentially identical results that were substantially lower than those generated by HIM1.5. In contrast, other studies where clade B was the predominant subtype showed that Q3 titres are similar to those measured by HIM1.5 and higher than those measured by Q2. Subtype analysis is ongoing to determine whether differences in subtype account for this discrepancy.
Copyright © 2000 - International AIDS Society (IAS). Reproduction of this abstract (other than one copy for personal reference) must be cleared through the IAS.
