Evaluation of Roche Cobas Taqman Quantitative HIV-1 RNA PCR against other HIV-1 commercial viral load tests to examine potential under-quantification

Background HIV-1 RNA quantification underpins the monitoring of virological response to antiviral therapy, achievement of viral suppression and early identification of viral escape. Most laboratories use commercial HIV-1 RNA viral load tests and the genetic diversity of HIV-1 requires that these are applicable across all subtypes. We introduced the Roche Cobas Ampliprep/Cobas Taqman (CAP/CTM) Real Time Quantitative HIV-1 RNA PCR into diagnostic service after conducting a favourable comparative evaluation of 191 samples with the Roche Cobas Amplicor v1.5 PCR assay [1]. However, concerns were raised when in subsequent routine use we identified 10 patients where there was significant under-quantification (details will be presented, five subtyped all non-B). A separate study reported that Roche CTM was under-quantifying a significant number of samples across a range of subtypes compared to Amplicor [2]. We have undertaken a larger evaluation of CAP/CTM versus Roche Amplicor and have included evaluation of a subset against the Abbott quantitative HIV-1 RNA real-time PCR test.