Evaluation of the Cavidi ExaVir Load Assay (Version 3) for Plasma

We evaluated the new low-cost ExaVir Load (version 3) reverse transcriptase viral load assay against the Roche Cobas Amplicor assay. Results for samples tested using the reverse transcriptase assay correlated well with those obtained with the Roche assay (r 0.85; n 202). The version 3 reverse transcriptase assay shows improved sensitivity compared to the previous version. Human immunodeficiency virus (HIV) load is the critical measure of response to antiretroviral therapy (12) and is useful for predicting the rate of HIV disease progression in untreated patients (7, 11). However, it is well recognized that the cost of viral load testing using nucleic acid-based tests is generally prohibitive in most resource-limited settings (2, 4, 5, 13). In this study, we compared the Roche Cobas Amplicor HIV-1 Monitor test (HIV RNA assay) (3), which measures HIV RNA, with the Cavidi ExaVir Load assay (HIV RT as-say), version 3, which quantifies reverse transcriptase (RT) enzyme activity (9, 10). Previous evaluation of HIV RT assa