HIV reverse transcriptase activity assay: a feasible surrogate for HIV viral load measurement in China

Assessment of the Cavidi ExaVir Load Assay for Monitoring Plasma Viral Load in HIV-2-Infected Patients

“…However, later reports showed no association between the presence of RT inhibitors or resistance mutations with differences between RT activity and HIV-1 RNA in the plasma (23,29,32,57,58). Although our study was not designed to investigate the effect of RT inhibitors on the performance of ExaVir Load in HIV-2 infection, our results agree with these reports since no significant differences were found between viral load measurements with ExaVir Load or qPCR in treated and untreated patients.…”

“…Thus, this method is, in principle, independent of the type, group, and subtype of HIV (5,20,(23)(24)(25). The ExaVir Load assay has been used extensively to monitor the viral load in HIV-1-infected patients with the same efficiency between subtypes and recombinant forms (20,23,(25)(26)(27)(28)(29) and with more consistent performance than qPCR methods in non-B subtypes (30). This characteristic, and its low cost, simplicity to operate, and commercial availability make it an attractive option for monitoring the HIV viral load in countries with limited resources.…”

“…This characteristic, and its low cost, simplicity to operate, and commercial availability make it an attractive option for monitoring the HIV viral load in countries with limited resources. Indeed, ExaVir Load assay versions 1 (26,31), 2 (24,28,29,32,33), and 3 (23,29,34), with sequentially improved sensitivity and shorter turnaround times (34,35), have been used in many resource-limiting settings, in Asia and in Africa, to monitor the viral load in HIV-1-infected pediatric and adult patients undergoing antiretroviral treatment. Overall, measurements with the ExaVir Load assay showed good agreement with "goldstandard" HIV-1 viral load assays, such as Abbott M2000sp/M2000rt RealTime HIV-1 (23,30), Roche Amplicor HIV-1 Monitor (24,25,27,28,33,36), Roche Cobas Amplicor (29,30,32,34,37), Versant Bayer HIV-1 bDNA (22,33), and bioMérieux NucliSense HIV-1 QT (26).…”

Low cost HIV-1 quantitative RT-PCR assay in resource-limited settings: Improvement and implementation

“…Although affordable alternative tests are available for measuring HIV RNA, such as the heat-associated HIV-1 p24 antigen enzymelinked immunosorbent assay (Bonard et al, 2003;Ribas et al, 2003;Mwapasa et al, 2010) and the reverse transcriptase activity kit assay from Cavide Exa Vir (Braun et al, 2003;Malmsten et al, 2003;Huang et al, 2010;Stewart et al, 2010), these have not been implemented widely in low income settings because they are labor-intensive and involve complex techniques. "in-house" realtime quantitative RT-PCR assays have the advantage that they are cheap, sensitive and easy to perform.…”

Assasying the Need of Commercial Plasma Viral Load Testing in Resource Limited Settings

“…Non Nucleic Acid Testing: The high cost of NAT test along with high cost of reagents and consumables restricts its implementation in recourse limited settings. In order to assay PVL monitoring in resource limited settings, alternative accessible inexpensive methods have been developed by different manufacturers and some of these have been validated in the recent years 16 such as the Cavidi ExaVir™ RT assay, [22][23][24] and PerkinElmer Ultrasensitive p24 assay, 23,25,26 are based on ELISA method, measuring the activity of reverse transcriptase (RT) enzyme and the concentration of p24 antigen. The use of these indirect measures of PVL require less equipment and skill , have thus been evaluated for resource-poor settings and include the ultrasensitive, heat-denatured p24 antigen quantification assay which is no longer being developed for viral load monitoring, and the ExaVir Load (Cavidi AB) reverse-transcriptase assay 13,27,28 .…”