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Can HIV reverse transcriptase activity assay be a low-cost alternative for viral load monitoring in resource-limited settings?
  1. Soham Gupta1,
  2. Riya Palchaudhuri1,
  3. Ujjwal Neogi2,
  4. Hiresave Srinivasa1,
  5. Per Ashorn3,
  6. Ayesha De Costa4,
  7. Clas Källander5,
  8. Anita Shet6
  1. 1Division of Clinical Virology, Department of Microbiology, St. John's Medical College, Bangalore, India
  2. 2Division of Clinical Microbiology, Department of Laboratory Medicine, Karolinska Institutet, Stockholm, Sweden
  3. 3Department for International Health, University of Tampere School of Medicine, Tampere, Finland
  4. 4Department of Public Health Sciences, Karolinska Institute, Stockholm, Sweden
  5. 5Cavidi AB, Uppsala, Sweden
  6. 6Department of Pediatrics, St John's Medical College Hospital, Bangalore, India
  1. Correspondence to Soham Gupta; soham.gupta{at} and Ujjwal Neogi; ujjwal.neogi{at}


Objective To evaluate the performance and cost of an HIV reverse transcriptase-enzyme activity (HIV-RT) assay in comparison to an HIV-1 RNA assay for routine viral load monitoring in resource limited settings.

Design A cohort-based longitudinal study.

Setting Two antiretroviral therapy (ART) centres in Karnataka state, South India, providing treatment under the Indian AIDS control programme.

Participants A cohort of 327 HIV-1-infected Indian adult patients initiating first-line ART.

Outcome measures Performance and cost of an HIV-RT assay (ExaVir Load V3) in comparison to a gold standard HIV-1 RNA assay (Abbott m2000rt) in a cohort of 327 Indian patients before (WK00) and 4 weeks (WK04) after initiation of first-line therapy.

Results Plasma viral load was determined by an HIV-1 RNA assay and an HIV-RT assay in 629 samples (302 paired samples and 25 single time point samples at WK00) obtained from 327 patients. Overall, a strong correlation of r=0.96 was observed, with good correlation at WK00 (r=0.84) and at WK04 (r=0.77). Bland-Altman analysis of all samples showed a good level of agreement with a mean difference (bias) of 0.22 log10copies/mL. The performance of ExaVir Load V3 was not negatively affected by a nevirapine/efavirenz based antiretroviral regimen. The per test cost of measuring plasma viral load by the Abbott m2000rt and ExaVir Load V3 assays in a basic lab setting was $36.4 and $16.8, respectively.

Conclusions The strong correlation between the HIV-RT and HIV-1 RNA assays suggests that the HIV-RT assay can be an affordable alternative option for monitoring patients on antiretroviral therapy in resource-limited settings.

Trial registration number ISRCTN79261738.

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