Access to affordable and accurate HIV-1 VL testing

World Health Organization (WHO) guidelines recommend the use of HIV-1 viral load (VL) testing as the preferred method for routine monitoring of patient responses to antiretroviral therapy and identification of treatment failure.

Unfortunately, in many low and middle income countries, access to VL testing is limited due to the expensive laboratory equipment and expensive diagnostic testing, with a single VL test costing up to USD 43.

From the health service provision perspective, the complex specimen collection, transportation and need for highly trained personnel to perform testing adds to the implementation barriers.

In order to overcome these health system challenges, and to increase the coverage of VL testing, dried blood spots (DBS) has been recommended and widely used as an alternative to plasma-based VL testing in resource-constrained settings. The use of DBS increases access to VL testing by simplifying sample collection, storage and transportation requirements.

The advantages gained by an increase in accessibility when using DBS is somewhat offset by the decrease in accuracy compared to when plasma samples are used. DBS use for VL testing in reference nucleic-acid based platforms can overestimate plasma VL and lead to unnecessary targeted VL testing for confirmation or premature regimen switching.

To address this technical challenge, Burnet Institute has developed a simple paper-based method of plasma separation for accurate VL testing: filtered and dried plasma spot (FDPS). When compared to traditional methods of separating plasma, the FDPS shows promising results with 94 percent plasma recovery, 93 percent leukocyte retention and close to 100 percent erythrocyte retention.

During preliminary testing of 200 patients from the HIV clinic at The Alfred Hospital, Melbourne, the technology showed greatly improved specificity (100 percent) over the use of DBS (46 percent) for detection of VL at greater than 1,000 copies/µl thus, identifying treatment failure in patients undergoing therapy (unpublished data).

Currently the FDPS has a detection limit of 400 copies/µl and work is ongoing to increase the volume of plasma collected and allow a lower detection threshold with the aim of reaching the standard 20 copies/µl that is achievable from liquid plasma.



Health Issue

Contact Details

For any general enquiries relating to this project, please contact:

Doctor Minh Duc Pham

Senior Research Officer




[email protected]