CROI focus shifts to HIV viral load testing in resource-limited settings

LOS ANGELES – The need for HIV viral load testing in resource-limited settings was emphasized by researchers from The University of Cape Town and YRG CARE in India at the 2007 Conference on Retroviruses and Opportunistic Infections (CROI). Their research showed the inadequacy of CD4 cell count as a marker of HIV progression and as a tool to combat drug resistance. They concluded that viral load testing should be implemented in addition to CD4 testing in resource-limited settings.

This marks a clear break from the existing policy on viral load testing in these settings. Organizations such as the World Health Organization (WHO) have previously stated that viral load testing is impractical for developing countries. In their 2006 guidelines on the provision of antiretrovirals in resource-limited settings, they said viral load testing was not practicable on a large scale. Instead, the guidelines advised using CD4 cell count or clinical observation to monitor the progress of antiretroviral therapy.

According to findings from the University of Cape Town presented at CROI, “CD4 cell count slope […] was poorly sensitive and specific to virologic failure.” In addition to poor correlation between CD4 count and viral load, the time delay in detection of viral adaptation with CD4 tests allows for the development of drug resistance. This limits future treatment options for an HIV patient. Viral load testing is part of standard treatment in developed countries because it solves these issues.

Results from studies on possible solutions were also presented at the conference. Researchers underscored the limitations of today’s nucleic acid–based assays. “The nucleic acid–based viral load assays (NAT) require infrastructure facilities and skilled personnel and they are expensive. An inexpensive and technically less-demanding method to quantify HIV-1 would be of great value for settings where NAT is impractical or resource-prohibitive.”

The team, which came from YRG CARE in Chennai, India, went on to cite Cavidi’s ExaVir™ Load RT activity assay as a viable option for testing viral load in resource-limited settings. The team singled out the assay as the most suitable solution available because it is cost-effective and has less technical requirements than other assays. They recommended further evaluation of the assay as an alternative to the traditional nucleic acid–based assays.