A team of researchers from Rice University (TX, USA) have recently reported proof-of-concept work towards the development of a simple, highly accurate diagnostic test to detect HIV and monitor disease progress in patients in low-resource settings.
Led by Rebecca Richards-Kortum, Professor at the university, the scientists originally intended to look for HIV in infants; however, the test can also help track viral loads in older patients.
“It’s important for clinicians to be able to quantitatively monitor patients’ viral loads in order to ensure the disease is responding to therapy,” said Zachary Crannell, co-lead author of the research.
The current gold standard for diagnosing HIV in infants and for monitoring viral loads requires equipment and expertise that is typically only available in a clinical setting. The new technique would replace a complex procedure that relies on PCR with one that relies on recombinase polymerase amplification, a method that in this case can quickly amplify blood-based genetic markers to quantifiable levels.
In this study, a specific sequence in HIV DNA is targeted and tagged with fluorescent probes, levels of which can be counted in a portable machine. Software analysis then allows clinicians to accurately determine whether the virus is present and to what extent.
The group noted that the test is calibrated by amplifying an internal positive control not found in human blood. “It’s amplified by the same primers as the HIV sequence, so it tells us that the assay is working properly,” explained co-lead author Brittany Rohrman.
The scientists hope that the technique can be employed to completely operate between room and body temperatures so that it can be performed at the point of care in the developing world.
Sources: Crannell ZA, Rohrman B, Richards-Kortum R. Quantification of HIV-1 DNA using real-time recombinase polymerase amplification. Anal. Chem. DOI: 10.1021/ac5011298 (2014) (Epub ahead of print); Rice developing mobile DNA test for HIV.