The Secret Life of HIV
Early-capture testing can detect HIV infections before symptoms arise, offering opportunities to decrease transmission and improve treatment
Michael Schubert |
Every so often, a discovery in the world of human immunodeficiency virus (HIV) research will prompt the use of the phrase “Holy Grail.” Usually, it’s a proposed treatment for the disease, or early-stage work on a possible preventative vaccine. But those may not be the only interventions deserving of a grand title. What if there were a way to detect HIV earlier than ever – during the acute phase of infection, when the disease is both most transmissible and potentially most treatable? A landmark study in the New England Journal of Medicine (1) details a cohort of high-risk individuals whose HIV status was tracked over time with twice-weekly nucleic acid testing, allowing researchers to detect the presence of the virus long before they became symptomatic or began secreting antibodies.
“The common tools for HIV diagnosis utilize the emerging antibody and HIV core antigen as targets of detection,” explains senior author Merlin Robb. “A person will have virus in the blood and genital secretions for perhaps a week or more before these tests are sensitive. Testing for nucleic acid of HIV closes that gap and permits the earliest identification of acute infection with HIV.” This type of testing is already standard for HIV monitoring in most clinical laboratories and blood banks, but isn’t yet commonly used for early capture. Robb would like this to change. “Acute HIV infection is thought to be an era of greater transmissibility, although there is an active debate on the proportion of new cases arising in association with acute infection. There is also increasing information that individuals in acute infection may be the best candidates for testing interventions for cure.” If either or both of these hypotheses proves true as the researchers collect more data, it will provide motivation to improve nucleic acid testing platforms; current assays are effective, but not portable, and developing smaller, faster tests would allow more widespread monitoring of high-risk populations.
Who is most likely to benefit from early-capture testing? “The highest risk groups for HIV infection are men who have sex with men without use of condoms, and injecting drug users. In some settings, high-risk women would also be ideal participants in frequent nucleic acid testing campaigns.” Robb feels that, in these communities, an inexpensive, accessible and reliable diagnostic platform might be able to identify patients in the acute stage of infection – giving doctors the opportunity to intervene to prevent transmission and potentially offer experimental strategies aimed at a cure. The advantages aren’t limited to people at risk of HIV, though. “There are many settings where identification of a pathogen which can be transmitted readily with high-grade pathogenicity would be very useful for epidemic evaluation and control. An example would be a nucleic acid testing device for Ebola, which could be carried into sometimes austere epidemic settings.”
Robb’s work continues – but now it serves a slightly different purpose. Having discovered that patients can be identified early by nucleic acid testing, he’s now attempting to turn that to both their advantage and his by offering them the opportunity to start treatment early and participate in research studies assessing reduction of the virus’ infectious reservoir.
- ML Robb et al., “Prospective study of acute HIV-1 infection in adults in East Africa and Thailand”, N Engl J Med, 374, 2120–2130 (2016). PMID: 27192360.