Super Saliva Test
Ultrasensitive PCR powers an oral fluid assay for earlier HIV diagnosis
William Aryitey |
The advent of antiretroviral therapies to control HIV and the use of pre-exposure prophylaxis has turned a once-terminal illness into a relatively manageable disease when caught early enough. But although great strides have been made to curb the virus, 36.7 million people worldwide currently live with HIV – nearly half of whom are unsure of the status of their infection (1). Clearly, without access to adequate testing, it’s difficult for both patients and the medical community to keep track. And that’s why Carolyn Bertozzi and her team decided to develop a highly sensitive HIV assay for saliva (2).
At the moment, there are two main types of tests for screening HIV, each with pros and cons: blood tests are highly sensitive, but have a poor rate of compliance despite being minimally invasive; oral fluid tests, on the other hand, although noninvasive, typically suffer from poor sensitivity because of the lower concentrations of anti-HIV antibodies. The new oral fluid assay addresses the challenge by using antibody detection by agglutination-PCR (ADAP) – making it 1,000–10,000 times more sensitive than existing tests. “ADAP is based on the concept of proximity ligation PCR, which we knew had the capability of ultrasensitive DNA detection. This ADAP was designed to bring the sensitivity of PCR to the problem of antibody detection,” says Bertozzi, lead investigator, and Anne T. and Robert M. Bass Professor of Chemistry at Stanford University. “The ADAP test can enable earlier detection of HIV infection in the context of population screening using oral fluid, which is easier to collect and far less risky for healthcare workers because, unlike blood, oral fluid is not infectious.”
Bertozzi acknowledges that translating the research to the clinic is no small feat: “The biggest hurdles that lie ahead are larger studies with longitudinal data to judge how ADAP compares with current oral and blood-based tests.” But the team also see great promise in the ADAP assays, and plan to develop analogous tests for other infectious and autoimmune diseases that produce autoantibody biomarkers.
- HIV.gov, “The global HIV/AIDS epidemic” (2017). Available at: bit.ly/2xpEQnn. Accessed February 1, 2018.
- CT Tsai et al., “Antibody detection by agglutination-PCR (ADAP) enables early diagnosis of HIV infection by oral fluid analysis”, Proc Natl Acad Sci USA, [Epub ahead of print] (2018). PMID: 29358368.