SEATTLE, – JUNE 18, 2019 – Ways to measure exposure to HIV could be important in helping identify those at the greatest risk of acquiring the virus, improving the design of future HIV prevention efficacy trials and public health interventions. In a recent study, conducted by the HIV Vaccine Trials Network (HVTN), headquartered at the Fred Hutchinson Cancer Research Center, researchers evaluated the use of self-administered daily vaginal swabs to detect HIV in conjunction with a mobile phone survey.
In the study, researchers enrolled fifty 18-to-25-year-old, sexually active HIV-negative women in Soweto, South Africa. Study participants were asked to self-administer daily vaginal swabs in conjunction with a daily mobile phone-based survey on sexual behavior over a period of 90 days. As part of the study, participants were also provided with HIV testing and counseling, STI testing and treatment, and a gynecological exam and Pap smear. Clinicians collected swabs at regular clinic visits over the course of the study, analyzing them for biomarkers of vaginal secretions, semen, and HIV.
Vaginal self-swabbing was well tolerated, and participants correctly swabbed vaginal secretions. The detection of Y chromosome in the vaginal swabs, a marker of semen exposure, was strongly associated with reporting sex without condoms in the mobile app, and rarely present after reports of abstinence or protected sex. Daily phone-based reporting of sexual behavior also proved more accurate than face-to-face interviews at the clinic. One possible explanation might be the privacy of the reporting method, and the shortened time required in remembering sexual activity and reporting it daily.
This study demonstrated that vaginal self-swabbing and biomarker testing can be useful to validate behavioral data collection methods, such as mobile phone-based questionnaires. Improving the sensitivity of HIV RNA detection in the vagina is essential to using this approach to consistently detect HIV exposure.
None of the participants acquired HIV during the study. To assess vaginal HIV exposure, all vaginal swabs that were linked to phone reports of sex without condoms were tested for HIV genetic material, or RNA. Analysis of the swabs found that only 1 of 69 samples collected between zero to one hour after sex had detectable HIV RNA. None of the 247 samples collected from one to four hours after sex had detectable HIV. None of the 185 samples with evidence of semen collected from four to 24 hours after sex had detectable HIV.
The detection of HIV in one sample demonstrates the possibility of detecting the virus through self-collected swabs. However, compared to current HIV transmission rates in the area, HIV exposure detection in the study was lower than expected. The researchers attribute this to several possible causes: overestimating current transmission rates, reduced risk of exposure due to increased awareness during the study, and the breakdown of HIV genetic material in the vagina over time.
“In the future, we plan to extend the work we have done to measure HIV exposures and condomless sex in women to also include men who have sex with men. We plan an additional study to establish similarities and differences in daily behavioral reporting by men who have sex with men using mobile apps, and to assess biomarkers of condomless sex and HIV exposures in the rectum like we did in the vagina,” said Maria Lemos, staff scientist at Fred Hutchinson Cancer Research Center and lead author of the study.
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Conflicts of Interest and Source of Funding:
The authors declare that no potential conflicts of interest exist. Research reported in this publication was supported by the National Institute of Allergy and Infectious Diseases (NIAID) of the National Institutes of Health U.S. Public Health Service Grants UM1AI068614 [HVTN LOC], UM1AI068635 [HVTN SDMC], UM1AI068618 [HVTN Laboratory Center], UM1AI069453 [Soweto-Bara CRS], UW CFAR P30AI027757 [UW, Virology Laboratory] and UM1AI106701 [ACTG Laboratory Center]. Dr. Dietrich received a Thuthuka award from the South African National Research Foundation (SA-NRF) and an HIV Initiatives Program Award. The content is solely the responsibility of the authors, and does not necessarily represent the official views of the National Institutes of Health or SA-NRF.
Maria Lemos PhD, Erica Lazarus, MBChB, Abby Isaacs, MSc, Janan Dietrich, PhD, Cecilia Morgan, PhD, Yunda Huang, PhD, Doug Grove MSc, Michele Andrasik, PhD, Fatima Laher, MBBCh, John Hural, PhD, Eva Chung PhD, Joan Dragavon MLM, Adrian Puren MBBCh, Reena K. Gulati MD, Robert Coombs MD, M. Juliana McElrath MD, Glenda Gray, MBBCh, and James Kublin, MD
About Fred Hutchinson Cancer Research Center
At Fred Hutchinson Cancer Research Center, home to three Nobel laureates, interdisciplinary teams of world-renowned scientists seek new and innovative ways to prevent, diagnose and treat cancer, HIV/AIDS and other life-threatening diseases. Fred Hutch’s pioneering work in bone marrow transplantation led to the development of immunotherapy, which harnesses the power of the immune system to treat cancer. An independent, nonprofit research institute based in Seattle, Fred Hutch houses the nation’s first National Cancer Institute-funded cancer prevention research program, as well as the clinical coordinating center of the Women’s Health Initiative and the international headquarters of the HIV Vaccine Trials Network.