Y chromosome DNA from male epithelial and sperm cells was detected in vaginal samples after unprotected sex in experimental studies. We assessed the strength of this association in an observational setting to examine the utility of Y chromosome DNA as a biomarker of recent sexual behaviors in epidemiological studies.
The HPV (human papillomavirus) Infection and Transmission Among Couples Through Heterosexual Activity cohort study enrolled 502 women attending a university or college in Montréal, Canada, and their male partners from 2005 to 2010. Participants completed self-administered questionnaires. We used real-time polymerase chain reaction to test women's baseline vaginal samples for Y chromosome DNA and assessed which sexual behaviors were independent predictors of Y chromosome DNA positivity and quantity with logistic and negative binomial regression.
Y chromosome DNA positivity decreased from 77% in women in partnerships reporting vaginal sex 0 to 1 day ago to 13% in women in partnerships reporting last vaginal sex of 15 or more days ago (adjusted odds ratio, 0.09; 95% confidence interval, 0.02–0.36). The mean proportion of exfoliated vaginal sample cells with Y chromosome DNA was much lower for women who reported always using condoms (0.01%) than for women who reported never using condoms (2.07%) (adjusted ratio, 26.8; 95% confidence interval, 8.9–80.5). No association was found with reported oral/digital sex frequency or concurrency of partnerships.
Y chromosome DNA quantity is strongly associated with days since last vaginal sex and lack of condom use in observational settings. Y chromosome DNA quantity may prove useful as a correlate of recent vaginal sex in observational studies lacking data on sexual behavior, such as surveillance studies of human papillomavirus infection prevalence.
In heterosexual couples in Montreal, we found that self-reported time since vaginal sex and condom use are strongly associated with the quantity of Y chromosome DNA in women's vaginal samples.
From the *Division of Cancer Epidemiology, Department of Oncology, McGill University, Montréal, Canada; †Department of Family and Community Medicine and Centre for Urban Health Solutions, Li Ka Shing Knowledge Institute, St. Michael's Hospital, Toronto, Canada; ‡Department of Family and Community Medicine and Dalla Lana School of Public Health, University of Toronto, Toronto, Canada; §Département de microbiologie et infectiologie, Centre Hospitalier de l’Université de Montréal, Montréal, Canada; ¶Département de microbiologie et immunologie, Université de Montréal, Montréal, Canada; ∥Department of Family Medicine, McGill University, Montréal, Canada; and **Department of Epidemiology, Biostatistics and Occupational Health, McGill University, Montréal, Canada
Additional collaborators in the HITCH study group: McGill Student Health Services: Gail Kelsall, Suzanne Dumais; Concordia University Student Health Services: Melanie Drew; Research nurses: Gail Kelsall, Suzanne Dumais, Natalia Morykon, Amela Rocamora, Nathalie Slavtcheva. Study management: Allita Rodriges. Study promotion: Vicky D’Anjou-Pomerleau, Jennifer Selinger, Elizabeth Montpetit-Dubrule, Jessica Sammut, Emilie Lapointe, Johanna Bleecker, Shady Rahayel; HPV DNA testing laboratories: Hélène Voyer, Véronique Legault, Emilie Comète.
Conflict of Interest and Sources of Funding: This work was supported by the Canadian Institutes for Health Research (CIHR) (grants MOP-68893 and CRN-83320 to ELF, and a Postdoctoral Fellowship Award to TM); the US National Institutes of Health (grant AI073889 to ELF); the Reseau Fonds de la Recherche en Santé du Québec (FRSQ) AIDS and Infectious Disease Network (SIDA-MI) (support for optimization of molecular techniques to FC); and supplementary and unconditional funding by Merck-Frosst Canada Ltd and Merck & Co Ltd to ELF. The funders played no role in the writing of the manuscript or the decision to submit it for publication. E.L.F. has served as occasional consultant to Merck, GSK, Roche, and BD. His institution has received grants from Merck and Roche. P.P.T. has received payment for lectures by Merck-Frosst Canada and Bayers. F.C. received grants through his institution for research projects from Roche and Merck, payments for lectures by Merck, Roche, and has participated in an expert group by Merck. All other authors report no potential conflicts of interest.
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Correspondence: Talía Malagón, PhD, Division of Cancer Epidemiology, Gerald Bronfman Department of Oncology, McGill University, 5100 Boulevard de Maisonneuve W, Suite 720, Montreal, QC, Canada H4A 3T2. E-mail: email@example.com.
Received for publication May 23, 2017, and accepted July 14, 2017.