Study Finds Repeated Semen Exposure Could Lower HIV Infection Risk

Women who are repeatedly exposed to semen have a decrease chance of becoming infected with HIV, as the vaginal tissue immune cells, which are susceptible to HIV, are altered.

That’s based on the latest information from researchers at the University of Puerto Rico and Wistar Institute in Philadelphia. However, there were also multiple researchers for the study that came from Duke University, Tulane University, the University of Pennsylvania, Ulm University, Mount Holyoke College and the University of Nebraska.

The study, which was recently published in the Nature Communications journal, would explain why a minute number of women who regularly engage in sex continue to test negative for HIV even though they involve themselves in high-risk behavior.

A 2015 study found that exposure to semen changed the cervicovaginal tissue in female sex workers, which means a lower risk for HIV infection.

The latest study looked at whether or not semen could aid in HIV resistance.

The HIV infection has been around for 30+ years, but the study is the first of its kind to demonstrate how semen exposure could affect tissue and reduce the spread of HIV in humans.

Luis J. Montaner, scientist and the study’s lead author, said the information isn’t just about the regulation of HIV transmission but helpful in future studies of female sex workers to come up with an HIV vaccine. He said condomless sex is thought to only increase infection rates. However, it appears that constant exposure to semen could reduce the transmission of HIV.

University of Puerto Rico Professor Edmundo N. Kraiselburd helped with the pre-clinical research project and oversaw the use of macaque primates to test prophylactic anti-HIV interventions. He said the macaque model research offers important information that can be used in determining human HIV infections.

For a period of five months, primates were exposed to semen two times a week with or within the simian immunodeficiency virus or SIV. (SIV is the primate’s equivalent to human HIV. The virus also causes a similar AIDS-like disease). After the exposure for this period, they were given low amounts of intravaginal SIV.

The monkeys exposed to semen regularly had a 42-percent drop in infection risk.

In fact, constantly being exposed to semen showed an increase in antiviral levels in cervicovaginal tissue including MX1, which connected positively with IFN-epsilon levels. IFN-epsilon offers direct anti-HIV properties and was noted as being seen in sex workers’ tissues where condomless sex took place.

There is still no idea if the news is good for the 17.4 million (51 percent) women who have HIV.

The study found primates who were not infected after exposure to low viral amounts later became infected when they were exposed to high virus doses. This simply means that repeated semen exposure offers some, not all, protection from an HIV infection.

Montaner said the study showed that semen exposure offers host resistance but won’t block an infection entirely. He said people should still use condoms and take PrEP to prevent the spread of HIV infection.