Semen Boost HIV Resistance in Women Sex Workers According to Study

Semen Exposure Found to Enhance Resistance to HIV Infection

Semen is a known vehicle for transmission of sexually transmitted infections (STIs), including human immunodeficiency virus (HIV). A recent study looks to challenge that view to some degree.

Sex Work

Sex Work

Somewhat contrary to expectations, researchers at The Wistar Institute and the University of Puerto Rico found that women’s resistance to HIV may build up with repeated semen exposure. They published their study that led to this finding in Nature Communications.

For decades, the belief has been that semen is a medium of passing on HIV-1 from men to women. This study seems to challenge that.

This new research may explain why some female sex workers across the globe do not develop infection. They seem not to become infected as much as expected, considering their continual involvement in high-risk sexual activity.

Researchers found that recurrent and continuous exposure to semen may alter the features of infection targets – circulating and vaginal tissue immune cells. This effect lowers the risk of having an infection.

“While HIV infection has been with us for more than 30 years, this is the first study that describes how semen exposure over time could result in local tissue changes that limit HIV infection in humans,” said study’s lead author Dr. Luis J. Montaner, D.V.M, D.Phil, the director of the HIV-1 Immunopathogenesis Laboratory at the Vaccine & Immunotherapy Center of The Wistar Institute.

Reduced risk of infection

The scientists had reported in previous work carried out in 2015 that recurring exposure to semen by female sex workers led to alterations of their cervicovaginal tissue. They considered the changes an indication of increased HIV resistance.

In the current study, the researchers continued further to find out how semen may contribute to infection resistance in hosts. They used non-human primates (NHP) domiciled at the Caribbean Primate Research Center for the project.

NHPs are commonly used in pre-clinical research for testing prophylactic treatments against HIV.

The team exposed animals to semen two times a week for about five months with or without inactivated simian immunodeficiency virus (SIV) particles.

SIV may be described as the simian version of HIV. It progresses to a disorder similar to AIDS.

The animals were given low doses of intravaginal SIV after the conditioning period.

The non-human primates that were frequently exposed to semen showed a 42 percent reduction in their risk of infection.

Exposure to semen seemed to result in lower CCR5 receptor expression. The CCR5 receptor serves as a binding site that enables HIV to penetrate into host cells.

Animals conditioned with semen had higher CCL5 cytokine levels. This is notable because the substance helps to naturally curb the virus in humans.

Increased protection

These findings all seem to point to greater protection for women exposed to semen on a recurrent basis.

Furthermore, the researchers observed that repeated semen exposure produced higher levels of MX1 and other antiviral factors in the cervicovaginal tissue. This was positively correlated with the amounts of a protein known as IFN-epsilon.

This protein offers protection against bacterial and viral pathogens and can be stimulated with semen. The scientists said IFN-epsilon possesses direct anti-HIV properties. It was generated in tissues obtained from sex workers who have sex without condoms.

“Currently, condomless sex is assumed to only promote the likelihood of infection,” Montaner said. “Our observation, however, raises the hypothesis that frequent semen exposure may potentially reduce HIV transmission.”

The Herbert Kean, M.D., Family Professor said the finding could shape future studies on HIV vaccines. Researchers often use female sex workers for such studies.

However, findings from this study do not suggest that semen exposure can prevent HIV infection. The organic fluid may only add to resistance to the virus.

Animals that were initially resistant to infection due to semen exposure became infected at high virus doses.

References

https://www.nature.com/articles/s41467-019-11814-5

 

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