New research suggests HIV reservoirs might be able to evade drug treatment by finding a home in male testes (or testicles), where they can remain protected from the body’s immune system for years.
Studies around testes are difficult to undertake, mainly because the tissue itself is hard to collect without removal of the testes—and most men aren’t willing to make that sacrifice for science! But, according to Scientific American, Jean-Pierre Routy, an infectious disease clinician and researcher at McGill University in Montreal, Canada, found a unique way around that roadblock. Dr. Routy, a surgeon who performs gender-affirming surgeries at GRS Montreal (a plastic surgery clinic) collected samples from transgender women who were undergoing bottom surgery.
The women gave consent for their tissues to be used for research after removal. Routy has collected nearly 100 samples, about a tenth of which were HIV-positive, offering him an unprecedented opportunity to examine HIV in testicular tissue. And his research is breaking new ground.
Data shows that inside the testes is what’s known as an “immune-privileged” site, where HIV can find protection from the immune system. Immune privilege allows foreign invaders the same protection from the immune system as sperm. “This is because antigens from invaders also do not seem to set off an inflammatory response, unlike elsewhere in the body,” according to Scientific American.
The same idea of immune privilege was evident in the recent Zika and Ebola outbreaks. Traces of these viruses were found in semen months after it had been cleared elsewhere in their bodies. For one man in Italy, Zika virus was detected in his semen nearly 134 days after his symptoms stopped. Meanwhile, his blood and saliva samples showed no trace of the virus.
Researchers have known that HIV can remain detectable in certain tissues (like the lymphatic system) and organs, while lowering to undectable levels in the blood. In these latent HIV reservoirs, the virus can remain dormant while a person is being treated with antiretrovirals, and it can exist even after the person living with HIV has become virally suppressed. If the HIV-positive person stops treatment, the latent virus can reawaken and reactivate, and viral loads can rebound.
After examining testicular tissues and blood samples from HIV-positive donors, Routy and his team found lingering viral DNA in at least one testicle of each donor, even though all the poz donors were on treatment and undetectable at the time.
It’s important for scientists to study testicular tissues, even if they are hard to come by. Routy stated, “If we don’t learn how [viruses] persist in the testes, then patients
will continue to transmit the virus to others and put people at risk.”
Studies like this show how including transgender subjects in scientific research can offer new avenues for investigation and groundbreaking insights that have broad applications.