New research has shown that HIV might be able to evade drug treatment by finding a home in men’s testes (or testicles), where they can remain protected from the body’s immune system for years.
Studies around testes are difficult to undergo, mainly because the tissue itself is hard to collect. But according to Scientific American, Jean-Pierre Routy, an infectious disease clinician and researcher at McGill University in Montreal, collected samples from transgender women undergoing bottom surgery at GRS Montreal, a center that facilities over 400 surgeries a year.
One of the first samples Routy collected was from an HIV-positive person, who gave their testes willingly to research after it was removed during surgery.
Since then, Routy received close to 100 testicular tissue samples from GRS Montreal to study the resistance of HIV in the body. Nearly a tenth of the samples he collected were HIV-positive.
Routy’s research is truly groundbreaking because while we know that latent HIV often hides inside reservoirs while the person is being treated with antiretrovirals and is undetectable (as soon as the person gets off treatment, the latent virus often awakens and becomes active in the body again), data shows that because inside the testes is what’s known as an “immune-privileged” site, HIV can often find protection from the immune system — even when a person is on treatment.
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,” Scientific American reports.
After examining testicular HIV-positive tissues and blood samples, Routy and his team found they all had lingering viral DNA in at least one testicle, even though they were all on treatment and were considered undetectable.
The team concluded that HIV could evade drug treatment by finding a home in the testes, though it’s still unclear how it managed to gain entry and stays without ever being detected by the immune system.
The same idea of immune privilege is evident in the recent Zika and Ebola outbreaks. Scientific American points out that people had traces of these viruses in their semen months after they contracted the viruses, and it had been cleared elsewhere in their bodies. For one man in Italy, Zika virus was detected in his semen nearly 134 days after its symptoms were gone, though blood and saliva samples showed no trace of the virus.
It’s cases like these that show how important it is for scientists to study testes, but samples are still hard to come by.
“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,” Routy stated.