Infection during sex: The monkeypox virus apparently also affects the testicles and epididymis in men and can then be transmitted via sperm and ejaculate. A US research team found evidence of this in macaques, in whose testicular tissue and epididymal tubules they were able to detect monkeypox. The viruses were still present there even following the acute infection had subsided – which might indicate a longer risk of infection through sexual transmission.
monkey pox are actually a very rare disease in humans and mainly limited to Africa. But since the beginning of May 2022, a monkeypox epidemic has been rampant, which has infected more than 50,000 people in 120 countries. In the course of this outbreak, the virus, originally from Nigeria, has already started to get better through mutations adapt to humans.
It is striking that among those affected there are a particularly large number of young gay men with skin lesions primarily in the genital area. This has long raised the suspicion that the monkeypox virus is not only transmitted via body fluids and skin lesions, but also via sperm and ejaculate. However, clear evidence for this has so far been lacking.
Does the virus also hide in sperm?
That’s why Jun Liu and his colleagues at the US Army Medical Research Institute of Infectious Diseases (USAMRIID) in Fort Detrick first looked for evidence of sexual transmission of the monkeypox virus in monkeys. To do this, they analyzed the testicular tissue of 21 long-tailed macaques (Macaca fascicularis) infected with the virus. This monkey species is considered a well-suited animal model for this viral disease because it reacts similarly to humans, even if the infection is usually more severe than in humans.
“We examined tissue samples from the acute phase of the infection as well as from the convalescence phase, in which the infection gradually subsides,” explains senior author Xiankun Zeng. In order to detect the presence of monkeypox viruses, the researchers used fluorescent markers for the virus antigen and also detection methods for the RNA of the pathogen.
Testicles and epididymis affected
The result: “We detected monkeypox virus antigens in 18 of 21 of the testicles examined,” reports the research team. The virus was therefore present in sperm precursor cells as well as in the seminiferous tubules and the interstitial cells of the testicles. “We also detected monkeypox viruses in the epidymial ducts of the epididymis, which are the sites of sperm production and maturation,” Liu and his team write.
In her opinion, this suggests that the monkeypox virus can also be transmitted via sperm and sperm fluid in the acute phase of the infection. This might explain why so many young men have become infected through same-sex sexual contact. “The testicles are involved in many viral infections, including Zika, Ebola, Marburg, and Crimean-Congo fever,” Liu and his colleagues explain. Because this organ, along with the eyes and brain, is one of those organs that are only partially accessible to the immune system.
Transmission even following the acute infection
However, the testicles and sperm are apparently not only a refuge for the monkeypox virus during an acute infection. Liu and his team were also able to detect monkeypox pathogens in two testicle samples from macaques that were already convalescent. These persisted up to 37 days following infection. While the skin lesions of these monkeys no longer contained any virus at this point, they were still present in the testicular tissue.
“Our data thus provide evidence that the monkeypox virus can be passed on via the sperm both in the acute phase of infection and in the convalescence phase,” says Zeng. The sexual transmission of the monkeypox virus might therefore still take place even following the superficial skin lesions and other acute signs of infection have subsided. Whether this is actually the case in humans must now be checked in further studies with human patients. (Nature Microbiology, 2022; doi: 10.1038/s41564-022-01259-w)
Quelle: US Army Medical Research Institute of Infectious Diseases (USAMRIID)
