Monkeypox virus was detected in the testicles of nonhuman primate survivors

According to a study published online today in the journal, scientists have detected the monkeypox virus
for the first time in the testicles of macaques during acute infection.
In addition, the team found preliminary evidence
of persistent infection in two virus-infected animals.
Their findings highlight the possibility that
the virus is transmitted sexually in humans.

The ongoing monkeypox outbreak in 2022 has been linked to
sexual contact with laboratory-confirmed infected patients.
Because the virus can be transmitted through direct contact with bodily fluids and skin lesions, understanding the biology of monkeypox infection testes and the release of the virus into semen is of great public health implications
.

Researchers at the U.
S.
Army Medical Research Institute of Infectious Diseases (USAMRIID) performed a retrospective analysis
of monkeypox virus infection on tissue samples from cynomolgus macaques.
Cynomolgus macaques are a widely used non-human primate model to study the disease and evaluate the effectiveness of medical countermeasures against monkeypox, such as vaccines and treatments
.

Dr.
Xiankun (Kevin) Zeng, senior author of USAMRIID, explains, "We tested tissue samples
obtained during the acute phase of the disease (when the infection peaked) and during the convalescent phase (when the infection gradually subsided).
We detected monkeypox virus in the interstitial cells and seminiferous ducts of the testicles and in the lumen of the epididymis, which is where
sperm are produced and maturation.
”

Importantly, Zeng said, the team also found preliminary evidence of persistent monkeypox virus infection in two convalescent crab-eating macaques that survived the viral infection
.
Using histological analysis to analyze disease processes in tissue samples under the microscope, the USAMRIID team found that while monkeypox virus was cleared from most organs and healed skin lesions during the recovery period, it could be detected for up to 37 days
after the macaque's testicles were exposed.

The USAMRIID researchers who led the former have previously demonstrated that Ebola, Marburg, Nipah and Crimean-Congo haemorrhagic fever viruses can persist in certain organs in nonhuman primate survivors with suppressed immune systems
.
These human-like immunoprivileged sites include the eyes, brain, and testicles
.
While close contact through sexual activity has been linked to transmission of monkeypox virus in the current global epidemic, it is unclear whether the virus replicates in the testicles or is transmitted
through semen.

"Our data provide evidence that monkeypox virus may enter semen during the acute and convalescent phases of crab-eating macaques," Zeng said
.
"Therefore, it seems reasonable
that in convalescent patients, human transmission may be through semen.
" The authors also note that persistent viruses may be cleared
over time.

Dr.
Jun Liu, the paper's first author, said that because this is a retrospective study using archival tissue, isolating the virus in semen is impossible
.
Further research is now needed to understand the origin, dynamics and effects of viral DNA in semen, as well as to confirm whether the semen of convalescent monkeypox patients contains infectious viruses – especially after the
skin damage has healed.

In addition, according to the authors, the monkey model may not fully reflect the situation with monkeypox in
humans.
These animals exhibit more severe and deadly diseases than those observed in humans, and have a shorter
incubation period in the animals.
In addition, animal samples used in the study were exposed to different isolates of the virus than the currently circulating strains
.

Retrospective detection of monkeypox virus in the testes of nonhuman primate survivors