A new study out of the U.S. Army Medical Research Institute of Infectious Diseases offered insight on how filoviruses, a group of viruses that cause hemorrhagic fever in humans, might persist.
The researchers at USAMRIID, at Fort Detrick, found persistent Marburg virus, a deadly type of filovirus that can infect humans, in other primates. More specifically, they found it in the testes of crab-eating macaques, according to the article published in Cell Host and Microbe.
USAMRIID scientists studied brain, eye, liver, lymph node, spleen and testes tissue from 97 macaques that had previously survived Marburg. They found the disease persisted in the testes, even after it had cleared the other target organs, such as the brain or liver.
The researchers knew the disease persisted, but the study showed some of the mechanisms of how the disease remained in the testes, said Dr. Travis Warren, one the authors of the paper and a principal investigator at USAMRIID.
“That’s a novel and new finding to the field,” Warren said.
Of the 73 male monkey survivors, 22 had MARV genomic RNA in their testes. Evidence of the disease was not found in the brains of the monkeys. Marburg virus damages the testes, leading to breakdown of the blood-testes-barrier that protects Sertoli cells, which help nourish sperm production.
With the barrier broken, the Sertoli cells are likely where Marburg is stored, at least in crab-eating macaques.
While the researchers said in the study that they believed the disease would clear the testes, more testing would be necessary to understand how frequently it would be cleared. While the Sertoli cells were affected, the disease does not seem to affect overall reproductive function, including sperm generation.
While Marburg is a different disease than Ebola, they are both filoviruses, and the research conducted at USAMRIID may shed light on ways Ebola persists as well, according to the study. The findings might indicate why human survivors of Ebola have Ebola RNA in their semen despite having no clinical signs of the disease, the authors wrote.
And although the study used crab-eating macaques, there could be some implications for humans, said Kevin Zeng, senior molecular scientist at USAMRIID. The findings could help lead to a test for filovirus persistence, he said.
It opens up new possibilities for therapeutic and counter measures, Warren said. Because of the ability of filoviruses to persist and re-emerge, it is important that researchers keep studying the disease, said Jun Liu, author of the paper and researcher at USAMRIID.
“It is important for us to keep researching the mechanisms of this virus,” Liu said.
Studying filoviruses is a part of USAMRIID’s public health mission, and it is important to keep studying the diseases in order to find better preventive and therapeutic measures, Warren said.
The scientists said they will continue to research filoviruses, including establishing an animal model that will better represent filoviruses in humans, Liu said.
Filoviruses are extremely infectious and are frequently fatal, according to the study.
“Therefore, a single case of filovirus persistence in a survivor of filovirus disease could pose a high risk for new outbreaks and considerable loss of lives,” according to the study.