Ebola virus can persist in the brain for years after infection and may be able to re-emerge to cause potentially fatal disease, according to new research in nonhuman primate models. The disease can reoccur even after highly effective monoclonal antibody treatment, suggesting Ebola may present a threat to patients years after treatment is received.
The research was published in the journal Science Translational Medicine.
“Ours is the first study to reveal the hiding place of brain Ebola virus persistence and the pathology causing subsequent fatal recrudescent Ebola virus-related disease in the nonhuman primate model,” Dr Xiankun (Kevin) Zeng, senior author of the paper, said in a statement.
Ebola virus is a rare but deadly virus that has caused outbreaks in Guinea and the Democratic Republic of Congo in recent years, with the DRC only declaring the outbreak over in December 2021. Spread through bodily fluids between humans and other primates, around 50 percent of cases are fatal, but new monoclonal antibody treatments approved in 2020 have improved survival odds in areas with access to prompt healthcare.
During the 2021 outbreak, some cases were linked to people who had previously contracted the disease in past outbreaks, suggesting the virus may be able to persist in the body for many years. However, researchers were unable to locate exactly where the virus was hiding.
To discover it, Zeng and a team from the U.S. Army Medical Research Institute of Infectious Diseases turned to nonhuman primate models, which allow researchers to study the progress of Ebola infection and whether it remains in the models once successfully treated.
The researchers took a sample of 36 rhesus macaques that had previously been infected with Ebola virus and had been treated with a monoclonal antibody therapy, and analyzed their organs for traces of the virus. Seven of these animals were found to harbor the virus within the ventricles and immune cells of the brain, and two animals subsequently died as a result of the virus flaring up once more in the brain. The recurrence appeared to be isolated to the brain, where the virus caused massive swelling and severe symptoms of Ebola infection.
“We found that about 20 percent of monkeys that survived lethal Ebola virus exposure after treatment with monoclonal antibody therapeutics still had persistent Ebola virus infection – specifically in the brain ventricular system, in which cerebrospinal fluid is produced, circulated, and contained – even when Ebola virus was cleared from all other organs,” continued Zeng.
Highlighting a potential for disease resurgence in people that receive antibody treatment, Zeng and colleagues suggest that further monitoring of the situation is required to fully protect people at risk from the deadly virus.
The results suggest a combination therapy of antivirals and antibody treatments may be required to fully eradicate Ebola from the systems of patients, though this would require clinical testing as results from primates do not always translate to humans.