Three years after an Ebola epidemic swept across West Africa, researchers have found a clue to how the virus may live on in the eyes of survivors suffering from uveitis -- one of the more serious and common complications of the disease.

About one in four Ebola survivors from Sierra Leone suffer from uveitis, or inflammation inside the eye, a condition that can result in vision loss or blindness. The eye now joins the testes as a location where live Ebola virus can be found up to one year post-infection.

A new study, titled "Retinal Pigment Epithelial (RPE) Cells are a Potential Reservoir for Ebola Virus in the Human Eye," and published in Translational Vision Science & Technology (TVST), describes how the cells responsible for isolating the eye from the immune system, known as immune privilege, may also prevent clearance of the virus from infected tissue.

The international and interdisciplinary team of investigators, led by Justine Smith, FRANZCO, PhD, Matthew Flinders Distinguished Professor of Ophthalmology at Flinders University School of Medicine in Australia, introduced live Ebola virus to RPE cells in vitro. The scientists observed the virus readily replicated in the cells, while the cells continued their native function of expressing molecules that limit the ability of the immune system to fight infection. The resulting subdued immune response may be responsible for the persistence of live virus in the eye.

Following these results, "there are so many questions that we can pursue," said Smith. "One is understanding why some Ebola survivors harbor the virus and develop uveitis, while others do not. That answer should help us better understand the mechanisms of post-Ebola eye disease, as well as provide some leads on how to manage it."