Pathogenesis of Uveitis in Ebola Virus Disease Survivors: Evolving Understanding from Outbreaks to Animal Models.

Ebola virus disease (EVD) and emerging infectious disease threats continue to threaten life, prosperity and global health security. To properly counteract EVD, an improved understanding of the long-term impact of recent EVD outbreaks in West Africa and the Democratic Republic of Congo are needed. In the wake of recent outbreaks, numerous health sequelae were identified in EVD survivors. These findings include joint pains, headaches, myalgias, and uveitis, a vision-threatening inflammatory condition of the eye. Retrospective and more recent prospective studies of EVD survivors from West Africa have demonstrated that uveitis may occur in 13-34% of patients with an increase in prevalence from baseline to 12-month follow-up. The clinical spectrum of disease ranges from mild, anterior uveitis to severe, sight-threatening panuveitis. Untreated inflammation may ultimately lead to secondary complications of cataract and posterior synechiae, with resultant vision impairment. The identification of Ebola virus persistence in immune privileged organs, such as the eye, with subsequent tissue inflammation and edema may lead to vision loss. Non-human primate models of EVD have demonstrated tissue localization to the eye including macrophage reservoirs within the vitreous matter. Moreover, in vitro models of Ebola virus have shown permissiveness in retinal pigment epithelial cells, potentially contributing to viral persistence. Broad perspectives from epidemiologic studies of the outbreak, animal modeling, and immunologic studies of EVD survivors have demonstrated the spectrum of the eye disease, tissue specificity of Ebola virus infection, and antigen-specific immunologic response. Further studies in these areas will elucidate the mechanisms of this highly prevalent disease with the potential for improved therapeutics for Ebola virus in immune-privileged sites.