Pathogenesis of Uveitis in Ebola Virus Disease Survivors

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Project Summary/ Abstract Ebola virus disease (EVD) has been associated with a high prevalence of uveitis in EVD survivors in the wake of the unprecedented West African EVD outbreak from 2014-2016. The spectrum of disease ranges from anterior uveitis to sight-threatening panuveitis with complete blindness. The sheer number of EVD survivors impacted has given us the unique opportunity to characterize the clinical features, structural complications leading to vision loss, and pathogenesis of uveitis. Besides the significant impact of vision loss on quality-of- life and activities of daily living, uveitis associated with Ebola virus (EBOV) has scientific and public health implications because of our prior identification of EBOV in the aqueous humor. Beyond the recent outbreak in West Africa, two more recent outbreaks in Democratic Republic of Congo underscore the global health mandate to fully understand the clinical and scientific implications of EVD sequelae. Emerging clinical, basic, and translational investigation has provided insight regarding the potential mechanisms of uveitis associated with EVD. We recently described our novel methodology to safely interrogate aqueous humor specimens for EBOV in EVD survivors; while these ocular fluid specimens tested negative for EBOV by RT-PCR, recent molecular pathologic analysis of ocular tissue in a non-human primate EVD survivor model has demonstrated that EBOV persists within the vitreous humor in macrophages, and is associated with uveitis and retinitis. Additional compelling immunologic studies of an EVD survivor with uveitis showed Ebola-specific T-cell and B-cell activation with signs of ongoing Ebola antigen stimulation after plasma clearance of EBOV. These findings were suggestive of long-term EBOV persistence, which are detectable by systemic T- and B-cell responses. To further characterize the prevalence and clinical spectrum of uveitis, role of EBOV persistence and immunologic mechanisms of uveitis in EVD survivors, we propose three Aims: 1) In Aim 1, the prevalence of uveitis will be compared between EVD survivors and close contacts in Sierra Leone. Clinical factors and host risk factors including HLA-typing will be assessed to determine if there are clinical and host-related determinants of uveitis development. 2) In Aim 2, EBOV persistence will be assessed using reverse transcriptase polymerase chain reaction (RT- PCR testing) of vitreous fluid and in situ hybridization techniques to detect EBOV genome in the vitreous. 3) In Aim 3, Ebola-specific immune responses will be assessed in the blood and ocular fluid of EVD survivors with uveitis, specifically evaluating activation of Ebola-specific B and T-cells, IgG subclass composition. Insights from this study will define the spectrum of uveitis associated with EVD, assess whether EBOV is harbored in the vitreous, and advance our understanding of the interplay between infection and immunity in EVD. Ultimately, these findings will define diagnostic strategies and future medical countermeasures for EBOV, as well as other viruses that may establish persistence in the unique immune privileged ocular environment.