Project Summary Intraocular infections due to bacteria, viruses, fungi, and parasites (infectious endophthalmitis) are among the most common and visually devasting causes of blindness. Endophthalmitis has high morbidity because the retina is intolerant of immunologic insult. Since initial clinical examination cannot determine the cause of intraocular inflammation (uveitis), doctors must wait for laboratory culture to identify a microbial agent. But waiting days to weeks for cultures to grow delays diagnosis and treatment, frequently results in debilitating visual morbidity and blindness. The proteome of adjacent vitreous can be characterized to uncover biomarkers for specific etiologies of uveitis. Since different causes of intraocular infection elicit different immune responses, we hypothesize that proteomic profile of the inflamed vitreous may reflect key molecular changes and guide diagnosis of intraocular infections. Our group has used large-scale proteomic platforms to analyze the protein signature in liquid vitreous biopsies from endophthalmitis patients. This approach allowed us to identify several candidate protein biomarkers that differentiate infectious from non-infectious uveitis and specific infectious types of endophthalmitis, including bacterial, viral, and fungal endophthalmitis. Our long-term goal is to find better and more specific molecular treatments for vitreoretinal disease. Our objective in this proposal is to use targeted proteomic platforms to validate sensitive and specific biomarkers that reliably differentiate different types of intraocular infection (e.g. bacterial, viral, and fungal). Our central hypothesis is that vitreous protein signatures can differentiate between non-infectious and infectious uveitis and the class of infection more-rapidly than conventional clinical testing. Our studies will test the hypothesis through two specific aims: (1) Validate proteomic biomarkers that differentiate infectious from non-infectious uveitis and (2) biomarkers that differentiate different classes of intraocular infection (e.g. bacterial, viral, and fungal). Impact. We expect that successful completion of these aims will validate sensitive and specific endophthalmitis biomarkers and lay the foundation for the development of clinical diagnostic tests for intraocular infection.