Fungal corneal ulcers are a significant cause of ocular morbidity and unilateral blindness worldwide.
Though such infections are most prevalent in tropical climates- accounting for up to 50% of all microbial
ulcers in Southern India- they are also commonplace in the subtropical United States. Moreover, from
2005 to 2006, the CDC reported an outbreak of 130 fungal ulcers associated with Renu Moisture Loc
contact lens solution, thereby demonstrating that fungal keratitis can transcend traditional geographical
barriers. The NEI funded Mycotic Ulcer Treatment Trial (MUTT) enrolled 323 patients across India to
determine the relative efficacy of topical voriconazole and natamycin monotherapies. The fact that
nearly 20% of all patients developed a corneal perforation or required corneal transplantation, despite
the closely monitored administration of the best drugs available, underscores a critical need for better
treatment options. This proposal seeks to discover novel antifungal strategies by uncovering pathways
important for fungal virulence. To this end, the researchers and clinicians that carried out the MUTT will
together leverage the vast collection of fungal specimens and clinical data obtained during that study.
A focus will be placed on Fusarium species as they are the most frequent cause of keratitis. In Aim 1,
the 128 Fusarium isolates from the MUTT (50% of culture-positive cases) will be scrutinized with
respect to basic growth parameters, stress resistance phenotypes, secreted protein profiles, and
immune cell interactions. These in vitro datasets will then be statistically assessed against the
prospectively collected patient information to determine which phenotypic parameters or secreted
proteins correlate with worsened clinical outcome. In this way, the discovery of fungal virulence
pathways will be informed by context-specific clinical data, as opposed to choosing candidate pathways
based on work in disparate organism or alternative disease models. Aim 2 will explore the regulation of
fungal virulence pathways by light, an environmental cue that is uniquely relevant to corneal infections.
Previous work has shown that fungal photosensory pathways centrally regulate metabolism, stress
resistance and even drug sensitivity in Aspergillus as well as all Fusarium species so far tested.
Accordingly, the in vitro and proteomics experiments described above will be performed in both the light
and dark to systematically determine the extent to which the environment might augment fungal
pathogenic potential and be exploited to a therapeutic end. Taken together, the work seeks to better
understand the pathogenesis of fungal corneal infection to inform better antifungal therapy for this
particularly severe form of keratitis.