Characterization of the Secretome of P. Destructans, the Causative Agent of White-Nose Syndrome in Bats

Brown University, Providence RI

Investigators

Abstract

White-Nose Syndrome (WNS) is a devastating disease that has killed around 6 million bats in the US since its discovery in 2007. The disease has spread across North America and has the potential to drive several native bat species to extinction. In addition to ecological damage, the disease is predicted to seriously impact the agricultural industry, as insectivorous bats are critical for the control of insect pests. The cause of WNS is the fungus Pseudogymnoascus destructans, which is highly invasive causing significant tissue destruction particularly to the membranous wings of bats. Little else is known about the biology of this fungal species or how it is able to cause disease in bats. This project will focus on identification and characterization of protease enzymes, which are catalysts in protein degradation, secreted by P. destructans that may promote the invasion and destruction of bat tissue. In particular, the presence of proteases will be evaluated as these represent important virulence factors in several mammalian fungal pathogens. The blocking of protease activities may therefore represent a therapeutic strategy for the prevention of WNS. The approach used in this proposal will first define the proteins secreted by P. destructans during laboratory culture, with a particular emphasis on identifying secreted proteases. Cutting-edge approaches will be used for the identification and subsequent characterization of proteases, including a multiplex substrate profiling technique coupled with iceLogo analysis to reveal the cleavage specificity of secreted proteases. Preliminary experiments using this approach have led to the identification and partial characterization of a novel subtilisin-like protease from the conditioned medium of P. destructans. This activity has been named Destructin-1 as it is able to degrade collagen, the major component of animal connective tissue. Additional proteases will be identified in P. destructans and compared to those in non-infectious species to identify potential virulence factors. To test if these proteases contribute to disease in the bat, inhibitors of proteases will be defined and these inhibitors tested in infection models to see if they block the progression of WNS. New genetic tools will also be developed for this fungal species to enable analysis by deletion of target genes. Together, these approaches will provide new insights into the biology of the P. destructans fungus and the means by which it causes disease in the mammalian host.