Meeting Abstract
The first opportunity for the immune systems of bats to recognize invasion by the white-nose syndrome (WNS) pathogen is in skin tissues where the fungus invades. Understanding skin immune defenses across bat species exhibiting differential disease and mortality is of critical importance. We hypothesize that immune defense proteins, known as antimicrobial peptides (AMPs), confer resistance to WNS because AMPs: 1) are abundant in skin, 2) are constitutively expressed and likely to remain functional during hibernation when invasion occurs, and 3) can have strong, immediate anti-fungal activities. The diversity of AMP repertoires and their antimicrobial functions are, however, unknown in species affected by WNS. To discover bat AMP repertoires, we deployed hidden Markov models calibrated using known, annotated AMP sequences from non-bat mammals. We applied this method to six bat and 21 non-bat mammal genome assemblies. We found >130 previously undiscovered AMP genes in bat genomes. We then modeled AMP evolution across all mammalian species. We found little diversification in bat alpha: α (browser-check: α)-defensins. In contrast, bat cathelicidin and beta: β (browser-check: β)-defensin diversity matches or exceeds diversity in other mammals. Additionally, AMP repertoires differed between two species variably impacted by WNS (Myotis lucifugus and Eptesicus fuscus). We hypothesize that differences in AMP diversity and function between bat species may explain differences in susceptibility to invasion and infection by the WNS pathogen and can lead to an effective control. We are currently exploring this question using proteomic analyses of skin tissues from five species variably impacted by WNS complemented by functional tests of bat AMP abilities.
