The evolution of antimicrobial peptides in Chiroptera

High viral tolerance coupled with an extraordinary regulation of the immune response makes bats a great model to study host-pathogen evolution. Although many immune-related gene gains and losses have been previously reported in bats, important gene families such as antimicrobial peptides (AMPs) remain understudied. We built an exhaustive bioinformatic pipeline targeting the major gene families of defensins and cathelicidins to explore AMP diversity and analyze their evolution and distribution across six bat families. A combination of manual and automated procedures identified 29 AMP families across queried species, with alpha-, beta-defensins, and cathelicidins representing around 10% of AMP diversity. Gene duplications were inferred in both alpha-defensins, which were absent in five species, and three beta-defensin gene subfamilies, but cathelicidins did not show significant shifts in gene family size and were absent in Anoura caudifer and the pteropodids. Based on lineage-specific gains and losses, we propose diet and diet-related microbiome evolution may determine the evolution of alpha- and beta-defensins gene families and subfamilies. These results highlight the importance of building species-specific libraries for genome annotation in non-model organisms and shed light on possible drivers responsible for the rapid evolution of AMPs. By focusing on these understudied defenses, we provide a robust framework for explaining bat responses to pathogens.

Automated summary

Bats have high viral tolerance and immune response regulation, making them a great model for studying host-pathogen evolution. This study focuses on antimicrobial peptides (AMPs), an important gene family that has been understudied in bats. By analyzing AMP diversity and evolution across six bat families, the researchers identified 29 AMP families, with alpha- and beta-defensins, and cathelicidins representing around 10% of AMP diversity. The results suggest that the evolution of alpha- and beta-defensins may be influenced by diet and diet-related microbiome, highlighting the importance of species-specific genome annotation in non-model organisms.