MorethanSkinDeep: Functional Genomic Basis for Resistance to Amphibian Chytridiomycosis

fajar rizki;

The amphibian- killing chytrid fungus Batrachochytrium dendrobatidis (Bd) is one of the most generalist pathogens known, capable of infecting hundreds of species globally and causing wide spread population declines and extinctions. However, some host species are seemingly unaffectedby Bd, tolerating or clearing infections without clinical signs of disease. Variationinhost immune responses is commonly evoked for these resistant or tolerant species, yet to date, we have no direct comparison of amphibian species responses to infection at the level of gene expression. In this study, we challenged four Central American frog species that vary in Bd susceptibility, with a sympatric virulent strain of the pathogen. We compared skin and spleen orthologous gene expression using differential expression tests and co expression gene network analyses. We found that resistant species have reduced skin inflammatory responses and increased expression of genes involved in skin integrity. In contrast, only highly susceptibles pecies exhibited suppression of splenic T-cell genes. We conclude that resistance to chytridiomycosis may be related to a species’ ability to escape the immunosuppressive activity of the fungus. Moreover, our results indicate that within-species differences in splenic proteolytic enzyme gene expression may contribute to intraspecific variation in survival. This first comparison of amphibian functional immunogenomic architecture in response to Bd provides insights into key genetic mechanisms underlying variation in disease outcomes among amphibian species