Data from: Susceptibility of amphibians to chytridiomycosis is associated with MHC class II conformation

The pathogenic chytrid fungus Batrachochytrium dendrobatidis (Bd) can
cause precipitous population declines in its amphibian hosts. Responses of
individuals to infection vary greatly with the capacity of their immune
system to respond to the pathogen. We used a combination of comparative
and experimental approaches to identify major histocompatibility complex
class II (MHC-II) alleles encoding molecules that foster the survival of
Bd-infected amphibians. We found that Bd-resistant amphibians across four
continents share common amino acids in three binding pockets of the MHC-II
antigen-binding groove. Moreover, strong signals of selection acting on
these specific sites were evident among all species co-existing with the
pathogen. In the laboratory, we experimentally inoculated Australian tree
frogs with Bd to test how each binding pocket conformation influences
disease resistance. Only the conformation of MHC-II pocket 9 of surviving
subjects matched those of Bd-resistant species. This MHC-II conformation
thus may determine amphibian resistance to Bd, although other MHC-II
binding pockets also may contribute to resistance. Rescuing amphibian
biodiversity will depend on our understanding of amphibian immune defence
mechanisms against Bd. The identification of adaptive genetic markers for
Bd resistance represents an important step forward towards that goal.