Divergent allele advantage in the MHC and amphibian emerging infectious disease

• Published in: Infection, genetics and evolution genetics and evolution, 2023-07, Vol.111, p.105429-105429, Article 105429
• Main Authors: Fu, Minjie, Eimes, John A., Waldman, Bruce
• Format: Article
• Language: English
• Subjects: Adaptive evolution; Alleles; Amphibian chytridiomycosis; Animals; Anura - genetics; Anura - microbiology; Batrachochytrium dendrobatidis; Chytridiomycota - genetics; Co-evolution; Communicable Diseases, Emerging - genetics; Disease Susceptibility - microbiology; Divergent allele advantage; Major Histocompatibility Complex; Mycoses - genetics; Mycoses - veterinary
• ISSN: 1567-1348; 1567-7257
• DOI: 10.1016/j.meegid.2023.105429

Genetic variation in the major histocompatibility complex (MHC) may be associated with resistance to the amphibian chytrid fungus Batrachochytrium dendrobatidis (Bd). The pathogen originated in Asia, then spread worldwide, causing amphibian population declines and species extinctions. We compared the expressed MHC IIβ1 alleles of a Bd-resistant species, Bufo gargarizans, from South Korea with those of a Bd-susceptible Australasian species, Litoria caerulea. The number of alleles suggest that at least six MHC IIβ1 loci are expressed in each of the two species. Amino acid diversity encoded by these MHC alleles was similar between species, but the genetic distance of those alleles known for potential broader pathogen-derived peptide binding was greater in the Bd-resistant species. In addition, we found a potentially rare allele in one resistant individual from the Bd-susceptible species. Deep next-generation sequencing recovered approximately triple the genetic resolution accessible from traditional cloning-based genotyping. Targeting the full MHC IIβ1 enables us to better understand how host MHC may adapt to emerging infectious diseases. •Similar numbers and amino acid diversity of MHC alleles are found in species resistant and susceptible to amphibian chytridiomycosis•Higher genetic divergence of MHC alleles was found in Asian-resistant species than in Australasian susceptible species•Long-term co-evolution between the Asian amphibian and chytrid fungus may lead to high genetic divergence of MHC alleles•A potentially rare allele was found in one resistant individual of the species susceptible to chytridiomycosis•Deep sequencing with replicates is necessary for accurate MHC genotyping and downstream analysis