Expansion of MHC-IIB Has Constrained the Evolution of MHC-IIA in Passerines.

ABSTRACT: The major histocompatibility complex (MHC) is central in adaptive immunity, with the highly polymorphic MHC genes encoding antigen-presenting molecules. Two MHC class II (MHC-II) loci, DA1 and DA2, predate the radiation of extant birds and persist throughout much of the avian phylogeny. Within each locus, the MHC-II molecules are encoded by A-genes (DAA) and B-genes (DAB), which are arranged in A-B dyads. However, in passerines (order Passeriformes), the DA2 locus has been lost, and the ancestral A-B dyad at the DA1 locus has been replaced by a putatively single A-gene (DAA1) and an array of highly polymorphic B-genes (DAB1). In this study, we genotyped the DAA1 gene of 15 passerine species and confirmed that passerines possess just one copy of DAA1. We then compared selection patterns in

SUBMITTER: Ruesink-Bueno IL 

PROVIDER: S-EPMC11562119 | biostudies-literature | 2024 Nov

REPOSITORIES: biostudies-literature