Immunoglobulin genetics of a model squamate reptile, Tiliqua rugosa

Squamate reptiles are a diverse group of terrestrial vertebrates that includes over 10,000 species. Despite their broad distribution, they are relatively understudied immunologically. Fortunately, recent advances in comparative genomics have facilitated studies of squamate immune systems, revealing their unique features. For example, squamates lack of γδ T cells entirely due to genomic deletions. Here we annotated and analyzed the loci encoding the Tiliqua rugosa immunoglobulin heavy and lambda light chains, revealing a remarkably large and complex number of variable region genes in both. Tiliqua rugosa lacks genes encoding a kappa light chain, which can be found in some but not all squamates. We also identified common reptile IgH isotypes including IgM, IgD, and IgY, but no IgA. Overall, T. rugosa, has the germline capability of generating a highly diverse antibody repertoire.