Description:
<jats:title>Abstract</jats:title><jats:p>The major histocompatibility complex (MHC) is central to maintaining the immunologic vigor of individuals and populations. Classical MHC class II genes were targeted for partial sequencing in sea otters (<jats:italic>Enhydra lutris</jats:italic>) from populations in California, Washington, and Alaska. Sequences derived from sea otter peripheral blood leukocyte mRNAs were similar to those classified as <jats:italic>DQA</jats:italic>, <jats:italic>DQB</jats:italic>, <jats:italic>DRA</jats:italic>, and <jats:italic>DRB</jats:italic> in other species. Comparisons of the derived amino acid compositions supported the classification of these as functional molecules from at least one <jats:italic>DQA</jats:italic>, <jats:italic>DQB</jats:italic>, and <jats:italic>DRA</jats:italic> locus and at least two <jats:italic>DRB</jats:italic> loci. While limited in scope, phylogenetic analysis of the <jats:italic>DRB</jats:italic> peptide‐binding region suggested the possible existence of distinct clades demarcated by geographic region. These preliminary findings support the need for additional MHC gene sequencing and expansion to a comprehensive study targeting additional otters.</jats:p>