Allelic diversity of antigen processing genes in wild mallards

Abstract

The recognition of virus infected cells by cytotoxic T lymphocytes is dependent on antigen presentation by MHC class I on the cell surface. Antigen presentation is critically dependent on the transporter associated with antigen processing (TAP), which facilitates the transport of peptides across the endoplasmic reticulum (ER) membrane. TAP specificity could affect the repertoire of peptides loaded on MHC class I. Here we analyzed the diversity of antigen presentation genes of 12 mallards, and the bidirectional promoter between TAP1 and TAP2. Alleles are from 94 - 100% similar with variation at 32 positions in TAP1 and 81 in TAP2. Non-conservative amino acid substitutions were observed in both TAPs, which align with peptide binding regions of the mammalian TAP. Polymorphism in functional regions of TAP could potentially restrict antigen presentation in ducks. This could contribute to the poor immune response to vaccines and the perpetuation of influenza virus in this host.