IgA is the most prevalent antibody at mucosal surfaces, where high-affinity IgA antibodies protect from microparasite infections such as Eimeria spp., while low-affinity IgA antibodies regulate commensal bacterial densities via immune exclusion (Cerutti and Rescigno, 2008; Macpherson et al., 2012). This evidence concerns the gene CD79A and infection.