To our knowledge there is only one study available in which N-linked glycans associated with SC of SIgA were involved in the protection of mice infected with S. flexneri by the respiratory route.29 Our results indicate that IgA glycosylation is important for amelioration of disease in the germ-free piglet infection model; their enzymatic removal results in a substantial loss of protection for piglets orally infected with pathogenic E. coli O55 when compared to the native SIgA. This evidence concerns the gene CD79A and infection.