Functional analysis of IgA antibodies specific for a conserved epitope within the M protein of group A streptococci from Australian Aboriginal endemic communities

Abstract

The mucosa is one of the initial sites of group A streptococcal (GAS) infection and salivary IgA (sIgA) is thought to be critical to immunity. However, the target epitopes of sIgA and the function of sIgA in GAS immunity, in particular the role of accessory cells and complement, is largely unknown. We studied the aquisition and the function of sIgA specific for a conserved region epitope, p145 (sequence: LRRDLDASREAKKQVEKALE) of the M protein. Peptide 145-specific sIgA is highly prevalent within an Aboriginal population living in an area endemic for GAS and acquisition of p145-specific sIgA increases with age, consistent with a role for such antibodies in immunity to GAS. Human sIgA and IgG ..