title: Immunological mimicry between retinal S-antigen and group A streptococcal M proteins.
abstract: Immunological mimicry between host and microbial proteins has been suggested as a potential mechanism in the development of uveitis in humans. In this study immunological crossreactivity between anti-streptococcal monoclonal antibodies (MAbs) and the human eye was investigated. In indirect immunofluorescence, we demonstrated novel immunological crossreactivity of two anti-streptococcal MAbs (27 and 112) with the rod outer (and inner) segments of the retina of the human eye. In further studies, retinal S-Ag, a uveitogenic protein in the rod outer (and inner) segments, was found to react with the anti-streptococcal MAbs. In addition, several uveitogenic peptides of S-Ag were recognized by the anti-streptococcal MAbs. In the ELISA and Western immunoblot, anti-S-Ag MAbs crossreacted with group A streptococci and the streptococcal M protein further demonstrating sites of antigenic similarity. Homology between the retinal S-Ag and streptococcal M protein was observed in amino acid sequences repeated in the B repeat region of the streptococcal M5 protein. These data show that retinal S-antigen has immunological similarities with streptococcal M protein, a major virulence determinant and strong bacterial cell surface antigen.
authors.affiliation: Department of Ophthalmology, University of Oklahoma Health Science Center, Oklahoma City 73190, USA.
authors.forename: M P
authors.initials: MP
authors.lastname: Lerner
authors.forename: L A
authors.initials: LA
authors.lastname: Donoso
authors.forename: R E
authors.initials: RE
authors.lastname: Nordquist
authors.forename: M W
authors.initials: MW
authors.lastname: Cunningham
mesh_terms: D000595:Amino Acid Sequence; D000942:Antigens, Bacterial; D019393:Arrestin / Q000737:chemistry*; D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins / Q000737:chemistry*; D015153:Blotting, Western; D002352:Carrier Proteins; D004797:Enzyme-Linked Immunosorbent Assay; D019084:Fluorescent Antibody Technique, Indirect; D006801:Humans; D018716:Molecular Mimicry; D008969:Molecular Sequence Data; D017386:Sequence Homology, Amino Acid; D013297:Streptococcus pyogenes / Q000276:immunology*; D014605:Uveitis / Q000276:immunology
chemical_list: D000942:Antigens, Bacterial; D019393:Arrestin; D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins; D002352:Carrier Proteins; C014689:streptococcal M protein