IDENTIFICATION OF ERYTHROCYTE-BINDING ANTIGENS IN HELICOBACTER-PYLORI

The surface antigens of Helicobacter pylori conferring erythrocyte-binding activity were obtained by adsorption onto formaldehyde-treated dog and goat erythrocytes from supernatant fractions of sonicated bacteria and elution using a high concentration of NaCl. The desorbed material was analysed by SDS-PAGE and immunoblotting with anti-whole-cell serum to agar-grown bacteria which had been absorbed with broth-grown, non-haemagglutinating cells (haemagglutination-associated antiserum). Two polypeptides with molecular masses of 25 and 59 kDa were revealed as erythrocyte-binding antigens. Strains which agglutinated both dog and goat erythrocytes possessed both these erythrocyte-binding antigens, whereas an antigenically cross-reactive 24 kDa polypeptide was present in a strain which only agglutinated goat erythrocytes. Haemagglutinin material was extracted from H. pylori using n-octylglucopyranoside and purified by Sepharose chromatography and sucrose density gradient ultracentrifugation. The purified extract directly agglutinated erythrocytes in a neuraminyl-lactose-sensitive and neuraminidase-sensitive manner. The 59 kDa polypeptide was not present in the purified haemagglutinin preparation. The haemagglutination-associated antiserum reacted strongly with the 25 kDa polypeptide band which was the most prominent polypeptide band on analysis of the purified haemagglutinin preparation by SDS-PAGE and silver staining. Thus, H. pylori possesses at least two adhesins, one of which recognises a N-acetylneuraminic acid (alpha-2-3) moiety of receptors, the other being of unknown receptor specificity. Differences in the antigenicity and molecular masses of these adhesins in individual strains may underlie differences in receptor-binding specificities and haemagglutination profiles.