Immunoblot analysis of cyanogen bromide-cleaved Moraxella bovis pilin reveals presence of shared antigenic determinants on pili from heterologous strains

Moraxella bovis pilus proteins, collected and purified from four strains of M. bovis, were cleaved with cyanogen bromide. Two major fragments were pro duced. Antisera were produced in rabbits to the pilin protein fragments and to whole uncleaved pill from these strains. Immunoblots of whole and cyano gen bromide-cleaved pilin were reacted with the homologous and heterologous antisera to whole pill and cleaved pilin. Antisera to whole pill reacted s trongly with homologous pilin. Weaker and inconsistent reactions were detec ted with heterologous pilin. Antisera produced to cyanogen bromide-cleaved pilin proteins reacted strongly with homologous and heterologous pilin frag ments and uncleaved pilin proteins. These findings demonstrate the presence of conserved antigenic determinants on pill from heterologous strains that are non-immunogenic in the intact pilus but are immunogenic after treatmen t with cyanogen bromide. Cyanogen bromide-treated pilus preparation might h ave potential as a vaccine because antibodies are induced against heterolog ous strains of M. bovis, whether these cross-reactive antibodies are protec tive remains to be determined. (C) 2001 Elsevier Science B.V. All rights re served.