Characterization and comparative bactericidal activity of monoclonal antibodies to Bordetella pertussis lipo-oligosaccharide A.

Spleen cells from mice immunized with a Bordetella pertussis N-lauroyl sarcosine membrane extract (SME) were used to generate hybridoma cells lines producing monoclonal antibodies (mAbs). Seven mAbs were shown to be specific to B. pertussis lipo-oligosaccharide (LOS) by immunoblotting of SME or purified LOS following SDS-PAGE. All mAbs reacted with the B. pertussis Tohama I strain of the LOS AB phenotype, and did not react with the atypical variant strain 134 of the LOS B phenotype. The immune reactivity of the mAbs was retained after treatment of SME with proteinase K and was lost after sodium periodate treatment. No cross-reactivity was observed with the mAbs when tested against B. parapertussis and other Gram-negative bacteria. However, all mAbs reacted with B. bronchiseptica. Binding assays with live B. pertussis cells demonstrated that mAbs strongly reacted with cell surface exposed antigenic determinants. High bacterial cell lytic capability was observed for five of these mAbs. Concentrations between 0.22 and 2.2 micrograms mAb ml-1 (0.1 and 1 microgram per 450 microliter assay) purified by protein A were required to kill at least 50% of the bacteria. Competition immunoassays with biotinylated antibodies showed that the bacteriolytic and non-bacteriolytic mAbs were directed to different epitopes of the B. pertussis LOS A.