Three monoclonal antibodies, MO8-X3C, MO8-X3E and MO8-X4B, directed against filamentous hemagglutinin (FHA) have been produced. We have characterized these monoclonal antibodies and investigated their role in inhibiting attachment of mammalian cells to FHA. The monoclonal antibodies have been purified by HPLC and used in ELISA and Western Blots to screen for FHA. MO8-X3C and MO8-X3E, both IgG1 subtype, can inhibit the attachment of Chinese hamster ovary (CHO) cells to purified FHA when this protein is coated on plastic wells. MO8-X3C has also been shown to inhibit the attachment of the whole bacteria, B. pertussis, to CHO cell monolayers. Furthermore, this monoclonal antibody, MO8-X3C, can also inhibit the invasion of HeLa cells by B. pertussis. These antibodies should be useful reagents for screening B. pertussis mutants expression of FHA and in the regulation and characterization of pertussis acellular vaccines. FHA is one of the primary candidates being considered for future pertussis acellular vaccines. Determining the binding epitope for these mAb on FHA should help elucidate the cell attachment site of FHA. We will also study the role of these mAbs directed against FHA in passive immunization of mice against B. pertussis infection to further understand the pathogenesis of B. pertussis and the different mechanisms of protection.
