has role protective antigen role protective antigen Bordetella pertussis protein PtxB Protegen ID: 384; NCBI Protein GI: 225311180; NCBITaxon: 520 Oliver He BALB/c mice were immunized with PTx vaccine on day 6 of life and then challenged with B. pertussis using the aerosol challenge model. These primed mice were significantly better protected against leukocytosis, weight loss, and proliferation of B. pertussis in the lungs following aerosol challenge than the nonprimed group. This protection correlated with levels of anti-PT antibody in serum present on the day of aerosol challenge [PubMed: 12117973]. protein Allen Xiang