The first group is composed of the seven known immunoreactive antigensincluding Prn, BrkA, GroEL, BipA, PtlF and two porins, OmpP and OmpQ, which havepreviously been well-characterized in B. p. With the exception ofthe Bvgi- phase-specific gene BipA, all other known pertussis antigens are virulentBvg+ phase-specific genes associated with the pathogenesis and virulence ofB. This evidence concerns the gene CIAO3 and pertussis.