B.parapertussis strain 10978 harboring a functional ptx-ptl promoter from B.pertussis produces the PtlE protein in a stable form. Is also able, but less efficiently, to produce and secrete the pertussis toxin (PTX). Belongs to the virB8 family. B.parapertussis and B.bronchiseptica seem not to produce the pertussis toxin (S1, S2, S4, S5 and S3) and ptl proteins (PtlA, PtlB, PtlC, PtlD, PtlE, PtlF, PtlG, PtlH and PtlI) in vivo due to changes in the promoter region of the ptx-ptl operon. However, it is possible that their promoter is active under certain, as-yet-undefined conditions and that B.parapertussis and B.bronchiseptica are therefore capable of producing these proteins.