Passive transfer of <i>B. parapertussis</i>–specific antibodies rapidly reduces <i>B. parapertussis</i> colonization in aP and wP vaccinated animals.

<p>Groups of four C57BL/6 mice were (B) left untreated (−) or vaccinated with (A) aP, (B) wPP or wP. Mice lacking a transfer of antibodies (−) or given naïve serum (NS), wP-induced serum (wP IS) or wPP-induced serum (wPP IS) were challenged with <i>B. parapertussis</i>. Mice were sacrificed three days post-challenge and the number of CFUs recovered from the respiratory tract is expressed as the Log₁₀ mean ± the standard error. ** indicates P≤0.01. The limit of detection is indicated as the lower limit of the <i>y</i> axes.