Suppression of mucosal Th17 memory responses by acellular pertussis vaccines enhances nasal Bordetella pertussis carriage.

Pertussis has made a spectacular rebound in countries that have switched from whole-cell (wPV) to acellular pertussis vaccines (aPV). Here, we show that, unlike wPV, aPV, while protective against lung colonization by Bordetella pertussis (Bp), did not protect BALB/c mice from nasal colonization, but instead substantially prolonged nasal carriage. aPV prevented the natural induction of nasal interleukin-17 (IL-17)-producing and interferon-γ (IFN-γ)-producing CD103 CD44 CD69 CD4-resident memory T (T) cells. IL-17-deficient, but not IFN-γ-deficient, mice failed to clear nasal Bp, indicating a key role of IL-17 T cells in the control of nasal infection. These cells appeared essential for neutrophil recruitment, crucial for clearance of Bp tightly bound to the nasal epithelium. Transfer of IL-17 T cells from Bp-infected mice to IL-17-deficient mice resulted in neutrophil recruitment and protection against nasal colonization. Thus, aPV may have augmented the Bp reservoir by inhibiting natural T cell induction and neutrophil recruitment, thereby contributing to the pertussis resurgence.