PT facilitates infection by aiding in adherence to ciliated airway epithelial cells and through disruption of host innate immune cell recruitment to the site of infection.34–36 In numerous studies it has been demonstrated that neutralization of PT alone ablates symptoms of the disease.37–40 Therefore, we proposed that neutralization of PT at the site of infection could inhibit the systemic long-range activity of PT before colonization of the respiratory tract. Here, F2 is linked to infection.