Mucosal IgA Antibodies are Critical for Bacterial Clearance of Bordetella pertussis in the Baboon Model.

Background: Despite the control of Bordetella pertussis with vaccine introduction, the incidence of pertussis has increased in the United States and globally. New vaccine strategies are clearly needed to regain control of this vaccine-preventable infection.

Methods: Experimental pertussis infection of baboons induces an acute respiratory illness with clinical and laboratory features similar to whooping cough in man. In a previous study, acellular pertussis-vaccinated (aP) baboons were protected from clinical illness but not from prolonged airway colonization. In contrast, convalescent baboons are protected from both clinical illness and colonization. These studies suggest that current aP vaccines may be ineffective at preventing airway colonization, contributing to resurgence of pertussis.

Results: In studies conducted at the University of Massachusetts Chan Medical School in Worcester, Massachusetts, mucosal IgG antibody responses in nasopharyngeal washes are similar in convalescent and vaccinated baboons. However, significantly higher mucosal anti-pertussis immunoglobulin A (IgA) responses are observed in convalescent animals.

Conclusions: These studies suggest that mucosal IgA responses to some pertussis antigens will result in bacterial clearance.