Maternal immunity provides protection against pertussis in newborn piglets

Pertussis continues to be a significant cause of morbidity and mortality in infants and young children worldwide. Methods to control the disease are based on vaccination with either whole-cell or acellular vaccines or treatment with antibiotics. However, despite worldwide vaccination infants are still at the highest risk for the disease. Here we used our newly developed newborn-piglet model to investigate whether transfer of maternal immunity can protect newborn piglets against infection with Bordetella pertussis. Pregnant sows were vaccinated with heat-inactivated B. pertussis or treated with saline (controls). Newborn piglets were allowed to suckle colostrum and milk for 4 to 5 days before they were challenged with 5 x 10(9) CFU of bacteria intrapulmonarily. Elevated levels of B. pertussis-specific secretory immunoglobulin A (S-IgA) and IgG antibodies were found in the colostrum and serum of vaccinated sows but not in those of control sows. Subsequently, significant levels of specific IgG and S-IgA were detected in the serum and bronchoalveolar lavage fluid of piglets born to vaccinated sows. Following infection with 5 x 10(9) CFU of B. pertussis, clinical symptoms, pathological alterations, and bacterial shedding were significantly reduced in piglets that had received passively transferred immunity. Thus, our results demonstrate that maternal immunization might represent an alternative approach to provide protection against pertussis in young infants.