Development of vertical transmission model for Bordetella bronchiseptica in pigs

Authors: Hau, Samantha; Devries, Alexandra; Arruda, Bailey; Nielsen, Daniel; PAYNE, BRIAN - Veterinary Pharmaceutical Solutions

Submitted to: Veterinary Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/18/2026
Publication Date: 2/19/2026
Citation: Hau, S.J., Devries, A.C., Arruda, B.L., Nielsen, D.W., Payne, B. 2026. Development of vertical transmission model for Bordetella bronchiseptica in pigs. Veterinary Microbiology. https://doi.org/10.1016/j.vetmic.2026.110953.
DOI: https://doi.org/10.1016/j.vetmic.2026.110953

Interpretive Summary: Porcine respiratory disease complex (PRDC) is the most costly disease impacting swine producers. PRDC is a complex infection caused by both viruses and bacteria. Bordetella bronchiseptica is a bacteria that contributes to PRDC infections. B. bronchiseptica is transmitted between dams and their piglets (vertically) or between piglets (horizontally) in the field. However, in a research setting, most studies use naïve animals and directly apply the bacteria to each animal. This results in no antibody response in the animals. This model of infection also results in higher bacterial exposure than what is seen in a natural setting. The lack of antibody response and high bacterial doses make testing intervention strategies, such as new treatments or new vaccines, more challenging. In this study, we developed a vertical transmission model. This model uses sows exposed prior to birth to transmit B. bronchiseptica to their offspring. The vertical transmission model ensures piglet receive maternal antibody and natural exposure to field-like doses of B. bronchiseptica. B. bronchiseptica transmission occurred in all litters by 2 weeks post-weaning. We found that piglets from some sows were colonized as early as 3 days of age. This work provides critical information on the transmission dynamics of B. bronchiseptica. It also provides a new model that will be essential for testing B. bronchiseptica interventions in neonatal pigs.

Technical Abstract: Bordetella bronchiseptica can cause respiratory disease in a wide range of animal species. In pigs, it can cause severe respiratory infections in piglets and contribute to porcine respiratory disease complex (PRDC) in older animals. In the field, B. bronchiseptica is transmitted vertically from sow to piglet in the farrowing house or between piglets at weaning. Although B. bronchiseptica is most commonly spread from pig to pig, researchers routinely use direct inoculation with high doses of bacteria when testing intervention strategies. Although this method produces consistent disease, it does not replicate the dynamics of natural field infection. To generate a model that replicates field settings and assesses the complex interaction between host immunity, maternally derived immunity, and infection, we developed a vertical transmission model for B. bronchiseptica. Sows were inoculated with B. bronchiseptica two weeks pre-farrow and piglet colonization status was assessed 1-3 days post-farrow, 2.5 weeks post-farrow, and 1 week post-weaning. We found maternal antibody and the timing of B. bronchiseptica transmission varied between sows, with transmission in some animals occurring within 3 days of farrowing. Additionally, all exposed piglets were colonized by 1 week post-weaning. This work presents a novel B. bronchiseptica model using vertical transmission, which provides a natural exposure route and dose. This model will be useful for future work investigating B. bronchiseptica intervention strategies of neonatal pigs.