Maternal vaccination with gamete-related antigens of Cystoisospora suis reduces clinical effects and oocyst excretion in an experimental model of suckling piglet coccidiosis.

The protozoan parasite Cystoisospora suis (Order Coccidia) is a major cause of gastrointestinal disease in suckling piglets, resulting in significant economic losses to the pig industry due to diarrhea, weight loss and increased susceptibility to secondary infections. Current control strategies are limited and rely primarily on strict hygiene measures and the use of toltrazuril, and reports on resistance against this drug in C. suis have been reported. To address the urgent need for alternative control measures, this study investigated maternal vaccination as an approach to confer passive immunity to piglets. We evaluated the immunogenicity and protective efficacy of a recombinant vaccine containing three antigens from the sexual stages of C. suis: CsTyRP, CsOWP1 and CsHAP2. Sows were vaccinated three times prior to parturition and antibody transfer to piglets via colostrum and the outcome of experimental infections of piglets with C. suis on the third day of life were assessed in comparison to an adjuvant-only (sham vaccinated) control group. Vaccinated sows developed significant antibody titers which were successfully transferred to their offspring. Piglets from vaccinated sows showed a significant reduction in oocyst shedding and improved weight gain compared to controls. We here provide the first evidence that a recombinant vaccine effectively reduces the clinical impact of C. suis in neonatal piglets and lays the groundwork for the development of sustainable vaccination strategies against mammalian coccidiosis.