Isolation and Characterization of Pasteurella multocida A from an Outbreak in Turkeys in Morocco and Vaccine Preparation and Evaluation.

Abstract

Pasteurella multocida is an important pathogen that causes fowl cholera (FC) in turkeys (Meleagris). The aim of this study was to isolate and characterize P. multocida from outbreaks of FC in turkeys for the first time in Morocco, both molecularly and pathologically, and to develop and evaluate an inactivated vaccine based on the isolated strain. Two farms in central Morocco were suspected of having FC. From each of these farms, two P. multocida isolates were characterized. Molecular analysis showed that both strains were identified as genotype A and serovars 3*4. Three oil-based vaccines were prepared using the virulent isolate strain after evaluating its pathogenicity in target species to determine the protective dose. The vaccines were evaluated through challenge tests and serologic responses. According to the results, a dose of 10⁹ colony-forming units showed 100% protection after challenge, and all animals became seropositive. Additionally, two vaccination programs were proposed to evaluate the duration of immunity: a double vaccination schedule vs. a triple vaccination schedule. The results indicated that the triple vaccination induced good protection after challenge and a high level of antibodies.