Protective Efficacy of Salmonella Local Strains Representing Groups B, C, D and E in a Prepared Polyvalent Formalin Inactivated Oil Adjuvant Vaccine in Layers

Salmonellosis is one of the most important bacterial diseases affecting poultry. Its importance is derived from the loss in productivity in affected birds and the hazard it causes for public health. Vaccination is the best mean for controlling salmonellosis in birds. In the present study, the immunizing and protective efficacy of local strains (S. Typhimurium, S. Infantis, S. Enteritidis and S. Meleagridis) and imported ones (S. Typhimurium and S. Enteritidis) in a prepared polyvalent and bivalent formalin inactivated oil adjuvant vaccines had been studied. A total of 150, six-weeks old SPF Lohmman layer chickens were divided into 3 groups; 50 chickens each. The 1 group was vaccinated with the polyvalent locally prepared vaccine, the st 2 group was vaccinated with the imported bivalent vaccine and the 3 group was kept unvaccinated as a nd rd control group. The three groups were challenged with virulent S. Typhimurium, S. Infantis, S. Enteritidis and S. Meleagridis strains (10 CFU/ml of each) 1ml orally, 3 weeks post boostering of the vaccines. The degree of 8 protection was assessed according to the severity of the clinical signs, the mortality and fecal shedding of the challenged organisms. Blood samples were collected weekly and humoral immune response was measured against Salmonella strains using micro-agglutination test (MAT) and ELISA. In Conclusion: the locally prepared polyvalent vaccine induced higher protection rates in challenge test with reduced fecal shedding and higher antibody response compared with the imported bivalent one.