Evaluation of protective efficacy of live attenuated Salmonella enterica serovar Gallinarum vaccine strains against fowl typhoid in chickens.

[typhoid]

Salmonella enterica serovar Gallinarum is the etiological agent of fowl typhoid , which constitutes a considerable economic problem for poultry growers in developing countries . The vaccination of chickens seems to be the most effective strategy to control the disease in those areas . We constructed S . Gallinarum strains with a deletion of the global regulatory gene fur and evaluated their virulence and protective efficacy in Rhode Island Red chicks and Brown Leghorn layers . The fur deletion mutant was avirulent and , when delivered orally to chicks , elicited excellent protection against lethal S . Gallinarum challenge . It was not as effective when given orally to older birds , although it was highly immunogenic when delivered by intramuscular injection . We also examined the effect of a pmi mutant and a combination of fur deletions with mutations in the pmi and rfaH genes , which affect O-antigen synthesis , and ansB , whose product inhibits host T -cell responses . The S . Gallinarum Î”pmi mutant was only partially attenuated , and the Î”ansB mutant was fully virulent . The Î”fur Î”pmi and Î”fur Î”ansB double mutants were attenuated but not protective when delivered orally to the chicks . However , a Î”pmi Î”fur strain was highly immunogenic when administered intramuscularly . All together , our results show that the fur gene is essential for the virulence of S . Gallinarum , and the fur mutant is effective as a live recombinant vaccine against fowl typhoid .

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Diseases presenting "double mutants" symptom

typhoid

werner syndrome

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