LIVE SALMONELLA VACCINE AND METHODS TO PREVENT FOWL TYPHOID

摘要

We constructed S. Gallinarum strains deleted for the global regulatory gene fur (Fig. 1) and evaluated their virulence and protective efficacy in Rhode Island Red chicks and Brown Leghorn layers. The fur deletion mutant was a virulent and, when delivered orally to chicks, elicited excellent protection against lethal S. Gallinarum challenge. 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 ΔAfur Δpmi and Δfur ΔansB double mutants were attenuated, but not protective when delivered orally to chicks. However, a Δpmi Δfur strain was substantially immunogenic when administrated intramuscularly. Altogether our results show that the fur gene is essential for virulence of S. Gallinarum and the fur mutant is effective as a live recombinant vaccine against fowl typhoid.