Short communication Effect of metC mutation on Salmonella Gallinarum virulence and invasiveness in 1-day-old White Leghorn chickens

Salmonella enterica serotype Gallinarum (S. Gallinarum) is the causative agent of fowl typhoid (FT) in chickens. FT is a severe systemic disease of chickens causing heavy economic losses to the poultry industry through mortality, reduced egg production and culling of precious breeding stocks. In this study, a metC (encoding cystathionine b lyase) mutant was produced from avirulent strainofS.Gallinarum byMini-Tn5 insertionalinactivation. Themutant wassignificantly attenuatedinvirulence for 1-day-old White Leghorn chickens. Inactivation of metC resulted in 10 4 -fold increase in the LD50 when compared with the wild type parent. The metC mutant showed an in vivo competitiveness defect in the challenged chickens and significantly lower (P < 0.01) bacterial burden in the reticuloendothelial organs when compared with the wild-type parent. These results indicate that metC gene is important for virulence of S. Gallinarum in chickens. # 2006 Elsevier B.V. All rights reserved.