This study was conducted to determine effects of graded doses of glutamine supplementation on the replication and distribution of Pasteurella multocida,and expression of major virulence factors in a mouse model.Mice were randomly assigned into the basal diet supplemented with 0%,0.5%,1.0% or 2.0% glutamine.Pasteurella multocida burden were detected in heart,liver,spleen,lung and kidney after 12 hrs of Pasteurella multocida infection.Meanwhile,the expression of major virulence factors,toll-like receptors (TLRs),proinflammatory cytokines (IL-1β,IL-6 and TNF-a),and anti-oxidative factors (GPX1 and CuZnSOD) was analyzed in the lung and spleen.Dietary 0.5% glutamine supplementation have no much significant effect on these data,compared to those with basa diet.However,our study showed that a high dose of glutamine supplementation increased the P.multocida burden (P<0.001) and expression of the genes for major virulence factors expression of (P<0.05),when compared to those with a low-dose group.In the lung,a high dose of glutamine supplementation inhibited proinflammatory responses (P<0.05) and TLRs signaling (P<0.05).In the spleen,the effect of glutamine supplementation on different components in TLR signaling depends on glutamine concentration,as a high dose of supplemental glutamine activated the proinflammatory response.In conclusion,glutamine supplementation increased P.multocida burden and expression of major virulence factors,while affecting the functions of the lung and spleen.