THE HOST RESPONSE TO LISTERIA-MONOCYTOGENES MUTANTS DEFECTIVE IN GENES ENCODING PHOSPHOLIPASES-C (PLCA, PLCB) AND ACTIN ASSEMBLY (ACTA)

Several genes involved in the determination of Listeria monocytogenes pathogenesis have been identified, Among them, plcA gene encodes phosp hatidylinositol-specific phospholipase C (PI-PLC), plcB gene encodes a broad-range phospholipase C (PC-PLC), and actA encodes a protein cont ributing to actin assembly in infected cells, The interaction of L, mo nocytogenes wild type (LO 28) strain and two derivative mutants, plcA( -)(BUG 206) and actA(-)/plcB(-)(LUT 12), with macrophages and T lympho cytes was investigated in a mouse model of listeriosis, Both mutants s howed evidence of attenuation, The plcA(-) mutant, but not the plcB(-) mutant, expressed an increase in susceptibility to the anti-listerial activity of macrophages, Both mutants showed a decreased ability to i nduce IL-12 production by bone marrow macrophages when co-stimulated w ith E. coli LPS or IFN-gamma, In vivo, L. monocytogenes plcA(-) mutant was found to be a more effective stimulator of T cells than the wild LO 28 strain.