Misregulation of the broad-range phospholipase C activity increases the susceptibility of Listeria monocytogenes to intracellular killing by neutrophils

Listeria monocytogenes is a facultative intracellular bacterial pathogen that tightly regulates the activities of various virulence factors during infection. A mutant strain (the plcBΔpro mutant) that has lost the ability to control the activity of a phospholipase C (PC-PLC) is attenuated a hundred fold in mice. This attenuation is not due to a lack of bacterial fitness, but appears to result from a modified host response to infection. The transcriptomic pattern of immunerelated genes in infected macrophages indicated no differential response to wild-type L. monocytogenes vs the plcBΔpro mutant. Cultures of bone marrow derived macrophages from BALB/c were infected with either wild type or mutant L. monocytogens for 3, 6, or 9 hrs. The macrophages were then collected and RNA isolated for microarray analysis of gene expression.