Differential intracellular replication and virulence gene expression of Listeria monocytogenes isolates in human epithelial and endothelial cell lines

Listeria monocytogenes isolated from a case of spontaneous abortion in a pregnant woman (placental tissue), a diseased sheep (blood) and fish were compared with respect to their capability to invade and replicate in human epithelial (Caco-2) and endothelial cells (HBMEC). Intracellular expression of various PrfA-dependent virulence genes that are of relevance for intracellular replication was determined. Our data show significant differences in the invasion and replication of L. monocytogenes strains in epithelial and endothelial cells in contrast to the control strain, EGD. The observations correlate with the different efficiency of intracellular expression of PrfA-regulated virulence genes in the two cell lines, as analysed by real-time PCR.