Disassembly of F-Actin Cytoskeleton after Interaction of Bacillus cereus with Fully Differentiated Human Intestinal Caco-2 Cells

Abstract

In the present study the role of direct procaryote-eucaryote interactions in the virulence of Bacillus cereus has been investigated. As a model of human enterocytes, differentiated Caco-2 cells were used. Infection of fully differentiated Caco-2 cells with B. cereus in exponential phase of growth, in order to minimize the concentration of spores or sporulating microorganisms, shows that a strain-dependent cytopathic effect develops. Interestingly, three hours-old cultures of some strains completely detached the cultured cells after 3 h post-infection, whereas no such effect was found with 16 h-old cultures. Infection of enterocyte-like cells with B. cereus leads to disruption of the F-actin network and necrosis. Even though, the effect of secreted factors cannot be ruled out, the direct eucaryote-procaryote interaction seems to be necessary. In addition, we observed that some B. cereus strains were able to internalize into Caco-2 cells. Our findings add a new insight on the mechanisms of virulence of B. cereus in the context of intestinal infection.