The positive and negative effects of TNF must be taken into account when its production is induced by candidates for protective vaccines. Although in vitro assays cannot entirely be used as substitutes for in vivo methods, the effective and specific blockage of bacterial attachment to HEp-2 cells strongly indicates that the antibodies induced by the recombinant Smeg and BCG generated to express BfpA and/or intimin may be active in vivo. In a previous study, we demonstrated that an IgY antibody raised against recombinant BfpA identifies E. coli Selleckchem JQ1 that express

BfpA, blocks colonization of HeLa cells by EPEC-EAF(+) in vitro and inhibits the in vitro growth of EPEC-EAF(+) but not of EPEC-EAF(−) (the BfpA-cured counterpart bacteria) [24]. More recently, we also showed that EPEC-EAF(+)-expressing BfpA, but not EPEC-EAF(−), induced apoptosis in HeLa cells. This effect was blocked by prior neutralization of BfpA with an IgY anti-BFP antibody [25]. These data agree with previous observations indicating that induction of epithelial cell death by E. coli depends on the expression of bundle-forming pili by the bacterium

[26]. Therefore, BfpA is an important virulence factor expressed by EPEC and is significantly involved in bacterial cell adhesion and induction of host cell death, either by necrosis or apoptosis. Intimin is a 94–97 kDa outer membrane protein [4] that mediates intimate contact between the bacteria and the target cell NVP-BKM120 order upon interaction with its translocated intimin receptor (Tir) [27]. Recent observations indicate that Lactobacillus casei expressing intimin-β fragments and containing the immunodominant epitopes of Int280 induced both humoral and cellular immune responses in mice. The antibodies were able to bind to EPEC and inhibit Liothyronine Sodium bacterial adhesion to the epithelial cell surface in vitro. C57BL/6 mice immunized with this recombinant

strain became partially protected against intestinal colonization by Citrobacter rodention, a mouse intestinal pathogen that also expresses intimin-β [28]. BfpA and intimin are therefore significant immunogens to be used in vaccines. We would like to thank the following individuals: Dr. Luciana C.C. Leite, Butantan Institute, São Paulo, Brazil, for her assistance and permission to use the Laboratory of Biotechnology IV; Dr. Brigitte Gicquel, Institute Pasteur, Paris, France, for providing the pMIP12 vector; Dr. Albert Schriefer, Fiocruz Institute, Salvador, Brazil, for providing the original enteropathogenic E. coli (EPEC)-EAF(+) and -EAF(−) strains; and Dr. Dunia Rodriguez for expert laboratory help and assistance in our results. “SBA-15 silica” was kindly provided by Osvaldo Augusto Sant́Anna, Butantan Institute, Brazil.