*2.1.2.4 SiiE*

*Microorganisms*

*2.1.1.6 Salmonella atypical fimbriae (Saf)*

*2.1.1.7 Typhimurium fimbriae std and stf operons*

during infection of bovine ileal loops [45].

*2.1.1.8 Enteritidis fimbrial SEF14*

afforded passive protection [49].

*2.1.2 Non-fimbrial adhesins*

*2.1.2.1 MisL*

*2.1.2.2 ShdA*

*2.1.2.3 BapA*

organism in feces [51].

*Salmonella* atypical fimbriae (Saf) are encoded by the chromosomal *safABD* operon. A group of BALB/c mice immunized subcutaneously with SafB/D- and recombinant cholera toxin B subunit (rCTB)-conjugated micro-particles had significantly lower CFU counts than the untreated control group [41]. Two additional functions - poly-adhesive and self-associating activities – were attributed to the Saf pili and appear to contribute to host recognition and biofilm formation [42].

*Std* operon is required for adherence to human colonic epithelial cells and for cecal colonization in the mouse by binding to cecal mucosa receptors containing α(1, 2) fucose residues [34, 43]. *Stf* fimbriae share homology with the MR/P fimbriae of *Proteus mirabilis* and *E. coli* Pap fimbriae [44]. *StfA* expression is induced

Enteritidis fimbrial SEF14 contributes to colonization of chicken intestine, liver,

<10 (wild type)) [48]. In the mouse model, egg-yolk derived anti-SEF14 antibodies

Four distinct non-fimbrial intestinal colonization factors have been identified:

S*hdA* gene is located in the 25-kb pathogenicity island called CS54 which is present only in *S*. *enterica* subspecies *enterica* [51]. ShdA is a large fibronectin/collagen I-binding outer membrane protein which is induced *in vivo* in the murine caecum [52]. It is required for Typhimurium colonization in the murine caecum and Peyer's patches of the terminal ileum [53] and for efficient and prolonged shedding of the

BapA is a huge surface-associated protein and secreted via its downstream type I secretion system, BapBCD. BapA contributes to murine intestinal colonization and

MisL encoded within the SPI-3, is an outer membrane fibronectin-binding autotransporter protein which is induced upon bacterial contact with the intestinal epithelial cells, and is required for colonization of the murine cecum and for intestinal persistence. MisL binds fibronectin and collagen IV via its passenger domain [50].

(mutant) vs.

spleen and reproductive organs [46, 47]. The fragment encoding genes responsible for SEF14 biosynthesis contain three genes, *sefABC*. The putative adhesion subunit encoded by *sefD* is essential for efficient uptake or survival of Enteritidis in macrophages, as the *sefD* mutants were not readily internalized by peritoneal macrophages compared with the wild-type bacteria soon after intraperitoneal infection of mice [48]. The *sefD* mutant was severely attenuated after both oral and

intraperitoneal infection of BALB/c mice (approximate LD50: >104

**172**

*SiiE* is a SPI4-encoded protein and works as the substrate protein of the T1SS. SiiE is secreted into the culture medium but mediates contact-dependent adhesion to epithelial cell surfaces. SiiE codes for a giant non-fimbrial adhesion of 600 kDa and consists of 53 repeats of immunoglobulin domains; this is a T1SSsecreted protein that functions as a non-fimbrial adhesion in binding to eukaryotic cells [55].
