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TABLE 5.2 STEC adherence factors—cont'd
Potential adhesins
Function
Porcine attaching-effacing
associated protein (Paa)
Required for the A/E activity by many A/E strains,
including O157:H7 and promotes initial bacterial
adherence ( An et al., 1999 ; Batisson et al., 2003 ).
STEC
autoagglutinatingadhesin
(Saa)
Plasmid encoded and isolated from LEE-negative STEC
( Paton et al., 2001 ). Saa-harboring STEC exhibit differential
binding properties to epithelial cells ( Toma et al., 2008 ).
Saa positive STEC frequently isolated from bovine rather
than human origin ( Jenkins et al., 2003 ).
Flagella
O157:H7 flagella agglutinates rabbit red blood cells,
promotes adherence to mucins I and II and persistence
in chicken in the absence of intimin
( Best et al., 2005 ; Erdem et al., 2007 ).
AdfO
Secreted from T2SS and encoded on the cryptic
prophage CP-933O, AdfO promotes for adherence of
EHEC to cultured HeLa cells ( Ho et al., 2008 ).
YodA
AdfO facilitates YodA secretion from pO157-encoded
T2SS and promotes adherence of EHEC to HeLa
cells and colonization of the infant rabbit intestine
( Ho et al., 2008 ).
StcE
A zinc metalloprotease secreted by the T2SS on the
plasmid pO157, cleaves serpin C1 esterase inhibitor
( Lathem et al., 2002 , 2004 ). Reduces the mucous
glycocalyx cell surface barrier and promotes a closer
interaction between the bacterium and host cell
( Grys et al., 2005 , 2006 ).
to bovine gut explants ( Xicohtencatl-Cortes et al., 2007 ). Moreover, HCP
generates an antibody response in patients with HUS, suggesting that these
pili are produced during infection ( Xicohtencatl-Cortes et al., 2007 ). EspA,
which forms a filamentous appendage from EHEC's T3SS, has been sug-
gested to be an adhesin promoting initial interaction between host cells and
bacteria ( Ebel et al., 1998 ). YodA and StcE, two effectors secreted through a
type II secretion system, promote EHEC adherence to cultured monolayers,
as well as during colonization of infant rabbits ( Grys et al., 2005 ; Ho et al.,
2008 ). Non-fimbrial EHEC adhesins include OmpA, and have been shown
to facilitate bacterial binding to cultured monolayers ( Torres and Kaper,
2003 ). Finally, H7 flagella have been hypothesized to promote adherence
to mucus and extracellular matrix proteins within the host intestinal tract
( Erdem et al., 2007 ).
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