title: Cooperation of Adhesin Alleles inSalmonella-Host Tropism.
abstract: Allelic combinations and host specificities for three fimbrial adhesins, FimH, BcfD, and StfH, were compared for 262 strains ofSalmonella entericaserovar Newport, a frequent human and livestock pathogen. Like FimH, BcfD had two major alleles (designated A and B), whereas StfH had two allelic groups, each with two alleles (subgroup A1 and A2 and subgroup B1 and B2). The most prevalent combinations of FimH/BcfD/StfH alleles inS. Newport were A/A/A1 and B/B/B1. The former set was most frequently found in bovine and porcine strains, whereas the latter combination was most frequently found in environmental and human isolates. Bacteria genetically engineered to express Fim, Bcf, or Stf fimbriae on their surface were tested with the different alleles for binding to human, porcine, and bovine intestinal epithelial cells. The major allelic combinations with bovine and porcine strains (A/A/A1) or with human isolates (B/B/B1) provided at least two alleles capable of binding significantly better than the other alleles to an intestinal epithelial cell line from the respective host(s). However, each combination of alleles kept at least one allele mediating binding to an intestinal epithelial cell from another host. These findings indicated that allelic variation in multiple adhesins ofS. Newport contributes to bacterial adaptation to certain preferential hosts without losing the capacity to maintain a broad host range.IMPORTANCESalmonella entericaremains a leading foodborne bacterial pathogen in the United States; infected livestock serve often as the source of contaminated food products. A study estimated that over a billionSalmonellagastroenteritis cases and up to 33 million typhoid cases occur annually worldwide, with 3.5 million deaths. Although manySalmonellastrains with a broad host range present preferential associations with certain host species, it is not clear what determines the various levels of host adaptation. Here, causal properties of host associations were determined with allelic variants of three colonization factors ofS. entericaserovar Newport, a most frequent zoonotic serovar. This is the first study that related not only individual but also a small group of host-associated gene variants with functional properties that cooperate to determine the level of host-adapted virulence. The detected associations should help to identify sources ofSalmonellainfections in both humans and animals.
authors.affiliation: Department of Pathobiology, University of Pennsylvania, School of Veterinary Medicine, Philadelphia, Pennsylvania, USA.
authors.forename: Leon
authors.initials: L
authors.lastname: De Masi
authors.affiliation: Department of Pathobiology, University of Pennsylvania, School of Veterinary Medicine, Philadelphia, Pennsylvania, USA.
authors.forename: Min
authors.initials: M
authors.lastname: Yue
authors.affiliation: Department of Pathobiology, University of Pennsylvania, School of Veterinary Medicine, Philadelphia, Pennsylvania, USA.
authors.forename: Changmin
authors.initials: C
authors.lastname: Hu
authors.affiliation: Department of Pathobiology, University of Pennsylvania, School of Veterinary Medicine, Philadelphia, Pennsylvania, USA.
authors.forename: Alexey V
authors.initials: AV
authors.lastname: Rakov
authors.affiliation: Department of Pathobiology, University of Pennsylvania, School of Veterinary Medicine, Philadelphia, Pennsylvania, USA.
authors.forename: Shelley C
authors.initials: SC
authors.lastname: Rankin
authors.affiliation: Department of Pathobiology, University of Pennsylvania, School of Veterinary Medicine, Philadelphia, Pennsylvania, USA.
authors.forename: Dieter M
authors.initials: DM
authors.lastname: Schifferli
keywords: Salmonella Newport; adhesins; allelic variation; fimbriae; host tropism