Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The . gov means it’s official. Federal government websites often end in . gov or . mil VSports app下载. Before sharing sensitive information, make sure you’re on a federal government site. .

Https

The site is secure V体育官网. The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely. .

. 2000 May;68(5):2720-7.
doi: 10.1128/IAI.68.5.2720-2727.2000.

The shdA gene is restricted to serotypes of Salmonella enterica subspecies I and contributes to efficient and prolonged fecal shedding (V体育平台登录)

R A Kingsley  1 , K van Amsterdam, N Kramer, A J Bäumler
Affiliations

The shdA gene is restricted to serotypes of Salmonella enterica subspecies I and contributes to efficient and prolonged fecal shedding

R A Kingsley et al. Infect Immun. 2000 May.

Abstract

Little is known about factors which enable Salmonella serotypes to circulate within populations of livestock and domestic fowl VSports手机版. We have identified a DNA region which is present in Salmonella serotypes commonly isolated from livestock and domestic fowl (S. enterica subspecies I) but absent from reptile-associated Salmonella serotypes (S. bongori and S. enterica subspecies II to VII). This DNA region was cloned from Salmonella serotype Typhimurium and sequence analysis revealed the presence of a 6,105-bp open reading frame, designated shdA, whose product's deduced amino acid sequence displayed homology to that of AIDA-I from diarrheagenic Escherichia coli, MisL of serotype Typhimurium, and IcsA of Shigella flexneri. The shdA gene was located adjacent to xseA at 52 min, in a 30-kb DNA region which is not present in Escherichia coli K-12. A serotype Typhimurium shdA mutant was shed with the feces in reduced numbers and for a shorter period of time compared to its isogenic parent. A possible role for the shdA gene during the expansion in host range of S. enterica subspecies I to include warm-blooded vertebrates is discussed. .

PubMed Disclaimer

Figures

FIG. 1
FIG. 1
Phylogenetic distribution of the shdA gene within the genus Salmonella. Southern blot analysis using representative serotypes of S. enterica (subspecies are indicated by roman numerals) and S. bongori is shown. Genomic DNA prepared from the serotypes indicated on the left (strain designations are indicated in parentheses) was hybridized with DNA probes pRA58 (left panel) and pRA38 (right panel). The location of these DNA probes (closed bars) relative to xseA and shdA (arrows) is indicated on the map shown at the top.
FIG. 2
FIG. 2
(Top) Comparison of the nucleotide sequences from E. coli (E.c.) and S. enterica serotype Typhimurium (S.t.) at the left boundary of the island. A putative termination loop located downstream of the shdA gene is indicated by arrows. (Bottom) Comparison of the genetic maps of E. coli and S. enterica serotype Typhimurium flanking the xseA gene. An approximately 30-kb DNA loop in the guaAB-hisS intergenic region, which is present in serotype Typhimurium but absent from E. coli, has been described by Riley and Krawiec (47) and is shown as an open bar.
FIG. 3
FIG. 3
(Top) Pustell alignment of the ShdA amino acid sequence against itself (window size, 10; minimum identity, 60%). Lines parallel to the diagonal identified direct amino acid repeats. A predicted signal peptide and the C-terminal domain, which has homology to AIDA-I, MisL, and IcsA, are indicated in the ShdA primary structure shown as an arrow below the Pustell alignment. The positions of nine copies of a 63-amino-acid repeat (hatched bars numbered 1 to 9) and three copies of a 102-amino-acid repeat (closed bars numbered I to III) are indicated in the N-terminal domain of ShdA. The location of four direct repeats of a 12-amino-acid sequence in the C-terminal domain of ShdA are indicated (A-D). (Bottom) A CLUSTAL alignment of repeats I to III, 1 to 9, and A to D is shown. Identical residues (shaded boxes) and residues with similar biochemical properties (open boxes) are indicated.
FIG. 4
FIG. 4
Recovery of bacteria from fecal pellets collected after inoculation of mice with an equal mixture of CL1509 (aroA) and RAK7 (shdA aroA). Data for days 1 to 6 were from 10 mice, and data for subsequent days were from 6 mice. (A) For each mouse, the output ratio (RAK7/CL1509) was determined daily. Data were converted logarithmically and are given as means ± standard errors (error bars). An asterisk below an error bar indicates that the RAK7/CL1509 output ratio was significantly different (P < 0.05) from that present in the inoculum. (B) Total numbers of CL1509 (open circles) and RAK7 (closed circles) recovered from fecal pellets of mice. The limit of detection (1.2 × 10−1 CFU/mg of feces) is indicated by a broken line. Each circle represents data for one strain from one animal. Animals for which no CFU of either CL1509 or RAK7 were detectable are indicated below the broken line along the x axis.
FIG. 5
FIG. 5
Recovery of bacteria from fecal pellets collected after inoculation of mice with an equal mixture of CL1509 (aroA) and AJB82 (invA aroA). (A) For each mouse, the output ratio (RAK82/CL1509) was determined daily. Data were converted logarithmically and are given as means ± standard errors (error bars). An asterisk below an error bar indicates that the RAK82/CL1509 output ratio was significantly different (P < 0.05) from that present in the inoculum. (B) Total numbers of CL1509 (open circles) and RAK82 (closed circles) recovered from fecal pellets of mice. The limit of detection (1.2 × 10−1 CFU/mg of feces) is indicated by a broken line. Each circle represents data for one strain from one animal. Animals for which no CFU of either CL1509 or RAK82 were detectable are indicated below the broken line along the x axis.
FIG. 6
FIG. 6
Recovery of bacteria from the intestinal organ culture model. Intestinal loops were infected with an equal mixture of RAK1 (shdA) and IR715 (wild type) (A) or AJB75 (invA) and IR715 (wild type) (B). The output ratios were determined for Peyer's patches (PP) and villous intestine (VI). Data were converted logarithmically and are given as means ± standard errors (error bars).
See this image and copyright information in PMC

References

    1. Aleksic S, Heinzerling F, Bockemühl J. Human infection caused by salmonellae of subspecies II to VI in Germany, 1977-1992. Zentbl Bakteriol. 1996;283:391–398. - V体育2025版 - PubMed
    1. Anderson R M. Evolutionary pressures in the spread and persistence of infectious agents in vertebrate populations. Parasitology. 1995;111(Suppl.):S15–S31. - PubMed
    1. Anderson R M, May R M. Coevolution of host and parasites. Parasitology. 1982;85:411–426. - PubMed
    1. Aserkoff B, Schroeder S A, Brachman P S. Salmonellosis in the United States—a five-year review. Am J Epidemiol. 1970;92:13–24. - PubMed
    1. Ausubel F M, Brent R, Kingston R E, Moore D D, Seidman J G, Smith J A, Struhl K, editors. Current protocols in molecular biology. J. New York, N.Y: Wiley & Sons; 1994.

Publication types

MeSH terms

LinkOut - more resources