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Infection and Immunity, December 2000, p. 6633-6642, Vol. 68, No. 12
Department of Molecular Microbiology and Division of
Infectious Disease, Department of Pediatrics, Washington University
School of Medicine, and St. Louis Children's Hospital, St. Louis,
Missouri
Received 15 February 2000/Returned for modification 13 April
2000/Accepted 13 September 2000
Yersinia enterocolitica is one of three pathogenic
Yersinia species that share a tropism for lymphoid tissues.
However, infection of an immunocompromised host is likely to result in
a systemic infection, which is often fatal. Little is known about the
bacterial proteins needed to establish such an infection. The genes
that encode these virulence factors are likely to be active only during systemic infection. A library of random cat fusions was
used to inoculate BALB/c mice. Fusions expressed during a systemic
infection were enriched by the administration of
chloramphenicol-succinate. Y. enterocolitica isolates
recovered from the mice were tested for chloramphenicol resistance in
vitro. Fusions that were inactive in vitro were analyzed further and
found to represent 31 allelic groups. Each was given a sif
(for systemic infection factor) designation. Based on homology to known
proteins, the sif genes are likely to encode proteins
important for general physiology, transcription regulation, and other
functions. During systemic infections, 13 of the sif-cat
fusions were able to outcompete the wild type in the presence of
chloramphenicol-succinate, confirming that the fusions were active. The
in vitro expression of several sif genes was determined,
showing modest changes in response to various growth conditions. A
mutation in sif15, which encodes a putative outer membrane
protein, caused attenuation during systemic infection but not during
colonization of the Peyer's patches. Comparisons between the Y. enterocolitica sif genes and the previously identified hre genes imply that very different groups of genes are
active during a systemic infection and during colonization of the
Peyer's patches.
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Copyright © 2000, American Society for Microbiology. All rights reserved.
Identification and Characterization of
Yersinia enterocolitica Genes Induced during Systemic
Infection
*
Corresponding author. Mailing address: Department of
Molecular Microbiology, Washington University School of Medicine,
Campus Box 8208, 660 S. Euclid Ave., St. Louis, MO 63130. Phone: (314) 286-2891. Fax: (314) 286-2896. E-mail:
virginia{at}borcim.wustl.edu.
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