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Colonization ability and pathogenic properties of a fim- mutant of an avian strain of Escherichia coli.
- Source :
-
Research in microbiology [Res Microbiol] 1998 Jul-Aug; Vol. 149 (7), pp. 473-85. - Publication Year :
- 1998
-
Abstract
- Several studies suggest that the expression of type 1 fimbriae is involved in the virulence of Escherichia coli in chickens, by promoting adhesion of bacteria to the respiratory tract, which is most probably the first step to occur in the infection, and by interacting with the immune response. In order to determine to what extent type 1 fimbriae were involved in the pathogenic process, the fim cluster of an avian pathogenic strain of E. coli, MT78 (O2:K1:H+), was modified in vitro and reintroduced in the parent strain via allele exchange using suicide vector pCVD442. The mutant strain thus generated (DM34) had its entire fim cluster removed. Its pathogenic properties were compared to those of the parent strain in an experimental reproduction of avain colibacillosis in 15-day-old chickens, after primary infection with infectious bronchitis virus followed by intratracheal inoculation of the challenge strain. In specific-pathogen-free (SPF) animals, mutant DM34 was less pathogenic than the parent strain and colonized the lungs of infected animals to a lower level. In germ-free chickens, although DM34 was less pathogenic than MT78 according to the differences in weight gains, it colonized the trachea, lungs and internal organs to the same extent as MT78. Our results suggest that, whereas type 1 fimbriae are not strictly required in colonization of the respiratory tract of germ-free chickens, they might be important in establishing a bacterial population in the lungs of SPF animals. The difference regularly observed in weight gains between mutant- and wild-type-inoculated chickens reflects a decreased pathogenicity of the fim- mutant. However, the isolation of E. coli in target organs and the observation of colibacillosis symptoms and lesions in mutant-inoculated chickens suggest that type 1 fimbriae by themselves play a limited role in pathogenicity.
- Subjects :
- Animals
Bacterial Adhesion
Base Sequence
Blotting, Southern veterinary
Body Weight
Cloning, Molecular
DNA, Bacterial chemistry
Electrophoresis, Agar Gel
Escherichia coli pathogenicity
Escherichia coli Infections microbiology
Fimbriae, Bacterial genetics
Gene Deletion
Genetic Vectors chemistry
Hemagglutination Tests veterinary
Infectious bronchitis virus pathogenicity
Lethal Dose 50
Microscopy, Electron
Molecular Sequence Data
Polymerase Chain Reaction veterinary
Respiratory Tract Infections microbiology
Specific Pathogen-Free Organisms
Virulence
Chickens microbiology
Escherichia coli genetics
Escherichia coli Infections veterinary
Fimbriae, Bacterial pathology
Poultry Diseases microbiology
Respiratory Tract Infections veterinary
Subjects
Details
- Language :
- English
- ISSN :
- 0923-2508
- Volume :
- 149
- Issue :
- 7
- Database :
- MEDLINE
- Journal :
- Research in microbiology
- Publication Type :
- Academic Journal
- Accession number :
- 9766199
- Full Text :
- https://doi.org/10.1016/s0923-2508(98)80002-8