Pathotyping avian pathogenic Escherichia coli strains in Korea.
To examine the genetic background of avian pathogenic Escherichia coli (APEC) that affects virulence of this microorganism, we characterized the virulence genes of 101 APEC strains isolated from infected chickens between 1985 ˜ 2005. Serotypes were determined with available anti-sera and median lethal doses were determined in subcutaneously inoculated chicks. The virulence genes we tested included ones encoding type 1 fimbriae (fimC), iron uptake-related (iroN, irp2, iucD, and fyuA), toxins (lt, st, stx1, stx2, and vat), and other factors (tsh, hlyF, ompT, and iss). Twenty-eight strains were found to be O1 (2.0%), O18 (3.0%), O20 (1.0%), O78 (19.8%), and O115 (2.0%) serotypes. The iroN (100%) gene was observed most frequently followed by ompT (94.1%), fimC (90.1%), hlyF (87.1%), iss (78.2%), iucD (73.3%), tsh (61.4%), fyuA (44.6%), and irp2 (43.6%). The strains were negative for all toxin genes except for vat (10.9%). All the strains were classified into 27 molecular pathotypes (MPs). The MP25, MP19, and MP10 pathotypes possessing iroN-fimC-ompT-hlyF-iucD-tsh-iss-irp2-fyuA (22.8%), iroN-fimC-ompT-hlyF-iucD-tsh-iss (21.8%), and iroN-fimC-ompT-hlyF-iss (11.9%) genotypes, respectively, were predominant. Redundancy of iron uptake-related genes was clearly observed and some strains were associated with higher mortality than others. Therefore, strains with the predominant genotypes can be used for diagnosis and vaccine.
Laboratory of Avian Diseases, College of Veterinary Medicine and BK21 for Veterinary Science, Seoul National University, Seoul 151-742, Korea.
Yong-Wun
YW
Jeong
Tae-Eun
TE
Kim
Jae-Hong
JH
Kim
Hyuk-Joon
HJ
Kwon
D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D002645:Chickens; D004926:Escherichia coli / Q000145:classification* / Q000235:genetics / Q000472:pathogenicity*; D004927:Escherichia coli Infections / Q000453:epidemiology / Q000382:microbiology / Q000662:veterinary*; D015964:Gene Expression Regulation, Bacterial / Q000502:physiology; D010802:Phylogeny; D011201:Poultry Diseases / Q000453:epidemiology / Q000382:microbiology*; D056910:Republic of Korea / Q000453:epidemiology; D014774:Virulence
D001426:Bacterial Proteins