Pathogenicity of Salmonella gallinarum isolated from chickens in Korea |
Hee-soo Lee1, Soon-jae Kim2, Ki-seuk Kim1, In-pil Mo1, Tae-jong Kim2 |
1National Veterninary Research Institute, RDA 2Department of Veterninary Medicine, Kon-Kuk University |
국내 분리주 Salmonella gallinarum의 닭에 대한 병원성 |
이희수1, 김순재2, 김기석1, 모인필1, 김태종2 |
1농촌진흥청 수의과학연구소 2건국대학교 수의학과 |
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Abstract |
Fowl typhoid(FT) caused by Salmonella gallinarum is an infectious, egg-transmitted disease and characterized by swollen bronze liver, greenish-yellow diarrhea and high mortality in growing and adult chickens. Since 1992 the outbreak of FT has been increased. Several problems have been occurred such as absence of appropriate vaccines and lack of useful therapeutic methods. In these studies we investigated the pathogenicity of S gallinarum isolated in chickens. To compare the pathogenicity among the species of chickens, all chickens were challenged intramuscularly or orally with $1{ imes}10^7$ CFU of S gallinarum. The brown-colored layers were more susceptible and white leghone chickens were more resistant than other species. In the brown layer chickens orally challenged, lethal doses ($LD_{50}$) of the isolates were inoculated at 1 day, 2 weeks, 4 weeks and 8 weeks old chickens with amount of $10^{4.2}$, $10^{4.7}$, $10^{7.0}$ and $10^{7.6}$ CFU, respectively. The chickens which were intramuscularly challenged with the less amount than $10^2$ CFU showed higher mortality than that of the chickens orally inoculated with same dose. Also, we investigated the recovery rates of bacteria from various organs of survival chickens which were challenged orally with $5{ imes}l0^7$ CFU of S gallinarum. The bacteria was more frequently and isolated earlier from the liver and spleen than from any other ogans. In the pathogenicity test, the white-leghorn chickens which were known as resistant-strain against Salmonella were artificially immunosuppressed using bursectomy and/or dexamethasone treatment. Mortality of chickens with both bursectomized and treated with dexamethasone was higher(90%) than that of the control group(10%), the bursectomized chickens(10%) and the dexamethasone only treated group(20%). It was suggested that the protective mechanism in chickens against S gallinarum may be required both the functions of B-cells and T-cells. |
Key Words:
Salmonella gallinarum, chicken, pathogenicity, immunosuppress |
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