|Budget Amount *help
¥2,100,000 (Direct Cost : ¥2,100,000)
Fiscal Year 1996 : ¥200,000 (Direct Cost : ¥200,000)
Fiscal Year 1995 : ¥500,000 (Direct Cost : ¥500,000)
Fiscal Year 1994 : ¥1,400,000 (Direct Cost : ¥1,400,000)
The optimum culture conditions for the production of exfoliative toxin (shET) by Staphylococcus hyicus strain P-1 were as follows : inoculation of 3 x 10^9 CFU of S.hyicus into 300ml of TY broth in 2,000ml Erlenmeyer flask, and incubation at 37ﾟC for 16h with shaking at 75 oscillations/min. The rate of shET production by the isolates from pigs with exudative epidermitis (EE) was 87.5%, while that of the isolates from healthy pigs was 76.1%. shETs were divided in two serotypes by immunodiffusion and western blotting. 42kb plasmids were observed in several shET-producing strains. The culture filtrates from 50 plasmidless (PL^-) strains reached with antiserum to shET from PL^- strain alone, while that from all of 27 plasmid-possesed (PL^+) strain reacted with antiserum to shET from PL^+ strain. Then we classified shET reacted with antiserm to shET from PL^- strain as shETA,and that reacted with antiserum to shET from PL^+ strain as shETB.A shETB-producing strainP-23 caused exfoliation in 1-day-old chicken, while plasmid-cured strains P-23C1 and P-23C2 could not cause any reaction. The synthesized DNA probe based on the conservative nucleotide sequence between the genes for production of S.aureus exfoliative toxins (ETA and ETB) hybridized with plamid DNA from PL^+ strain and chromosomal DNA from PL^- strain. Piglets inoculated with shETA- and shETB- producing strains caused typical clinical signs of EE,such as exudation, exfoliation and crusting, while piglets inoculated with shET-nonproducing strain and plasmid-cured strains could not cause any signs.
In this study, we suggest that shETA- and shETB- producing strains of S.hyicus cause EE,shET-producing strains are divided in three groups, shETA-producing strains, shETB-producing strains and strains producing both toxins, and shETA and shETB are synthesized by S.hyicus under chromosomal and plasmid-control, respectively.