INVESTIGATIONS ON THE IMMUNORESPONSE DURI NG EDEMA DISEASE OF PIGLETSAFTER WEANING BY USING A RECOMBINANT B SUBUNIT OF SHIGA-LIKE TOXIN IIE

An outbreak of edema disease (ED) was monitored in 80 piglets after we aning over a period of 4 weeks. The shedding of Shiga-like toxin-II(e) 1) producing Escherichia coli strains, the serum bactericidal activity (SBA) against SLTEC-II(e), and the antibody response against SLT-II(e ) were investigated. The antibody response was monitored by utilizing a glutathion-S-transferase (GST) + SLT-II(e) B/SUB fusion protein (FRA NKE et al., in press) for immunoblot assays. E. coli-strain GO15III (0 141:K85ac) was diagnosed as SLT-II(e)-producing E. coli by polymerase chain reaction, DNA hybridization and cytotoxicity assays. Maximum exc retion of GO 15III appeared between days 8 and 15 after weaning. On da y 1 after weaning no piglet shed GO15III, while the number increased o n day 8 to 53 (66.2%) and on day 15 to 59 (73.8%) of the piglets. 4 we ek after weaning, GO15III was only isolated from 23 (28.8%) of the pig lets. In parallel, serum bactericidal activity against GO15III increas ed significantly in the sera of 73 (91.2%) piglets, reaching a stable maximum from day 15 on. During the first two weeks after weaning, no p iglet yielded detectable SLT-II(e)-IgG. However, the number of SLT-II( e)-IgG positive piglets increased steadily from day 15. On day 15, 5(6 .2%) piglets were positive in SLT-II(e)immunoblot analysis and 29 days after weaning the number increased to 31 (38.8%). These data represen t the first serological monitoring of a natural outbreak of edema dise ase in piglets after weaning by using a recombinant fusion protein (GS T+SLT-(e) B/SUB). The recombinant protein proved to be a useful diagno stical tool for monitoring the specific antibody status of piglets.