Active Immunization of Cows with a Salmonella Typhimurium Mutant Bacterin-toxoid and the Passive Transfer of Anti-core-antigen

Gram-negative endotoxins have been implicated in the pathogenesis of equine CHO laminitis, bovine coliform mastitis, and adult and neonatal septicemias. Fortuitously, the demonstration that cattle and horses could be protected from various Gram-negative endotoxins via anti-core-antigen antibodies offers viable possibilities for immunologically protecting animals from the deadly effects of endotoxemia. The anti-core-antigen antibody research work conducted prior to investigations in cattle and horses was centered around laboratory animal studies utilizing a mutant Salmonella typhimurium or the J5 mutant of E. coli utilizing laboratory animal and human clinical endotoxemia cases. This foundation of knowledge has recently been applied to problems in catle and horses and has added a new immunological dimension to the possibilities for controlling Gram-negative endotoxin meditated diseases. The specific source or sources of endotoxin involved in a particular case of endotoxemia may be one or more members of the large Gramnegative family Enterobacteriaceae. Because there are hundreds of serotypes, it is impractical to combine sufficient autogenous vaccines to provide broad-spectrum protection. Thus, there is a paramount need for a single source bacterin that provides cross-protection against virtually all Gramnegative endotoxins. The R-mutants of Gram-negative bacteria are biochemically characterized by their relative absence of oligosaccharides (“O”) side chain attachments. The relative degree of “O” side chain absence is designated by the capital letter R accompanied by the small case letters “a” through “e” with Re mutant of S. typhimurium completely lacking “O” side chains. In contrast, the J5 E. coli mutant is characterized as Rc and possesses some “O” side chains. Removal of these “O” side chains via mutation allows the core antigen of the cell wall to be presented to the immune system for the subsequent production of cross-protective antibodies. A mutant S. typhimurium bacterin-toxoid was administered to cows late in gestation, first), to learn if seroconversion could be achieved in cows, second) to learn if the anti-core-antigen antibody titer in the colostrums was higher in the vaccinated cows than in control cows, and third) to determine whether or serum anti-core-antigen antibody titers in calves that suckled vaccinated cows were higher than in calves that suckled unvaccinated cows.