"R"-living vaccine against colibacillosis. Communication I

After our estimation of the LD100 of enteropathogenic E. coli 0149 and 0138 (and their toxins) in rabbits and mice (intravenously and subcutaneously or intraperitoneally, respectively), rabbits and mice were vaccinated subcutaneously by the living "R" 0149 vaccine. All animals showed resistance against the LD100 of both E. coli serotypes; this state of resistance lasted 1-5 months in rabbits, and 1-3 months in mice. Sera of vaccinated rabbits showed bactericidal activity against both E. coli serotypes. The R-E-system of rabbits which were immunized by the endotoxin of "R" 0149 living vaccine, showed mobilization of immunocytes. The vaccine seems to be harmless to newborn piglets after oral vaccination; 2 colostrum deprived piglets, despite vaccination at once after birth, did not survive the big chalenge with 100 ml of broth culture of E. coli 0149 "S" (anapylactic shock). But in comparison to 1 not vaccinated control piglet, the two piglests showed only few E. coli colonies in the intestines, while the intestine of the control animal was very massively colonized by the virulent strain. As the immunizing potency of the "R" 0149 living vaccine was clearly shown in rabbits and mice, further investigations on piglets (newborns, weaning epriod, and after weaning) are needed, to state whether the value of this vaccine corresponds with the immunizing potency shown in our preliminary experiments. The "R"-vaccine seems to open some perspective in colibacillosis prevention of children and animals, and therefore it deserves our attention.