Protective characteristics of the antigen common to Pseudomonas and Vibrio and significance of bacterial endotoxins in protection against selected bacterial infections.

The protective effect of different vaccines against the killing activity of Pseudomonas aeruginosa and Vibrio parahaemolyticus for mice was studied. Cross experiments confirmed the high protective effect of the Pseudomonas common antigen (original endotoxin protein) contained in Pseudomonas vaccine, which, together with other soluble components, substantial afforded protection of mice against vibrios and thus confirmed the antigenic relationship between Pseudomonas and Vibrio. Satisfactory results were also obtained by vaccination with selected bacterial endotoxin lipopolysaccharides derived from some members of the Enterobacteriaceae family, which in some cases afforded 70-90% and in others only a 20-50% protection against Pseudomonas and Vibrio infection. The protective effect was reduced by up to 2/3 was obtained with vaccines subjected to alkaline hydrolysis. A single dose of Propionibacterium parvum cells not followed by specific vaccination afforded up to 50% protection against challenge with P. aeruginosa or V. parahaemolyticus. Special characteristics of the vaccines studied and their protective effects in relation to some immunological aspects of nonspecific resistance are discussed.