EFFICACIES OF ALKALINE PROTEASE, ELASTASE AND EXOTOXIN-A TOXOID VACCINES AGAINST GUT-DERIVED PSEUDOMONAS-AERUGINOSA SEPSIS IN MICE

The protective efficacies of vaccines prepared from Pseudomonas aerugi nosa alkaline protease, elastase and exotoxin A toxoids against gut-de rived P. aeruginosa sepsis in mice were evaluated. Specific pathogen-f ree mice given P. aeruginosa strain D4 orally followed by cyclophospha mide (to promote translocation across the gut wall) died of bacteraemi a. Mice immunised with one of the three individual toxoid vaccines wer e not significantly protected when compared to control mice immunised with bovine serum albumin. Combined immunisation with alkaline proteas e and elastase toxoids likewise showed no significant protective activ ity. However, combined immunisation with alkaline protease and exotoxi n A toxoids significantly increased the survival rate, which reached 6 0% (compared with a 7.1% survival rate in the control group). These re sults show that alkaline protease and exotoxin A play important roles as pathogenic factors in gut-derived sepsis and that a combination of the two exoenzyme toxoids represents a logical candidate for vaccinati on against P. aeruginosa sepsis.