EFFECTIVENESS OF IMMUNIZATION WITH SINGLE AND MULTICOMPONENT VACCINES PREPARED FROM A COMMON ANTIGEN (OEP), PROTEASE AND ELASTASE TOXOIDS OF PSEUDOMONAS-AERUGINOSA ON PROTECTION AGAINST HEMORRHAGIC PNEUMONIA IN MINK DUE TO P-AERUGINOSA

Abstract

Toxoids of protease and elastase of P. aeruginosa were prepared by treatment with 8% formalin plus 0.2 M lysine and by 4% formalin, respectively. The 2 toxoids elicited high antibody titers as estimated by the enzyme-neutralizing and passive hemagglutination tests. The effectiveness of immunizing minks with a single component-vaccine consisting of the common antigen (OEP) of P. aeruginosa or the protease toxoid (PT) or the elastase toxoid (ET) and with 2-(PT and ET) or 3-(OEP, PT and ET) component-mixed vaccines on previously hemorrhagic pneumonia was investigated. Female Sapphire minks, 3.5 mo. old, were immunized 3 times in 1 mo. with a total of 1 mg of each of the 3 antigens in the single component vaccine and with a total of 2 or 3 mg (equal amounts of each component) in the 2- or 3-component vaccines. Two or 3 wk after the last immunization, the animals were challenged by intranasally inoculating an inoculum containing serial dilutions of 103-1010 of live bacteria. In nonimmunized minks and minks immunized with potassium aluminum sulfate (potash alum) alone, the LD50 values were approximately 103-104. In the case of OEP-vaccinated minks, the LD50 value was about 106. In minks immunized with the 3-component-vaccine the LD50 value was about 108-109, indicating that the 3-component mixed vaccine was remarkably more effective than the single OEP vaccine component. In minks immunized with PT and/or ET, the LD50 values were about 108-109. The effectiveness of the vaccine made with ET or PT alone was discussed. The pathological findings of the minks were described.