The protective efficacies of eight
vaccine preparations consisting of Pseudomonas aeruginosa
outer-membrane protein F,
elastase and
exotoxin A
toxoid, administered either individually or in various combinations, were determined in a rat model of chronic pulmonary
infection. Rats were immunised intramuscularly at 2-week intervals (days 0, 14 and 28). On day 42, blood was collected and
antisera were obtained from each
vaccine group for use in an
enzyme-linked
immunosorbent assay which determined the titre of
IgG antibodies elicited by each
vaccine. Also on day 42, rats were challenged by intratracheal inoculation of a clinical isolate of P. aeruginosa encased within
agar beads. On day 49, the animals were killed and the lungs were examined macroscopically for the presence of lesions and fixed for histological examination. When compared with control rats immunised with
bovine serum albumin, rats immunised with
protein F alone as a
vaccine received significant protection against the development of severe pulmonary lesions.
Elastase used alone as a
vaccine provided some protection against severe lung lesions and reduced the incidence of microscopic peribronchial
inflammation. However, the combination of
protein F plus
elastase as a
vaccine did not afford protection from severe lesions, and there was an increased incidence of necrotising
granulomas in the lungs from this
vaccine group. Protection against lung lesions from the three-component
vaccine consisting of
protein F,
elastase and
exotoxin A
toxoid was similar to that provided by the
protein F
vaccine. Neither macroscopic nor histological evidence showed any enhancement of protective efficacy for the three-component
vaccine over that of the
protein F
vaccine.(ABSTRACT TRUNCATED AT 250 WORDS)