Immunogenicity of a XXXX bacterin containing attachment and cornea-degrading enzyme antigens.

@entity21138 @entity5965 @entity941 @entity2499 @entity291
An adjuvanted @entity5965 bacterin containing attachment antigens and cornea-degrading enzyme antigens protected @entity291 from @entity21138 ( @entity21138 ) when experimentally challenged with homologous and heterologous challenge cultures of @entity2499 . This bacterin also protected @entity291 against field exposure to @entity2499 . Transmission electron microscopy and @entity941 labeled anti-M. bovis pili antiserum showed pili on the @entity2499 bacterin strain. Scanning electron microscopy demonstrated a fibrillar glycocalyx. The bacterin strain of @entity2499 , but not all strains of @entity2499 , destroyed @entity291 corneal cell monolayers in vitro. @entity291 corneal cells began to separate from each other within 5 min after @entity2499 organisms were added and adhered to the cell monolayers. @entity5965 organisms remained attached to the disintegrating cells as the cell membrane separated and was digested. Vaccination stimulated bacterial agglutination antibodies. However, protection against experimental challenge was more closely related to the cornea-degrading enzyme content of the experimental bacterins. Twenty-two of 29 @entity291 (76%) vaccinated with bacterins containing a relative enzyme activity (REA) greater than 0.4 were protected in a rigorous challenge of immunity test. Only 1 of 21 non-vaccinated @entity291 (5%) was free of @entity21138 . Ninety-two percent (24/26) of @entity291 vaccinated with a bacterin containing a REA greater than 0.29 remained free of @entity21138 following field exposure, whereas 47% (8/17) non-vaccinated @entity291 developed @entity21138 . Only 8 of 12 @entity291 (67%) vaccinated with a bacterin containing a REA of 0.09 remained free of @entity21138 . In a larger field efficacy test consisting of 32 herds in six states, the incidence of @entity21138 in individual herds ranged from 0% to 55%. The overall rate of infection was 11.2%. Vaccination of @entity291 with an @entity2499 bacterin that contained a REA of 0.63 reduced the incidence of @entity21138 from 11.2% (217/1931) in the non-vaccinated controls to 4.3% (66/1520) in @entity291 vaccinated once and to 3.1% (48/1536) in @entity291 vaccinated twice.
