Experimental vibrio fetus infection in cows. Studies on the immunising properties of living organisms injected subcutaneously

Bactericidal effect and serological response of blood and secretions in bovine vibriosis

Udder infection of vaccinated heifers with Vibrio fetus var. venerealis led to an early and severe reaction consisting of local swelling, hyperthermia, and increased blood leukocyte counts. This reaction was absent or less pronounced in heifers not previously vaccinated. This was interpreted as an immediate hypersensitivity reaction elicited in the vaccinated heifers. Specific antibodies were found in udder exudate from vaccinated heifers. Immune serum and udder exudate were moderately bactericidal and had a strong immunosuppressive and opsonophagocytic effect in rabbits. Immune cervicovaginal mucus was neither bactericidal nor opsonophagocytic or immunosuppressive. This would suggest that antibodies found in cervicovaginal mucus are not protective. It appeared that the immediate hypersensitivity observed and the subsequent transfer of antibodies from serum to udder exudate would provide by analogy a possible explanation of the mechanisms of immunity to bovine vibriosis.

Immunisation against bovine vibriosis due to Campylobacter fetus subsp. fetus biotype intermedius

A vaccine prepared from Campylobacter fetus subsp. fetus biotype venerealis gave only partial protection to heifers and bulls against genital infection with C. fetus subsp. fetus biotype intermedius. Heifers and bulls were fully immunised against C. fetus subsp. venerealis biotype intermedius by administration of a vaccine prepared from homologous organisms.

Studies on veneral transmission of Campylobacter fetus by immunised bulls

Temporary contamination of the penis and prepuce with Campylobacter fetus subsp. venerealis and Campylobacter fetus subsp. venerealis biotype intermedius may occur when immunised bulls mate with infected heifers. However, 2 experiments showed that this contamination was not a significant cause of genital infection in susceptible heifers that subsequently mated with bulls.

Immunisation of cattle against vibriosis with vaccines prepared from Campylobacter fetus subsp fetus

Subcutaneous administration of vaccines prepared from cells of Campylobacter fetus subsp fetus strain A28 to heifers gave substantial protection against infertility due to C. fetus subsp venerealis strain B6. Strains A28 and B6 had different heat-stable antigens and conformed respectively to serotype B and serotype A of Berg et al (1971). The results suggested that the protective antigens were heat-labile antigens common to both strains. Although vaccines prepared from serotype B strains of C. fetus subsp fetus could be used to immunise cattle against vibriosis, the results did not suggest that their use in preference to those prepared from C. fetus subsp venerealis would offer any advantages.