The Journal of Medical Microbiology, Vol 13, Issue 2 265-271, Copyright © 1980 by Society for General Microbiology
Passive protection of lambs against enteropathogenic Escherichia coli: role of antibodies in serum and colostrum of dams vaccinated with K99 antigen
J. A. Morris, C. Wray and W. J. Sojka
Lambs from suckling ewes vaccinated with the K99 antigen were resistant to
challenge with K99-positive enteropathogenic Escherichia coli. Serum and
colostrum from these ewes were compared with samples from control ewes to
establish methods for monitoring vaccination and to determine the mechanism
of protection. Vaccination stimulated production of K99 antibodies. These
could be detected by an indirect haemagglutination test and a
haemagglutination-inhibition test. Antiglobulin and gel-diffusion tests
were less reliable. Experiments with brush-border cells from calf intestine
showed that the antibodies were associated with anti-adhesive activity. The
antibodies were predominantly IgG and did not neutralise the activity of
heat-stable enterotoxin. It was concluded that neutralisation of the
adhesive properties of the K99-positive E. coli by colostral antibodies
significantly contributed to the resistance of the lambs from vaccinated
ewes.
