IMMUNE-RESPONSES OF BOVINE FETUS AND NEONATE TO ESCHERICHIA-COLI - QUANTITATION AND QUALITATION OF HUMORAL IMMUNE-RESPONSE

  • 1 January 1976
    • journal article
    • research article
    • Vol. 37  (6) , 639-647
Abstract
The humoral immune responses of fetuses and neonates to E. coli O26:K60:NM were studied in 26 Angus-Hereford crossbred calves. Bacterin (5.0 .times. 1010 organisms) was injected in utero directly into the amniotic fluid of 17 7-8.5 mo. old fetuses (principals). Saline solution was injected in the same manner into 9 control fetuses. Colostrum-deprived neonates were allotted to 10 groups and were euthanized at birth or were subjected to oral revaccination, challenge inoculation with the homologous organism, or both. [At birth the calves exhibited colisepticemia toxemia, anorexia, CNS depression, dehydration and weakness. Three calves not studied post-natally died at parturition.] The resistance to challenge exposure was a function of previous in utero injection of bacterin, age when challenged, and dose of challenge organisms used. Control calves were susceptible to only a large challenge dose; almost all of the principal calves were resistant. Revaccination of principal calves with bacterin at birth, exposure to the large challenge dose, or both, caused a marked increase in anti-O26 passive hemagglutination titers. Quantitative and qualitative radioimmunoassay indicated that the immune response to the O26 antigen was mainly of the immunoglobulin M (IgM) class, although there were also demonstrable changes in IgG1 and IgG2. The actively acquired immune responses were serotype specific, and there was no cross reactivity with 4 other E. coli serotypes. An unidentified immunoprecipitate band was observed in immunoelectrophoretograms of whole bovine serum which may represent another class of Ig or which may be a subclass of IgG1 or IgG2.