Humoral immunity in the ewe. 3. The influence of adjuvants and immunisation regimes on immune reactivity in the breeding ewe and her progeny.

Breeding ewes were immunised with clostridial vaccine using different inoculation schedules. Results, showing differences in the class of antibody produced, were heavily dependent on the vaccination regime used. Immunoglobulin M (IgM) levels were significantly lower in ewes given double doses of vaccine compared to ewes given a single inoculation or no treatment at all (P less than 0.01). Neonatal lambs showed significant de novo IgM production with interference in this antibody production in the lambs of ewes vaccinated with the clostridial vaccine (P less than 0.05). Immunoglobulin G1 (IgG1) levels were significantly increased in all lambs which had mothers vaccinated with the clostridial vaccine prior to or during pregnancy (P less than 0.025). The greatest quantity of IgG1 was transferred to lambs when their mothers were given a double injection with primary inoculation prior to conception and booster prepartum (P less than 0.025). No antigen specific immunoglobulin G2 (IgG2) was detected in the lambs. Ewes were also immunised with BSA and their isotype specific serum antibody response was compared with their respective lambs. There was no detectable anti-BSA IgM in the lambs of all groups of ewes though specific IgG1 antibodies could be readily detected in the lambs of hyperimmunised ewes. The efficiency of transfer was related directly to the ability of the adjuvant to maximise IgG1 production in the ewe. Although immunised ewes produced high levels of IgG2, this was not transferred passively to the lamb.