The effect of passive immunization on active immunity against Clostridium perfringens type D in lambs

Lambs in different stages of development of active immunity against Clostridium perfringens type D were treated with partially purified immunoglobulin in an attempt to superimpose a passive immunity on an existing or developing active immunity. Three different studies were undertaken to determine the impact of partial purified immunoglobulins on these vaccinated animals. In 2 of the 3 studies, active immunity was induced by administering the normal routine enterotoxaemia vaccinations and allowing the basic immunity to become established, for a period ranging from 2 weeks for the animals in study 1 and 4 months for those in study 2, before passive immunization with the partially purified immunoglobulins took place. An increase in the epsilon antibody titre occurred in each of the 2 studies after the animals were passively immunized with immunoglobulin, though this increase was not statistically significant (P greater than 0.05). In the 3rd study, when the animals were given the initial vaccination of the Onderstepoort enterotoxaemia oil adjuvant vaccine together with the immunoglobulin, an immediate increase in the epsilon antitoxin titre occurred that was statistically significant (P less than 0.05) 2-14 days after administration. No negative effects were noted on the development of an initial active immunity or an existing active immunity against Clostridium perfringens type D when they were passively immunized with partially purified immunoglobulin.