Immunity to Lancefield's group E Streptococcus: passive protection of swine.

Healthy swine from one source were randomly allotted to 3 groups of 3 pigs each. Troup I and II pigs were parenterally dosed with serum obtained from swine in the convalescent stage of streptococcic lymphadenitis of swine. Group III pigs were contact controls. The swine of all groups were orally exposed to Lancefield's group E Streptococcus sp. During the next 3 weeks, the controls evidenced little resistance to the development of streptococcic lymphadenitis of swine, whereas the principals evidenced considerable resistance to development of the disease.