EFFECT OF FREUNDS ADJUVANTS ON GUINEA-PIGS INFECTED WITH, OR VACCINATED AGAINST, TRICHOSTRONGYLUS-COLUBRIFORMIS

Soluble antigens that protected guinea pigs against experimental chall enge with Trichostrongylus colubriformis were found to be less effecti ve if injected as emulsions in Freund's adjuvants. This occurred despi te the production of higher antibody titres in guinea pigs given emuls ified antigen. Investigations of this phenomenon showed that an intrap eritoneal injection of Freund's complete adjuvant (FCA) delayed reject ion of primary infections and partially abrogated resistance to challe nge infection. Administration of FCA/antigen emulsion to infected guin ea pigs resulted in a prolonged blood eosinophilia which parallelled t he increased longevity of the parasitosis. These findings suggest the need for caution in the selection of adjuvants for vaccination against gastrointestinal nematodes.