Hyperimmune hens as a novel source of anti-Cryptosporidium antibodies suitable for passive immune transfer.

Leghorn hens were subcutaneously immunized with 25 micrograms of Cryptosporidium parvum oocyst emulsified in Freund's complete adjuvant. A booster dose was injected 5 weeks later. Anti-Cryptosporidium activities of yolks and sera measured by an enzyme-linked immunosorbent assay (ELISA), demonstrated high levels in both sera and egg yolks which persisted for at least 17 wk. Preparations from yolks with high, medium and low anti-Cryptosporidium ELISA activities were used in a neonatal mouse model to assess their biological activities. A significant parasite reduction (P less than or equal to 0.001) was found between the high and all other groups. Hyperimmune eggs could be used as a source for passive immunity in cryptosporidiosis.