title: Attempts to immunize chickens with Cryptosporidium baileyi oocyst extract.
abstract: In order to study the possibility of immunization against Cryptosporidium baileyi with extracted crude antigen, Arbor Acres chickens were injected intramuscularly with 80 micrograms of C. baileyi oocyst-derived proteins (uninfected immunized, UI) or inoculated orally with 8 x 10(5) viable C. baileyi oocysts (infected control, IC) at 1 wk of age. The immunization was repeated in the UI group at 2 wk of age. Uninfected (UC) birds served as controls. All animals in UI, IC, and UC groups were challenged orally with 8 x 10(5) C. baileyi oocysts at the age of 4 wk. Blood samples were collected when birds were 4 and 6 wk of age, and sera were examined by enzyme-linked immunosorbent assay for the presence of antibodies against C. baileyi. Total oocyst output of UI chickens was about 60% of that of UC birds after challenge, and the prepatent and patent periods were nearly identical in the latter 2 groups. In contrast, IC birds developed complete resistance to challenge infections. These results suggest that immunization with the oocyst extract of C. baileyi may confer some degree of protection against oral challenge; however, the protection is less effective than that induced by primary oral infection. The lack of significant difference between the antibody responses of IC and UI animals to C. baileyi at 2 wk of age suggests that serum antibodies play little role in acquired resistance to challenge infection.
authors.affiliation: Department of Parasitology and Zoology, University of Veterinary Science, Budapest, Hungary.
authors.forename: S
authors.initials: S
authors.lastname: Hornok
authors.forename: T
authors.initials: T
authors.lastname: Sréter
authors.forename: L
authors.initials: L
authors.lastname: Békési
authors.forename: Z
authors.initials: Z
authors.lastname: Széll
authors.forename: I
authors.initials: I
authors.lastname: Varga
mesh_terms: D000818:Animals; D000913:Antibodies, Protozoan / Q000097:blood; D000953:Antigens, Protozoan / Q000008:administration & dosage / Q000276:immunology / Q000302:isolation & purification; D002645:Chickens / Q000469:parasitology*; D003457:Cryptosporidiosis / Q000517:prevention & control*; D003458:Cryptosporidium / Q000276:immunology*; D004797:Enzyme-Linked Immunosorbent Assay / Q000662:veterinary; D007114:Immunization / Q000379:methods / Q000662:veterinary*; D007273:Injections, Intramuscular / Q000662:veterinary; D008297:Male; D010063:Ovum / Q000276:immunology; D011201:Poultry Diseases / Q000517:prevention & control*; D015800:Protozoan Proteins / Q000008:administration & dosage / Q000276:immunology / Q000302:isolation & purification; D011897:Random Allocation
chemical_list: D000913:Antibodies, Protozoan; D000953:Antigens, Protozoan; D015800:Protozoan Proteins