Attempts to immunize cattle against Ostertagia ostertagi infections employing 'normal' and 'chilled' (hypobiosis-prone) third stage larvae.
Immunity to Ostertagia ostertagi infections in calves develops slowly and only becomes manifest towards the end of a grazing season in which they have been exposed to the parasite. In an attempt to hasten the onset of immune reactions, three immunization protocols were set up. Twenty four heifers were allocated into four groups. Beginning in January, animals in two of the groups were inoculated with four 1-monthly increasing dosages of either 'normal' or 'chilled' (hypobiosis-prone) larvae, those in the third group received a single large infection with 'chilled' larvae and those in the fourth group served as non-infected controls. All animals were turned out on a common pasture in late April. Development of immunity was evaluated through determinations of faecal egg counts, live weight gains, serum pepsinogen levels and specific serum antibody responses of three isotypes (IgG1, IgG2 and IgA). Significantly reduced egg excretions in the immunized groups were apparent early in the season, indicating that the immunizations had, in this respect, been efficacious. The 'chilled' and 'normal' larvae seemed equally efficient given as multiple and single infections. A single large dosage of 'chilled' larvae seemed to have adverse effects. Only moderate antibody responses were elicited probably because of low challenge infection level on pasture. Considerable variation in responses existed between and within the four groups, for which reason conclusions regarding correlations between antibody isotype responses and immune effects on parasites could not be made.
Christensen
C M
CM
Royal Veterinary and Agricultural University, Department of Veterinary Microbiology, Frederiksberg, Denmark.
Nansen
P
P
Henriksen
S A
SA
Monrad
J
J
Satrija
F
F
D000818:Animals; D000909:Antibodies, Helminth / Q000096:biosynthesis; D002417:Cattle; D002418:Cattle Diseases / Q000517:prevention & control*; D003080:Cold Temperature; D005243:Feces / Q000469:parasitology; D005260:Female; D007114:Immunization / Q000662:veterinary*; D007070:Immunoglobulin A / Q000096:biosynthesis; D007074:Immunoglobulin G / Q000096:biosynthesis; D007814:Larva / Q000276:immunology; D010028:Ostertagia / Q000276:immunology*; D010029:Ostertagiasis / Q000517:prevention & control / Q000662:veterinary*; D010270:Parasite Egg Count / Q000662:veterinary; D010435:Pepsinogens / Q000097:blood; D015430:Weight Gain
D000909:Antibodies, Helminth; D007070:Immunoglobulin A; D007074:Immunoglobulin G; D010435:Pepsinogens