Preliminary observations on the potential of gut membrane proteins of Haemonchus contortus as candidate vaccine antigens in sheep on naturally infected pasture.
In a trial lasting 11 months in South Africa, faecal egg counts and haematocrits of sheep vaccinated with gut membrane proteins of adult Haemonchus contortus were compared with unvaccinated controls grazing pasture contaminated with the parasite. Vaccination reduced egg output by >82% on average during one 4 month period of the trial and simultaneously significantly reduced the degree of anaemia and deaths due to haemonchosis. Although vaccine immunity was not sufficiently long lasting to prevent a surge in egg output which occurred after the onset of a period of irrigation, re-vaccinating the sheep at this point cleared their newly acquired infection and rapidly restored protection to approximately the level observed beforehand. It was clear that a vaccine based on parasite gut membrane proteins could offer substantial benefits in the control of natural haemonchosis.
Smith
W D
WD
Moredun Research Institute, Pentlands Science Park, Bush Loan, Penicuik, Scotland EH26 OPZ, Midlothian, UK. smitd@mri.sari.ac.uk
van Wyk
J A
JA
van Strijp
M F
MF
D000818:Animals; D000871:Anthelmintics / Q000627:therapeutic use; D000947:Antigens, Helminth / Q000276:immunology*; D018826:CD13 Antigens; D004591:Electrophoresis, Polyacrylamide Gel / Q000662:veterinary; D010450:Endopeptidases / Q000276:immunology*; D005243:Feces / Q000469:parasitology; D006188:Haemonchiasis / Q000276:immunology / Q000517:prevention & control / Q000662:veterinary*; D006189:Haemonchus; D015801:Helminth Proteins / Q000276:immunology*; D006400:Hematocrit / Q000662:veterinary; D008562:Membrane Glycoproteins / Q000276:immunology*; D008565:Membrane Proteins / Q000276:immunology*; D010270:Parasite Egg Count / Q000662:veterinary; D012756:Sheep; D012757:Sheep Diseases / Q000276:immunology / Q000469:parasitology / Q000517:prevention & control*; D013019:South Africa; D014611:Vaccination / Q000662:veterinary*
D000871:Anthelmintics; D000947:Antigens, Helminth; D015801:Helminth Proteins; D008562:Membrane Glycoproteins; D008565:Membrane Proteins; D010450:Endopeptidases; D018826:CD13 Antigens; C080908:H11 protein, Haemonchus contortus; C119206:galactose-containing glycoprotein, Haemonchus contortus