Protection studies with recombinant excretory/secretory proteins of Haemonchus contortus.
The efficacy of two recombinant proteins of Haemonchus contortus was studied in both adult sheep and young lambs. These 15 and 24 kDa excretory/secretory proteins were given combined, either supplemented or not with a glycan-rich insect cell extract. In 9-month-old sheep (trial 1), faecal egg output and worm burden were reduced by 49% and 55%, respectively, after vaccination with rec15/24, and by 46% and 65% after vaccination with rec15/24 and glycan extract. No reduction in egg output or number of worms was found in young lambs using the above recombinant proteins plus glycan-rich extract (trial 2). When trial 1 was repeated (trial 3), the protection could not be reproduced, possibly due to differences in batches of recombinant proteins. In all sheep, independent of their age, rec15/24-specific immunoglobulin (Ig)G1 and IgA titres were present, but 9-month-old protected sheep had significantly higher IgA titres than the lambs. Addition of glycans resulted in lower rec15/24-specific IgG1 and IgA in 9-month-old sheep after challenge. This did not affect the level of protection. A significant negative correlation was found between IgA and worm numbers in protected sheep immunized with rec15/24 supplemented with glycans. Total IgE and rec15/24 specific IgE titres were low. The number of eosinophils, mast cells, sheep mast cell protease (SMCP)+ cells and IgA+ cells did not differ between the protected and unprotected sheep, but the lambs had significantly fewer mast cells independent of their immunization.
Vervelde
L
L
Utrecht University, Faculty Veterinary Medicine, Department of Infectious Diseases and Immunology, Division of Parasitology and Tropical Veterinary Medicine, Utrecht, The Netherlands. l.vervelde@vet.uu.nl
Van Leeuwen
M A W
MA
Kruidenier
M
M
Kooyman
F N J
FN
Huntley
J F
JF
Van Die
I
I
Cornelissen
A W C A
AW
D000818:Animals; D000947:Antigens, Helminth / Q000276:immunology*; D006189:Haemonchus / Q000737:chemistry / Q000276:immunology*; D007070:Immunoglobulin A / Q000032:analysis; D007073:Immunoglobulin E / Q000032:analysis; D007074:Immunoglobulin G / Q000032:analysis; D007150:Immunohistochemistry; D008213:Lymphocyte Activation / Q000276:immunology; D011994:Recombinant Proteins / Q000276:immunology; D012756:Sheep; D012757:Sheep Diseases / Q000469:parasitology / Q000517:prevention & control*; D014611:Vaccination / Q000662:veterinary
D000947:Antigens, Helminth; D007070:Immunoglobulin A; D007074:Immunoglobulin G; D011994:Recombinant Proteins; D007073:Immunoglobulin E