Protection of sheep and cattle against haemoncose after immunization with antigens from the intestinal membrane of Haemonchus contortus.

Abstract

This study will be carried out to assess the protection of a vaccine against haemoncose in sheep and cattle. The vaccine will be made up of antigens from the H. contortus intestinal membrane. Two experiments will be performed: in the first, the vaccine will be given to periparturient ewes and in their lambs. Thirty-three ewes of Bergamacia breed will be distributed in three experimental groups: Group 1 (n=11), control, vaccinated only with QuilA adjuvant; Group 2 (n=11), vaccinated with 5 µg of antigens; Group 3 (n=11), vaccinated with 50 µg of antigens. Four doses of vaccine will be given to the ewes: three doses prior to lambing and one dose four weeks after lambing. The lambs born from ewes in all groups will also be in other three experimental groups: Group 1, control; Group 2, vaccinated with 5 µg of antigens; Group 3, vaccinated with 50 µg of antigens. Lambs will receive five doses of the vaccine, the first three doses with intervals of three weeks each and the last two doses with intervals of six weeks. When the lambs complete 26 weeks of age, euthanasia will be performed in order to collect and quantify the gastrointestinal worms. The second experiment will be carried out with 24 Nelore calves, which will be divided into two groups: one is the control treated as previously and the other is vaccinated seven times with 50 µg of antigens for seven months. As calves complete 55 weeks of age, euthanasia will be performed in order to collect and quantify the gastrointestinal worms. In both experiments faecal, blood and immunological examinations will be performed, data will be submitted to analyses of variance, and means will be compared by Student's t test.