Immune response of excretory/secretory antigen of Haemonchus contortus in sheep

Excretory/Secretory (E/S) antigen was isolated from live adult Haemonchus contortus by in vitro culture and used for assessing the protective potential in sheep. On immuno- blot studies, it was demonstrated that the total E/S antigen showed five reactive bands at 24, 29, 46, 66 and 93 kDa. In protection trial, sheep were immunized intramuscularly with 500 μg of total E/S antigen along with montanide as adjuvant on day 0, 30 and 60. On ELISA, it was observed that the mean absorbance values were significantly (P≤0.01) higher up to 20 weeks post-immunization in Gr-I (Immunized with E/S antigen) compared to Gr-II (unimmunized control). Further, the mean faecal egg count (FEC) per g of faeces was lower in Gr-I (500.00±91.29 to 700.00±93.49) compared to Gr-II (2200.00±108.01 to 5100.00±169.56) and the reduction in mean FEC was 76.8%. Similarly, the mean abomasal worm counts were lower in Gr-I (1078.33±72.54) than Gr-II (3280.00±147.19) and the reduction in mean abomasal worm count was 67.12%. It was concluded that the total E/S antigen induced significantly higher protection levels in terms of reduction in mean faecal egg counts and abomasal worm counts.