Serum IgG (a), IgE (b) and IgA (c) responses (mean ± S.E.) to H. contortus ES products. Animals were vaccinated in week 0, 2.5 and 5 (i) and challenged in week 6 (c) with 10 000 L₃H. contortus. Group 1 (■) was vaccinated with cystatin-binding fraction, group 2 (▲) with total ES and group 3 (●) was the adjuvant control group. * Indicates significant difference between the groups (P < 0.05). (d) Mucus IgA- (black bar), IgG- (white bar) and IgE- (striped bar) mean antibody levels (± S.E.) to H. contortus ES 33 days after challenge infection. # indicates significant difference with group 3, * indicates significant difference with group 2.