Vaccination of goats against Haemonchus contortus with a recombinant cysteine protease

Due to critical functions in worm physiology, Haemonchus contortus cysteine proteases are potential candidates for immunological control of haemonchosis. However, only limited information is available on the immunoprotective potential of these molecules in goat. In the present study, HC58 DNA vaccine, a cysteine protease of adult H. contortus worms, was evaluated for protection against homologous challenge infection. Sixteen goats were allocated to four experimental groups of 4 animals each. HC58 DNA vaccine was administered 28 and 14 days before oral challenge with a dose of 5000 infective H. contortus L-3 (third larval stage). HC58 DNA vaccine was transcribed at local muscle injection sites and expressed in vivo 7 and 10 days after primary and booster vaccination, respectively. The group (mean +/- S.D.) fecal eggs per gram count (FEC), percentage L-3 and worm burdens for Group 1 (HC58 DNA vaccine) dropped by 28.02, 47.6 and 28.3%, respectively. Corresponding reductions for Group 2 (recombinant HC58 protein) were 26.36, 31.6 and 16.1%, respectively (P < 0.05). Accordingly, there was a slight but significant difference in the worm burden for Groups 1 and 2 of 532.25 +/- 143.54 and 622.5 +/- 71.29, respectively, as opposed to 741.5 +/- 241.45 in Group 4 (unvaccinated positive control) (P < 0.05). Vaccinated goats mounted high serum IgA, IgG and mucosal IgA antibody responses subsequent to L-3 challenge. These findings suggested that HC58 DNA vaccine conferred some protection against H. contortus infection in goat. (C) 2006 Elsevier B.V. All rights reserved.