Vaccination of goats against Haemonchus contortus with the gut membrane proteins H11/H-gal-GP

Abstract

Forty goats, aged from 2 to 5 months were subjected to two different immunization protocols with a vaccine containing Haemonchus contortus gut membrane proteins H11/H-gal-GP to evaluate protection against H. contortus on pre-contaminated pastures. Goats were allocated to four groups of ten, three of them received their first vaccination before turnout. One group (V4) was then vaccinated at 4-week-intervals whereas another two groups (V6 and V6SEP) were vaccinated at 6-week-intervals. A control group (CTRL) remained unvaccinated. In May, after the second vaccination, all goats were turned out on pastures which had been previously contaminated with H. contortus eggs by seeder sheep for a period of six weeks. Goats of groups V4, V6 and CTRL were grazed together, whereas V6SEP was kept separately at an identical stocking rate. Clinical (PCV, FAMACHA, body weight), parasitological (faecal egg count, FEC) and serological (antibody titres) parameters were measured fortnightly. All goats were stabled in October, drenched with levamisole and two weeks later infected with 5000 L3 of H. contortus and slaughtered four weeks later for determination of abomasal worm burdens. Group mean FEC peaked 42-56days after turnout. Significantly lower FEC were observed in V6SEP vs CTRL between D 28 and 70 (p<0.01). Mean egg output of all groups decreased substantially and fluctuated at low levels until the end of the grazing period (D 154). Goats responded to vaccination with increasing antibody titres peaking after every booster. Mean worm burdens deriving from experimental infections were reduced by 89, 65 and 47% in groups V4, V6 and V6SEP, respectively, compared with the controls. The difference was significant for V4 (p<0.01). Antibody titres measured 14days before slaughter did not correlate statistically with the worm burdens. It was concluded that the vaccination protocol did not result in sufficient protection on pasture, as antibody titres were still low at the time the goats were exposed to larval contamination on pasture after turnout.

Immunization of Goats with Recombinant Protein 14-3-3 Isoform 2(rHcftt-2) Induced Moderate Protection against Haemonchus contortus Challenge

“…In this research, goats immunized with rHcftt2 showed a significant 26.46% reduction in egg output, and the same vaccinated animals displayed a 32.22% reduction in the amount of adult H. contortus collected from the abomasa compared with the positive control group at the end of the trial. The female adult reduction was higher than the male reduction, most likely indicating the higher blood intake of the female worms [8]. Unfortunately, the reductions of adult worms were not statistically significant, probably due to the presence of nonresponsive animals in each group and the sampling size.…”

“…Until now, many native and recombinant proteins have been investigated in different immunization trials against H. contortus and most cases demonstrated variable reduction in fecal egg output and worm burdens [3,[6][7][8][9]. DNA vaccines have also been tested and showed partial protection against H. contortus [10][11][12].…”

Immune response in goats vaccinated with thiol‐binding proteins from Haemonchus contortus

“…To date, several native and recombinant antigens have been tested in immunization trials against H. contortus and a variable degree of protection has been found in most cases . Similarly, different vaccination strategies have also been tested, including the use of different adjuvants or DNA vaccines .…”

Helminth Vaccines in Ruminants

“…Vaccination of young goats did not sufficiently protect against H contortus infections on pasture. 12 For the production of this vaccine, the native antigens need to be extracted and purified locally from adult H contortus derived from infected sheep. A vaccine based on recombinantly expressed antigens would have advantages compared with a native antigen vaccine for reproducibility of product batches, biosafety, and global distribution.…”