Correlation of parasitological and immunological parameters in sheep with high and low resistance to haemonchosis

Abstract

Correlation of parasitological immunological parameters in sheep with high and low resistance to haemonchosis. Can. J. Anim. Sci. 86: 363-371. Parasitological and immunological parameters of Blackbelly (Bb), a haemonchosis high-resistance sheep breed, and Columbia (Cb) a haemonchosis low-resistance breed were compared. Two experiments were performed: Bb and Cb lambs were infected weekly with 1000 third-stage larvae (L3) of Haemonchus contortus for 6 wk. In the first experiment, faecal egg counts (FEC) and blood eosinophils (BE) were determined for 15 wk. In the second experiment, the following parameters were measured weekly: FEC, plasma proteins, serum IgG to H. contortus L3 levels by ELISA and L3 antigens recognized by Western blot; animals were euthanized after 15 weeks and autopsies were performed to evaluate the total adult phases (AP), eosinophils and mast cells in the fundic abomasal region (FAR), pyloric abomasal region (PAR) and abomasal lymph node (ALN).Fecal egg counts and AP were significantly higher (P < 0.05) in Cb lambs. BE showed a significant increase (P < 0.05) in both breeds at week 9 and, subsequently, Cb lambs presented a sudden decrease in these levels. The Bb lambs revealed a higher amount (P < 0.05) of antibodies between weeks 9 and 15 of the experiment, and Cb lambs showed a reduction in antibody levels at week 9. The Western blot revealed 11 bands of H. contortus L3 antigens; no differences were observed between breeds. The number of tissue eosinophils per cm 2 in PAR and ALN was higher (P < 0.05) in the Bb lambs. No differences were found (P > 0.05) in the number of mast cells per cm 2 in the sampled regions of both infected groups. The increase and maintenance of serum antibodies and circulating and local eosinophils in resistant animals agrees with the development and maintenance of a Th 2 type immune response. The initial increase and further reduction of serum antibodies and circulating and local eosinophils in the low-resistance lamb breed suggest an initial Th 2 type response and a subsequent change to a Th 1 type response. Les animaux ont été sacrifiés au bout de 15 semaines et on a pratiqué une autopsie pour évaluer le nombre total de phases adultes du parasite (PA), d'éosinophiles et de mastocytes dans la région gastrique (RG), la région pylorique (RPC) et les ganglions lymphatiques (GL) de la caillette. Le nombre d'oeufs et de PA dans les fèces était significativement plus élevé (P < 0,05) chez les agneaux Cb. Les auteurs ont relevé une hausse significative (P < 0,05) du NES chez les deux races la neuvième semaine; par la suite, cette concentration baissait subitement chez les agneaux Cb. Les agneaux Bb présentaient une concentration plus élevée (P < 0,05) d'anticorps entre la 9 e et la 15 e semaine de l'expérience alors que cette concentration était plus basse chez les agneaux Cb, la neuvième semaine. Le transfert de Western révèle 11 bandes pour les antigènes des L3 de H. contortus; aucune variation n'a été relevée à cet égard entre les deux races. Les agneaux Bb présentaie...

Effect of Ovar‐DRA and Ovar‐DRB1 genotype in small ruminants with haemonchosis

“…The IgG response was stronger in St. Croix sheep followed by those of Katahdin and Dorper sheep. For IgG, some studies suggest an association between IgG levels and resistance and others relate the IgG production to nematode infection …”

“…Selection for nematode resistance in breeds of sheep and goats has been focused on indicator traits such as FEC . Based on FEC, subtropical and tropical breeds such as St. Croix, Katahdin, Barbados Black Belly, Gulf Coast Native or Santa Ines have been characterized as moderately resistant to H. contortus compared with South African or temperate breeds such as Dorper, Columbia, INRA 401 and Suffolk . However, FEC phenotyping in sheep and goats for selective breeding programmes requires the exposure of the animals to gastrointestinal nematodes, and this has a negative effect on the lifetime production and subsequently will impact the economic status of producers.…”

Immune Responses Associated with Resistance to Haemonchosis in Sheep

“…The serum antibody response has been widely studied although results have been variable. While some studies show an association between serum IgG levels and resistance [47], others found an association with infection but not with resistance [33, 45]. Abomasum antibodies are more important than serum antibodies in the protection against gastroenteric nematodes.…”

“…Thus, both groups respond to the presence of the parasite but do so in different manners. Compared with resistant sheep, susceptible sheep produce relatively more IFN γ and less parasite-specific serum antibodies, blood eosinophils, and abomasum eosinophils [98]; therefore susceptibility is most likely associated with a Th1 type response [47, 50], while resistance includes a Th2 type response. A differential response has also been observed in different abomasum regions.…”

Decrease in establishment of Haemonchus contortus caused by inoculation of a Taenia hydatigena larvae vesicular concentrate

“…The larvae 3 (L3) used in the experimental infections were obtained from fecal larval cultures of H. contortusinfected lambs, maintained through successive infections in lambs those were free from gastrointestinal nematodes (Muñoz-Guzmán et al, 2006).…”