concanavalin-a and Haemonchiasis

Haemonchus contortus is the most economically important blood feeding nematode parasite of sheep and goats all over the world. Enolase in helminth parasites is a multi-functional enzyme which involves in glycolysis and host tissue invasion. In this study, the recombinant H. contortus enolase (rHcENO) was evaluated for its immunoprophylactic efficacy in sheep along with Con A purified native glycoproteins in a vaccine challenge trial. Group I and Group II experimental sheep were immunized thrice with rHcENO and Con A purified native glycoproteins along with Montanide ISA 61 VG adjuvant. The animals were challenged with 5000 L3 stage active H. contortus larvae after 21 days of third immunization. A significant increase in the IgG titre was observed in rHcENO and Con A purified native glycoproteins immunized animals as compared to the control animals. Immunoprotective efficacy of Con A purified native glycoproteins was comparatively higher than rHcENO antigen.

Topics: Amino Acid Sequence; Animals; Antibodies, Helminth; Base Sequence; CD4-Positive T-Lymphocytes; CD8-Positive T-Lymphocytes; Concanavalin A; Electrophoresis, Polyacrylamide Gel; Enzyme-Linked Immunosorbent Assay; Feces; Glycoproteins; Haemonchiasis; Haemonchus; Immunity, Cellular; Models, Molecular; Molecular Sequence Data; Parasite Egg Count; Phosphopyruvate Hydratase; Recombinant Proteins; Sequence Alignment; Sheep; Vaccines

High levels of protection can be attained against Haemonchus contortus challenge infection in sheep using native antigens isolated from the gut of the adult parasite. However, vaccination with recombinant forms of these antigens, or components thereof, has disappointingly failed to generate similar levels of protection, suggesting that appropriate nematode glycosylation may be a prerequisite for protection. The free-living nematode, Caenorhabditis elegans is closely related to H. contortus and has been shown to share similar glycan moieties. In order to investigate the potentially protective role of these glycan moieties, a complex set of glycoproteins was isolated from C. elegans using ConA-lectin chromatography and their efficacy as immunogens against H. contortus challenge infection evaluated in sheep. Despite the generation of a high titre systemic IgG antibody response to the C. elegans glycoproteins and the ability of these antibodies to bind to the microvillar surface of the gut of H. contortus, no protection against challenge infection was observed. Serum antibodies to the C. elegans glycoproteins cross-reacted with the H. contortus host-protective antigen, H-gal-GP, by ELISA, although the level of cross-reactivity was not of a magnitude considered protective. Qualitative differences were also determined between the glycan epitopes of the C. elegans ConA-binding proteins and those of H-gal-GP, suggesting the presence of H. contortus-specific patterns of glycosylation.

Topics: Animals; Antibodies, Helminth; Caenorhabditis elegans Proteins; Concanavalin A; Enzyme-Linked Immunosorbent Assay; Epitopes; Glycosylation; Haemonchiasis; Haemonchus; Immunoglobulin G; Intestinal Diseases, Parasitic; Protein Binding; Sheep; Sheep Diseases; Vaccines

Peanut and ConA lectins were used as ligands to isolate glycoproteins from detergent extracts of adult Ostertagia ostertagi membranes. As judged by their profiles following SDS-PAGE, these fractions closely resembled the equivalents from Haemonchus contortus which are derived from the nematode intestinal cell microvillar membranes and which are highly protective when used as antigens. Groups of calves were immunized with the peanut and ConA binding fractions of Ostertagia, either as separate or pooled antigens mixed with QuilA as adjuvant. All calves, including controls immunized with adjuvant only, were challenged with a single dose of infective Ostertagia larvae and faecal egg counts were monitored for 5 weeks. In two experiments where the antigen fractions were pooled, moderate (30-50%), but statistically significant reductions in egg output were observed, but the number of worms was not diminished. No significant protection was observed in a third trial where groups of calves were immunized with peanut or ConA binding proteins given separately. Two further trials were conducted in sheep immunized with the same Ostertagia fractions but challenged with Haemonchus. Irrespective of whether they were administered separately or together, the Ostertagia antigens cross protected efficiently against Haemonchus reducing egg counts by between 81% and 97% and worm numbers by between 57% and 84%.

Topics: Adjuvants, Immunologic; Animals; Antibodies, Helminth; Antigens, Helminth; Cattle; Cattle Diseases; Concanavalin A; Evaluation Studies as Topic; Haemonchiasis; Haemonchus; Helminth Proteins; Immunization; Intestines; Membrane Glycoproteins; Ostertagia; Ostertagiasis; Parasite Egg Count; Peanut Agglutinin; Sheep; Sheep Diseases

Eighteen female lambs with prior exposure to Haemonchus contortus infections were ovariectomized and assigned to 1 of 3 replacement regimens: 0, 25, or 250 mg of progesterone/d delivered IM. After 3 weeks of hormonal treatment, all lambs were inoculated with 100,000 infective larvae of H contortus. After 8 weeks of hormonal treatment, a blastogenic assay was performed on blood lymphocyte populations, and the abomasum from each lamb was obtained for larval and adult worm recoveries of H contortus. Lambs of the 25 mg of progesterone group had significantly (P < 0.05) reduced blastogenic response to concanavalin A and greater adult and larval populations, compared with controls. Lambs of the 250 mg of progesterone group had worm burdens and lymphocyte blastogenesis values intermediate between those of the other treatment groups.

Topics: Animals; Concanavalin A; Female; Haemonchiasis; Haemonchus; Immune Tolerance; Lymphocyte Activation; Progesterone; Sheep; Sheep Diseases