ovalbumin and Trichostrongylosis

Antibody levels were compared in guinea pigs with genetically determined differences in their ability to generate protective immunity against the small-intestine nematode parasite Trichostrongylus colubriformis. Animals with the most effective immune response (high responders) developed significantly higher anti-T. colubriformis IgG1 antibody titres than low-responder animals. However, there were no significant differences between their IgG1 antibody responses to a systemically administered protein antigen (ovalbumin). High-titre anti-T. colubriformis serum from high-responder animals did not transfer significant passive protective immunity to low-responder recipients. It is suggested that anti-T. colubriformis IgG1 antibodies mediate the release of mast-cell and basophil products at the site of infection and thus contribute to the more effective immunity expressed by high-responder animals.

Topics: Animals; Antibodies, Helminth; Antigens, Helminth; Guinea Pigs; Immunity, Innate; Immunization; Immunoglobulin Isotypes; Ovalbumin; Trichostrongylosis; Trichostrongylus

Parasite-naive guinea pigs with genetically determined differences in responsiveness to infection with the gastrointestinal nematode parasite Trichostrongylus colubriformis were sensitised to ovalbumin and later challenged by exposure to an ovalbumin aerosol. The resultant cellular migration into the lungs was assessed by histological examination of the lungs and enumeration of cells in bronchoalveolar lavage fluid 24 h, 72 h and 7 days later. Compared with parasite-low-responder guinea pigs, there were approximately 10 times more eosinophils in lavage fluid from parasite-high-responder animals but similar numbers of neutrophils.

Topics: Aerosols; Animals; Antigens; Bronchoalveolar Lavage Fluid; Chemotaxis, Leukocyte; Eosinophilia; Eosinophils; Guinea Pigs; Hypersensitivity; Lung; Male; Neutrophils; Ovalbumin; Trichostrongylosis; Trichostrongylus

Lambs weaned at eight weeks old were compared with control lambs which remained with their dams; both groups grazed the same pasture. Weaning significantly reduced the growth rate, control lambs being, on average, 6 kg heavier than weaned lambs at 15 weeks old. When contamination of pasture with larval parasites was light, both groups of lambs suffered only modest parasitic infections. When lambs were experimentally infected with 5000 Haemonchus contortus and 10,000 Trichostrongylus colubriformis larvae at eight weeks old, the mean faecal egg count for weaned lambs was twice that for controls at 12 weeks old (P less than 0.001) and weaned lambs suffered a significantly greater decline in packed cell volume than controls over the next four weeks. Antibody responses following immunisation with either ovalbumin or Brucella abortus at four and at eight weeks old, did not differ significantly between control and weaned lambs. In contrast serum antibody responses to H contortus and T colubriformis differed significantly between the two groups, with controls responding earlier and more strongly than weaned lambs. The practical significance of these findings is that up to three months old, suckled lambs, when faced with a substantial parasite challenge, have much better prospects than weaned lambs.

Topics: Animals; Antibodies, Helminth; Antibody Formation; Body Weight; Brucella abortus; Feces; Haemonchiasis; Haemonchus; Intestinal Diseases, Parasitic; Ovalbumin; Parasite Egg Count; Sheep; Sheep Diseases; Trichostrongylosis; Trichostrongylus; Weaning

Sheep in five age groups (two weeks, 10 weeks, 18 weeks, six months and four years old) were immunised systemically, twice, with ovalbumin or Brucella abortus (live or killed) and antibody responses in blood were measured. The animals were also infected with the nematode parasites Trichostrongylus colubriformis and Haemonchus contortus and faecal egg counts and serum antibody responses to larval antigens were measured. The experiments were designed so that, as far as possible, the effect of age per se could be dissociated from the combined effects of age and prior exposure to antigen. The effects of the age of sheep were more marked for antibody responses to Brucella abortus lipopolysaccharide than to ovalbumin. Older animals had much greater resistance to infection with internal parasites, as shown by the magnitude of the faecal egg count. In contrast to older lambs, neonatal lambs (infected with H contortus at two weeks old) had consistently declining concentrations of anti-H contortus antibody in their serum, mounted no detectable autogenous anti-H contortus antibody response in blood and appeared to develop no resistance to the parasite. Post natal ontogeny of immune responses was different for the various antigens/pathogens.

Topics: Aging; Animals; Antibodies, Bacterial; Antibodies, Helminth; Antibody Formation; Brucella abortus; Enzyme-Linked Immunosorbent Assay; Feces; Haemonchiasis; Haemonchus; Male; Ovalbumin; Parasite Egg Count; Sheep; Sheep Diseases; Trichostrongylosis; Trichostrongylus

Weaned merino lambs, grazing pastures low in selenium, were used to investigate the effect of selenium status on immunity to trichostrongylids. Six weeks following selenium supplementation to 14 of the 27 sheep using intraruminal selenium pellets, 5000 Ostertagia circumcincta and 5000 Trichostrongylus colubriformis larvae were administered orally to all sheep. At four weeks after infection, the mean total worm burden in the selenium supplemented sheep (5537 +/- 343, n = 14) was not significantly different (P greater than 0.05) from that in the unsupplemented sheep (5614 +/- 374, n = 12) and faecal worm egg concentrations were also similar in the two treatment groups. At this time, mean red cell glutathione peroxidase activities in the supplemented and unsupplemented groups were 430 and 11 U g-1 haemoglobin, respectively, and clinical white muscle disease had been observed in the latter group. These results suggest that increasing selenium status of selenium deficient sheep by the use of intraruminal selenium supplementation, has a negligible effect on resistance to an artificial challenge infection of O circumcincta and T colubriformis.

Topics: Animals; Body Weight; Erythrocytes; Feces; Glutathione Peroxidase; Ostertagiasis; Ovalbumin; Parasite Egg Count; Pepsinogens; Selenium; Sheep; Sheep Diseases; Trichostrongyloidiasis; Trichostrongylosis; Weaning

Topics: Animals; Edetic Acid; Gerbillinae; Intestinal Absorption; Intestinal Mucosa; Ovalbumin; Permeability; Trichostrongyloidiasis; Trichostrongylosis