How lambs control infection with Ostertagia circumcincta

MJ Stear*, S Strain, SC Bishop

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract / Description of output

Two of the most important questions for immunologists studying nematode infections are what effect does the host response have on the parasite and which components of the host response are responsible for these effects. The number of nematodes and the mean length of adult female Ostertagia circumcincta was measured in over 500 6-7 month old lambs of the Scottish Blackface breed. Quantitative genetic analyses indicated that there was substantial genetic variation among lambs in faecal egg counts and in worm length but the analyses provided no evidence for genetic variation in worm numbers. Separate analyses have shown a strong relationship between decreased worm length and decreased worm fecundity. Therefore, genetic resistance in lambs appears to be due to control of worm growth and not to control of worm numbers. The only immune response that is consistently associated with reduced worm length is the IgA response to fourth-stage larvae. The association is remarkably strong. After allowing for the influence of worm number on worm length (density-dependence) essentially all of the variation among deliberately infected lambs in worm length can be accounted for, in a statistical sense, by variation in the strength and specificity of the local IgA response. Therefore, the IgA mediated suppression of worm growth and fecundity appears to be the major mechanism of resistance to O. circumcincta in lambs. (C) 1999 Elsevier Science B.V. All rights reserved.

Original languageEnglish
Pages (from-to)213-218
Number of pages6
JournalVeterinary Immunology and Immunopathology
Issue number1-2
Publication statusPublished - 15 Dec 1999
Event5th International Veterinary Immunology Symposium - LUDHIANA, India
Duration: 8 Nov 199813 Nov 1998

Keywords / Materials (for Non-textual outputs)

  • genetics
  • immunology
  • parasitology
  • sheep
  • Teladorsagia circumcincta
  • Ostertagia circumcincta
  • IgA
  • fecundity
  • growth
  • Nematoda


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