Immunological paradigms and the pathogenesis of ovine chlamydial abortion

Gary Entrican, Sean Wattegedera, Nick Wheelhouse, Alasdair Allan, Mara Rocchi

Research output: Contribution to journalArticlepeer-review


Successful mammalian pregnancy involves complex immunological interactions between the mother and foetus that are not yet fully understood. A number of immunological paradigms have been established to explain the failure of the maternal immune system to reject the semi-allogeneic foetus, mainly based on studies in mice and humans. However, as placental structure, gestation periods and number of concepti per pregnancy can vary greatly between mammals, it is not always clear how applicable these immunological paradigms are to reproduction in other species. Here, we discuss the predictions of three important immunological paradigms in relation to the pathogenesis of ovine enzootic abortion (OEA), a common cause of infectious abortion in sheep and other ruminants. OEA is caused by the intracellular Gram-negative bacterium Chlamydophila abortus that exhibits a tropism for placental trophoblast. The paradigms of particular relevance to the pathogenesis of OEA are as follows: (i) intracellular bacterial infections are controlled by T(H)1-type CD4(+ve) T cells; (ii) indoleamine 2,3-dioxygenase is expressed in the placenta to prevent immunological rejection of the semi-allogeneic foetus; and (iii) pregnancy is a maternal T(H)2-type phenomenon. We discuss the relevance and validity of these paradigms for chlamydial abortion and reproductive immunology in sheep.
Original languageEnglish
Pages (from-to)287-94
Number of pages8
JournalAmerican Journal of Reproductive Immunology
Issue number4
Publication statusPublished - Oct 2010


  • Abortion, Septic
  • Abortion, Veterinary
  • Animals
  • Chlamydophila
  • Chlamydophila Infections
  • Female
  • Histocompatibility, Maternal-Fetal
  • Placenta
  • Pregnancy
  • Sheep
  • Sheep Diseases
  • Trophoblasts

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