School of Animal Biology, University of Western Australia, M085, 35 Stirling Highway, Crawley, WA 6009, Australia.
Vet Parasitol. 2010 Jun 24;170(3-4):230-7. doi: 10.1016/j.vetpar.2010.02.033. Epub 2010 Feb 26.
Sheep that are highly resistant to parasitic nematodes can suffer bad diarrhoea due to the inflammation associated with rejection of ingested larvae from pasture. We hypothesised that challenging parasite-resistant sheep indoors with nematode larvae would result in reduced faecal dry matter, and that faecal dry matter would be lowest in sheep challenged with a mixture of Trichostrongylus colubriformis and Teladorsagia circumcincta compared to those challenged with either species alone. We also hypothesised that inflammatory cells and serum antibodies and interleukin-5 would be highest in those sheep that received the mixed larval challenge. We found that faecal dry matter was reduced (P<0.05) in challenged sheep compared to unchallenged sheep, with the fastest reduction being in those sheep challenged with only Tric. colubriformis. At 14 and 23 days after challenge began, there were no differences in faecal dry matter between the three challenged groups. Within the abomasum, there were no differences in inflammatory cell numbers between unchallenged sheep and those challenged only with Tric. colubriformis. Cell numbers in sheep challenged with Tela. circumcincta were higher (P<0.05) than those in unchallenged sheep, but there were no differences between sheep challenged only with Tela. circumcincta or as a mixed challenge. In the small intestine, inflammatory cell numbers were higher (P<0.05) in sheep that received the mixed challenge compared to controls. Cell numbers in sheep challenged with either Tela. circumcincta or Tric. colubriformis were also slightly higher than those in controls. Larval challenge increased (P<0.05) levels of IgA and IgE in serum, but there were no differences between the three challenged groups. Larval challenge also increased (P<0.05) levels of IL-5, with the greatest increase being in those sheep challenged with both species. We concluded that both Tela. circumcincta and Tric. colubriformis can cause immune-mediated diarrhoea in sheep, and that a mixed challenge will not necessarily lead to worse diarrhoea or higher concentrations of antibodies in serum. We also concluded that challenge with Tric. colubriformis leads to no inflammation in the abomasum, but challenge with Tela. circumcincta may lead to some inflammation in the small intestine.
对寄生性线虫具有高度抗性的绵羊可能会因排斥从牧场摄入的幼虫而引起严重腹泻。我们假设，在室内用线虫幼虫挑战抗寄生虫的绵羊会导致粪便干物质减少，并且与单独挑战一种物种相比，用捻转血矛线虫和奥斯特线虫混合物挑战的绵羊的粪便干物质最低。我们还假设，在接受混合幼虫挑战的绵羊中，炎症细胞和血清抗体以及白细胞介素-5 最高。我们发现，与未受挑战的绵羊相比，受挑战的绵羊的粪便干物质减少（P<0.05），而仅接受捻转血矛线虫挑战的绵羊的粪便干物质减少最快。在挑战开始后的 14 天和 23 天，三组受挑战的绵羊之间的粪便干物质没有差异。在皱胃中，未受挑战的绵羊与仅接受捻转血矛线虫挑战的绵羊之间的炎症细胞数量没有差异。接受奥斯特线虫挑战的绵羊的细胞数量较高（P<0.05），但与仅接受奥斯特线虫挑战或混合挑战的绵羊之间没有差异。在小肠中，接受混合挑战的绵羊的炎症细胞数量较高（P<0.05），与对照组相比。接受奥斯特线虫或捻转血矛线虫挑战的绵羊的细胞数量也略高于对照组。幼虫挑战增加了血清中 IgA 和 IgE 的水平（P<0.05），但三组受挑战的绵羊之间没有差异。幼虫挑战还增加了白细胞介素-5 的水平（P<0.05），其中两种物种均受到挑战的绵羊增加幅度最大。我们得出的结论是，奥斯特线虫和捻转血矛线虫都可以引起绵羊的免疫介导性腹泻，而混合挑战不一定会导致更严重的腹泻或血清中抗体浓度更高。我们还得出结论，捻转血矛线虫的挑战不会导致皱胃发炎，但奥斯特线虫的挑战可能会导致小肠有些炎症。
