Abstract
BackgroundThe abomasal helminth Teladorsagia circumcincta is one of the most economically important parasites affecting sheep in temperate regions. Infection is particularly detrimental to lambs, in which it can cause pronounced morbidity and severe production losses. Due to the spreading resistance of this parasite to all classes of anthelmintic drugs, teladorsagiosis is having an increasingly severe impact on the sheep industry with significant implications for sheep welfare. Protective immunity develops slowly, wanes rapidly and does not appear to be as effective in young lambs. To investigate the development of immunity to T. circumcincta in sheep and lambs, we used cytokine transcript profiling to examine differences in the abomasal mucosa and gastric lymph node of naïve and previously infected sheep and lambs following challenge.ResultsThe results of these experiments demonstrated that the abomasal mucosa is a major source of cytokines during abomasal helminth infection. A local Th2-type cytokine response was observed in the abomasal mucosa and gastric lymph node of the previously infected sheep and lambs when compared with those of the naïve during the early stages of infection. In contrast, a pro-inflammatory component more was evident in the abomasal mucosa and gastric lymph node of the naïve sheep when compared with those of the previously infected, which was not observed in the lambs.ConclusionsThe greater levels of Th2-type cytokine transcripts in both the abomasum and gastric lymph node of the previously infected compared with naïve sheep and lambs emphasises the importance of these mechanisms in the immune response to T. circumcincta infection. Younger lambs appear to be able to generate similar Th2-type responses in the abomasum suggesting that the increased morbidity and apparent lack of resistance in younger lambs following continuous or repeated exposure to T. circumcincta is unlikely to be due to a lack of appropriate Th2-type cytokine production.
Highlights
The abomasal helminth Teladorsagia circumcincta is one of the most economically important parasites affecting sheep in temperate regions
Significantly higher numbers of T. circumcincta were recovered from the abomasum of naive yearlings than from the corresponding previously infected (PI) group
In contrast to observations of O. ostertagi infection in cattle [42], transcript levels of IFNγ were not significantly greater in the abomasum of yearling sheep infected with T. circumcincta. These results indicate that cells within the abomasal mucosa itself appear to be a major source of cytokine production, and show evidence of a marked Th2-type immune response occurring during infection of yearling sheep with T. circumcincta
Summary
The abomasal helminth Teladorsagia circumcincta is one of the most economically important parasites affecting sheep in temperate regions. Infection is detrimental to lambs, in which it can cause pronounced morbidity and severe production losses. The abomasal nematode Teladorsagia circumcincta is one of the most economically important parasites to affect the farming of sheep and goats in temperate and subtropical areas [1,2,3,4,5]. This parasite is especially detrimental to younger lambs, in which it can cause pronounced morbidity and severe production losses if not controlled. Clinical consequences of infection range from sub-optimal weight gain, to inappetence, weight loss, protein deficiency and diarrhoea [22,25]
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