Pathobiology of Heterakis gallinarum mono- and co-infection with Histomonas meleagridis in layer chicken
Résumé
Not much is known about the induction and modulation of gut-associated immune reactions after nematode infection in chicken. The objective of this study was to compare the pathogenesis, induction of immune reactions and electrophysiological changes of the gut after mono-infection with Heterakis gallinarum (H. g.) and after dual infection with H. g. and Histomonas meleagridis (H. m.) in layer chicken. In two experiments three-week old chicken were inoculated with embryonated H. g. eggs, which were positive for H. m. While birds of the first experiment were left untreated, those of the second were treated with dimetridazol to prevent H. m. co-infection. Mild to moderate histological lesions and local immune reactions with a significant increase in CD4+, CD8α+, TCRαβ+ and TCRδγ+ cells in the lamina propria and induction of the Th2- cytokine IL-13 dominated the H. g. immune response at two weeks post infection (pi). Co-infection with H. g. and H. m. induced an increase in mRNA expression of the Th1 cytokine IFN-γ, furthermore a decrease in splenic CD4+ cells and severe destruction of the cecal mucosa in association with strong T cell infiltration in the cecal lamina propria. No obvious effects on the chloride secretion of the cecal epithelium, which was investigated once the mucosa had almost recovered from the infection, could be observed in either of the two experiments. These results suggest that the local T cell reactions to nematode infections in chicken may be comparable to mammals and may be shifted from a Th2 to a Th1 dominated response when accompanied by a protozoan infection.
Domaines
Biologie animale
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