IL-4 dependent resistance to the tapeworm Mesocestoides corti (Cestoda) in mice

Three-week Mesocestoides corti infections of C57BL/6 mice showed significantly raised parasite counts in animals with a targeted knockout of the IL-4 gene. By contrast, antibody neutralization of IL-5 and inhibition of eosinophilia had no effect on parasite numbers. In SV/129 mice, knockout of the interferon gamma receptor and inducible nitric oxide synthase genes had no significant effect on parasite counts. In IL-4(-/-)mice the dominant IgG1 antibody response was dramatically reduced, with a concomitant increase in IgG2a/b responses and a partial twofold reduction in IgM and IgE responses. We conclude that murine resistance to M. corti is dependent on IL-4, but occurs independently of IL-5 and eosinophils. This provides the first direct evidence for IL-4 mediated immunity of mice to infection with a tissue-dwelling platyhelminth

Mutual interactions of the apicomplexan parasites Toxoplasma gondii and Eimeria tenella with cultured poultry macrophages

Abstract Background Toxoplasma gondii and Eimeria tenella are two common parasites in poultry. Mixed infections are likely to occur frequently in chickens due to the high prevalence of both pathogens. In this study, we investigate the co-occurrence of the two pathogens in the same immunocompetent host cell population towards potential parasite-parasite as well as altered patterns of parasite-host interactions. Methods Primary macrophages from chicken blood were co-infected in vitro with T. gondii tachyzoites (RH strain) and E. tenella sporozoites (Houghton strain) for 72 h. Morphological observations by light microscopy and assessments of parasite replication by quantitative real-time PCR (qPCR) were performed at 24, 48 and 72 h post-infection (hpi). Six host cell immune factors previously linked to T. gondii or E. tenella infection were selected for gene expression analysis in this study. Results Distinct morphological changes of macrophages were observed during mixed infection at 24 hpi and immunological activation of host cells was obvious. Macrophage mRNA expression for iNOS at 48 hpi and for TNF-α at 72 hpi were significantly elevated after mixed infection. Distinct upregulation of IL-10 was also present during co-infection compared to Eimeria mono-infection at 48 and 72 hpi. At 72 hpi, the total number of macrophages as well as the number of both parasites decreased markedly. As measured by qPCR, E. tenella population tended to increase during T. gondii co-infection, while T. gondii replication was not distinctly altered. Conclusions Mutual interactions of T. gondii and E. tenella were observed in the selected co-infection model. The interactions are supposed to be indirect considering the observed changes in host cell metabolism. This study would thus help understanding the course of co-infection in chickens that may be relevant in terms of veterinary and zoonotic considerations