Phenotypic and genetic variation in the response of chickens to Eimeria tenella induced coccidiosis

Abstract

BackgroundCoccidiosis is a major contributor to losses in poultry production. With emerging constraints on the use of in-feed prophylactic anticoccidial drugs and the relatively high costs of effective vaccines, there are commercial incentives to breed chickens with greater resistance to this important production disease. To identify phenotypic biomarkers that are associated with the production impacts of coccidiosis, and to assess their covariance and heritability, 942 Cobb500 commercial broilers were subjected to a defined challenge with Eimeria tenella (Houghton). Three traits were measured: weight gain (WG) during the period of infection, caecal lesion score (CLS) post mortem, and the level of a serum biomarker of intestinal inflammation, i.e. circulating interleukin 10 (IL-10), measured at the height of the infection.ResultsPhenotypic analysis of the challenged chicken cohort revealed a significant positive correlation between CLS and IL-10, with significant negative correlations of both these traits with WG. Eigenanalysis of phenotypic covariances between measured traits revealed three distinct eigenvectors. Trait weightings of the first eigenvector, (EV1, eigenvalue = 59%), were biologically interpreted as representing a response of birds that were susceptible to infection, with low WG, high CLS and high IL-10. Similarly, the second eigenvector represented infection resilience/resistance (EV2, 22%; high WG, low CLS and high IL-10), and the third eigenvector tolerance (EV3, 19%; high WG, high CLS and low IL-10), respectively. Genome-wide association studies (GWAS) identified two SNPs that were associated with WG at the suggestive level.ConclusionsEigenanalysis separated the phenotypic impact of a defined challenge with E. tenella on WG, caecal inflammation/pathology, and production of IL-10 into three major eigenvectors, indicating that the susceptibility-resistance axis is not a single continuous quantitative trait. The SNPs identified by the GWAS for body weight were located in close proximity to two genes that are involved in innate immunity (FAM96B and RRAD).Electronic supplementary materialThe online version of this article (10.1186/s12711-018-0433-7) contains supplementary material, which is available to authorized users.

Effects of Eimeria tenella infection on chicken caecal microbiome diversity, exploring variation associated with severity of pathology

“…Furthermore, the study of Boulton et al . from which samples in this study originate, suggest females are inherently more tolerant to Eimeria infection than males, as infected females had significantly more lesions than males without an associated change in body weight gain [ 12 ]. Additionally, differences in species, strain and level of Eimeria parasite infection may explain between study variations in alpha diversity [ 56 ].…”

“…tenella infection, while others were severely affected remains unknown. Host immune parameters such as the magnitude of interferon gamma and interleukin-10 responses have been implicated in the outcome of infection [ 12 ]. It is now hypothesised that a combination of factors are involved and results from this study suggest either a functional role for the enteric microbiome, or microbial variation as a consequence of infection.…”

“…Eimeria tenella specifically infect epithelial cells of the caecal crypts of Lieberkhün, resulting in the induction of a range of pro- and anti-inflammatory cytokines including interleukin (IL)-6, IL-17A, IL-10 and interferon (IFN)-γ [ 7 – 11 ]. Infection may also result in haemorrhagic lesions of varying severity, influenced by parasite dose size and age of the bird, as well as host genotype and previous infection history [ 12 , 13 ]. The presence of Eimeria species can also exacerbate the outcome of co-infection with bacterial pathogens such as C .…”

Coheritability and Coenvironmentability as Concepts for Partitioning the Phenotypic Correlation

“…These parameters could be utilized as objective means to construct common-cause classification of diseases that cluster together diseases with genetic and environmental similarities under the premise that shared genetics and environment would manifest similarities between diseases that have a common-cause nosology (Wang et al 2017). A promising application is enhancing the capability to recognize biomarkers and traits that are readily impacted by a disease challenge (Boulton et al 2018, de Matos et al 2018). Clinical diagnostics if construed as a type of indirect selection would benefit by helping detect measurable traits (i.e.…”

Cytokine Gene Expression and IgA Production in the Spleen of Chickens Infected with Eimeria tenella

“…The spleen is considered as the most important immune organ that helps the body filter the blood and fight infection because of its specialised structure in combination with a highly organised lymphoid compartment (Springer, 1995;Serbina et al, 2003;Mebius and Kraal, 2005;Bronte and Pittet, 2013;Ren et al, 2019). Adaptive immunity, as well as innate immunity (Min et al, 2013;Tian et al, 2014), protects hosts against coccidial infections (Yun et al, 2000;Boulton et al, 2018). For example, infected chickens produce three classes of antibodies, namely, IgA, IgY and IgM (Sun et al, 2012), in response to Eimeria spp.…”