Deciphering host responses to Eimeria infections for implementing integrated breeding strategies for improved resistance to coccidiosis
Résumé
In the context of intensification and specialization of poultry production, animal health issues are of increasing importance to the breeding sector because of huge related production losses caused for ex. by coccidiosis. Because of the multiple factors controlling host responses to Eimeria infections, most effective disease control strategies should be developed in an integrated animal health management approach, including prevention, cure, environment control and breeding for disease resistance. Yet, traits like resistance to coccidiosis are scarcely selected for because of a lack of easy measurable and relevant phenotypes and associated genetic markers which could be integrated in running breeding programs.
Therefore, our objectives are the identification of useable phenotypes and, using major advances in animal genomics, genes, gene products and regulatory networks involved in host pathogen interactions with a twofold goal: their use in selection and a better understanding of their functions and the underlying mechanisms.
We performed an experimental infection with 2024 commercial broilers and measured phenotypes of animals’ response (body weight gain (BWG), temperature, lesions and many blood parameters). Animals were genotyped using a 580K SNP panel, and the genome-wide association study evidenced genomic regions (22 SNPs) highly significantly associated to BWG, plasma colour and plasma β2-globuline concentration. Three SNPs associated with BWG explained 7,5% of the total variance for BWG in challenged birds. In parallel, transcriptomics analysis of liver and spleen was performed. The analysis of biological functions of genes showed the major role played by biological pathways of metabolism and some innate immune parameters. Interactions analysis showed very significant networks centred on tissue repair or cardiovascular functions, i.e. general robustness related functions. The genetic markers identified can be used now in selection programmes. Next step is to investigate how this can be applied to breeding in combination with novel vaccination.