Genome-Wide Scan of Resistance to Necrotic Enteritis in Chickens

Necrotic enteritis (NE) is an infectious disease caused by toxins, affecting 40% of the commercial broilers. The chicken lines selected and inbred for resistance to Marek's disease were found to be also resistance to NE. Two highly inbred chicken lines of Fayoumi and ADOL were applied to identify the regions responding to intensive artificial selection for resistance to NE in chickens. We scanned the genome of resistant line and susceptible line in each breed with 60K SNP panels. A total of 155 regions completely fixed in resistant or susceptible lines were found across the genome of both breeds. The comparison of divergently fixed regions between breeds allowed reducing the number of candidate region involved in the resistance to NE. Consequently, common haplotype of 5 regions (>200 Kb & 50 SNP) subject to the susceptibility to disease were detected in the resistant or susceptible lines of 2 different chicken breeds. Annotation of the regions spanning divergently fixed regions revealed a set of candidate genes such as IL12A and TLR4 participating in immune response. The comparative analysis of both breeds revealed the evidence of selection in the region of the 6.2-6.4 Mb on chromosome 18, which overlap a previously reported QTL on disease resistance in broiler. Besides, consensus haplotypes associated with resistance to NE were found in regions of possibly relevant genes including myostatin (MSTN) and myosin (MYH3) that play an important role in muscle development. The high-resolution genome scans of divergent selection within- and between-breed suggest the candidate genes influencing the resistance to necrosis enteritis for the future study.