GCG and infection: In addition, there was a significant interactive effect of NE infection and E. faecium treatment on MyD88, NF-κB, IL-1β, IL-4, iNOS, PI3K, GLP-2, HSP70 and HSP90 mRNA expression (P < 0.05); specifically, NE-infected birds fed with E. faecium displayed a notable increase in the mRNA levels of these genes.