The DEGs in cluster 2 were mainly enriched in KEGG pathways related to disease and immune responses (influenza A, legionellosis, antigen processing and presentation, measles, MAPK signaling pathway, FoxO signaling pathway, melanoma, toxoplasmosis, linoleic acid metabolism, estrogen signaling pathway, longevity-regulating pathway—multiple species, pathogenic Escherichia coli infection, Toll and Imd signaling pathway). The gene discussed is TLR4; the disease is legionellosis.