The top 30 pathways identified as enriched in the infected cells by the Kyoto Encyclopedia of Genes and Genomes (KEGG) are shown in Figure 4B. The cytokine–cytokine receptor interaction, chemokine signaling pathway, and tumor necrosis factor (TNF) signaling pathway were the most enriched upon host cell infection, which indicated the central importance of the signaling pathways in the pathogenesis of H. parasuis. Here, TNF is linked to infection.