TNF and infection: KEGG analysis identified substantially reduced enrichment of genes involved in cytokine-chemokine, NF-κB, tumor necrosis factor (TNF), nod-like receptor (NLR), and phosphatidylinositol 3-kinase (PI3K)-AK strain transforming protein (AKT) signaling pathways in Delta infection compared with B.6, B.1.1.8, and Alpha infections (Fig. 5F, Fig. S2B).