C3 and legionellosis: KEGG enrichment analysis illustrated that these genes were associated with the prion disease (C7, CYCS, HSPA1L, TUBA1B, TUBB), legionellosis (C3, CYCS, HSPA1L, HSPA8), systemic lupus erythematosus (C3, C7, H2AFX, H2AFZ HIST1H2BK), phagosome (C3, TUBA1B, TUBA1C, TUBB), gap junction (C3, TUBA1B, TUBA1C, TUBB), complement and coagulation cascades (KNG1, C3, C7), and neutrophil extracellular trap formation (C3, H2AFX, H2AFZ, HIST1H2BK).