PLB1 and coinfection: PLB1 gene expression was upregulated in the co-infection group at 24 hours after infection (P = 0.0193) (Fig. 3), but SAP4 gene expression was upregulated in the co-infection group at both 6 and 24 hours after infection (P = 0.0019, P = 0.0062) (Fig. 3).