TLR4 and infection: However, the significant up-regulation of TLR2 (PDCoV: 4.33-fold changes; p = 0.0039) mRNA level was detected in the single-PDCoV group, and that of TLR4 (PDCoV: 16.01-fold changes; p < 0.0001; PEDV: 5.35-fold changes; p = 0.0367) in both single-infection groups was detected at 5 DPI as compared with control animals.