TLR4 and infection: However, at the 8th week post-infection, PD-1 (P = 0.0420), PD-L1 (P = 0.0406), TCR (P = 0.0423), Bcl-2 (P = 0.0178), Caspase-3 (P = 0.0349) and TLR4 (P = 0.0449) were upregulated in undernutrition 75% + infection group.