Dribbling through the host defence: targeting the TLRs by pathogens

The immune system is well-equipped with sensors that detect invading pathogens and dictate subsequent immune responses for clearing the infections. One such class of sensor is the toll-like receptor (TLR), that can sense diverse molecules of pathogen origin such as proteins, lipids, carbohydrate, DNA, RNA, and trigger suitable immune responses to prevent infections. However, successful pathogens have evolved strategies to bypass the TLR-driven host immune responses to enable their survival inside the host. In this review, we have discussed about the recent advances in TLR biology and strategies adopted by various pathogens (bacteria, virus, and parasites) to subvert the TLR-signalling for evading host-immune attack. Further, we have discussed how TLRs are linked in augmenting infection burden and disease severity in host during co-infection. This information is likely to be helpful to design TLR-based immunotherapeutics to control various infections and pathophysiological disorders.