Exploiting viral sensing mediated by Toll-like receptors to design innovative vaccines

Toll-like receptors (TLRs) are transmembrane proteins belonging to the family of pattern-recognition receptors. They function as sensors of invading pathogens through recognition of pathogen-associated molecular patterns. After their engagement by microbial ligands, TLRs trigger downstream signaling pathways that culminate into transcriptional upregulation of genes involved in immune defense. Here we provide an updated overview on members of the TLR family and we focus on their role in antiviral response. Understanding of innate sensing and signaling of viruses triggered by these receptors would provide useful knowledge to prompt the development of vaccines able to elicit effective and long-lasting immune responses. We describe the mechanisms developed by viral pathogens to escape from immune surveillance mediated by TLRs and finally discuss how TLR/virus interplay might be exploited to guide the design of innovative vaccine platforms.