Toll-Like Receptors in Antiviral Innate Immunity

Abstract

Toll-like receptors (TLRs) are fundamental sensor molecules of the host innate immune system, which detect conserved molecular signatures of a wide range of microbial pathogens and initiate innate immune responses via distinct signaling pathways. Various TLRs are implicated in the early interplay of host cells with invading viruses, which regulates viral replication and/or host responses, ultimately impacting on viral pathogenesis. To survive the host innate defense mechanisms, many viruses have developed strategies to evade or counteract signaling through the TLR pathways, creating an advantageous environment for their propagation. Here we review the current knowledge of the roles TLRs play in antiviral innate immune responses, discuss examples of TLR-mediated viral recognition, and describe strategies used by viruses to antagonize the host antiviral innate immune responses.

Graphical abstract

Highlights

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  TLRs are membrane-bound sensors that activate innate immune responses to viruses.

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  TLRs recognize viral proteins on cell surface or viral nucleic acids in endosomes.

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  TLRs employ distinct pathways to induce interferon (IFN) antiviral and/or inflammatory responses.

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  Viruses have evolved elaborate tactics to circumvent TLR-mediated innate immunity.

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  TLRs regulate viral pathogenesis and are amenable to therapeutic purposes.