Toll-like receptors, chemokine receptors and death receptor ligands responses in SARS coronavirus infected human monocyte derived dendritic cells

Law, Helen KW; Cheung, Chung Yan; Sia, Sin Fun; Chan, Yuk On; Peiris, JS Malik; Lau, Yu Lung

The majority of TLR research is focussed on the downstream signalling pathways triggered by the binding of specific ligands to TLRs. Activation of TLRs induce signalling cascades which activate transcription factors and gene expression for anti-inflammatory responses [9] . The identification of such ligands may have therapeutic applications for the treatment of SARS. In a recent study on the control of coronavirus infection by plasmocytoid DCs (pDCs), it was demonstrated that mouse hepatitis virus (MHV) induces Type I IFN response and the recognition of MHV is mediated by TLR7 [26] . The authors demonstrated that SARS-CoV also induced a strong Type I interferon response in human pDCs and proposed that TLR7 may play a similar role in SARS-CoV infection. Another group developed a recombinant mouse-adapted SARS-CoV (rMA15) that was lethal in BALB/c mice and demonstrated that MyD88 played an important role in SARS-CoV pathogenesis [27] . Both groups suggested the involvement of TLR7/MyD88/IFNα dependent signaling and further exploration is needed to determine if TLR7 agonist may elicit potent antiviral effects against SARS-CoV infection.