Treffer: Sensing of Ebinur Lake virus by distinct pattern recognition receptors dictates cell-type specific innate immunity and pathogenesis.

Ebinur Lake virus (EBIV) is a recently identified orthobunyavirus with broad host range and zoonotic potential, posing a public health risk. However, the mechanisms underlying EBIV pathogenesis and host innate immune responses remain unclear. Here, we investigated the pattern recognition receptors (PRRs) responsible for sensing EBIV infection and subsequent pathogenesis. EBIV infects diverse cell types and exhibits broad tissue tropism in vivo. In vitro, RIG-I was essential for type I interferon (IFN-I) and inflammatory responses in HEK293 and A549 cells. In contrast, both RIG-I and MDA5 contributed to IFN-I induction in Huh-7 and HCT116 cells, correlating elating with the s pecific accumulation of viral dsRNA intermediates in these cell types. Both RIG-I and MDA5 preferentially recognize RNA derived from the viral S segment; however, they have different abilities in sensing incoming viral genomic RNA bearing a 5'-phosphate motif and the replication intermediates. In vivo, RIG-I deficiency severely impairs host defense, while MDA5 deficiency has a more restricted effect in the spleen and liver. In addition to RIG-I and MDA5, TLR7, which is predominantly expressed in dendritic cells, also plays a crucial role for host defense by mediating systemic inflammatory cytokine production without significantly impacting IFN-I response. Our findings suggest that multiple innate sensing receptors, including RIG-I, MDA5, and TLR7, are differentially involved in host defense against EBIV by mediating IFN-I and inflammatory responses, respectively, in a cell-specific manner. [ABSTRACT FROM AUTHOR]