CHSE-214: A model for studying extracellular dsRNA sensing in vitro

Double-stranded RNA (dsRNA) is produced by almost all viruses during their replicative cycle and is a potent inducer of the innate antiviral immune response including inducing expression of type I interferons (IFNs) and interferon-stimulated genes (ISGs). During lytic virus infections intracellular dsRNA can escape into the extracellular space, where surface pattern recognition receptors, such as class A scavenger receptors (SR-As) facilitate its binding and entry into neighbouring cells. Studying extracellular dsRNA entry is difficult due to the ubiquitous expression profile and compensatory dsRNA binding characteristics of SR-As; a SR-A deficient cell line has yet to be identified. The present study suggests the Chinook salmon embryonic cell line, CHSE-214, as a model for studying extracellular dsRNA sensing in vitro. CHSE-214 is unable to bind and respond to extracellular dsRNA, can only respond to dsRNA when it is transfected into the cells, and is able to bind dsRNA when overexpressing human SR-AI. The applications for this model could include elucidating: dsRNA binding and entry mechanisms, including sequence and length effects, as well as SR-A and other putative surface dsRNA receptor ligand binding studies.