Elucidation of novel pathways components of C. elegans viral immunity

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This research program represents a new direction in my laboratory towards the discovery of novel pathways involved in viral innate-immunity using C. elegans as a model organism that build from preliminary data obtained by undergraduate students in my laboratory. The pathways of interest are currently unknown in the worm, but exist in vertebrates. Their discovery in C. elegans would provide an important advance in knowledge in this model organism that would give us novel insights into the conservation of these processes during evolution and therefore, their importance in vertebrates. The C. elegans innate immune system is remarkably efficient at distinguishing non-pathogenic from pathogenic bacteria. But its genome does not contain the important pathway components that are involved in viral immune response for infection in mammalian. In vertebrates the innate immune response is mounted by specific receptors that recognize viral nucleic-acids called Pathogens Recognition Receptors (PRR). These receptors recognize viral nucleic acids by a binding domain called Oligonucleotide Binding domain (OB). During infection these PRR recognize viral nucleic-acids and as a result a series of signaling events take place to up regulate anti-viral mechanisms. In C. elegans these PRR’s as well as the molecular components that activate the viral immune response are unknown and it remains to be discovered if some members of the OB fold family in C. elegans are PRR. We have established in my laboratory the C. elegans infection system by the dsRNA Orsay virus. We can now use reverse genetics tools that have been extensively developed for this model organism and from which many reagents can be made available to us to identify the pathways components activated by this virus.Long term: Our long term goal is to identify the molecular components of the unknown viral immunity pathways activated by orsay virus infection in the model organism C. elegans. We may reveal an ancient dsRNA antiviral immune pathway that is currently unknown and possibly conserved in animals. Short term: The current program can be described by two shorter objectives. (i) Determine the role of the OB fold in C. elegans infected by nodavirus orsay. Which OB fold are the pattern recognition receptors of the orsay-virus nucleic-acids that trigger the immune response in C. elegans . Do they exist? We will use OB fold knockdown strains and/or transgenic line over-expressing OB gene promotor or coding region to determine if the virus interfere with gene expression for some of these genes. (ii) Determine which antiviral host effectors are regulated as a result of pathway activation after orsay virus infection. We will use RNA sequencing techniques to profile differentially expressed genes between infected and non infected strains.Impact : The proposed research in objective 1 may identify the unknown Pattern Recognition Receptor(s) that are mounting the viral immune response in C. elegans. Identifying them is an important advance in basic knowledge of this organism. Objective 2 will give insight into how C. elegans mounts the innate immune response against viral infection, despite having few of the known vertebrate pathway components. The identification of components of such a novel signaling cascade has real potential for the discovery of novel antiviral effectors and regulators in vertebrates. These novel features of viral innate immune response may be an ancient mechanism evolutionarily conserved within vertebrates. Further studies on these effectors and regulators could lead to candidate targets for novel antiviral and anti-inflammatory therapies as well as new biomarkers for infection that may have been missed in vertebrates.