Rabies virus (RABV) is a causative agent of lethal neurological disease, a member of Lyssavirus genus, belonging to Rhabdoviridae family in the order Mononegavirales. It presents a public health threat in the world resulting in more than 59,000 human deaths every year around the world. RABV possesses negative strand RNA genome, 11.9 kb, encoding five viral proteins: Nucleoprotein (N), Phosphoprotein (P), Matrix protein(M), glycoprotein (G) and polymerase or large protein (L). Structural modelling of L protein suggested that L contained different conserved domains: i) RdRp for RNA transcription and replication, ii) capping domain and iii) methyltransferase domain (MTase). The MTase domain is suggested to mediate the transfer of methyl molecule on mRNA cap structure and or at the ribose 2’OH of RNA residues. The MTase domain is assumed to be acquired for: 1) mRNA translation into viral proteins and, 2) protection of viral RNA from detection by host cytoplasmic sensors: RIG like receptors (RLR) such as RIG-I and MDA-5. However the RABV MTase domain role in pathogenicity and immune evasion is not known.
The objective of the project was to characterize the MTase domain and identify the critical residues involved in this function. To this aim, mutations of this domain are introduced by site directed mutagenesis, and recombinant viruses were recovered and characterized.
We want to evaluate the ability of MTase mutants to modify viral RNAs and eventually cellular RNA.
The use nanopore technology could permit to identify eventual internal 2’O-methylated residues in RABV mRNAs but also in cellular RNA
