The Mononegavirales order is composed of viruses with a non-segmented negative-strand RNA genome and contains viruses such as Ebola, Nipah, rabies, measles, and mumps viruses. To transcribe and replicate their genome, mononegaviruses share sophisticated molecular mechanisms. The genome is tightly enwrapped by a homopolymer of viral nucleoproteins (N), thus forming a large ribonucleoprotein complex termed nucleocapsid. The polymerase complex is made of the large protein (L), which performs all the catalytic activities, and its oligomeric cofactor the phosphoprotein (P). The polymerase complex both transcribes the genome into capped and polyadenylated mRNA and replicates the genome into a full-length, non-modified, and encapsidated antigenome. Using vesicular stomatitis virus (VSV) as a prototype, we aim to decipher the molecular mechanisms used by mononegaviruses to synthesize their RNAs. We investigated the interaction sites between P and L, the role of the oligomerization of P, the specificity of RNA encapsidation in vitro, and the structure of the polymerase complex bound to a monomeric N protein.​.​

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