• measles virus
• vaccine
• yeast

The Viral Genomics and Vaccination Unit of Pasteur Institute has been involved since years in the development of vaccines and new vaccine strategies against multiple infectious diseases. The Unit has recently undertaken the development of a new subunit vaccine platform. This platform is based on recombinant Pichia pastoris yeasts that express antigens of choice, which are multimerized on measles virus nanoparticles inside the yeast cell. This is possible since measles virus nucleoprotein (N) is able to self-assemble around RNA molecules, forming helical multimeric structures called ribonucleoparticles (RNP) and it is composed of two domains: a globular N-terminal domain Ncore, which contains the multimerization site, and a flexible C-terminal domain Ntail. The latter is showed to be structurally disordered and overhang from the surface of the RNP structure, thus, it represents an attractive linker for fusing antigens of interest and then multimerizing them on the RNP particle.
The first proof of concept of this vaccine platform was tested in a rodent malaria infection model with the CS antigen of Plasmodium berghei (PbCS), a species of Plasmodium parasite that infects mice. Despite first promising results, the vaccine platform had to be further optimized and my master thesis, inserted in this context, focused on optimization of RNP paticle by identifying the optimal lenght of the Ntail for antigen fusion, hence minimizing partial dissociation of the antigen from RNP, dissociation which is due to the final disordered segment. For this purpose, truncated forms of N proteins were designed and generated and therefore recombinant P.pastoris yeasts were analysed.
The obtained results showed an higher expression level in generated recombinant proteins even if, on the other hand, the level of the degradation didn’t change.