The invention relates to a mutant of an arenavirus having improved antitumoral properties. The invention also relates to a method of generating such an arenavirus mutant, related pharmaceutical compositions, medical uses, methods of treatment, and isolated proteins and nucleic acids.

The invention relates to recombinant measles virus expressing Lassa virus polypeptides, and concerns in particular immunogenic LASV particles expressed by a measles virus and/or virus like particles (VLPs) that contain proteins of a Lassa virus. These particles are recombinant infectious particles able to replicate in a host after an administration. The invention provides means, in particular nucleic acid constructs, vectors, cells and rescue systems to produce these recombinant infectious particles. The invention also relates to the use of these recombinant infectious particles, in particular under the form of a composition, more particularly in a vaccine formulation, for the treatment or prevention of an infection by Lassa virus.

The invention relates to recombinant measles virus expressing Lassa virus polypeptides, and concerns in particular immunogenic LASV particles expressed by a measles virus and/or virus like particles (VLPs) that contain proteins of a Lassa virus. These particles are recombinant infectious particles able to replicate in a host after an administration. The invention provides means, in particular nucleic acid constructs, vectors, cells and rescue systems to produce these recombinant infectious particles. The invention also relates to the use of these recombinant infectious particles, in particular under the form of a composition, more particularly in a vaccine formulation, for the treatment or prevention of an infection by Lassa virus.

The invention relates to a mutant of an arenavirus having improved antitumoral properties. The invention also relates to a method of generating such an arenavirus mutant, related pharmaceutical compositions, medical uses, methods of treatment, and isolated proteins and nucleic acids.

The invention relates to genetically modified arenaviruses suitable for the treatment of neoplastic diseases, such as cancer. The arenaviruses described herein may be suitable for treatment of neoplastic diseases and/or for the use in immunotherapies. In particular, provided herein are methods and compositions for treating a neoplastic disease by administering a genetically modified arenavirus, wherein the arenavirus has been engineered to include a nucleotide sequence encoding one or more antigenic fragment(s) of mutant KRAS alone or to further include a nucleotide sequence encoding one or more antigenic fragment(s) of a mutated cancer driver gene (e.g., a mutant TP53) or a tumor-associated antigen.

The invention relates to methods of treating or preventing a tumor.