CONTEXT

Viral fusion proteins are transmembrane glycoproteins implicated in the early stages of the viral cycle of enveloped viruses. These glycoproteins are involved in the merging and consecutive fusion between the viral envelope and the targeted cell membrane. In later stages of viral cycle, these viral glycoproteins are expressed at the viral surface of infected cells and trigger the fusion with adjacent cells, forming giant muntinucleated cells (syncytia).

We investigated the effect of 20 different combinations of 12 amino-acid substitutions within functional domains of the parainfluenza virus type 5 (PIV-5) F glycoprotein, by performing cell surface expression measurements, quantitative fusion and syncytia assays (Terrier et al. 2009). We found that combinations of mutations conferring an autonomous phenotype with mutations leading to an increased fusion activity were compatible and generated functional PIV-5 F proteins.

Reference : Terrier O, Durupt F, Cartet G, Thomas L, Lina B, Rosa-Calatrava M. Engineering of a parainfluenza virus type 5 fusion protein (PIV-5 F): development of an autonomous and hyperfusogenic protein by a combinational mutagenesis approach. Virus Res. 2009 Dec;146(1-2):115-24.

TECHNICAL DESCRIPTION

The invention relates to a panel mutant proteins of the fusion protein (F protein) of the Parainfluenza virus type 2 and type 5 (PIV-2 and PIV-5), which are autonomous and hyperfusogenic as a result of a combinational mutagenesis approach.

BENEFITS

The present invention allows increased fusion of both (i) viral membrane with cellular membrane and (ii) between the membrane of infected cells and mock-infected adjacent cells. The different fusogenic characteristics harboured by the different engineered mutants of the invention allow to modulate the level of fusion.

INDUSTRIAL APPLICATIONS

The present invention relates to products derived therefrom such as: nucleic acids, vectors, cells; fusion inhibitors, antibodies, aptamers, interfering RNA; myelomae, hybridomae, progenitor and stem cells. The present invention also relates to said mutant proteins and products derived therefrom used in medical applications and biotechnologies.

Example (main application): The mutant protein F PIV-5 or PIV-2 can be used to construct or implement existing oncolytic vectors, to increase the dissemination and by-stander effect leading to consecutive higher efficiency of the vectors inside solid tumors.

Claims focus also on the use of our fusogenic mutant protein for the optimization of vaccines based on envelopped viruses.

DEVELOPMENT STAGE

We have developed different replicative oncolytic adenovirus expressing hyperfusogenic mutant proteins of PIV-5 to induce syncytia and increase their dissemination in solid tumor (intratumoral injection of melanoma). We have validated these fusogenic oncolytic vectors in vitro: effective production, effective functionality for replication, induction of fusion and cytotoxycity) and we have validated the vectors in vivo in collaboration with IDIBELL institute ( Barcelona): we have demonstrated significant enhanced oncolytic efficacy both in nude mice and immunocompetent Hamster tumor models (better survival, lower tumor growth).

A collaborative contract is under signature with IDIBELL in order to develop Ad vectors (already validated in clinical study ) expressing our Fus proteins of interest.

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