Identification and Attenuation of the Immunosuppressive Domains in Fusion Proteins of Enveloped RNA Viruses

Abstract

The present invention relates to enveloped RNA viruses. The invention in particular relates to the generation of superior antigens for mounting an immune response by first identifying then mutating the immunosuppressive domains in fusion proteins of enveloped RNA viruses resulting in decreased immunosuppressive properties of viral envelope proteins from the viruses.

1 .- 66 . (canceled) 
     
     
         67 . A peptide providing immunosuppressive properties, said peptide comprising an amino acid sequence selected from the sequences shown in Table 1 or selected from SEQ ID NOS:1-200. 
     
     
         68 . The peptide according to claim  1  comprising the amino acid sequence of an immunosuppressive domain. 
     
     
         69 . A peptide having the amino acid sequence of an immunosuppressive domain, said peptide identified by a method for identifying an immunosuppressive domain in a fusion protein of an enveloped RNA virus having a lipid membrane, said method comprising:
 a) identifying at least one well-conserved domain among the group consisting of the membrane-associated domains of the fusion protein and the surface-associated domains of the fusion protein;   b) providing at least one peptide with the sequence of said identified at least one well-conserved domain;   c) optionally dimerizing or multimerizing said at least one peptide; and   d) testing said at least one peptide or said at least one optionally dimerized or multimerized peptide for immunosuppressive activity.   
     
     
         70 . The peptide according to  claim 69 , wherein said at least one peptide is dimerized or multimerized. 
     
     
         71 . The peptide according to claim  3 , wherein the identification of said at least one well-conserved domain is performed using the group consisting of the surface-associated domains of the fusion protein in one or more different conformations of the fusion protein undergoing fusion. 
     
     
         72 . A mutated peptide providing reduced immunosuppressive properties, said mutated peptide comprising a mutated sequence selected from SEQ ID NOS:201-203 or a variant of an amino acid sequence selected from the sequences shown in Table 1 or selected from SEQ ID NOS:1-200, wherein said mutated sequence comprises from 1 to 4 amino acid substitutions, or at least one amino acid insertion, or at least one amino acid deletion. 
     
     
         73 . A mutated peptide providing reduced immunosuppressive properties, said mutated peptide being obtainable as a selected mutated peptide by a method for decreasing or completely abrogating the immunosuppressive properties of an immunosuppressive domain of a fusion protein of an enveloped RNA virus having a lipid membrane, said method comprising the steps of:
 a) mutating an immunosuppressive domain of said fusion protein to provide at least one mutated peptide;   b) optionally dimerizing or multimerizing said at least one mutated peptide;   c) selecting one of said at least one mutated peptide or said at least one optionally dimerized or multimerized mutated peptide showing reduced immunosuppressive properties;   d) preparing a mutant of said at least one fusion protein or said at least one optionally dimerized or multimerized mutated peptide containing said selected mutated peptide having reduced immunosuppressive properties; and   e) confirming expression of said at least one mutated fusion protein or said at least one optionally dimerized or multimerized mutated peptide on a cell surface or a viral envelope surface.   
     
     
         74 . The mutated peptide according to  claim 73 , wherein a plurality of mutated peptides are provided in step (a), optionally utilized in step (b), and utilized in steps (c)-(e). 
     
     
         75 . The mutated peptide according to  claim 73 , wherein said at least one mutated peptide or said at least one optionally dimerized or multimerized mutated peptide has immunosuppressive properties which are reduced by at least 25% compared to a dimerized wildtype version of the same peptide(s). 
     
     
         76 . The mutated peptide according to  claim 73 , wherein said mutated immunosuppressive domain is selected from SEQ ID NOS:201-203 or is mutated to provide a knock-out mutant of a sequence selected from the sequences shown in Table 1 or selected from SEQ ID NOS:1-200. 
     
     
         77 . An enveloped RNA virus that is not a retrovirus, lentivirus, or filovirus, wherein an immunosuppressive domain of a fusion protein of the virus has been modified or mutated to decrease or completely abrogate immunosuppression by an immunosuppressive domain of the fusion protein. 
     
     
         78 . A virus selected from the viruses shown in Table 1 comprising an immunosuppressive domain that has been modified or mutated to decrease or completely abrogate immunosuppression by an immunosuppressive domain of a fusion protein of the virus. 
     
     
         79 . A vaccine composition comprising a virus according to  claim 78 . 
     
     
         80 . A vaccine composition comprising an envelope protein from a virus according to  claim 78 . 
     
     
         81 . A method of treating or ameliorating a symptom caused by a virus infection of an individual, or prophylactically treating an individual, the method comprising administering an effective amount of the vaccine composition according to  claim 79 . 
     
     
         82 . A method of reducing or abolishing an immune response in an individual, the method comprising administering to said individual an effective amount of the peptide according to  claim 67 . 
     
     
         83 . The method according to  claim 82 , wherein the immune response comprises cytokine secretion or proliferation of T-cells.