TC-83-derived alphavirus vectors, particles and methods

Abstract

The present disclosure provides TC-83 VEE-derived replicons, alphaviral replicon particles and immunogenic compositions containing TC-83 alphaviral replicon particles which direct the expression of at least one antigen when introduced into a suitable host cell. The TC-83 VEE-derived ARPs described herein are improved in that they are subject to a lower vector-specific immune response than prior art ARPs.

1 . A method for preparing TC-83 derived alphaviral replicon particles (ARPs), said method comprising the steps of: 
 (a) introducing a TC-83-derived alphaviral replicon nucleic acid into a host cell, said replicon nucleic acid comprising at least a virus packaging signal and at least one heterologous coding or functional sequence expressible in said alphaviral replicon nucleic acid, wherein said host cell comprises at least one helper function, to produce a modified host cell;    (b) culturing said modified host cell under conditions allowing expression of the at least one helper function, allowing replication of said TC-83-derived alphaviral replicon nucleic acid and packaging of said alphaviral replicon nucleic acid to form ARPs;    
     
     
         2 . The method of  claim 1 , further comprising the steps of: 
 (c) contacting the modified host cells after step (b) with an aqueous solution having an ionic strength of at least 0.2 M to release the ARPs into the aqueous solution to produce a ARP-containing solution;    (d) collecting ARPs from the ARP-containing solution of step (c).    
     
     
         3 . The method of  claim 1  or  2 , wherein the at least one helper function in the host cell of step (a) is encoded by a nucleic acid sequence stably integrated within the genome of said host cell.  
     
     
         4 . The method of  claim 1 , wherein the at least one helper function in the host cell is introduced on at least one helper nucleic acid which encodes a capsid protein capable of binding said alphaviral replicon nucleic acid, and at least one alphaviral glycoprotein, wherein said alphaviral glycoprotein associates with said alphaviral replicon nucleic acid and said capsid protein, wherein the at least one helper nucleic acid molecule is introduced into the host cell together with said alphaviral replicon nucleic acid.  
     
     
         5 . The method of  claim 1 , wherein the at least one helper function is encoded by at least two helper nucleic acid molecules wherein each of said two helper nucleic acid molecules encodes at least one viral helper function.  
     
     
         6 . The method of  claim 2 , wherein the ionic strength is between 0.5 M and 5 M.  
     
     
         7 . The method of  claim 1 , wherein the at least one helper nucleic acid molecule is a DNA molecule.  
     
     
         8 . The method of  claim 1 , wherein the replicon nucleic acid is introduced into said host cell by electroporation.  
     
     
         9 . The method of  claim 1  or  2 , further comprising a cell washing step, prior to step (c) of  claim 2 .  
     
     
         10 . The method of  claim 9 , wherein the cell washing solution contains no salt and further comprises DNAse.  
     
     
         11 . A method of preparing TC-83 derived alphavirus replicon particles comprising introducing an alphavirus replicon vector and one or more helper nucleic acid molecules into an alphavirus-permissible cells via electroporation, wherein the alphavirus-permissive cells in a culture medium during electroporation are at a concentration of least 10 8  cells/ml medium and wherein the alphavirus RNA replicon vector added to the cells prior to electroporation at a concentration of approximately 35 μg per ml.  
     
     
         12 . The method of claims of  claim 1  or  11 , wherein the electroporation is carried out in an electroporation cuvette wherein a gap between electrodes is between 0.4 and 1.0 cm.  
     
     
         13 . The method of  claim 10 , wherein the helper nucleic acid is a single DNA molecule encoding all alphavirus structural proteins.  
     
     
         14 . The method of  claim 13 , wherein the DNA helper is at a concentration of least 100 μg/ml.  
     
     
         15 . The method of  claim 1  or  11 , wherein the alphavirus-permissible cell culture is a Vero cell culture.  
     
     
         16 . The method of  claim 1  or  11 , wherein step (d) is followed by an ion exchange chromatography step.  
     
     
         17 . The method of  claim 1  or  11 , wherein the salt wash step used in the method is selected from the group consisting of NaCl, KCl, MgCl 2 , CaCl 2 , NH 4 Cl, (NH 4 ) 2 SO4, NH 4 HCO 3 .. and NH 4  Acetate  
     
     
         18 . An alphavirus replicon particle preparation prepared by the method of  claim 1  or  17 .  
     
     
         19 . An TC-83-derived alphavirus replicon nucleic acid.  
     
     
         20 . A method of producing an immune response in a subject, comprising administering to the subject an effective amount of a composition comprising infectious, propagation-defective alphavirus particles and a pharmaceutically-acceptable carrier, wherein each particle comprises an alphavirus replicon RNA comprising an alphavirus packaging signal and one or more heterologous RNA sequence(s) encoding an immunogen, and wherein said alphavirus replicon RNA lacks sequences encoding alphavirus structural proteins, and wherein each particle comprises structural proteins from VEETC83.  
     
     
         21 . The method of  claim 20 , wherein the composition is administered via intramuscular, subcutaneous or intraperitoneal injection.  
     
     
         22 . The method of  claim 20 , wherein the alphavirus replicon RNA is from Venezuelan equine encephalitis virus. there are two heterologous RNA sequences.  
     
     
         24 . A composition comprising infectious, propagation-defective alphavirus particles, wherein the particles comprise Venezuelan equine encephalitis virus TC83 structural proteins and an alphavirus replicon RNA, said alphavirus replicon RNA comprising an alphavirus packaging signal and one or more heterologous RNA sequence(s) encoding at least one immunogen, and said alphavirus replicon RNA lacking sequences encoding structural proteins.  
     
     
         25 . The composition of  claim 24 , wherein the alphavirus replicon RNA is from Venezuelan equine encephalitis virus.  
     
     
         26 . The composition of  claim 24 , wherein said composition is a pharmaceutical formulation.  
     
     
         27 . A helper cell for producing infectious, propagation-defective alphavirus particles comprising: 
 (a) an alphavirus replicon RNA encoding a heterologous RNA sequence and lacking sequences encoding alphavirus structural proteins;    (b) a first helper RNA encoding at least one but not all Venezuelan equine encephalitis virus TC83 structural proteins; and    (c) a second helper RNA not encoding at least one Venezuelan equine encephalitis virus TC83 structural protein encoded by the first helper RNA and encoding at least one Venezuelan equine encephalitis virus TC83 structural protein not encoded by the first helper RNA.    
     
     
         28 . A helper cell for producing infectious, propagation-defective alphavirus particles comprising: 
 (a) an alphavirus replicon RNA encoding a heterologous RNA sequence and lacking sequences encoding alphavirus structural proteins; and    (b) one or more helper DNA plasmids encoding all of the Venezuelan equine encephalitis virus TC83 structural proteins.