Attenuation of encephalitogenic alphavirus and uses thereof

Abstract

The present invention is drawn to generating attenuated and less cytopathic forms of New World alphaviruses that can be used in immunogenic compositions as vaccines against both Old and New World alphaviruses. In this regard, the present invention discloses that the N-terminal, ˜35-aa-long peptide of VEEV, EEEV and, most likely, of WEEV capsid proteins plays the most critical role in the downregulation of cellular transcription and development of cytopathic effect. The identified, VEEV-specific peptide, C VEE 30-68, includes two domains with distinguished functions. The integrity of both domains determines not only the intracellular distribution of C VEE , but is also essential for direct capsid function in the inhibition of transcription. The replacement of the N-terminal fragment of C VEE by its SINV-specific counterpart in VEEV TC-83 genome does not affect virus replication in vitro, but makes it less cytopathic and more attenuated in vivo.

1 . A method of attenuating New World encephalitogenic alphavirus comprising:
 mutating one or more than one amino acids in the amino terminal region of the capsid protein of the alphavirus; or   replacing the entire capsid protein or amino terminal region of the capsid protein of the alphavirus by capsid protein or amino terminal region of a less pathogenic Old World alphavirus.   
     
     
         2 . The method of  claim 1 , wherein said mutation comprises point mutations in the amino terminal of the capsid protein. 
     
     
         3 . The method of  claim 1 , wherein the amino acid(s) mutated or replaced comprises amino acids 33-68 of Venezuelan Equine Encephalitis virus capsid protein, amino acids 36-72 of Eastern Equine Encephalitis virus capsid protein or amino acids 36-72 of Western Equine Encephalitis virus capsid protein. 
     
     
         4 . The method of  claim 1 , wherein the Old World alphavirus is Sindbis, Semliki Forest, Ross River, Aura and other antigenically related viruses. 
     
     
         5 . The method of  claim 1 , wherein the attenuated New World, encephalitogenic alphavirus is capable of replicating in vitro but cannot cause disease in animals and in immunized individuals. 
     
     
         6 . An immunogenic composition, comprising:
 the attenuated New World encephalitogenic alphavirus of  claim 1 .   
     
     
         7 . The immunogenic composition of  claim 6 , wherein the New World encephalitogenic alphavirus comprises mutations of one or more than one amino acids in the amino terminal of the capsid protein of the alphavirus, deletion of entire capsid protein or deletion of amino terminal of the capsid protein. 
     
     
         8 . The immunogenic composition of  claim 7 , wherein the deleted capsid protein or amino terminal of the capsid protein is replaced by capsid protein or amino terminal of the capsid protein of less a pathogenic Old World alphavirus. 
     
     
         9 . The immunogenic composition of  claim 7 , wherein the amino acid(s) mutated or replaced comprises amino acids 33-68 of Venezuelan Equine Encephalitis virus capsid protein, amino acids 36-72 of Eastern Equine Encephalitis virus capsid protein or amino acids 36-72 of Western Equine Encephalitis virus capsid protein. 
     
     
         10 . The immunogenic composition of  claim 7 , wherein the Old World alphavirus is Sindbis, Semliki Forest, Ross River, Aura and other antigenically related viruses. 
     
     
         11 . A method of preventing an infection caused by Old and New World encephalitogenic alphavirus in a subject, comprising:
 administering an immunologically effective amount of the immunogenic composition of  claim 7  to said subject.   
     
     
         12 . The method of  claim 11 , wherein the New World encephalitogenic alphavirus is Venezuelan Equine Encephalitis virus, Western Equine Encephalitis virus or Western Equine Encephalitis virus. 
     
     
         13 . The method of  claim 11 , wherein the Old World alphavirus is Sindbis virus, Semliki Forest virus, Ross River virus or Aura virus. 
     
     
         14 . The method of  claim 11 , wherein the immunogenic composition is administered subcutaneously or intramuscularly. 
     
     
         15 . The method of  claim 11 , wherein the subject is a human or an animal, wherein said subject is a healthy subject or a subject who is likely to be exposed to the alphavirus.