RNA transformation vectors derived from an uncapped single-component RNA virus

Abstract

This invention is directed to a plus strand RNA viral vector for transformation of a host organism with a foreign RNA, and expression of said foreign RNA. The foreign RNA is inserted into an infective RNA viral segment containing cis-acting viral replication elements, and allowed to infect the host organism. The RNA vector is modified to obtain infectivity by not incorporating a cap at the 5′ end of the genome. The modified RNA is able to tolerate the exogenous RNA segment without disrupting the replication of the modified RNA, in the absence of a trans-acting viral replication element in a single component plant virus host cell.

What is claimed is:  
     
         1 . An uncapped RNA molecule of a single-component, single-stranded (+) sense RNA virus capable of infecting a host plant cell, which uncapped RNA molecule comprises: 
 a) a cis-acting viral replication element obtained from a single-component (+) strand RNA plant virus,    b) no base, or a single base, or a sequence of bases located at the 5′ terminus of the viral sequence, and    c) an exogenous RNA segment capable of expressing its function in a host plant cell; wherein said exogenous RNA segment is located in a region of said uncapped RNA molecule able to tolerate said exogenous RNA segment without disrupting RNA replication of said uncapped RNA molecule; and wherein said uncapped RNA molecule is capable of replication in the absence of a trans-acting viral replication element.    
     
     
         2 . The uncapped RNA molecule of  claim 1 , wherein the exogenous RNA segment codes for a peptide or protein.  
     
     
         3 . The uncapped RNA molecule of  claim 1 , wherein the exogenous RNA segment comprises an antisense RNA.  
     
     
         4 . The uncapped RNA molecule of  claim 1 , wherein the exogenous RNA segment comprises a structural RNA.  
     
     
         5 . The uncapped RNA molecule of  claim 1 , wherein the exogenous RNA segment comprises a regulatory RNA.  
     
     
         6 . The uncapped RNA molecule of  claim 1 , wherein the exogenous RNA segment comprises RNA having catalytic properties.  
     
     
         7 . The uncapped RNA molecule of  claim 1 , wherein said RNA virus is a tobamo virus.  
     
     
         8 . The uncapped RNA molecule of  claim 7 , wherein said RNA virus is a tobacco mosaic virus.  
     
     
         9 . The uncapped RNA molecule of  claim 1 , encapsidated with viral coat protein.  
     
     
         10 . The uncapped RNA molecule of  claim 1 , wherein said host plant is Nicotiana.  
     
     
         11 . A method of modifying a host plant cell phenotypically, said method comprising introducing into the cell an uncapped RNA molecule capable of infecting said host cell, wherein said uncapped RNA molecule comprises: 
 a) a cis-acting viral replication element obtained from a single-component, single stranded (+) sense RNA plant virus;    b) no base, or a single base, or a sequence of bases located at the 5′ terminus of the viral sequence; and    c) an exogenous RNA segment in a region of said uncapped RNA molecule able to tolerate said exogenous RNA segment without disrupting RNA replication of said uncapped RNA molecule, wherein said uncapped RNA molecule is capable of replication in the absence of a trans-acting viral replication element; whereby the exogenous RNA segment confers a detectable trait in the host cell, thereby modifying said host cell.    
     
     
         12 . The method of  claim 11 , wherein the exogenous RNA segment codes for a peptide or protein.  
     
     
         13 . The method of  claim 11 , wherein the exogenous RNA segment comprises an antisense RNA.  
     
     
         14 . The method of  claim 11 , wherein the exogenous RNA segment comprises a structural RNA.  
     
     
         15 . The method of  claim 11 , wherein the exogenous RNA segment comprises a regulatory RNA.  
     
     
         16 . The method of  claim 11 , wherein the exogenous RNA segment comprises RNA having catalytic properties.  
     
     
         17 . The method of  claim 11 , wherein said RNA plant virus is a tobamo virus.  
     
     
         18 . The method of  claim 11 , wherein the host plant cell is a dicotyledonous plant cell.  
     
     
         19 . A DNA transcription vector comprising cDNA having one strand complementary to an uncapped RNA molecule capable of infecting a host plant cell, which uncapped RNA molecule comprises: 
 a) cis-acting viral replication element obtained from a single-component, single-stranded (+) sense RNA plant virus,    b) no base, or a single base, or a sequence of bases located at the 5′ terminus of the viral sequence; and    a) an exogenous RNA segment capable of expressing its function in a host cell in a region of said uncapped RNA molecule able to tolerate said exogenous RNA segment without disrupting RNA replication of said uncapped RNA molecule; and wherein said uncapped RNA molecule is capable of replication in the absence of a trans-acting viral replication element.    
     
     
         20 . An uncapped RNA molecule capable of infecting a host plant cell, said uncapped RNA molecule having no cap at the 5′ terminus of the viral sequence, said uncapped RNA molecule comprising: 
 (a) the entire genome of a single-component, single-stranded (+) sense RNA virus, without a cap sequence and  
 (b) an exogenous RNA segment, capable of expressing its function in a host plant cell, said exogenous RNA segment inserted into said genome of the RNA virus under the control of a subgenomic promoter.  
 
     
     
         21 . An uncapped RNA molecule according to  claim 19 , further comprising one or more nucleotide base molecules inserted at the 5′ terminus of the viral sequence.