Novel hybrid pesticidal toxins

Abstract

The invention concerns novel hybrid pesticidal toxins. These toxins are expressed as the fusion protein of a chimeric gene. Specifically exemplified is a novel B.t. hybrid toxin. These novel toxins have increased toxicity against target pests. The invention also concerns a process for preparing a hybrid virus having an altered insect host range.

1 . A hybrid pesticidal protein toxin comprising a cytotoxic agent and a pest gut epithelial cell recognition portion of a protein said cytotoxic agent and said recognition portion not being naturally contiguous.  
     
     
         2 . The toxin, according to    claim 1   , wherein said cytotoxic agent is an ADP-ribosylating enzyme.  
     
     
         3 . The toxin, according to    claim 2   , wherein said ADP-ribosylating enzyme is diphtheria toxin.  
     
     
         4 . The toxin, according to    claim 1   , wherein said cytotoxic agent is a ribosome inactivating enzyme selected from the group consisting of ricin, dianthin, saporin, gelonin, tritin, abrin, and modeccin.  
     
     
         5 . The toxin, according to    claim 1   , wherein said cytotoxic agent is a ribosome inactivating enzyme obtainable from a seed selected from the group consisting of barley, rye, corn, and wild bean.  
     
     
         6 . The toxin, according to    claim 3   , wherein the diphtheria toxin used is the A fragment of the diphtheria toxin, plus the B fragment of the diphtheria toxin which has been truncated at the carboxyl terminus to remove the eukaryotic recognition region.  
     
     
         7 . The toxin, according to    claim 1   , wherein said pesticidal protein toxin is a Bacillus thuringiensis protein toxin.  
     
     
         8 . The toxin, according to    claim 7   , wherein said Bacillus thuringiensis protein toxin is expressed by the gene fragment from Bacillus thuringiensis Var. kurstaki H.D.-73.  
     
     
         9 . The toxin, according to    claim 1   , wherein said cytotoxic agent and pest gut epithelial cell recognition portion of a protein are linked together by a peptide linker of suitable length and amino acid composition to minimize susceptibility to insect protease cleavage.  
     
     
         10 . The toxin, according to    claim 9   , wherein said peptide linker consists of four or less amino acids.  
     
     
         11 . The toxin, according to    claim 9    wherein said peptide linker does not contain lysine residues.  
     
     
         12 . A toxin, according to    claim 1   , wherein said pest gut epithelial cell recognition portion of a protein is a nuclear polyhedrosis virus recognition fusogen.  
     
     
         13 . The toxin, according to    claim 12   , wherein said nuclear polyhedrosis virus recognition fusogen is linked to a cytotoxic agent by a peptide linker of suitable length and amino acid composition to minimize susceptibility to insect protease cleavage.  
     
     
         14 . The toxin, according to    claim 13   , wherein said peptide linker consists of four or less amino acids  
     
     
         15 . The toxin, according to    claim 12   , wherein said peptide linker does not contain lysine residues.