Expression of Protective Antigens in Transgenic Chloroplasts and the Production of Improved Vaccines

Abstract

Vaccines for conferring immunity in mammals to infective pathogens are provided, as well as vectors and methods for plastid transformation of plants to produce protective antigens and vaccines for oral delivery. The invention further provides transformed plastids having the ability to survive selection in both the light and the dark, at different developmental stages by using genes coding for two different enzymes capable of detoxifying the same selectable marker, driven by regulatory signals that are functional in proplastids as well as in mature chloroplasts. The invention utilizes antibiotic-free selectable markers to provide edible vaccines for conferring immunity to a mammal against Bacillus anthracis , as well as Yersina pestis . The vaccines are operative by parenteral administration as well. The invention also extends to the transformed plants, plant parts, and seeds and progeny thereof. The invention is applicable to monocot and dicot plants.

1 - 25 . (canceled) 
     
     
         26 . An orally-administrable vaccine composition comprising a chloroplast expressed protective antigen for conferring immunity to said antigen in a mammal, said vaccine comprising edible plant material. 
     
     
         27 . The vaccine composition of  claim 26 , wherein said antigen confers an immunoprotective response in said mammal. 
     
     
         28 . The vaccine composition of  claim 26 , wherein said plant material comprises a chloroplast expression vector encoding said antigen, said antigen being fused to a sequence encoding cholera toxin B (CTB), said CTB forming CTB pentamers which exhibit intact transcytosis to the external basolateral membrane of intestinal epithelium. 
     
     
         29 . The vaccine composition of  claim 26 , wherein said vaccine composition is heat-stable. 
     
     
         30 . The vaccine composition of  claim 26 , wherein said plant is selected from the group consisting of tomato, carrot, low nicotine tobacco, corn, and ryegrass. 
     
     
         31 . A method for inducing an immune response against an antigen, comprising feeding to said mammal an effective amount of the vaccine composition of claim  1 . 
     
     
         32 . An orally-administrable vaccine composition as claimed in claim  1 , for conferring immunity to  Yershina pestis  to a mammal, said vaccine comprising plant material comprising V and F1 antigens of  Y. pestis.    
     
     
         33 . The vaccine composition of  claim 32 , wherein said plant material comprises a plant plastid genome having a genetic sequence encoding for V and F1 antigens of  Y. pestis.    
     
     
         34 . A process for vaccinating a mammal against  Yershina pestis  comprising feeding to said mammal an effective amount of the vaccine composition of  claim 32 . 
     
     
         35 . An orally-administrable vaccine composition as claimed in claim  1  for conferring immunity to  Bacillus anthracia  to a mammal, said vaccine comprising plant material comprising anthrax protective antigen. 
     
     
         36 . The composition of  claim 35 , wherein said vaccine is free of both anthrax edema factor and anthrax lethal factor.