Expanding the t cell repertoire to include subdominant epitopes by vaccination with antigens delivered as protein fragments or peptide cocktails

Abstract

A convenient way of inducing a broad recognition of dominant and subdominant responses to epitopes of any given antigen of importance for prophylaxis or treatment of a chronic disease is provided. The method involves immunizing with pools of overlapping fragments (synthetic peptides, e.g., 10-30 mers with 2-20 aa overlap) of the desired antigen in appropriate adjuvants. The T cell repertoire is primed to include not only the immunodominant epitope recognized when the intact molecule is used for immunization and induced by the chronic infection itself, but induce a much broader and balanced response to a number of the subdominant epitopes as well. The vaccination with peptide mix induces a T-cell response that includes response to subdominant epitopes is important for protection against chronic disease that on their own induces a response focused only on immunodominant epitopes.

1 . An immunogenic composition against a chronic disease such as a bacterial, viral or parasitic infection or cancer comprising a peptide mixture consisting of adjacent overlapping peptides spanning the whole amino acid sequence of a protein that is expressed during the chronic phase of the disease, wherein the peptides are from a hepatitis C virus protein. 
     
     
         2 . (canceled) 
     
     
         3 . The immunogenic composition according to  claim 1 , where the peptides are independently 10 to 30 amino acids long. 
     
     
         4 . The immunogenic composition according to  claim 3 , wherein the peptides are independently 12 to 20 amino acids long. 
     
     
         5 - 7 . (canceled) 
     
     
         8 . The immunogenic composition according to  claim 1 , delivered in a delivery system comprising an adjuvant. 
     
     
         9 . The immunogenic composition according to  claim 8 , where the adjuvant is based on cationic liposomes. 
     
     
         10 . The immunogenic composition according to  claim 8 , where the peptides are delivered encapsulated in the liposomes. 
     
     
         11 . The immunogenic composition according to  claim 9 , where one or more of the peptides are lipidated. 
     
     
         12 . The immunogenic composition according to  claim 9 , where each peptide in the peptide mix is mixed or incorporated individually into liposomes prior to making the peptide mixture. 
     
     
         13 . The immunogenic composition according to  claim 8 , where the adjuvant is DDA/TDB. 
     
     
         14 . A method of preparing an immunogenic composition according to  claim 1 , where the peptide mixture is prepared by proteolytic cleavage of the protein with two or more proteolytic cleavage agents. 
     
     
         15 . The method of preparing an immunogenic composition according to  claim 14 , where the proteolytic cleavage agent is chosen among proteolytic enzymes such a trypsin, V-8 protease, AspN or chymotrypsin or chosen among chemical agents such as CNBr or BNPS-skatole. 
     
     
         16 . A method for prophylaxis or treatment of a chronic disease in an animal comprising administering to the animal the immunogenic composition according to  claim 1 . 
     
     
         17 . The method according to  claim 16  where the prophylaxis or treatment is boosted by administering a second immunogenic composition comprising the full size protein spanned by the peptide mixture in adjuvant or expressed in a live delivery system. 
     
     
         18 - 20 . (canceled) 
     
     
         21 . The method according to  claim 16 , wherein said animal is a mammal. 
     
     
         22 . The method according to  claim 21 , wherein said mammal is a human.