Chimeric peptides as immunogens, antibodies thereto, and methods for immunization using chimeric peptides or antibodies

Abstract

The invention provides a chimeric peptide or mixture of chimeric peptides that can be formulated as an immunizing composition and used in a method for immunization of a mammal against an internal peptide cleavage product derived from a precursor or mature protein, for which the peptide cleavage product and the precursor or mature protein are self molecules. The chimeric peptide or peptides have an end-specific B cell epitope from a naturally-occurring internal peptide cleavage product of a precursor or mature protein, as a free N- or C-terminus, fused with or without spacer residues to a T helper cell epitope derived from a living source different from that of the internal peptide cleavage product.

1 . A chimeric peptide represented by formula (I) or formula (II),
   N—(S) m -(T h ) n   (I)
     (T h ) n —(S) m —C  (II)
   
       or chimeric peptides which are mixtures of formula (I) peptides, mixtures of formula (II) peptides, or mixtures of formula (I) and formula (II) peptides, wherein:
 N is the first 2, 3, 4, or 5 amino acid residues from the free N-terminus of a naturally-occurring internal peptide cleavage product which, when naturally-occurring in a mammal, is derived from a precursor protein or a mature protein; 
 C is the last 2, 3, 4, or 5 amino acid residues from the free C-terminus of said naturally-occurring internal peptide cleavage product; 
 T h  is a T helper cell epitope; 
 S is a spacer amino acid residue; 
 m is 0, 1, 2, 3, 4, or 5; and 
 n is 1, 2, 3, or 4. 
 
     
     
         2 . The chimeric peptide or peptides according to  claim 1 , wherein said internal peptide cleavage product is an amyloid β peptide, which, when naturally-occurring, is derived from cleavage of β amyloid precursor protein (βAPP). 
     
     
         3 . The chimeric peptide or peptides according to  claim 2 , wherein said internal peptide cleavage product has an amino acid sequence selected from the group consisting of SEQ ID NOs:2, 3, 4, 5, 6, 7, and mixtures thereof. 
     
     
         4 . The chimeric peptide or peptides according to  claim 1 , wherein N is the first 2 or 3 amino acid residues from the free N-terminus of said internal peptide cleavage product. 
     
     
         5 . The chimeric peptide or peptides according to  claim 1 , wherein C is the last 2 or 3 amino acid residues from the free C-terminus of said internal peptide cleavage product. 
     
     
         6 . The chimeric peptide or peptides according to  claim 1 , wherein T h  is a promiscuous T helper cell epitope. 
     
     
         7 . The chimeric peptide or peptides according to  claim 6 , wherein said promiscuous T helper cell epitope is derived from tetanus toxin, pertussis toxin, diphtheria toxin, measles virus F protein, hepatitis B virus surface antigen,  Chlamydia trachomitis  major outer membrane protein,  Plasmodium falciparum  circumsporozoite,  Schistosoma mansoni  triose phosphate isomerase, or  Escherichia coli  TraT. 
     
     
         8 . The chimeric peptide or peptides according to  claim 7 , wherein said promiscuous T helper cell epitope has an amino acid sequence selected from the group consisting of SEQ ID NOs:8 to 27. 
     
     
         9 . The chimeric peptide or peptides according to  claim 1 , wherein S is glycine. 
     
     
         10 . An immunizing composition, comprising an immunizing effective amount of the chimeric peptide or peptides according to  claim 1  and a pharmaceutically acceptable carrier, excipient, diluent, or auxiliary agent. 
     
     
         11 . The immunizing composition according to  claim 10 , wherein said pharmaceutically acceptable auxiliary agent is an adjuvant. 
     
     
         12 . The immunizing composition according to  claim 11 , wherein said adjuvant is alum. 
     
     
         13 . A method for immunization against the free N-terminus or free C-terminus of an internal self peptide cleavage product derived from a precursor protein or a mature protein, comprising administering to a mammal the immunizing composition according to  claim 10 , for which the internal peptide cleavage product is a self molecule of the mammal. 
     
     
         14 . The method according to  claim 13 , wherein the mammal is a human. 
     
     
         15 . The method according to  claim 14 , wherein the internal self peptide cleavage product is an amyloid β peptide, which when naturally-occurring, is derived from cleavage of β amyloid precursor protein, whereby said method raises antibodies specific to the free N-terminus and/or free C-terminus of the amyloid β peptide. 
     
     
         16 . A molecule comprising the antigen-binding portion of an antibody specific for the chimeric peptide according to  claim 1 . 
     
     
         17 . The molecule according to  claim 16 , wherein said antibody is a monoclonal antibody. 
     
     
         18 . A method for passive immunization, comprising administering to a mammal the molecule of  claim 16 . 
     
     
         19 . The method according to  claim 18 , wherein the mammal is human. 
     
     
         20 . The method according to  claim 19 , wherein said chimeric peptide against which the antibody is raised is one where the internal peptide cleavage product is an amyloid β peptide, which, when naturally-occurring, is derived from cleavage of β amyloid precursor protein (βAPP).