Catalytic antibodies and a method of producing same

Abstract

The present invention relates generally to a growth factor precursor and its use to select production of antigen specific catalytic antibodies. Such catalytic antibodies are produced following B cell activation and proliferation induced by catalytic cleavage products of a target antigen portion of the growth factor precursor of the present invention. A particularly useful form of the growth factor precursor is as a nucleic acid vaccine. The nucleic acid vaccine of the present invention preferably further comprises a molecular adjuvant. Another aspect of the present invention comprises a growth factor precursor in multimeric form. The growth factor precursor of the present invention is useful for generating catalytic antibodies for both therapeutic, diagnostic and industrial purposes.

1 . A growth factor precursor comprising a recombinant polypeptide chain or a molecule having modular peptide components or a synthetic equivalent thereof wherein said polypeptide chain or modular peptide molecule comprises at least one B cell surface molecule binding portion, at least one T cell surface molecule binding portion capable of providing T cell dependent help to a B cell, an antigen cleavable by a catalytic antibody and a peptide portion comprising domains from both a variable heavy chain and a variable light chain of an immunoglobulin and wherein said variable heavy chain and variable light chain domains in the growth factor precursor, associate together by intra- and/or inter-domain bonding and substantially prevent the at least one B cell surface molecule binding portion from interacting with a B cell surface molecule such that upon cleavage of said antigen by a catalytic antibody, the peptide comprising said variable heavy chain and variable light chain domain permits the at least one B cell surface molecule binding portion to interact with a B cell surface molecule.  
     
     
         2 . A growth factor precursor comprising a recombinant polypeptide chain or a molecule having modular peptide components or a synthetic equivalent thereof wherein said polypeptide chain or modular peptide molecule comprises at least one B cell surface molecule binding portion, at least one T cell surface molecule binding portion capable of providing T cell dependent help to a B cell, an antigen cleavable by a catalytic antibody and a peptide portion comprising domains from both a variable heavy chain and a variable light chain of an immunoglobulin and wherein said variable heavy chain and variable light chain domains in the growth factor precursor associate together by intra- and/or inter-domain bonding and substantially prevent the at least one B cell surface molecule binding portion from interacting with a B cell surface molecule such that upon cleavage of said antigen by a catalytic antibody, the peptide comprising said variable heavy chain and variable light chain domain permits the at least one B cell surface molecule binding portion to interact with a B cell surface molecule wherein if said growth factor precursor comprises a single B cell surface molecule binding portion, then the growth factor precursor further comprises a multimerising inducing element.  
     
     
         3 . A growth factor precursor according to  claim 1  or  2  further comprising a multimerizing inducing element.  
     
     
         4 . A growth factor precursor according to  claim 1  or  2  further comprising a multimerizing inducing element wherein the multimerizing inducing element is a signal peptide.  
     
     
         5 . A growth factor precursor according to  claim 4  wherein the signal peptide is from ompA or a functional equivalent or derivative thereof.  
     
     
         6 . A growth factor precursor according to  claim 1  or  2  wherein the B cell surface molecule binding portion is the immunoglobulin binding domain from protein L from  Peptostreptococcus magnus  or a derivative or functional equivalent hereof.  
     
     
         7 . A growth factor according to  claim 1  or  2  wherein the variable heavy and light chains masking the B cell surface molecule binding portion are stabilised by inter- and/or intra-domain disulphide bridges.  
     
     
         8 . A recombinant or synthetic growth factor precursor comprising the structure:  
       I′AX 1 [X 2 ] d [X 3 ] a [A] r I″ 
       wherein: 
 X 1  and X 3  are B cell surface molecule binding portions;  
 a is 0 or 1 or>1;  
 I′ and I″ are either both present or only one is present and they may be the same or different and each is a blocking reagent for X 1  and/or X 3  such as a variable heavy and light chain or a sc-ds-Fv molecule;  
 A is the target antigen for which a catalytic antibody is sought;  
 X 2  is an entity providing T cell dependent help to a B cell;  
 d is 0, 1 or >1;  
 r is 0, 1 or >1,  
 wherein a catalytic antibody on the surface of said B cell is capable of cleaving all or part of A from said recombinant or synthetic molecule resulting in the molecule [A′]X 1 X 2 [X 3 ] a [A′] wherein A′ is optionally present and is a portion of A after cleavage with the catalytic antibody wherein said resulting molecule is capable of inducing B cell mitogenesis of the B cell to which X 1  and X 3  bind.  
 
     
     
         9 . An isolated nucleic acid molecule comprising a sequence of nucleotides encoding a recombinant growth factor according to  claim 1  or  2  or  8 .  
     
     
         10 . A method for producing catalytic antibodies to a specific antigen, said method comprising administering to an animal an effective amount of a growth factor precursor comprising an antigen capable of interacting with a B cell bound catalytic antibody said antigen fused to a B cell surface molecule binding portion for a time and under conditions for said antigen to be cleaved and for the remainder of the molecule to induce B cell mitogenesis.  
     
     
         11 . A method according to  claim 10  wherein the growth factor comprises a portion capable of providing T cell dependent help for a B cell.  
     
     
         12 . A method according to  claim 10  further comprising the sequential or simultaneous administration of a molecule capable of providing T cell dependent help for a B cell.  
     
     
         13 . A composition comprising the recombinant or synthetic growth factor precursor thereof according to any one of claims I or 2 and one or more pharmaceutical carriers and/or diluents.  
     
     
         14 . A composition comprising a catalytic antibody generated to the growth factor precursor thereof according to any one of claims  1  or  2 .  
     
     
         15 . A recombinant or synthetic growth factor precursor thereof which comprises (fie structure:  
       [I′AX 1 [X 2 ′] o [X 2 X 3 [A] p I″] n ] m    
       wherein: 
 I′ and I″ are both present or only one is present and each is a blocking reagent for X 1  and/or X3 such as a variable heavy or light component or an sc-ds-Fv;  
 A is the target antigen for which a catalytic antibody is sought;  
 X 1  and X 3  are B cell surface molecule binding portions;  
 X 2  and X 2 ′ may be the same or different and each is an entity capable or providing T cell dependent help for a B cell;  
 o may be 0 or 1;  
 p may be 0 or 1;  
 n indicates the multimeric nature of the component in parentheses and may be 0, 1 or >1;  
 m indicates the multimeric nature of the component in parenthesis and may be 1 or >1;  
 
     
     
         16 . The use of the products of catalysis of a growth factor precursor according to  claim 1  or  2  to induce B cell mitogenesis to generate catalytic antibodies to a specific antigen.  
     
     
         17 . A catalytic antibody generated using the growth factor precursor thereof according to  claim 1  or  2 .  
     
     
         18 . A nucleic acid molecule according to  claim 9  further comprising a nucleotide sequence encoding a molecular adjuvant.  
     
     
         19 . A nucleic acid molecule according to  claim 18  wherein the molecular adjuvant is selected from C3d, CTLA4 and CD40L.