Antibodies targeting a galactan-based o-antigen of k. pneumoniae

Abstract

The invention provides for an isolated antibody that specifically recognizes a galactan-III epitope of the lipopolysaccharide (LPS) O-antigen structure of Klebsiella pneumoniae, which epitope is incorporated in galactan-III repeating units, wherein the galactan-III repeating unit is a branched galactose homopolymer of Formula (I). The invention further provides for a pharmaceutical or diagnostic preparation comprising said antibody, and a method of producing said antibody.

1 - 29 . (canceled) 
     
     
         30 . An isolated nucleic acid encoding an isolated antibody comprising an antigen-binding site that specifically recognizes a galactan-III epitope of the lipopolysaccharide (LPS) O-antigen structure of  Klebsiella pneumoniae , which epitope is incorporated in galactan-III repeating units, wherein each galactan-III repeating unit is a branched galactose homopolymer of Formula (I) 
       
         
           
           
               
               
           
         
         which antigen-binding site is of an antibody heavy chain variable region (VH), which comprises a combination of VH-CDR sequences designated as CDR1 to CDR3, and an antibody light chain variable region (VL), which comprises a combination of VL-CDR sequences designated as CDR4 to CDR6, 
         wherein the antibody is selected from the group consisting of:
 i) is an antibody which comprises
 a) a CDR1 consisting of the amino acid sequence of SEQ ID NO:7; 
 b) a CDR2 consisting of the amino acid sequence of SEQ ID NO:8; 
 c) a CDR3 consisting of the amino acid sequence of SEQ ID NO:9; 
 d) a CDR4 consisting of the amino acid sequence of SEQ ID NO:19; 
 e) a CDR5 consisting of the amino acid sequence of SEQ ID NO:20; and 
 f) a CDR6 consisting of the amino acid sequence of SEQ ID NO:18; 
 
 ii) is an antibody which comprises
 a) a CDR1 consisting of the amino acid sequence of SEQ ID NO:1; 
 b) a CDR2 consisting of the amino acid sequence of SEQ ID NO:2; 
 c) a CDR3 consisting of the amino acid sequence of SEQ ID NO:3; 
 d) a CDR4 consisting of the amino acid sequence of SEQ ID NO:13; 
 e) a CDR5 consisting of the amino acid sequence of SEQ ID NO:14; and 
 f) a CDR6 consisting of the amino acid sequence of SEQ ID NO:15; 
 
 iii) is an antibody which comprises
 a) a CDR1 consisting of the amino acid sequence of SEQ ID NO:4; 
 b) a CDR2 consisting of the amino acid sequence of SEQ ID NO:5; 
 c) a CDR3 consisting of the amino acid sequence of SEQ ID NO:6; 
 d) a CDR4 consisting of the amino acid sequence of SEQ ID NO:16; 
 e) a CDR5 consisting of the amino acid sequence of SEQ ID NO:17; and 
 f) a CDR6 consisting of the amino acid sequence of SEQ ID NO:18; 
 
 iv) is an antibody which comprises
 a) a CDR1 consisting of the amino acid sequence of SEQ ID NO:10; 
 b) a CDR2 consisting of the amino acid sequence of SEQ ID NO:11; 
 c) a CDR3 consisting of the amino acid sequence of SEQ ID NO:12; 
 d) a CDR4 consisting of the amino acid sequence of SEQ ID NO:19; 
 e) a CDR5 consisting of the amino acid sequence of SEQ ID NO:17; and 
 f) a CDR6 consisting of the amino acid sequence of SEQ ID NO:18; 
 
 v) is an antibody which comprises
 a) a CDR1 consisting of the amino acid sequence of SEQ ID NO:4; 
 b) a CDR2 consisting of the amino acid sequence of SEQ ID NO:5; 
 c) a CDR3 consisting of the amino acid sequence of SEQ ID NO:6; 
 d) a CDR4 consisting of the amino acid sequence of SEQ ID NO:19; 
 e) a CDR5 consisting of the amino acid sequence of SEQ ID NO:20; and 
 f) a CDR6 consisting of the amino acid sequence of SEQ ID NO:18; 
 
 and 
 vi) is an antibody which comprises
 a) a CDR1 consisting of the amino acid sequence of SEQ ID NO:10; 
 b) a CDR2 consisting of the amino acid sequence of SEQ ID NO:11; 
 c) a CDR3 consisting of the amino acid sequence of SEQ ID NO:12; 
 d) a CDR4 consisting of the amino acid sequence of SEQ ID NO:19; 
 e) a CDR5 consisting of the amino acid sequence of SEQ ID NO:20; and 
 f) a CDR6 consisting of the amino acid sequence of SEQ ID NO:18. 
 
 
       
     
     
         31 . An expression cassette or a plasmid comprising a coding sequence to express a protein comprising a heavy chain variable region (VH) and light chain variable region (VL) of an antibody comprising an antigen-binding site that specifically recognizes a galactan-III epitope of the lipopolysaccharide (LPS) O-antigen structure of  Klebsiella pneumoniae , which epitope is incorporated in galactan-III repeating units, wherein each galactan-III repeating unit is a branched galactose homopolymer of Formula (I) 
       
         
           
           
               
               
           
         
         which antigen-binding site is of an antibody VH, which comprises a combination of VH-CDR sequences designated as CDR1 to CDR3, and an antibody VL, which comprises a combination of VL-CDR sequences designated as CDR4 to CDR6, 
         wherein the antibody is selected from the group consisting of:
 i) is an antibody which comprises
 a) a CDR1 consisting of the amino acid sequence of SEQ ID NO:7; 
 b) a CDR2 consisting of the amino acid sequence of SEQ ID NO:8; 
 c) a CDR3 consisting of the amino acid sequence of SEQ ID NO:9; 
 d) a CDR4 consisting of the amino acid sequence of SEQ ID NO:19; 
 e) a CDR5 consisting of the amino acid sequence of SEQ ID NO:20; and 
 f) a CDR6 consisting of the amino acid sequence of SEQ ID NO:18; 
 
 ii) is an antibody which comprises
 a) a CDR1 consisting of the amino acid sequence of SEQ ID NO:1; 
 b) a CDR2 consisting of the amino acid sequence of SEQ ID NO:2; 
 c) a CDR3 consisting of the amino acid sequence of SEQ ID NO:3; 
 d) a CDR4 consisting of the amino acid sequence of SEQ ID NO:13; 
 e) a CDR5 consisting of the amino acid sequence of SEQ ID NO:14; and 
 f) a CDR6 consisting of the amino acid sequence of SEQ ID NO:15; 
 
 iii) is an antibody which comprises
 a) a CDR1 consisting of the amino acid sequence of SEQ ID NO:4; 
 b) a CDR2 consisting of the amino acid sequence of SEQ ID NO:5; 
 c) a CDR3 consisting of the amino acid sequence of SEQ ID NO:6; 
 d) a CDR4 consisting of the amino acid sequence of SEQ ID NO:16; 
 e) a CDR5 consisting of the amino acid sequence of SEQ ID NO:17; and 
 f) a CDR6 consisting of the amino acid sequence of SEQ ID NO:18; 
 
 iv) is an antibody which comprises
 a) a CDR1 consisting of the amino acid sequence of SEQ ID NO:10; 
 b) a CDR2 consisting of the amino acid sequence of SEQ ID NO:11; 
 c) a CDR3 consisting of the amino acid sequence of SEQ ID NO:12; 
 d) a CDR4 consisting of the amino acid sequence of SEQ ID NO:19; 
 e) a CDR5 consisting of the amino acid sequence of SEQ ID NO:17; and 
 f) a CDR6 consisting of the amino acid sequence of SEQ ID NO:18; 
 
 v) is an antibody which comprises
 a) a CDR1 consisting of the amino acid sequence of SEQ ID NO:4; 
 b) a CDR2 consisting of the amino acid sequence of SEQ ID NO:5; 
 c) a CDR3 consisting of the amino acid sequence of SEQ ID NO:6; 
 d) a CDR4 consisting of the amino acid sequence of SEQ ID NO:19; 
 e) a CDR5 consisting of the amino acid sequence of SEQ ID NO:20; and 
 f) a CDR6 consisting of the amino acid sequence of SEQ ID NO:18; 
 
 and 
 vi) is an antibody which comprises
 a) a CDR1 consisting of the amino acid sequence of SEQ ID NO:10; 
 b) a CDR2 consisting of the amino acid sequence of SEQ ID NO:11; 
 c) a CDR3 consisting of the amino acid sequence of SEQ ID NO:12; 
 d) a CDR4 consisting of the amino acid sequence of SEQ ID NO:19; 
 e) a CDR5 consisting of the amino acid sequence of SEQ ID NO:20; and 
 f) a CDR6 consisting of the amino acid sequence of SEQ ID NO:18. 
 
 
       
     
     
         32 . A host cell comprising an expression cassette or a plasmid of  claim 31 . 
     
     
         33 . A method of producing an antibody wherein a host cell of  claim 32  is cultivated or maintained under conditions to produce said antibody. 
     
     
         34 . A method of identifying a candidate antibody comprising:
 a) providing a sample containing an antibody or antibody-producing cell; and   b) assessing for binding of an antibody in or produced by the sample with a galactan-III epitope of the lipopolysaccharide (LPS) O-antigen structure of  Klebsiella pneumoniae , which epitope is incorporated in galactan-III repeating units, wherein each galactan-III repeating unit is a branched galactose homopolymer of Formula (I)   
       
         
           
           
               
               
           
         
         wherein a positive reaction between the antibody and the epitope identifies the antibody as candidate antibody. 
       
     
     
         35 . A method of identifying a candidate antibody comprising:
 a) providing a sample containing an antibody or antibody-producing cell; and   b) assessing for binding of an antibody in or produced by the sample with a galactan-III epitope of the lipopolysaccharide (LPS) O-antigen structure of  Klebsiella pneumoniae , which epitope is incorporated in galactan-III repeating units, wherein each galactan-III repeating unit is a branched galactose homopolymer of Formula (I)   
       
         
           
           
               
               
           
         
       
       wherein a specific positive reaction between the antibody and the galactan-III epitope relative to the galactan-I epitope identifies the antibody as candidate antibody. 
     
     
         36 . A method of producing an antibody, comprising
 a) providing a candidate antibody identified by
 1) providing a sample containing an antibody or antibody-producing cell; and 
 2) assessing for binding of an antibody in or produced by the sample with a galactan-III epitope of the lipopolysaccharide (LPS) O-antigen structure of  Klebsiella pneumoniae , which epitope is incorporated in galactan-III repeating units, wherein each galactan-III repeating unit is a branched galactose homopolymer of Formula (I) 
   
       
         
           
           
               
               
           
         
         wherein a positive reaction between the antibody and the epitope identifies the antibody as candidate antibody or wherein a specific positive reaction between the antibody and the galactan-III epitope relative to the galactan-1 epitope identifies the antibody as candidate antibody; and 
         b) producing a monoclonal antibody, or a humanized or human form of the candidate antibody, or a derivative thereof with the same epitope binding specificity as the candidate antibody.