Neisseria meningitidis serogroup a capsular polysaccharide acetyltransferase, methods and compositions

Abstract

Provided are recombinant DNA molecules that do not occur in nature encoding an O-acetyltransferase, vectors that direct expression of an O-acetyltransferase, recombinant host cells which express an O-acetyltransferase, methods for recombinant production of an O-acetyltransferase, methods for acetylating capsular polysaccharides, especially those of a Serogroup A Neisseria meningitidis using a recombinant O-acetyltransferase, and immunogenic compositions comprising the acetylated capsular polysaccharide.

1 . A DNA molecule comprising a Serogroup A  Neisseria meningitidis  O-acetyltransferase coding sequence and transcriptional control sequences with which said O-acetyltransferase coding sequence is not associated in nature, said coding sequence and said transcriptional control sequences being operably linked.  
     
     
         2 . The DNA molecule of  claim 1 , wherein said O-acetyltransferase consists of the amino acid sequence of SEQ ID NO:2.  
     
     
         3 . The DNA molecule of  claim 2 , wherein said O-acetyltransferase coding sequence is as given in SEQ ID NO:1.  
     
     
         4 . The DNA molecule of  claim 1 , further comprising a sequence encoding an affinity tag and fused in frame selected from the group consisting of a streptavidin tag, a flagellar antigen epitope tag, a polyhistidine tag, a glutathione-S-transferase tag or a calmodulin tag or a streptactin tag.  
     
     
         5 . The DNA molecule of  claim 1 , further comprising vector sequences functional in a bacterial cell.  
     
     
         6 . The DNA molecule of  claim 5 , wherein the vector sequences are functional in  Escherichia coli.    
     
     
         7 . A bacterial host cell in which the DNA molecule of  claim 1  is stably maintained.  
     
     
         8 . A method for recombinantly producing an O-acetyltransferase comprising the step of culturing the bacterial host cell of  claim 6  under conditions such that the O-acetyltransferase is expressed.  
     
     
         9 . The method of  claim 7  further comprising recovering the O-acetyltransferase.  
     
     
         10 . A method for acetylating Serogroup A capsular polysaccharide prepared from  Neisseria meningitidis , said method comprising the step of contacting an isolated capsular polysaccharide with the O-acetyltransferase produced by the method of  claim 9 .  
     
     
         11 . An improved immunogenic composition comprising an acetylated capsular polysaccharide of  Neisseria meningitidis , wherein the improvement comprises acetylation of the capsular polysaccharide according to the method of  claim 10.