Protein D—an IGD binding protein of Haemophilus influenzae

Abstract

A novel surface exposed protein of Haemophilus influenzae or related Haemophilus species is described. The protein named protein D is an Ig receptor for human IgD and has an apparent molecular weight of 42,000. Protein D can be detected in all of 116 encapsulated and non-encapsulated isolates of H. influenzae studied. The protein from all strains shows in addition to the same apparent molecular weight immunogenic similarities since protein D from all strains interacts with three different mouse monoclonal antibodies and monoclonal human IgD. A method for purification of protein D is described. Cloning of the protein D gene from H. influenzae in E. coli is described as well as the nucleotide sequence and the deduced amino acid sequence.

1. A purified and isolated protein D, wherein said protein D:
 is isolatable from a Haemophilus species;  
 has an apparent molecular weight of 42,000 Daltons, as determined by sodium dodecyl sulphate polyacrylamide gel electrophoresis under reducing conditions and comparison to molecular weight standards; and  
 binds at least one monoclonal antibody that also binds protein D consisting of the amino acid sequence of SEQ ID NO: 3.  
 
     
     
       2. The purified and isolated protein D of  claim 1 , wherein the protein D is isolated from Haemophilus influenzae, Haemophilus haemolyticus, or Haemophilus aegypticus. 
     
     
       3. A purified and isolated peptide consisting of an immunogenic fragment of the protein D of  claim 1 . 
     
     
       4. A purified and isolated fusion protein wherein the protein D of  claim 1  is fused with another polypeptide. 
     
     
       5. A purified and isolated fusion protein wherein the peptide of  claim 3  is fused with another polypeptide. 
     
     
       6. A fusion product comprising the protein D of  claim 1  bound to a polypeptide, carbohydrate, or matrix. 
     
     
       7. A fusion product comprising the peptide of  claim 3  bound to a polypeptide, carbohydrate, or matrix. 
     
     
       8. An immunogenic composition comprising the protein D of  claim 1  and a pharmaceutical carrier. 
     
     
       9. An immunogenic composition comprising the peptide of  claim 3  and a pharmaceutical carrier. 
     
     
       10. An immunogenic composition comprising the fusion protein of  claim 4  and a pharmaceutical carrier. 
     
     
       11. An immunogenic composition comprising the fusion protein of  claim 5  and a pharmaceutical carrier. 
     
     
       12. An immunogenic composition comprising the fusion product of  claim 6  and a pharmaceutical carrier. 
     
     
       13. An immunogenic composition comprising the fusion product of  claim 7  and a pharmaceutical carrier. 
     
     
       14. The fusion product of  claim 6 , wherein the binding is covalent. 
     
     
       15. The fusion product of  claim 7 , wherein the binding is covalent.