Immunogenic composition

Abstract

The present invention discloses modified Staphylococcus aureus HIa proteins which show reduced tendency to aggregate, improving protein stability and yield. Said modified HIa proteins optionally also contain glycosylation site consensus sequences. The invention also discloses a conjugate comprising a modified HIa protein and an antigen (for example a Staphylococcus aureus saccharide antigen), wherein the antigen is linked to an amino acid residue of the modified HIa protein.

1 - 49 . (canceled) 
     
     
         50 . A conjugate comprising an HIa protein comprising an amino acid sequence at least 80% identical to SEQ ID NO: 1, the HIa protein comprising: a) a substitution of histidine at position 48 of SEQ ID NO: 1 with cysteine, b) a substitution of glycine at position 122 of SEQ ID NO: 1 with cysteine, and c) optionally a substitution of histidine at position 35 of SEQ ID NO: 1, wherein the HIa protein is linked to a saccharide antigen. 
     
     
         51 . The conjugate of  claim 50 , the histidine at position 35 of SEQ ID NO: 1 being substituted. 
     
     
         52 . The conjugate of  claim 51 , the histidine at position 35 of SEQ ID NO: 1 being substituted to leucine. 
     
     
         53 . The conjugate of  claim 50  comprising a consensus sequence selected from: A) D/E-X-N-Z-S/T (SEQ ID NO: 11), wherein X and Z are independently any amino acid apart from proline, and B) K-D/E-X-N-Z-S/T-K (SEQ ID NO: 12), wherein X and Z are independently any amino acid apart from proline. 
     
     
         54 . The conjugate of  claim 53 , wherein the consensus sequence has been substituted for one or more amino acids selected from K131, S203, S239 and K273 of SEQ ID NO. 1. 
     
     
         55 . The conjugate of  claim 53 , wherein X is Q (glutamine) and Z is R (arginine). 
     
     
         56 . The conjugate of  claim 54 , the amino acid sequence being at least 85% identical to the amino acid sequence of SEQ ID NO: 7. 
     
     
         57 . The conjugate of  claim 50 , the HIa protein further comprising a signal sequence, which is capable of directing the HIa protein to the periplasm of a host cell, optionally the signal sequence being selected from SEQ ID NOs: 13-21, and optionally the signal sequence being at the N-terminus of the HIa protein. 
     
     
         58 . The conjugate of  claim 50 , the saccharide antigen being a polysaccharide or oligosaccharide antigen. 
     
     
         59 . The conjugate of  claim 50 , the saccharide antigen being a bacterial capsular saccharide. 
     
     
         60 . The conjugate of  claim 59 , the bacterial capsular saccharide being a  Staphylococcus aureus  capsular saccharide. 
     
     
         61 . The conjugate of  claim 60 , the  Staphylococcus aureus  capsular saccharide selected from  S. aureus  serotype 5 or 8 capsular saccharide. 
     
     
         62 . The conjugate of  claim 61 , the  Staphylococcus aureus  capsular saccharide being  S. aureus  serotype 5. 
     
     
         63 . An immunogenic composition comprising an immunologically effective amount of the conjugate of  claim 50 . 
     
     
         64 . The immunogenic composition of  claim 63  further comprising a pharmaceutically acceptable excipient or carrier 
     
     
         65 . A method of inducing an immune response to  Staphylococcus aureus  in a subject, the method comprising administering to the subject the conjugate of  claim 50  in an amount effective to induce the immune response. 
     
     
         66 . The method of  claim 65 , wherein the conjugate is administered in combination with an adjuvant. 
     
     
         67 . The method of  claim 66 , wherein the adjuvant is administered before, concomitantly with, or after administration of the conjugate. 
     
     
         68 . The method of  claim 66 , wherein the adjuvant is selected from an aluminum salt, 3-De-O-acylated monophosphoryl lipid A (MPL), and imidazopyridine compound, an imidazoquinoxaline compound, and a saponin. 
     
     
         69 . The method of  claim 68 , the adjuvant comprising 3D-MPL and QS-21 in a liposome.