Polypeptide carrier protein

Abstract

The invention relates to polypeptide carrier proteins that comprise at least five CD4+ T cell epitopes, for conjugation to capsular polysaccharides. The carrier proteins are useful as components of vaccines that can elicit a T-cell dependent immune response. These vaccines are particularly useful to confer protection against infection from encapsulated bacteria in infants between the ages of 3 months and about 2 years.

1 . A carrier protein comprising at least five CD4+ T cell epitopes. 
     
     
         2 . A carrier protein according to  claim 1 , wherein the CD4+ epitopes are derived from a pathogenic bacterium or virus. 
     
     
         3 . A carrier protein according to  claim 1 , wherein the CD4+ epitopes are derived from tetanus toxin,  Plasmodium falciparum  circurnsporozite protein, hepatitis B surface antigen, hepatitis B nuclear core protein, influenza matrix protein, influenza haernagglutinin, diptheria toxoid, diptheria toxin mutant CRM 197, group B  Neisseria meningitidis  outer membrane protein complex, pertussis toxin or heat shock protein 70. 
     
     
         4 . A carrier protein according to  claim 1 , wherein the CD4+ epitopes are selected from P23TT, P32TT, P21TT, PfCs, MOTT, P2TT, HBVnc, HA, HbsAg, MT and hsp70 CD4+ epitopes. 
     
     
         5 . A carrier protein according to  claim 1 , that comprises the P23TT, P32TT, P21TT, PfCs, MOTT, P2TT, HBVnc, HA, HbsAg and MT CD4+ epitopes. 
     
     
         6 . A carrier protein according to  claim 1 , that comprises the P23TT, P32TT, P21TT, PfCs, P3 OTT, P2TT, HBVnc, HA, HbsAg, MT and hsp70 CD4+ epitopes. 
     
     
         7 . A carrier protein according to  claim 1 , that comprises the P23TT, P32TT, P21TT, PfCs, P30TT and P2TT CD4+ epitopes. 
     
     
         8 . A carrier protein according  claim 1 , wherein the CD4+ epitopes are human CD4+ epitopes. 
     
     
         9 . A carrier protein which comprises one or more of N6, N10 or N19 proteins. 
     
     
         10 . A carrier protein according to  claim 1 , in an oligomeric form. 
     
     
         11 . A carrier protein according to  claim 1 , conjugated to a polysaccharide. 
     
     
         12 . A carrier protein according to  claim 11 , wherein the polysaccharide is an  Haemophilus influenzae  type B polysaccharide. 
     
     
         13 . A carrier protein according to  claim 11 , wherein the polysaccharide is derived from  S. pneumoniae, N. meningitidis, S. aureus, Klebsiella , or  S. typhimurium.    
     
     
         14 . A carrier protein according to  claim 11 , wherein the polysaccharide is conjugated to the protein by a covalent linkage. 
     
     
         15 . A carrier protein according to  claim 11 , wherein the polysaccharide is conjugated to the protein by reductive amination. 
     
     
         16 . A carrier protein according to  claim 11 , wherein there are between two and ten protein units for each polysaccharide unit. 
     
     
         17 . A composition comprising the carrier protein of  claim 1 . 
     
     
         18 . A method of vaccinating a mammalian subject comprising administering the carrier protein of  claim 1  to said subject. 
     
     
         19 . A method of protecting a mammalian subject from a disease caused by an encapsulated bacterium comprising administering the carrier protein of  claim 1  to said subject. 
     
     
         20 . A nucleic acid molecule which encodes a carrier protein according to  claim 1 . 
     
     
         21 . The nucleic acid molecule of  claim 20  which comprises DNA. 
     
     
         22 . A cloning or expression vector comprising a nucleic acid molecule according to  claim 20 . 
     
     
         23 . A host cell transformed or transfected with the vector of  claim 22 . 
     
     
         24 . A transgenic animal that has been transformed by a nucleic acid molecule according to  claim 20 . 
     
     
         25 . A transgenic animal that has been transformed by the vector of  claim 22 . 
     
     
         26 . A method of preparing a carrier protein comprising expressing a vector according to  claim 22  in a host cell and culturing said host cell under conditions where said protein is expressed, and recovering said expressed protein. 
     
     
         27 . The method of  claim 26 , further comprising the step of conjugating the recovered protein to a polysaccharide. 
     
     
         28 . The method of  claim 26 , wherein the host cell is an  E. coli  bacterium. 
     
     
         29 . A method of producing a carrier protein according to  claim 1 , comprising
 (a) constructing oligonucleotide molecules that encode said epitopes;   (b) annealing the oligonucleotide molecules to form duplexes;   (c) introducing the oligonucleotide duplexes into an expression vector so as to encode a fusion protein;   (d) introducing the expression vector into a host cell to allow expression of the fusion protein; and   (e) isolating the fusion protein produced from a culture of said host cells.   
     
     
         30 . The method of  claim 29 , further comprising (f) conjugating the fusion protein to a polysaccharide. 
     
     
         31 . The method of  claim 29 , wherein the host cell is an  E. coli  bacterium.