Bifunctional protein anchors

Abstract

The disclosure relates to the areas of immunology and vaccine delivery. More specifically, it relates to a bacterial vaccine delivery technology with built-in immunostimulatory properties which allow the immobilization of any antigen of interest, without prior antigen modification. Provided is an antigen-loaded immunogenic carrier complex comprising at least one bifunctional polypeptide attached to an immunogenic carrier, the bifunctional polypeptide comprising a peptidoglycan binding domain (PBD) through which the polypeptide is attached to the carrier, fused to an antigen binding domain (ABD) to which at least one antigen of interest is bound. Also described is a pharmaceutical (e.g., vaccine) composition comprising an antigen-loaded immunogenic carrier complex.

1 .- 14 . (canceled) 
     
     
         15 . A method of delivering an antigen of interest to a subject, the method comprising:
 delivering to the subject an antigen loaded immunogenic carrier complex comprising:
 at least one bifunctional polypeptide attached to an immunogenic carrier, said bifunctional polypeptide comprising a peptidoglycan binding domain (PBD) through which the bifunctional polypeptide is attached to said immunogenic carrier, fused to an antigen binding domain (ABD) that non-covalently binds the antigen of interest, 
   wherein said PBD comprises a LysM domain, provided that the PBD is able to attach to the cell wall of a Gram-positive microorganism; and   wherein at least one antigen of interest is non-covalently bound to said ABD.   
     
     
         16 . The method according to  claim 15 , wherein delivery to the immune system comprises delivery to a mucosal site. 
     
     
         17 . (canceled) 
     
     
         18 . The method according to  claim 15 , wherein at least two bifunctional polypeptides are attached to the immunogenic carrier, each bifunctional polypeptide having a distinct ABD and distinct antigen of interest. 
     
     
         19 . The method according to  claim 15 , wherein the immunogenic carrier comprises a non-viable spherical peptidoglycan particle obtained from a Gram positive bacterium. 
     
     
         20 . The method according to  claim 19 , wherein the bacterium is a non-pathogenic bacterium. 
     
     
         21 . The method according to  claim 20 , wherein the bacterium is selected from the group consisting of a  Lactococcus , a  Lactobacillus , a  Bacillus  and a  Mycobacterium  ssp. 
     
     
         22 . The method according to  claim 15 , wherein the PBD comprises the C-terminal peptidoglycan binding domain of the  Lactococcus lactis  cell wall hydrolase AcmA. 
     
     
         23 . The method according to  claim 15 , wherein the ABD binds an antigen selected from the group consisting of a polypeptide, carbohydrate, lipid, polynucleotide, pathogenic antigen, inactivated viral particle, and purified antigenic determinant.