Structure‐based design of a Plasmodium vivax Duffy‐binding protein immunogen focuses the antibody response to functional epitopes

Abstract

The Duffy‐binding protein (DBP) is a promising antigen for a malaria vaccine that would protect against clinical symptoms caused by Plasmodium vivax infection. Region II of DBP (DBP‐II) contains the receptor‐binding domain that engages host red blood cells, but DBP‐II vaccines elicit many non‐neutralizing antibodies that bind distal to the receptor‐binding surface. Here, we engineered a truncated DBP‐II immunogen that focuses the immune response to the receptor‐binding surface. This immunogen contains the receptor‐binding subdomain S1S2 and lacks the immunodominant subdomain S3. Structure‐based computational design of S1S2 identified combinatorial amino acid changes that stabilized the isolated S1S2 without perturbing neutralizing epitopes. This immunogen elicited DBP‐II‐specific antibodies in immunized mice that were significantly enriched for blocking activity compared to the native DBP‐II antigen. This generalizable design process successfully stabilized an integral core fragment of a protein and focused the immune response to desired epitopes to create a promising new antigen for malaria vaccine development.