APC-Targeted DNA Vaccination Against Reticulocyte-Binding Protein Homolog 5 Induces Plasmodium falciparum-Specific Neutralizing Antibodies and T Cell Responses

Abstract

Targeted delivery of antigen to antigen presenting cells (APCs) is an efficient way to induce robust antigen-specific immune responses. Here, we present a novel DNA vaccine that targets the Plasmodium falciparum reticulocyte-binding protein homolog 5 (PfRH5), a leading blood-stage antigen of the human malaria pathogen, to APCs. The vaccine is designed as bivalent homodimers where each chain is composed of an amino-terminal single chain fragment variable (scFv) targeting unit specific for major histocompatibility complex class II (MHCII) expressed on APCs, and a carboxyl-terminal antigenic unit genetically linked by the dimerization unit. This vaccine format, named “Vaccibody”, has previously been successfully applied for antigens from other infectious diseases including influenza and HIV, as well as for tumor antigens. Recently, the crystal structure and key functional antibody epitopes for the truncated version of PfRH5 (PfRH5ΔNL) were characterized, suggesting PfRH5ΔNL to be a promising candidate for next-generation PfRH5 vaccine design. In this study, we explored the APC-targeting strategy for a PfRH5ΔNL-containing DNA vaccine. BALB/c mice immunized with the targeted vaccine induced higher PfRH5-specific IgG1 antibody responses than those vaccinated with a non-targeted vaccine or antigen alone. The APC-targeted vaccine also efficiently induced rapid IFN-γ and IL-4 T cell responses. Furthermore, the vaccine-induced PfRH5-specific IgG showed inhibition of growth of the P. falciparum 3D7 clone parasite in vitro. Finally, sera obtained after vaccination with this targeted vaccine competed for the same epitopes as PfRH5-specific mAbs from vaccinated humans. Robust humoral responses were also induced by a similar P. vivax Duffy-binding protein (PvDBP)-containing targeted DNA vaccine. Our data highlight a novel targeted vaccine platform for the development of vaccines against blood-stage malaria.

Targeting neoantigens to APC-surface molecules improves the immunogenicity and anti-tumor efficacy of a DNA cancer vaccine

“…Strategies to enhance the immunogenicity of pDNA vaccines include new backbone designs containing immunostimulatory sequences, co-administration of genetic adjuvants, or facilitated delivery by gene guns or electroporation (9). Targeting antigens to the surface of APCs is another successful strategy to amplify the magnitude of humoral and cellular responses induced by pDNAdelivered epitopes in preclinical settings (9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20)(21). APC-targeting pDNA vaccines encode fusion proteins consisting of an antigen fused to a molecule with the ability to bind receptors on the surface of professional APCs, hereon called APC-binding molecule.…”

The Dual Action of Human Antibodies Specific toPlasmodium falciparumPfRH5 and PfCyRPA: Blocking Invasion and Inactivating Extracellular Merozoites

“…The copyright holder for this preprint this version posted February 7, 2023. ; https://doi.org/10.1101/2023.02.07.527440 doi: bioRxiv preprint characterized and are compelling malaria vaccine candidates with experimental vaccination of non-human primates and humans with PfRH5 producing potent neutralizing antibodies [16,17].…”

“…PfRH5, PfCyRPA, PfRIPR, PfCSS and PfPTRAMP are required for merozoite invasion of erythrocytes with PfRH5, PfCyRPA, PfRIPR each able to stimulate the production of cross-strain neutralizing antibodies [6,[9][10][11][12][13][14][15]. Of the five PCRCR components, PfRH5, PfCyRPA and PfRIPR are the most well characterized and are compelling malaria vaccine candidates with experimental vaccination of non-human primates and humans with PfRH5 producing potent neutralizing antibodies [16,17].…”

The dual action of human antibodies specific to Plasmodium falciparum PfRH5 and PfCyRPA: Blocking invasion and inactivating extracellular merozoites

“…PfRH5, PfCyRPA, PfRIPR, PfCSS and PfPTRAMP are required for merozoite invasion of erythrocytes with PfRH5, PfCyRPA, PfRIPR each able to stimulate the production of cross-strain neutralizing antibodies [ 6 , 9 – 15 ]. Of the five PCRCR components, PfRH5, PfCyRPA and PfRIPR are the most well characterized and are compelling malaria vaccine candidates with experimental vaccination of non-human primates and humans with PfRH5 producing potent neutralizing antibodies [ 16 , 17 ]. Understanding the effect of antibodies targeting the PCRCR complex antigens, both in isolation and combination, is now critical to effective next-generation blood-stage vaccine design.…”