IMX313 domain (IMX313)

The **IMX313 domain** is a synthetic, engineered 55-amino-acid protein domain derived as a hybrid from the oligomerization domains of chicken complement inhibitor C4b-binding protein (C4bp), which shares approximately 21% homology with the human analogue. Its primary function is to **self-assemble into stable heptameric (seven-unit) nanoparticles** when fused genetically to an antigen, resulting in increased immunogenicity of the fused antigen by promoting higher-order multimerization. This multimerization has been shown to significantly enhance antibody and sometimes T-cell responses to the antigen, improving vaccine efficacy in preclinical and early clinical studies, particularly for malaria (e.g. *Plasmodium falciparum* Pfs25-IMX313) and tuberculosis (e.g. Ag85A-IMX313) vaccines. IMX313 itself does not function as a direct biological target (such as a receptor or enzyme) but rather serves as a molecular scaffold for antigen display in novel vaccine constructs[1][2][3][4][5][6]. IMX313 is not an endogenous protein, nor is it listed as a validated therapeutic target for drug discovery, and is instead a biotechnological tool for immunogen design[2][3][4]. Fusion of antigens to IMX313 is required for its adjuvant-like properties; mixing IMX313 as a separate protein with an antigen does not produce the same effect[5]. Early-phase clinical trials have shown favorable safety and immunogenicity, with no significant immune reactivity to the human homolog detected[2][3]. IMX313 is not associated with small-molecule drugs and does not itself serve as a biomarker; safety concerns are specific to the context of the antigen to which it is fused and to the theoretical risk of breaking immunological tolerance to self-proteins. Summary: - IMX313 is a synthetic oligomerization domain used to assemble antigens into higher-order structures, acting as a vaccine immunogenicity enhancer by multivalency, but is not a molecular therapeutic target in the conventional sense. - It is most accurately classified as an engineered protein domain used as a vaccine design tool. - Not applicable for lists of canonical "therapeutic targets," drug interactions, biomarkers, or mechanism-of-action in isolation. If structured fields are required for a molecule that is a genuine therapeutic target (e.g., receptor, enzyme), IMX313 does not qualify; record this entry as non-target/informational and flag as "is_incorrect: true" for this reason[2][3][4][5][6].

Other names

Hybrid chicken C4b-binding protein oligomerization domainC4bp oligomerization domainC4bp (IMX313 variant) domain