Description

Product Description

NPNA Hexamer (CAS 114332-71-7) is a synthetic peptide antigen representing a repeating epitope motif from the Plasmodium falciparum circumsporozoite protein (CSP), a major surface antigen expressed during the sporozoite stage of malaria infection. This peptide, consisting of six tandem NPNA repeats, serves as an important tool for understanding malaria immunology and for developing next-generation sporozoite-based vaccines.

Background and Biological Context

Malaria remains one of the world’s most severe parasitic diseases, caused by Plasmodium species and transmitted through Anopheles mosquitoes. The CSP protein, located on the surface of P. falciparum sporozoites, plays a vital role in parasite motility, hepatocyte invasion, and host immune evasion. The central domain of CSP consists of repeating tetrapeptide motifs—NANP and NVDP repeats—that are highly immunogenic and recognized by neutralizing antibodies.

The NPNA repeat unit, a structural variant of the NANP motif, has been widely used in synthetic vaccine constructs due to its antigenic mimicry and enhanced immunoreactivity. When presented as a hexameric tandem peptide, NPNA mimics the repetitive pattern found in the natural CSP structure, promoting B-cell receptor cross-linking and strong antibody production.

Structural and Functional Properties

NPNA Hexamer (sequence: (NPNA)₆) forms a flexible and repetitive conformation that mimics the antigenic structure of the CSP central domain. It acts as a minimal epitope capable of inducing cross-reactive antibodies against native P. falciparum sporozoites.

This synthetic peptide can be conjugated to carrier proteins such as KLH (Keyhole Limpet Hemocyanin) or BSA (Bovine Serum Albumin) to enhance immunogenicity in experimental models. When used as a peptide-carrier conjugate, NPNA Hexamer elicits strong humoral immune responses, including high-affinity IgG antibodies that can neutralize sporozoite infectivity and prevent hepatocyte invasion.

Applications in Vaccine Development

NPNA Hexamer is a critical component in the rational design of malaria subunit vaccines. Its use spans multiple research domains, including:

• Antigen design and optimization for CSP-based vaccines.

• Epitope mapping and immunogenicity testing in animal and human models.

• Antibody binding studies for structural immunology and epitope-specific analysis.

• Development of diagnostic assays for malaria exposure and vaccine efficacy.

Historically, the RTS,S/AS01 (Mosquirix™) malaria vaccine, the first WHO-approved malaria vaccine, is based on the CSP antigen containing NANP repeat units similar to NPNA Hexamer. This demonstrates the translational value of NPNA-like motifs in vaccine design.

Immunological Mechanisms

Upon immunization, NPNA Hexamer stimulates the production of neutralizing antibodies that bind to the repetitive region of CSP on sporozoites, blocking their ability to invade hepatocytes. These antibodies:

• Recognize conserved epitopes across P. falciparum strains.

• Inhibit the motility of sporozoites in host tissue.

• Interfere with the infection process before the parasite reaches the liver.

This antibody-mediated neutralization mechanism underpins the protective efficacy of CSP-based vaccines and highlights NPNA Hexamer as a valuable immunogenic tool for pre-erythrocytic stage malaria research.

Research and Experimental Applications

• Synthetic peptide vaccine development

• ELISA and immunoblot assays for anti-CSP antibody detection

• Peptide conjugation and carrier design

• Monoclonal antibody generation against malaria epitopes

• Host-parasite interaction modeling

Summary

NPNA Hexamer provides a reliable and reproducible model for studying malaria immunogenicity and vaccine mechanisms. Its defined composition, structural stability, and immunological relevance make it indispensable for advancing malaria vaccine research and developing targeted prophylactic interventions.

Product Specifications

Synonyms

• Plasmodium falciparum CSP repeat peptide

• (NPNA)₆ peptide

• Malaria sporozoite antigen mimic

• NPNA tandem repeat peptide

Mechanism of Action

NPNA Hexamer acts as a structural and functional mimic of the CSP central repeat region from P. falciparum sporozoites. When introduced into a biological system, it elicits humoral immune responses by activating B-cell receptors (BCRs) specific for repetitive peptide motifs.

The multivalent NPNA repeat structure enables efficient cross-linking of BCRs on antigen-specific B cells, leading to enhanced antibody production and memory B cell formation. The antibodies generated against NPNA Hexamer recognize the native CSP antigen, thereby mediating protection against sporozoite invasion.

This immunogenic mechanism follows the principle of epitope repetition enhancing immunogenicity, commonly used in viral and parasitic vaccine design. By mimicking the native CSP conformation, NPNA Hexamer ensures high-affinity antibody binding and durable immune responses.

Side Effects / Safety Notes

NPNA Hexamer is non-toxic and biologically inert under experimental conditions. It does not possess any intrinsic pharmacological activity and should be used only for research purposes. Standard laboratory PPE, including gloves and eye protection, should be worn when handling this peptide.

Disclaimer

This product is for research use only and not intended for human or veterinary administration. The information provided is for scientific research and educational purposes. Compliance with institutional safety and regulatory guidelines is required for handling and use.

Keywords

NPNA hexamer, malaria vaccine peptide, CSP repeat peptide, Plasmodium falciparum antigen, sporozoite surface peptide, malaria immunogenic epitope, synthetic malaria peptide, vaccine antigen mimic, peptide-based malaria research, NPNA peptide antigen

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