Shark VNAR antibody - thermostable reagent for malaria rapid diagnostic tests

Overview

This solution leverages a novel single-domain antibody known as VNAR (Variable New Antigen Receptor), isolated from sharks, to overcome one of the most persistent limitations of malaria rapid diagnostic tests (RDTs): temperature sensitivity. The lead candidate, clone G1, specifically binds the Plasmodium falciparum histidine-rich protein 2 (PfHRP2) antigen. Unlike conventional monoclonal antibodies that lose binding stability above 60°C, VNAR G1 retains approximately 80% of its binding activity after one hour at 90°C and outperforms IgG antibodies across extended incubation at multiple temperatures. By enabling diagnostic kits to be stored at room temperature, this technology has the potential to simplify logistics, reduce cold-chain costs, and expand reliable malaria testing into resource-limited and field settings.

Technical specifications

Key features:

• Target specificity: Binds the PfHRP2 malaria antigen with retained affinity under extreme heat
• Exceptional thermostability: Functional after one hour at 90°C with approximately 80% activity retained; outperforms IgG, which loses stability at 60°C
• Soluble recombinant expression: Produced in an E. coli expression system, supporting scalable and cost-effective manufacturing
• Single-domain format: VNAR antibodies are smaller and structurally simpler than conventional antibodies, offering potential advantages in stability and engineering
• Phage display derivation: Isolated from a semi-synthetic shark VNAR library using biopanning against PfHRP2

Potential applications:

• Rapid diagnostic test kits for malaria that can be stored at ambient temperatures
• Point-of-care diagnostics in tropical, remote, or resource-limited environments
• Reagent for further diagnostic platform development and prototype integration

Technology readiness level

The VNAR G1 clone has been successfully isolated, recombinantly expressed in soluble form in E. coli, and verified for both antigen specificity and thermostability in laboratory and product verification studies. The antibody is positioned for integration into a malaria RDT prototype, with large-scale production and diagnostic platform development as the current focus. Future validation efforts are also being directed toward adapting the VNAR phage display pipeline to Dengue virus E protein targets, with plans to establish bacterial expression systems, purify recombinant antigens, and conduct biopanning over a projected one-year research timeline.