# Generating fast-on rate reagents for lateral flow assays to detect HCV

> **NIH NIH R43** · TANGO BIOSCIENCES, INC. · 2023 · $275,606

## Abstract

Hepatitis C virus (HCV) is a small, enveloped RNA virus that causes hepatitis C and some forms
of liver cancer and lymphoma. Many infected individuals are asymptomatic, which makes early
diagnosis challenging. In the proposed work, we will apply phage-display to produce avidity-
boosted and fast on-rate recombinant affinity reagents for use in capture and detection of HCV
core Ag in lateral flow assays (LFAs). This project is a collaboration between Tango Biosciences,
and the University of Houston laboratory of Prof. Richard Willson. Tango is a start-up specializ-
ing in innovative techniques in the phage-display and avidity engineering of combinatorial pep-
tides, antibody fragments, and antibody surrogates. Dr. Willson has extensive technical and
translational experience with LFAs.For Specific Aim #1, Tango will generate recombinant affinity
reagents by phage-display that bind the HCV core antigen (cAg) with high affinity and fast on-
rates. Tango will discover monobodies and human single-chain variable fragments (scFvs) that
bind different epitopes of cAg via Megaprimer Shuffled Tandem Affinity Reagents (MegaSTAR).
Tango will mutagenize the coding regions of individual monobodies/scFvs and select for fast on-
rates (critical in LFA) and slow off-rates. Tandem high-avidity forms of the best monobodies/
scFvs will be constructed with different length linkers for phage-display and conversion into LFA
reporter nanoparticles. We will aim for the following performance metrics for optimized affinity
reagents: on-rates of 108 M-1 sec-1 and dissociation constants of ≤ 1 pM. In Specific Aim #2, viri-
ons and soluble forms of the optimized affinity reagents will be formatted by Dr. Willson's team
as capture and detector reagents in phage LFAs. After systematically testing buffers, conjugate
and blocking chemistries, the goal will be to reach a limit of detection (LOD) of cAg (spiked into
human plasma) of 0.5 pM (10 pg/mL), which is sensitive enough to detect 85% of HCV infec-
tions. We will validate the optimized LFA format by spiking cAg over a range of concentrations
into commercial, de-identified human plasma from both sexes, a range of ages, and varied dis-
ease and metabolic backgrounds, to detect any cofounding biological variables. Finally, the best
affinity reagents and prototype LFA will be evaluated in the laboratory of an HCV expert. Suc-
cessful completion of this work will lead to a prototype LFA for HCV cAg and establish a re-
search paradigm applicable for the development of superior LFAs for detecting infections.
-1-

## Key facts

- **NIH application ID:** 10697630
- **Project number:** 1R43AI172709-01A1
- **Recipient organization:** TANGO BIOSCIENCES, INC.
- **Principal Investigator:** BRIAN KENNETH KAY
- **Activity code:** R43 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2023
- **Award amount:** $275,606
- **Award type:** 1
- **Project period:** 2023-04-13 → 2025-03-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10697630

## Citation

> US National Institutes of Health, RePORTER application 10697630, Generating fast-on rate reagents for lateral flow assays to detect HCV (1R43AI172709-01A1). Retrieved via AI Analytics 2026-05-22 from https://api.ai-analytics.org/grant/nih/10697630. Licensed CC0.

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