# Shark nanobodies enable identification of pan-sarbecovirus and pan-merbecovirus spike RBD sites of vulnerability

> **NIH NIH R21** · UNIVERSITY OF MARYLAND BALTIMORE · 2024 · $228,712

## Abstract

PROJECT SUMMARY
 SARS-CoV-2, a betacoronavirus, is the etiologic agent of the ongoing COVID-19 pandemic. In response,
worldwide efforts have led to the rapid development of multiple vaccine candidates that have shown efficacy in
controlled clinical trials and effectiveness in the general population. Despite these advances, viral variants of
concern (VOC) continue to emerge, while the pandemic potential of future coronavirus zoonotic spillovers
remains high. Thus, the overall aim of our research efforts is to guide pan-coronavirus vaccine research and the
provision of immunotherapeutic molecules with broad specificity for future pandemic prevention. To this end we
will interrogate VNAR nanobody repertoires cloned from nurse sharks that have received sequential
heterologous CoV spike ferritin nanoparticle (SpFN) immunizations, i.e., primed with SARS-CoV-2 SpFN, and
recalled with either SARS-CoV-1 SpFN or MERS-CoV SpFN, to identify broadly conserved, neutralizing
epitopes. Isolated nanobodies will be produced in recombinant form and evaluated for function and specificity
using binding, affinity, and competition mapping assays, followed by viral neutralization, and in vivo protection
studies. Based upon our preliminary studies we anticipate that we will find VNAR nanobodies that can target (i)
pan-sarbecovirus epitopes, (ii) pan-merbecovirus epitopes, and potentially (iii) pan-sarbecovirus-merbecovirus
epitopes. To explore this further we will undertake detailed structural biology studies of our current set of broadly
sarbecovirus-reactive VNARs as well as any newly identified VNARs. Using X-ray crystallography and Cryo-EM
imaging we will determine the binding epitope of each VNAR. This atomic level information will be used to map
cross-neutralizing CoV immune epitopes and provide information that can be used in the design of new
immunogens that will elicit pan-sarbecovirus and pan-merbecovirus protective immune responses.
 The proposed research is significant because it will provide unique information that can be used to guide
next generation immunogen design and vaccination strategies for protection against SARS-CoV-2 VOC and
future sarbecovirus and merbecovirus zoonotic spillover events. The novelties of our project are (1) the
immunization of nurse sharks with heterologous and highly immunogenic CoV SpFN molecules to elicit broadly
neutralizing antibody responses; (2) the use of structurally unique VNAR nanobodies to probe sites of
vulnerability on sarbecovirus and merbecovirus spike proteins; (3) utilization of a broad panel of sarbecovirus
and merbecovirus RBD molecules to assess the breadth of recognition for both binding and structural studies;
(4) the combination of cross-functional and long-standing expertise in shark immunology and VNAR
identification, vaccine design and structural biology, and small animal challenge studies.

## Key facts

- **NIH application ID:** 10791903
- **Project number:** 5R21AI175680-02
- **Recipient organization:** UNIVERSITY OF MARYLAND BALTIMORE
- **Principal Investigator:** Helen M. Dooley
- **Activity code:** R21 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2024
- **Award amount:** $228,712
- **Award type:** 5
- **Project period:** 2023-02-17 → 2025-01-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10791903

## Citation

> US National Institutes of Health, RePORTER application 10791903, Shark nanobodies enable identification of pan-sarbecovirus and pan-merbecovirus spike RBD sites of vulnerability (5R21AI175680-02). Retrieved via AI Analytics 2026-06-12 from https://api.ai-analytics.org/grant/nih/10791903. Licensed CC0.

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