# Alicanto: Proteogenomic discovery of single chain antibodies in llama

> **NIH NIH R44** · ABTERRA BIOSCIENCES, INC. · 2021 · $491,915

## Abstract

Heavy chain-only antibodies (HCAbs) are a unique class of antibodies only produced in
camelids and cartilagenous fish. Unlike conventional antibodies that consist of two heavy
chains and two light chains, HCAbs consist only of heavy chains. The antigen-binding portion of
the camelid HCAb, called the VHH, is a polypeptide fragment with wide utility across
crystallography, imaging, and therapeutics. The small size and comparatively simple structure
of the VHH as compared to conventional antibodies makes them economical to produce and
structurally stable at a wider pH and temperature range.
 Growing evidence suggests that the epitopes targeted by HCAbs are distinct from those
targeted by conventional antibodies. Concave domains, such as enzyme active sites, are one
category that are preferentially targeted by HCAbs than conventional antibodies. This is in part
due to the ability of VHHs to produce convex conformations which enables targeting of sites
that are inaccessible to conventional antibodies.
 Phage display is the predominant method for discovering novel VHHs. HCAb transcripts
are cloned into phagemids, and phages that express a VHH that binds the target are enriched
through the process of panning. Attrition at cloning, panning, or final selection reduces the
accessible diversity of the immune system, and delivers antibodies that may not be as diverse
as the response mounted by the original host organism.
 In contrast to display-based methods, Alicanto combines next-generation sequencing
and mass spectrometry to directly identify antigen-specific circulating HCAbs from camelids.
Assessment of circulating HCAbs in serum is the primary method by which an immunization is
determined to be successful. While the serum is discarded after screening in the phage display
workflow, Alicanto uses mass spectrometry to identify the individual HCAbs comprising the
target-specific circulating antibodies. This enables Alicanto to discover low abundance
antibodies against challenging targets such as peptides and small molecules. By constructing
an in silico library of HCAb sequences using next-generation sequencing, Alicanto precludes the
need to clone into an intermediate host such as phages. Through direct analysis of the immune
response of llamas, Alicanto will deliver more, high affinity VHHs for use in research,
diagnostics, and therapeutics.

## Key facts

- **NIH application ID:** 10665445
- **Project number:** 6R44AI141046-04
- **Recipient organization:** ABTERRA BIOSCIENCES, INC.
- **Principal Investigator:** Stefano Romoli Bonissone
- **Activity code:** R44 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2021
- **Award amount:** $491,915
- **Award type:** 6
- **Project period:** 2021-07-03 → 2024-03-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10665445

## Citation

> US National Institutes of Health, RePORTER application 10665445, Alicanto: Proteogenomic discovery of single chain antibodies in llama (6R44AI141046-04). Retrieved via AI Analytics 2026-05-24 from https://api.ai-analytics.org/grant/nih/10665445. Licensed CC0.

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