Next Article in Journal / Special Issue
Single-Domain Antibodies and Their Formatting to Combat Viral Infections
Previous Article in Journal / Special Issue
Selection of Single-Domain Antibodies towards Western Equine Encephalitis Virus
Article Menu

Export Article

Open AccessArticle

A Collection of Single-Domain Antibodies that Crowd Ricin Toxin’s Active Site

Department of Pharmaceutical Chemistry and Macromolecule and Vaccine Stabilization Center, University of Kansas, Lawrence, KS 660451, USA
Division of Infectious Diseases, Wadsworth Center, New York State Department of Health, Albany, NY 12208, USA
New York Structural Biology Center (NYSBC), New York, NY 10027, USA
Department of Chemistry and Ralph Adams Institute for Bioanalytical Chemistry, University of Kansas, Lawrence, KS 660451, USA
Author to whom correspondence should be addressed.
These authors contributed equally to this manuscript.
Antibodies 2018, 7(4), 45;
Received: 26 November 2018 / Revised: 10 December 2018 / Accepted: 11 December 2018 / Published: 17 December 2018
(This article belongs to the Special Issue Nanobody)
PDF [11718 KB, uploaded 18 December 2018]


In this report, we used hydrogen exchange-mass spectrometry (HX-MS) to identify the epitopes recognized by 21 single-domain camelid antibodies (VHHs) directed against the ribosome-inactivating subunit (RTA) of ricin toxin, a biothreat agent of concern to military and public health authorities. The VHHs, which derive from 11 different B-cell lineages, were binned together based on competition ELISAs with IB2, a monoclonal antibody that defines a toxin-neutralizing hotspot (“cluster 3”) located in close proximity to RTA’s active site. HX-MS analysis revealed that the 21 VHHs recognized four distinct epitope subclusters (3.1–3.4). Sixteen of the 21 VHHs grouped within subcluster 3.1 and engage RTA α-helices C and G. Three VHHs grouped within subcluster 3.2, encompassing α-helices C and G, plus α-helix B. The single VHH in subcluster 3.3 engaged RTA α-helices B and G, while the epitope of the sole VHH defining subcluster 3.4 encompassed α-helices C and E, and β-strand h. Modeling these epitopes on the surface of RTA predicts that the 20 VHHs within subclusters 3.1–3.3 physically occlude RTA’s active site cleft, while the single antibody in subcluster 3.4 associates on the active site’s upper rim. View Full-Text
Keywords: toxin; antibody; camelid; vaccine; biodefense; hydrogen exchange-mass spectrometry toxin; antibody; camelid; vaccine; biodefense; hydrogen exchange-mass spectrometry

Graphical abstract

This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited (CC BY 4.0).

Supplementary material


Share & Cite This Article

MDPI and ACS Style

Angalakurthi, S.K.; Vance, D.J.; Rong, Y.; Nguyen, C.M.T.; Rudolph, M.J.; Volkin, D.; Middaugh, C.R.; Weis, D.D.; Mantis, N.J. A Collection of Single-Domain Antibodies that Crowd Ricin Toxin’s Active Site. Antibodies 2018, 7, 45.

Show more citation formats Show less citations formats

Note that from the first issue of 2016, MDPI journals use article numbers instead of page numbers. See further details here.

Related Articles

Article Metrics

Article Access Statistics



[Return to top]
Antibodies EISSN 2073-4468 Published by MDPI AG, Basel, Switzerland RSS E-Mail Table of Contents Alert
Back to Top