A Monoclonal Antibody with a High Affinity for Ricin Isoforms D and E Provides Strong Protection against Ricin Poisoning

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

In this manuscript the authors describe the obtention and characterisation of monoclonal antibodies against the isoform E of ricin. Ricin is an extraordinarily toxic type 2 ribosome-inactivating protein (RIP) obtained from castor bean seeds that can be used as a weapon of war or in terrorist attacks. As the authors point out, there are currently no prophylaxis or commercial treatments for ricin poisoning.

General comments:

The authors describe the neutralising and protective efficacy of some of the monoclonal antibodies obtained against the isoforms D and E of ricin, by in vitro assays and by in vivo protection assays using a murine model challenged intranasally with a high dose of ricin. One of the antibodies provided a survival rate of 90% when administered 6 hours after ricin exposure and 35% when administered 24 hours after exposure. In addition, the surviving mice showed long-term immunity to high doses of ricin.

The subject addressed in this manuscript is worthy of investigation, the information presented is new and the conclusions are supported by experimental data. On this basis, the article deserves to be published with minor changes.

Specific comments:

Introduction:

Page 1, lines 31-32: change “type 2 ribosome inactivating glycoprotein” by “type 2 ribosome-inactivating protein (RIP)”

Page 1, line 33: change “N-glycosidase” by “rRNA N-glycosylase (EC 3.2.2.22)” (This is the name accepted by the International Union of Biochemistry and Molecular Biology)

Page 1, lines 34-36: Insert a current reference about the mechanism of ricin inhibition. For example, “Grela P, Szajwaj M, Horbowicz-Drożdżal P, Tchórzewski M. How Ricin Damages the Ribosome. Toxins (Basel). 2019 Apr 27;11(5):241. doi: 10.3390/toxins11050241”

Results:

Figure 1 (and maybe others): The symbols and lettering are very small and difficult to read. Try to make all figures and lettering as large as possible.

Tabla 1: Revise and rewrite the title of the table.

Tabla 3: The column headings in the table are confusing. Rearrange them.

Discussion:

Another possibility of ricin poisoning could be accidental ingestion of seeds (e.g. in the case of children). Which tissues would be affected? In this case, could the antibodies described in this manuscript be useful?

Comments on the Quality of English Language

English language is fine

Author Response

Thank you for the careful reading of the manuscript and the suggestions of improvement we have taken into account. Please see the attachment for a detailed response to your comments.

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

In the article entitled "A high-affinity monoclonal antibody to ricin isoforms D and E provides strong protection against ricin poisoning", the authors describe the neutralizing and protective efficacy of a new generation of high-affinity anti-ricin mAbs directed against ricin isoforms D and E. The most interesting data concern the in vivo assays, which revealed that the RicE5 mAb conferred over 90% survival in a mouse model following intranasal challenge with 5 LD₅₀ ricin and treated by intravenous administration of mAb 6 hours after ricin exposure.

The authors have conducted a considerable amount of experiments, very well conducted and possessing scientific rigor and thoroughness. The experimental design is appropriate and the methods are very well described. The discussion of the results is very complete, citing the relevant literature on the topic.

I have no particular objections to raise. The only improvement that can be made concerns some figures of the results whose quality should be improved. For example, figure 1 is very small and difficult to interpret both in the digital and paper versions.

I believe that this paper could be of considerable interest to readers, considering that the use of ricin as a chemical weapon is becoming more and more frequent, as also underlined by the authors.

Author Response

Thank you very much for taking the time to review this manuscript. We have considered your suggestion and changed all the figures to make them more readable.