Polysaccharides and Lectins: A Natural Complementary Approach against the SARS-CoV-2 Pandemic

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

Dear Authors,

Thank you for providing an interesting manuscript. After reviewing the text, I have identified specific areas that require corrections and explanations.

Major points

1.    The manuscript is comprehensive, but it could be more concise. I suggest considering shortening some parts to maintain the reader's interest and focus. For example, I see limited significance in Tables 1 and 2, and their removal could help streamline the manuscript without compromising its content. Instead, I would suggest putting some antiviral activity of polysaccharides or lectins in tables.  

2.    To make the manuscript more visually appealing to the readers, I would encourage you to prepare some Figures, for example, depicting the potential anti-SARS-CoV-2 activity of polysaccharides.

3.    When used in the text for the first time, all abbreviations should be explained. Please carefully check the text.

4.    The section headers in 3.2, 3.3 and 3.4, as well as 4.2, 4.3, and 4.4 consist of only one word, which does not look visually appealing.

5.    There are numerous Latin plant names or words that should be written in italics.

·         Interestingly, some English words or phrases have been incorrectly written in italics. For example, please see lines 448 and 468.

Minor points

·         The manuscript needs some minor corrections in terms of grammar and style.

·         Please correct the numbers in the cited values, like IC50 or TCID50/ml, to subscript.

·         There are many multiple spaces in the text.

·         Line 266 – correct “SAR-CoV-2”

·         Line 383 – “interfered in vivo in the replication viral cycle” – this should be corrected, for example, “interfered in vivo in the virus replication cycle” or “(…) viral replication cycle” or just “(…) virus replication”.

Comments on the Quality of English Language

Overall the quality of the English language is acceptable. However, the text could benefit from some minor language and style revisions to improve its clarity and coherence.

Author Response

Reviewer 1
Dear Reviewer, 
Thank you very much for all your notes, time, efforts, and support in improving our paper; we have carefully read the comments and have revised/ completed the manuscript accordingly. Our responses are given in a point-by-point manner below (in blue). To improve the quality of the manuscript, the text was modified, completed, corrected, and restructured. 
Dear Authors,
Thank you for providing an interesting manuscript. After reviewing the text, I have identified specific areas that require corrections and explanations.
Major points
1.    The manuscript is comprehensive, but it could be more concise. I suggest considering shortening some parts to maintain the reader's interest and focus. For example, I see limited significance in Tables 1 and 2, and their removal could help streamline the manuscript without compromising its content. Instead, I would suggest putting some antiviral activity of polysaccharides or lectins in tables. 
Thank you for your valuable comment, the tables have been changed 
Table.  Summaries of the Antiviral Activity of Polysaccharides against SARS-CoV-2
Polysaccharide    Source    Structure    Antiviral Activity against SARS-CoV-2    References
Heparin    Animal tissues    Highly sulfated glycosaminoglycan    Binds to RBD protein, inhibits viral attachment, induces conformational changes in spike protein receptor-binding domain, reduces viral titers    [48, 49, 51-56, 58-66]
Chondroitin Sulfates    Bovine, porcine, chicken cartilage, shark cartilage    Linear polysaccharide with varying sulfation patterns    Competitive inhibitor of S-protein RBD binding, inhibits viral replication    [45, 67-76]
Hyaluronans    Non-sulfated GAG    Repeating D-glucuronic acid and D-N-acetylglucosamine residues    Binds to SARS-CoV-2 spike glycoprotein, promotes ARDS, contributes to cytokine storm    [77-81]
Marine Polysaccharides    Algae    Varied structures with high degree of sulfation    Block replication phase, destabilize SARS-CoV-2 spike protein    [82-128]
Galactans, Sulfated Galactans    Red seaweeds    Chains of alternating residues with sulfation    Inhibit viral binding and penetration, suppress viral replication    [129-138]
Alginate    Brown algae    Alternating α-L-guluronic acid and β-D-mannuronic acid residues    Inhibits ACE2-S-protein RBD binding, suppresses viral gene expression    [104, 118-126]
Plant Polysaccharides    Medicinal plants    Diverse structures and derivatives    Inhibit S-protein binding, suppress viral replication    [139-146]
Mushroom Polysaccharides    Edible, medicinal mushrooms    Immunomodulatory, antioxidant, antiviral    Inhibit viral entry, replication, and protein expression    [147-161]
 

Table . Antiviral Activity of Lectins against SARS-CoV-2
Lectin    Source    Antiviral Activity    References
Mannose-specific/mannose-binding lectins (MBL)    Various sources    Strong complement cascade induction, anti-infectivity, DC-SIGN antagonists, immunoadjuvants, and glycomimetic approach efficacies useful against COVID-19 and SARS-CoV-2 infections    [183]
FRIL    Plant-derived    Directly binds to virus particles, demonstrates antiviral activity against a SARS-CoV-2 strain originating from Taiwan    [186]
Wheat germ agglutin/lectin    Plant-derived    Exhibits antiviral efficacy against SARS-CoV-2 and its Variants of Concern (VoC), Alpha and Beta    [187]
Lentil lectin    Derived from Lens culinaris    Demonstrates highly potent and broad-spectrum antiviral activity against various SARS-CoV-2 mutant strains and variants, including epidemic variants such as B.1.1.7, B.1.351, and P.1    [188]
Recombinant lectins    Synthetic    Serve as new anti-SARS-CoV-2 agents by targeting SARS-CoV-2-associated glycans    [189]
Plant lectins    Various sources    Varied antiviral activity spectrum against SARS-CoV-2, potent against viral entry targets    [171], [185], [190]
Griffithsin lectin (GRFT)    Source unspecified    Binds to the SARS-CoV-2 spike protein and prevents infection    [191]
H84T-banana lectin (H84T-BanLec)    Engineered    Inhibits SARS-CoV-2, MERS-CoV, and other human-pathogenic coronaviruses at nanomolar concentrations    [192]
NTL-125    New plant lectin    Blocks SARS-CoV-2 interaction with hACE2    [193]
AcmJRL    Pineapple-derived    Binds the SARS-CoV-2 spike protein in a carbohydrate-dependent manner    [195]

2.    To make the manuscript more visually appealing to the readers, I would encourage you to prepare some Figures, for example, depicting the potential anti-SARS-CoV-2 activity of polysaccharides.
Thank you for your valuable comment. We have added the figure to the section 5. Unveiling the Interplay: Complementary and Competitive Actions of Lectins and Pol-ysaccharides in Combating SARS-CoV-2.
3.    When used in the text for the first time, all abbreviations should be explained. Please carefully check the text.
Thank you for your comment. We meticulously reviewed the text and ensured that each abbreviation was appropriately defined upon its initial mention
4.    The section headers in 3.2, 3.3 and 3.4, as well as 4.2, 4.3, and 4.4 consist of only one word, which does not look visually appealing.
Thank you for your comment. The sections have been changed 
5.    There are numerous Latin plant names or words that should be written in italics.
Thank you for your comment. We meticulously revised the text to ensure that all plant names were appropriately formatted in italics
·         Interestingly, some English words or phrases have been incorrectly written in italics. For example, please see lines 448 and 468.
Thank you for your comment. The error has been rectified 
Minor points
·         The manuscript needs some minor corrections in terms of grammar and style.
Thank you for your comment. The grammar and style have been corrected
·         Please correct the numbers in the cited values, like IC50 or TCID50/ml, to subscript.
Thank you for your comment. The numbers have been corrected
·         There are many multiple spaces in the text.
Thank you for your comment. The multiple spaces has been deleted
·         Line 266 – correct “SAR-CoV-2”
Thank you for your comment. The error has been rectified 
·         Line 383 – “interfered in vivo in the replication viral cycle” – this should be corrected, for example, “interfered in vivo in the virus replication cycle” or “(…) viral replication cycle” or just “(…) virus replication”.
Thank you for your valuable comment The phrase "interfered in vivo in the replication viral cycle" has been duly noted and addressed.

Thank you. Kind regards!

 

 

 

 

 

 

Reviewer 2 Report

Comments and Suggestions for Authors

General evaluation:  aim, novelty, and significance

This review article entitled (Polysaccharides and Lectins: A Natural Complementary Approach against the SARS-CoV-2 Pandemic ) aims to cast light on natural products and their derivatives as reservoirs for potential therapeutic compounds against SARS-CoV-2 and can be transformed into antiviral drugs, particularly, lectin and polysaccharides isolated from fauna and flora. The review objective intends to analyze the specific role of polysaccharides and lectins and their synergy against this deadly SARS-CoV-2 virus.

The review was based on a primary literature search conducted on Google Scholar, PubMed and web of sciences using relevant keywords like “SARS-CoV-2 Variants”; “Antiviral Strategies”; “Antiviral Polysaccharides”; “Antiviral Lectins”; and “Synergistic effect”.

The results demonstrated that lectins and polysaccharides exhibit antiviral activities against SARS-CoV-2 via mechanisms related to the binding and steric blocking, binding of glycan-based decoys, chemical reactions, virus particle disruption strategies, and steric blocking for competitive inhibition to block SARS-CoV-2 and its variants entry.

The review aimed to analyze the rationale behind combining polysaccharides and lectins, and emphasize the complementary mechanisms of action. This is a good axe in the article, but the authors need to demonstrate further both the similarity and complementarity of action between these two antiviral agents.

As the article focuses simultaneously on multiple stages of the viral life cycle, this study may provide a comprehensive potential dual strategy for inhibiting viral propagation and enhancing the durability of the treatment over time.

Hence, presenting polysaccharides and lectins (glycoprotein) in one study is a novel study that may help us understand lectins' biological roles. This study is significant and may reveal some unknown areas in the field.

Since lectins are proteins containing various sugar structures, it will be interesting to compare the role of the sugar moiety of lectin with the whole sugar entity of polysaccharides. This comparison will give a great deal of depth to the article.

The review research used a group of keywords; “SARS-CoV-2 Variants”; “Antiviral Strategies”; “Antiviral Polysaccharides”; “Antiviral Lectins”; and “Synergistic effect” which participated to the structure and content of the article. However the keywords of the article are different form these keywords (Human coronaviruses; natural products and isolates; antiviral activity; polysaccharides; lectins). The first group of keywords are more relevant to the article content and should also be seen in the article's keywords.

The potential complementary mechanisms of action between lectins and polysaccharides should be presented in a graphical diagram, showing the multiple stages of the viral life cycle and the target of the antiviral actions associated with the antiviral factor. This may comprehensively present the inhibition of viral propagation.

Since there is a common factor between lectin and the polysaccharides, which is the sugar units, there may be both syngenesis and competition between them. So, the entry (5.) May be modified into Competitive and complementary actions between lectins and polysaccharides targeting virus. So, this section may investigate the potential competitiveness and complementation between lectins and polysaccharides.The order of the sub-entries ma n the following order:

3.1. Polysaccharides background

3.2. Chemical structure

3.3. Bio-sources

3.4. Classification

3.5. Anti- SARS-CoV-2 activity

And

4.1. Lectin background

4.2. Chemical structure

4.3. Bio-sources

4.4. Classification

4.5. Anti- SARS-CoV-2 activity

Minor changes

L23-25, change into (Infection with the novel coronavirus SARS-CoV-2, the cause of coronavirus disease (COVID-19), has emerged as a global pandemic with a high toll on casualties, economic impact, and human lifestyle.)

L28, change (This raises) to (This context raises)

L31-32, change into (Among these substances, lectin and polysaccharides isolated from fauna and flora emerge as complementary strategies for treating coronavirus infection.)

L32-43, change into (The review objective is to cover and analyze the specific role of polysaccharides and lectins and their synergy in the fight against this deadly SARS-CoV-2 virus)

L57, change (difficulties including) to (difficulties, including)

L59, change (campaigns therefore) t0 (campaigns, therefore)

L62, change (It is therefore imperative) to (It is therefore, imperative)

L64, change (This highlights) to (This context highlights)

L65, change (in-depth exploration) to (the in-depth exploration)

L87, change (mammals causing) to (mammals, causing)

L90, change (the coronaviruses group) to (the coronavirus group)

L113, change (known also as complex) to (also known as complex)

L124, change (the ability also) to (the ability also)

L125, change (have the ability also) to (have also the ability)

L129, change (The increasing enthusiasm in medical) to (The increasing enthusiasm for medical)

L135, change (as viscosifying additives) to (as viscosity-promoting additives,)

L171, change (have a very) to (have very)

L189, change (and particularly) to (, particularly)

L278, change (sulfate groups position) to (sulfate group position)

L279, change (and particularly) to (, particularly)

L282, change (polysaccharidic structures) to (polysaccharide structures)

L294, change (Salih et al., [83] describes) to (Salih et al., [83] describe)

L301, change  to (the studies are consistently  indicating)

L302, change (the studies are consistent to indicate) to (the studies are consistently indicating)

L359, change (and particularly) to (, particularly)

L360, change (disaccharides chains) to (disaccharide chains)

L391, change (who describes) to (who described)

L393, change (in the treatment of) to (in treating)

L394, change (evidence towards the antiviral) to (evidence of the antiviral)

L398, change (recent identified) to (recently identified)

L445, change (, however,) to (; however,)

L448, change (and particularly) to (, particularly)

L461, change (to significantly inhibit in vitro ACE2--SARS-CoV-2 S) to (to inhibit in vitro ACE2--SARS-CoV-2 S significantly)

L478, change (influence significantly) to (significantly influence)

L480, change (showed higher) to (showed a higher)

L485, change (, majority of these) to (, the majority of these)

L498, change (promissing) to (promising)

L515, change (that is found) to (found)

L522, change into (Another application area for lectins is cancer diagnosis and therapy [164-166].)

L540, change (varied proteins) to (variable proteins)

L542, change (sequence which determines) to (sequence determining)

L561-563, change into (Many biological events, including viral adherence to host cell membranes, depend on the interaction of lectins and glycoproteins.)

L626-628, change into (Polysaccharides, essential macromolecules found in various organisms, and lectins, proteins playing a crucial role in sugar recognition, offer unique characteristics enhancing the antiviral effects, when combined together)

L639, change (to simultaneously target multiple crucial points in the viral life cycle.) into (to target multiple crucial points in the viral life cycle simultaneously)

L660, change (makes it challenging the virus) to (makes it challenging for the virus)

 

 

 

Comments on the Quality of English Language

English needs extensive editing

Author Response

Reviewer 2
Dear Reviewer, 
We would like to express our sincere gratitude for your thorough review of our manuscript. We are particularly grateful for your positive feedback regarding the overall quality of our paper and for highlighting the improvements made in English language usage. Your recognition of our efforts is truly encouraging and motivates us to continue striving for excellence in our research. In addition, we appreciate your constructive criticism regarding the need to further demonstrate the competitivity of action between polysaccharides and lectins. We have carefully read the comments and have revised/ completed the manuscript accordingly. Our responses are given in a point-by-point manner below (in blue). 

Comments and Suggestions for Authors
General evaluation:  aim, novelty, and significance

This review article entitled (Polysaccharides and Lectins: A Natural Complementary Approach against the SARS-CoV-2 Pandemic ) aims to cast light on natural products and their derivatives as reservoirs for potential therapeutic compounds against SARS-CoV-2 and can be transformed into antiviral drugs, particularly, lectin and polysaccharides isolated from fauna and flora. The review objective intends to analyze the specific role of polysaccharides and lectins and their synergy against this deadly SARS-CoV-2 virus.

The review was based on a primary literature search conducted on Google Scholar, PubMed and web of sciences using relevant keywords like “SARS-CoV-2 Variants”; “Antiviral Strategies”; “Antiviral Polysaccharides”; “Antiviral Lectins”; and “Synergistic effect”.

The results demonstrated that lectins and polysaccharides exhibit antiviral activities against SARS-CoV-2 via mechanisms related to the binding and steric blocking, binding of glycan-based decoys, chemical reactions, virus particle disruption strategies, and steric blocking for competitive inhibition to block SARS-CoV-2 and its variants entry.

The review aimed to analyze the rationale behind combining polysaccharides and lectins, and emphasize the complementary mechanisms of action. This is a good axe in the article, but the authors need to demonstrate further both the similarity and complementarity of action between these two antiviral agents.

As the article focuses simultaneously on multiple stages of the viral life cycle, this study may provide a comprehensive potential dual strategy for inhibiting viral propagation and enhancing the durability of the treatment over time.

Hence, presenting polysaccharides and lectins (glycoprotein) in one study is a novel study that may help us understand lectins' biological roles. This study is significant and may reveal some unknown areas in the field.

Since lectins are proteins containing various sugar structures, it will be interesting to compare the role of the sugar moiety of lectin with the whole sugar entity of polysaccharides. This comparison will give a great deal of depth to the article.
Thank you for your valuable comment. We have addressed this point in the complementary and competitiveness section.

The review research used a group of keywords; “SARS-CoV-2 Variants”; “Antiviral Strategies”; “Antiviral Polysaccharides”; “Antiviral Lectins”; and “Synergistic effect” which participated to the structure and content of the article. However the keywords of the article are different form these keywords (Human coronaviruses; natural products and isolates; antiviral activity; polysaccharides; lectins). The first group of keywords are more relevant to the article content and should also be seen in the article's keywords.
Thank you for your comment. The Keywords have been changed as requested 

The potential complementary mechanisms of action between lectins and polysaccharides should be presented in a graphical diagram, showing the multiple stages of the viral life cycle and the target of the antiviral actions associated with the antiviral factor. This may comprehensively present the inhibition of viral propagation.
Thank you for your comment. We have added the requested graphical diagram to the section 5. Unveiling the Interplay: Complementary and Competitive Actions of Lectins and Pol-ysaccharides in Combating SARS-CoV-2.

Since there is a common factor between lectin and the polysaccharides, which is the sugar units, there may be both syngenesis and competition between them. So, the entry (5.) May be modified into Competitive and complementary actions between lectins and polysaccharides targeting virus. So, this section may investigate the potential competitiveness and complementation between lectins and polysaccharides.The order of the sub-entries ma n the following order:

3.1. Polysaccharides background

3.2. Chemical structure

3.3. Bio-sources

3.4. Classification

3.5. Anti- SARS-CoV-2 activity

And

4.1. Lectin background

4.2. Chemical structure

4.3. Bio-sources

4.4. Classification

4.5. Anti- SARS-CoV-2 activity
Thank you for your keen observation and insightful feedback. We have incorporated the suggested point into our paper, adding a section on the competitiveness between lectin and polysaccharides to the complementary section. 
Additionally, the section headings have been updated.

Minor changes

L23-25, change into (Infection with the novel coronavirus SARS-CoV-2, the cause of coronavirus disease (COVID-19), has emerged as a global pandemic with a high toll on casualties, economic impact, and human lifestyle.)

L28, change (This raises) to (This context raises)

L31-32, change into (Among these substances, lectin and polysaccharides isolated from fauna and flora emerge as complementary strategies for treating coronavirus infection.)

L32-43, change into (The review objective is to cover and analyze the specific role of polysaccharides and lectins and their synergy in the fight against this deadly SARS-CoV-2 virus)

L57, change (difficulties including) to (difficulties, including)

L59, change (campaigns therefore) t0 (campaigns, therefore)

L62, change (It is therefore imperative) to (It is therefore, imperative)

L64, change (This highlights) to (This context highlights)

L65, change (in-depth exploration) to (the in-depth exploration)

L87, change (mammals causing) to (mammals, causing)

L90, change (the coronaviruses group) to (the coronavirus group)

L113, change (known also as complex) to (also known as complex)

L124, change (the ability also) to (the ability also)

L125, change (have the ability also) to (have also the ability)

L129, change (The increasing enthusiasm in medical) to (The increasing enthusiasm for medical)

L135, change (as viscosifying additives) to (as viscosity-promoting additives,)

L171, change (have a very) to (have very)

L189, change (and particularly) to (, particularly)

L278, change (sulfate groups position) to (sulfate group position)

L279, change (and particularly) to (, particularly)

L282, change (polysaccharidic structures) to (polysaccharide structures)

L294, change (Salih et al., [83] describes) to (Salih et al., [83] describe)

L301, change  to (the studies are consistently  indicating)

L302, change (the studies are consistent to indicate) to (the studies are consistently indicating)

L359, change (and particularly) to (, particularly)

L360, change (disaccharides chains) to (disaccharide chains)

L391, change (who describes) to (who described)

L393, change (in the treatment of) to (in treating)

L394, change (evidence towards the antiviral) to (evidence of the antiviral)

L398, change (recent identified) to (recently identified)

L445, change (, however,) to (; however,)

L448, change (and particularly) to (, particularly)

L461, change (to significantly inhibit in vitro ACE2--SARS-CoV-2 S) to (to inhibit in vitro ACE2--SARS-CoV-2 S significantly)

L478, change (influence significantly) to (significantly influence)

L480, change (showed higher) to (showed a higher)

L485, change (, majority of these) to (, the majority of these)

L498, change (promissing) to (promising)

L515, change (that is found) to (found)

L522, change into (Another application area for lectins is cancer diagnosis and therapy [164-166].)

L540, change (varied proteins) to (variable proteins)

L542, change (sequence which determines) to (sequence determining)

L561-563, change into (Many biological events, including viral adherence to host cell membranes, depend on the interaction of lectins and glycoproteins.)

L626-628, change into (Polysaccharides, essential macromolecules found in various organisms, and lectins, proteins playing a crucial role in sugar recognition, offer unique characteristics enhancing the antiviral effects, when combined together)

L639, change (to simultaneously target multiple crucial points in the viral life cycle.) into (to target multiple crucial points in the viral life cycle simultaneously)

L660, change (makes it challenging the virus) to (makes it challenging for the virus)
Thank you very much for pointing out the English errors. This makes our paper more coherent. We have corrected all the grammar and orthographic errors as requested.

 

Thank you! Kind regards.

Reviewer 3 Report

Comments and Suggestions for Authors

Major comments:

1. The scope of the manuscript is very interesting. However, in its current form, the manuscript fails to uncover the beauty of this topic.
2. As a systematic review, this manuscript looks suboptimal in terms of data representation. For example, in tables #1 and 2, I recommend including only those polysaccharides/lectins whose activity against SARS-CoV-2 has been studied.
3. Consider analyzing the models used in the analyzed data. It could be a whole paragraph where you describe a variety of in vitro and in vivo models, their advantages, and disadvantages.
4. The manuscript would significantly benefit from including the possible mechanisms of anti-SARS-CoV-2 protection provided by lectins/polysaccharides. A picture of SARS-CoV-2 protein/proteins (or cellular receptors) interacting with lectins/polysaccharides would help readers understand these mechanisms.

 

Minor comments:

1. Line 27: portion – proportion
2. Line 49: …Coronavirus 2 (SARS-CoV-2) emergence…
3. Lines 53-54: The word “heightened” is used twice.
4. Line 559: Lectins against SARS-CoV-2
5. Line 569: The effectiveness of lectins against SARS-CoV-2 and its antigenic variants remains unclear seems contradictory to line 582: For various RNA viruses, including SARS-CoV-2, lectins exhibit strong anti-infectivity capabilities.

Author Response

Reviewer 3
Dear Reviewer,
Thank you very much for all your notes, time, efforts, and support in improving our paper; we have carefully read the comments and have revised/ completed the manuscript accordingly. Our responses are given in a point-by-point manner below (in blue). To improve the quality of the manuscript, the text was modified, completed, corrected, and restructured. 

Major comments:
⦁    The scope of the manuscript is very interesting. However, in its current form, the manuscript fails to uncover the beauty of this topic.
⦁    As a systematic review, this manuscript looks suboptimal in terms of data representation. For example, in tables #1 and 2, I recommend including only those polysaccharides/lectins whose activity against SARS-CoV-2 has been studied.
Thank you for your valuable comment, the tables have been changed 
Table.  Summaries of the Antiviral Activity of Polysaccharides against SARS-CoV-2
Polysaccharide    Source    Structure    Antiviral Activity against SARS-CoV-2    References
Heparin    Animal tissues    Highly sulfated glycosaminoglycan    Binds to RBD protein, inhibits viral attachment, induces conformational changes in spike protein receptor-binding domain, reduces viral titers    [48, 49, 51-56, 58-66]
Chondroitin Sulfates    Bovine, porcine, chicken cartilage, shark cartilage    Linear polysaccharide with varying sulfation patterns    Competitive inhibitor of S-protein RBD binding, inhibits viral replication    [45, 67-76]
Hyaluronans    Non-sulfated GAG    Repeating D-glucuronic acid and D-N-acetylglucosamine residues    Binds to SARS-CoV-2 spike glycoprotein, promotes ARDS, contributes to cytokine storm    [77-81]
Marine Polysaccharides    Algae    Varied structures with high degree of sulfation    Block replication phase, destabilize SARS-CoV-2 spike protein    [82-128]
Galactans, Sulfated Galactans    Red seaweeds    Chains of alternating residues with sulfation    Inhibit viral binding and penetration, suppress viral replication    [129-138]
Alginate    Brown algae    Alternating α-L-guluronic acid and β-D-mannuronic acid residues    Inhibits ACE2-S-protein RBD binding, suppresses viral gene expression    [104, 118-126]
Plant Polysaccharides    Medicinal plants    Diverse structures and derivatives    Inhibit S-protein binding, suppress viral replication    [139-146]
Mushroom Polysaccharides    Edible, medicinal mushrooms    Immunomodulatory, antioxidant, antiviral    Inhibit viral entry, replication, and protein expression    [147-161]

Table 2. Antiviral Activity of Lectins against SARS-CoV-2
Lectin    Source    Antiviral Activity    References
Mannose-specific/mannose-binding lectins (MBL)    Various sources    Strong complement cascade induction, anti-infectivity, DC-SIGN antagonists, immunoadjuvants, and glycomimetic approach efficacies useful against COVID-19 and SARS-CoV-2 infections    [183]
FRIL    Plant-derived    Directly binds to virus particles, demonstrates antiviral activity against a SARS-CoV-2 strain originating from Taiwan    [186]
Wheat germ agglutin/lectin    Plant-derived    Exhibits antiviral efficacy against SARS-CoV-2 and its Variants of Concern (VoC), Alpha and Beta    [187]
Lentil lectin    Derived from Lens culinaris    Demonstrates highly potent and broad-spectrum antiviral activity against various SARS-CoV-2 mutant strains and variants, including epidemic variants such as B.1.1.7, B.1.351, and P.1    [188]
Recombinant lectins    Synthetic    Serve as new anti-SARS-CoV-2 agents by targeting SARS-CoV-2-associated glycans    [189]
Plant lectins    Various sources    Varied antiviral activity spectrum against SARS-CoV-2, potent against viral entry targets    [171], [185], [190]
Griffithsin lectin (GRFT)    Source unspecified    Binds to the SARS-CoV-2 spike protein and prevents infection    [191]
H84T-banana lectin (H84T-BanLec)    Engineered    Inhibits SARS-CoV-2, MERS-CoV, and other human-pathogenic coronaviruses at nanomolar concentrations    [192]
NTL-125    New plant lectin    Blocks SARS-CoV-2 interaction with hACE2    [193]
AcmJRL    Pineapple-derived    Binds the SARS-CoV-2 spike protein in a carbohydrate-dependent manner    [195]

3. Consider analyzing the models used in the analyzed data. It could be a whole paragraph where you describe a variety of in vitro and in vivo models, their advantages, and disadvantages.
Thank you for your thoughtful review and valuable feedback. We have made this table englobing the in vivo and in vitro method cited in our text with their advantage and disadvantage 
Table. Methods for Evaluating Antiviral Activity of Polysaccharides Against SARS-CoV-2
Method    Description    In Vitro/In Vivo    Advantages    Disadvantages
Plaque Inhibition Assay    Assess antiviral activity of heparins against live SARS‐CoV‐2 by measuring plaque formation in Vero E6 cells.    In Vitro    Provides direct evidence of antiviral activity.    Limited to assessing activity in cell culture; may not fully replicate in vivo interactions.
Docking Models    Evaluate binding affinity of specific polysaccharides to S-protein of SARS-CoV-2 using docking models.    In Vitro    Enables screening of compounds for further testing.    Results may not always correlate with experimental data; simplifications in computational model.
Cytopathic Assay    Determine antiviral activity of ulvan extracts from Ulva sp. against SARS-CoV-2 in VERO E6 cells.    In Vitro    Provides quantitative data on antiviral activity.    Relies on cell culture systems, may not fully replicate in vivo conditions.
Binding Affinity Studies    Evaluate binding affinity of polysaccharides to COVID-19 main protease using in silico methods.    In Vitro    Offers insights into potential therapeutic targets.    Computational results may not fully represent biological reality.
Mouse Model Studies    Assess in vivo antiviral activity of synthetic mimetics and natural polysaccharides in K18-hACE2 mouse models.    In Vivo    Provides insights into in vivo efficacy and safety.    Results may not always translate to humans; ethical considerations limit use of animal models.
Randomized Clinical Trials    Evaluate therapeutic effects of heparin in hospitalized COVID-19 patients for thromboprophylaxis.    In Vivo    Provides crucial data on therapeutic efficacy.    Time-consuming and expensive; large sample sizes may be needed; ethical considerations; results may not generalize to all patient populations.

 

4. The manuscript would significantly benefit from including the possible mechanisms of anti-SARS-CoV-2 protection provided by lectins/polysaccharides. A picture of SARS-CoV-2 protein/proteins (or cellular receptors) interacting with lectins/polysaccharides would help readers understand these mechanisms.
Thank you for your valuable comment. A figure of Potential anti-SARS-CoV-2 activity of lectins has been added 
 
Figure 1. Potential anti-SARS-CoV-2 activity of lectins.
Minor comments:
⦁    Line 27: portion – proportion
The correction has been made.
⦁    Line 49: …Coronavirus 2 (SARS-CoV-2) emergence…
The correction has been made.
⦁    Lines 53-54: The word “heightened” is used twice.
The second heightened has been replaced with “increased”. 
⦁    Line 559: Lectins against SARS-CoV-2 
The correction has been made. The title of the section has been modified to Mechanisms of Action of Lectins in Combating Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) as requested by the other reviewers 
⦁    Line 569: The effectiveness of lectins against SARS-CoV-2 and its antigenic variants remains unclear seems contradictory to line 582: For various RNA viruses, including SARS-CoV-2, lectins exhibit strong anti-infectivity capabilities.
You're correct that the two statements may appear contradictory. Let us clarify:
The statement "The effectiveness of lectins against SARS-CoV-2 and its antigenic variants remains unclear" acknowledges that while some studies have shown promising results for lectins against SARS-CoV-2, there is still uncertainty surrounding their overall effectiveness, especially considering the evolving nature of the virus and its antigenic variants. Further research is needed to fully understand how lectins may be used as antiviral agents against SARS-CoV-2, including its variants, and to determine their efficacy, safety, and potential clinical applications. 
On the other hand, the statement "For various RNA viruses, including SARS-CoV-2, lectins exhibit strong anti-infectivity capabilities" suggests that in general, lectins have shown promise in inhibiting the infectivity of RNA viruses, including SARS-CoV-2, in some research studies. This indicates that lectins can potentially interfere with viral attachment, entry, or replication processes, thereby reducing infectivity.
In summary, while there is evidence to suggest that lectins can exhibit anti-infectivity capabilities against SARS-CoV-2 and other RNA viruses, uncertainties remain regarding their effectiveness, particularly in the context of SARS-CoV-2 variants.

Thank you! Kind regards/

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

Dear Authors,

Thank you for acknowledging my previous comments. I appreciate the significant effort you have put into revising the manuscript, which has led to substantial improvements.

Comments on the Quality of English Language

Only minor corrections are needed.

Reviewer 2 Report

Comments and Suggestions for Authors

The authors have responded positively and appropriately to the raised comments, rendering their article more communicating and more inspiring. So, it is recommended for publication in its revised form

Reviewer 3 Report

Comments and Suggestions for Authors

Thank you for addressing all my comments