Gene-Based Therapy: A New Approach to Feline Induced Sterilization?

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

The manuscript discusses the need for controlling the feline population, especially in feral, wild, and captive settings. It highlights the shift towards using gene editing for sterilization due to concerns about traditional methods. The objective of the review paper is to provide an overview of recent advances in gene-based contraception and discuss their potential benefits and implications for population control and animal welfare. The manuscript provides a clear theoretical introduction to the feasibility of gene therapy.

It would be even better if various cost-effective methods could be discussed. After all, this is a societal issue, and the actual expenses are also a crucial factor.

Comments on the Quality of English Language

no

Author Response

I would like to thank the referee for the time and effort put into the evaluation of the MS.

In an attempt to meet the suggestion of discussing various cost-effective methods, a few sentences were added (please see lines 129 to 140); even though the costs of implementing fertility control measures for free-ranging populations vary with the geographic region, the governmental support and the desired outcome, several factors were identified and discussed.

I hope that these sentences may allow the readers to estimate the costs considering their regional context.

Best regards

Rita

 

Reviewer 2 Report

Comments and Suggestions for Authors

Review reports

Brief summary 

The present study aimed to provide a comprehensive overview of the hormonal and non-hormonal pharmacologic methods for induced sterilization available for felids (domestic or wild species) and comprehensively introduces the most recent advances in gene-based fertility control, highlighting effectiveness, advantages or limitations, and implications of the gene-based sterilization for animal welfare and population control strategies as topics of interest for pet owners, authorities, and veterinarians.

General concept comments 

The manuscript is clear, relevant for the field and presented in a well-structured manner. Description of the methods is consistent, well structured and highlight what are the advantages and disadvantages of the gene-based sterilization for animal welfare and population control. Concluding remarks are well structured and emphasizes that gene-based sterilization is still largely experimental and still faces numerous scientific, ethical and regulatory challenges.

 

Specific comments 

Line 99 As a suggestion I would make discursive instead of numbered list the description of the three alternative pathways that may be used in cats to control of the hypothalamus-pituitary axis.

Line 441 and 449 replace “(“ with “.”

Line 480 replace with the correct form of “analogues—agonists”

Comments on the Quality of English Language

English language fine.

Author Response

Thank you very much for taking the time to review this manuscript and your kind support.

Your suggestions have been introduced in the MS: the numbered list the descriptions were converted into cursive text. I also complete the information with information regarding male-related melatonin treatments and, as per another referee suggestion, with a comparative table regarding the advantages and disadvantage of the progesterone-alternative methods available. The brackets before some journal’s names in the reference list were removed, and the title of Padula’s reference was corrected.

I hope the MS may now be considered suitable for publication,

My best regards

Rita

Reviewer 3 Report

Comments and Suggestions for Authors

Induced sterilization of felids is critical issues in controlling feline population and avoid the disturbance during estrus. This review comprehensively overviewed the methods of induced sterilization and their advantages and disadvantages. This review is very interesting and scientifically sound. Some issues should be addressed before consideration of acceptance for publication.

1.     In section 3.2. Gene-based sterilization, author should list the specific genes which was modified rather than discussed too much details of reference 1 (from Line 316-356).

2.     Figure 1 and 2 are not good quality and unnecessary.

3.     Conclusion was also not well written because It looks like discussion.

 

4.     Gene therapy is a promising method of induced sterilization, any suggestions can be provided in section ‘3.3. Risks and limitations in gene therapy’.

Comments on the Quality of English Language

The english language of this review is slightly verbose and needs further modification and improvement.

Author Response

Thank you very much for your time and effort put into carefully revising the manuscript

Comments and Suggestions for Authors

… Some issues should be addressed before consideration of acceptance for publication.

1. In section 3.2. Gene-based sterilization, author should list the specific genes which was modified rather than discussed too much details of reference 1 (from Line 316-356).

As per your suggestion, the text formerly comprised within lines 316 – 356 was compact, focusing now on the results of the gene-based sterilization treatment. The text was condensed into a total of 15 lines.

2. Figure 1 and 2 are not good quality and unnecessary.

I partially agree with you on the need for the figures 1 and 2. Figure 1 was removed to respond to your concerns. However, I would like to retain Figure 2 (with the editor's agreement, of course), as it could interest the reader novice in the topic.

3. Conclusion was also not well written because It looks like discussion.

The conclusion was reformulated to comply with your comment.

4. Gene therapy is a promising method of induced sterilization, any suggestions can be provided in section ‘3.3. Risks and limitations in gene therapy’.

Some additional comments were introduced to the section "3.3. Risks and limitations in gene therapy". More than suggestions, the sentences represent questions that might be posed from the results obtained so far, which may also open new roads to those investing in the theme. 

 

Comments on the Quality of English Language

The english language of this review is slightly verbose and needs further modification and improvement.

A colleague revised the language in the last version of the MS. I hope it now matches your expectations.

 

Reviewer 4 Report

Comments and Suggestions for Authors

This an interesting review among the gene therapy applied to sterilization of cats. The manuscript is well written and structured, and the scientific interest is elevated.

Author Response

Thank you very much for taking the time to review this manuscript and your kind support.

Some changes were introduced in the MS as per the review process. I hope that this new version still meets your standard

My best regards

Rita

Reviewer 5 Report

Comments and Suggestions for Authors

This review is more descriptive and not based on analytical methods. So, the authors do not evaluate critical measures to compare different methods such as duration of suppressive effect on sexual behaviour and function (ovarian and testicular function), start of efficacy after treatment, undesirable side effects, etc. Therefore, it is not possible to support the statements with statistical data. Reviews also define which literature was included and the criteria for inclusion. In addition, the methods to search literature and the outcome on this is also given in a thorough review.

Abstract: should provide more insight information an conclusions drawn from the literature reviewed.

Lines 100-164: the reader would expect also a summary on reports which used these approaches and also comparisons on pros and contras.

Which measures were applied to compare the different methods. This point is missing. The review should incorporate some statistical comparisons on the different measures to evaluate the use of the different approaches/drugs.

The main disadvantages and adverse effects may be summarized in a table.

In addition, quantification of adverse or undesired effects are welcomed.

Finally, a weighting score may be developed and then this weighting may give some more objective conclusions.

Weightings may be different for domestic cats, free-roaming cats, feral populations (different species as well), and captive populations.

Gene therapy is a long section but gene therapy approches are far away to be used. The reader may ask why the authors give this section so much room when it finally turns out that gene therapy is still on an experimental level and the risks are largely unknown. Therefore, this section should be condensed and the authors may show whether there are successful comparable examples which may have shown how to reach this aim.  

Author Response

thank you very much for your time and effort put into carefully revising the manuscript. In the revised MS, I´ve tried to address the shared concerns.

This review is more descriptive and not based on analytical methods. So, the authors do not evaluate critical measures to compare different methods such as duration of suppressive effect on sexual behaviour and function (ovarian and testicular function), start of efficacy after treatment, undesirable side effects, etc. Therefore, it is not possible to support the statements with statistical data. Reviews also define which literature was included and the criteria for inclusion. In addition, the methods to search literature and the outcome on this is also given in a thorough review.

Which measures were applied to compare the different methods. This point is missing. The review should incorporate some statistical comparisons on the different measures to evaluate the use of the different approaches/drugs.

The main disadvantages and adverse effects may be summarized in a table.

In addition, quantification of adverse or undesired effects are welcomed.

Finally, a weighting score may be developed and then this weighting may give some more objective conclusions.

Weightings may be different for domestic cats, free-roaming cats, feral populations (different species as well), and captive populations.

Answering the comment regarding the style and method used for the literature review, I must state that the paper represents a narrative review, not a systematic or a meta-analysis. Consequently, the description of key terms and searched databases is absent from this article. Also, no statistical analysis was computed to estimate the effect/efficacy of the treatments. The methods were compared based on reported clinical outcomes and, in the case of the gene-bases sterilization, using the descriptions of the experimental study. The decision to use a narrative review hindered using points or scores to weigh and compare the treatment outcomes or the statistical analysis of the clinical results.

To answer the referee's concerns, the term “narrative review” was used in the abstract section and in the main text to clarify the type of review used herein.

Abstract: should provide more insight information an conclusions drawn from the literature reviewed.

The abstract was modified to include information and conclusions drawn from the literature reviewed; however, it is limited by the existing word’s limitations.

Lines 100-164: the reader would expect also a summary on reports which used these approaches and also comparisons on pros and contras.

A table was introduced (now table 1) to summarize the main disadvantages and side-effects associated to drugs alternative to progestogens. 

 

Gene therapy is a long section but gene therapy approches are far away to be used. The reader may ask why the authors give this section so much room when it finally turns out that gene therapy is still on an experimental level and the risks are largely unknown. Therefore, this section should be condensed and the authors may show whether there are successful comparable examples which may have shown how to reach this aim.

I understand your concerns with the length of the section on gene-based therapy. Please remind the intended audience for this paper, as expressed in lines 146-fw. Most veterinarians, students, and pet owners are aware of the classic and alternative approaches to felid contraception but are relatively unaware of the gene therapy methods. This section addresses the fundamental aspects of gene therapy and the production of gene-vectored products, as it was the method used to present the recently proposed new contraceptive vaccine for cats. I think that this section is essential in the MS.

Moreover, considering the reported outcomes, the gene-based contraception proposed for felids falls short in the foreseen suppression of reproductive activity; discussion of the shortcomings of the method from a clinical point of view is not helpful for practitioners but may also allow researchers to explore new approaches. Due to the topic's novelty, the discussion of the outcomes is limited. However, a few sentences were introduced in section “3.3. Risks and limitations in gene therapy” that represent questions that might be posed from the results obtained so far.

 

Reviewer 6 Report

Comments and Suggestions for Authors

The paper is well written and organised, I recommend its publication in the current form.

Author Response

Thank you very much for your kind support. Some changes were introduced in the MS as per the review process. I hope that this new version still meets your standards.

 

My best regards

Rita

Round 2

Reviewer 3 Report

Comments and Suggestions for Authors

The manuscript was well revised and satisfied with my concerns. No further comments.

Reviewer 5 Report

Comments and Suggestions for Authors

The authors have improved their manuscript. I have no further comments.