PONE-D-20-26324

Association between Trypanosoma cruzi genotypes and chronic Chagas disease clinical presentation and outcome in an urban cohort in Brazil.

PLOS ONE

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PLOS ONE

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Reviewers' comments:

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Comments to the Author

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Reviewer #1: Yes

Reviewer #2: Yes

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2. Has the statistical analysis been performed appropriately and rigorously?

Reviewer #1: Yes

Reviewer #2: N/A

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Reviewer #1: Yes

Reviewer #2: Yes

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Reviewer #1: Yes

Reviewer #2: Yes

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5. Review Comments to the Author

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Reviewer #1: This is an interesting study that sought to evaluate a possible association between the infective T. cruzi genotype and the clinical manifestation of Chagas disease in Brazilian patients. Although the results confirm data from other authors that TcII is prevalent in patients from various regions of Brazil and that DTU TcII promotes the indeterminate, cardiac and cardiodigestive forms in the chronic phase, the study deserves to be published not only because it expands knowledge on the subject, but also because it is a well-conducted study that also analyzes the progression of the disease in some patients.

To supplement the MS, this reviewer raises some relevant points that must be taken into account before the final acceptance. These points are listed below:

- Title: Association between Trypanosoma cruzi genotypes and chronic Chagas disease clinical presentation and outcome in an urban cohort in Brazil.

The title is very assertive. The reader is induced to think that the authors found this association, when, in fact, TcII is responsible for cardiac, indeterminate and cardiodigestive forms. Therefore, the following title is suggested:

Association between Trypanosoma cruzi DTU TcII and chronic Chagas disease clinical presentations and outcome in an urban cohort in Brazil.

Background

Line 32: Substitution: This study aimed to identify the potential association between T. cruzi genotypes and the clinical presentations of chronic Chagas disease.

Methodology/Principal Findings

Suggestion: Start by describing the characteristics of the patients. Then, describe the DTU typing method and the data obtained.

Conclusions/Significance

Provide percentages:

Line 49 - TcII was the main T. cruzi DTU identified in chronic Chagas disease Brazilian patients (45.2%)….

Line 51 - Other DTU found in much less frequency (4.7%) was TcVI.

Introduction

Line 82 -…… Latin America, mainly in Argentina, Brazil, Mexico, Bolivia and Colombia [2,3].

Why are countries mentioned in this order? Is it in decreasing order of prevalence? If not, quote in alphabetical order: Argentina, Bolivia, Brazil, Colombia and Mexico

Line 101 – Reassess the sentence: “Therefore, TcII, TcV, and TcVI are the T. cruzi genotypes with the highest pathogenic potential as they are related both to cardiac and digestive chronic clinical Chagas disease forms [6]”.

This reviewer does not agree with the statement that these DTUs have the highest pathogenic potential BECAUSE they cause cardiac and digestive forms. TcI is also highly pathogenic and causes severe cardiomyopathy in chronic chagasic patients in Argentina (Burgos et al. Clin Infect Dis. 2010; 51: 485–495) and Colombia (Ramírez et al. PLoS Negl Trop Dis. 2010 doi: 10.1371 / journal.pntd.0000899) as well as Venezuela.

Methods. Patients and Study Design:

Briefly inform the tests used for clinical evaluation of the cardiac, digestive and cardiodigestive forms.

Results

Line 208 – Inform percentage: Most patients were women (72.2%) and were infected by vector borne transmission (Table 2).

Line 260 – Rephrase: A total of 8 patients (18.6%) with the cardiac or cardiodigestive forms progressed during the study follow-up,

Discussion

Some relevant aspects should be included in the Discussion to make it more comprehensive and hypotheses should be raised by the authors to explain some observations.

- In the cohort, there were no patients with only the digestive form. On the other hand, 23% of the patients had the cardiodigestive form. Since several authors show that TcII promotes the digestive form (cite references). To what factors do the authors attribute the findings of the present study? (see Lines 322-331).

- Comment on a possible criticism:

Although a few reports have shown that the parasite population infecting specific organs can be genetically distinct from the population found in the patients’ blood (cite references), it is unlikely that this occurs in the cohort of patients here analyzed.

- A clear conclusion of the study is that TcII promotes different clinical presentations of ChD. The studies by Lages-Silva et al. (Ref. 23), which indicate that the genetic variability within TcII is not associated with the clinical manifestation, should be cited.

- On Line 346 the authors mention that “immunologic factors of the host together with parasite genetic variation contribute to the diversity of Chagas disease clinical presentation [6]”. Authors should further develop this hypothesis by presenting some studies that can support it.

The sentences below can be improved

Line 282 Therefore, it is needed to describe which T. cruzi DTUs are found in patients with Chagas disease in Brazil and which clinical presentations and outcomes can be associated to those DTUs.

Line 299 Our (?) predominance of patients with cardiac form can

Move Fig. 2 to Supplemental data.

Reviewer #2: This study aims at identifying T. cruzi parasite genotypes and correlate these with clinical manifestations in a convenience sample of patients. It is an important topic and the study is overall well performed and well presented. The major limitation is the methodological approach used, which is not the most appropriate for such studies. Indeed, genotyping by PCR from isolated parasites generates bias as in vitro culture selects for strains growing faster in the selected medium, and genotyping by PCR only detects the dominant strains in potential mixtures of strains. More sensitive approaches based on direct genotyping by sequencing, and particularly deep sequencing, have shown that infections with multiple strains/DTUs can be frequent in some regions (see for example Villanueva-Lizama et al., J Infect Dis, 2019. 219(12): 1980-1988) and may have been overlooked in this study. These aspects should at least be discussed.

Minor comments:

Follow-up time should be indicated for each patient in Table 4. Also, were any patient’s samples genotyped at more than 1 time point during their follow-up? If yes, were there any changes in parasite genotypes over time as seen in some studies? Has parasitemia been quantified in these patients? Were the patients treated? If yes, how did they respond to treatment? These aspects would enrich the study.

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Reviewer #1: No

Reviewer #2: Yes: Eric Dumonteil

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PONE-D-20-26324R1

Association between Trypanosoma cruzi DTU TcII and chronic Chagas disease clinical presentation and outcome in an urban cohort in Brazil.

PLOS ONE

Dear Dr. Roberto Saraiva,

Thank you for submitting your manuscript to PLOS ONE. After careful consideration, we feel that it has merit for publication with a couple of minor edits. Therefore, we invite you to submit a revised version of the manuscript that addresses the points raised during the review process.

Editor Comments:

The authors well addressed the reviewers' comments. For the final acceptance of the article, I'm asking authors make a couple of minor edits on page 22, line 434, change "Limitations" by "Study limitations," and on page 18, line 349, replace "in the present article" with " in this study. "

Please submit your revised manuscript by 11/11/2020. If you will need more time than this to complete your revisions, please reply to this message or contact the journal office at plosone@plos.org. When you're ready to submit your revision, log on to https://www.editorialmanager.com/pone/ and select the 'Submissions Needing Revision' folder to locate your manuscript file.

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If applicable, we recommend that you deposit your laboratory protocols in protocols.io to enhance the reproducibility of your results. Protocols.io assigns your protocol its own identifier (DOI) so that it can be cited independently in the future. For instructions see: http://journals.plos.org/plosone/s/submission-guidelines#loc-laboratory-protocols

We look forward to receiving your revised manuscript.

Kind regards,

Claudia Patricia Herrera, Ph.D.

Academic Editor

PLOS ONE

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[NOTE: If reviewer comments were submitted as an attachment file, they will be attached to this email and accessible via the submission site. Please log into your account, locate the manuscript record, and check for the action link "View Attachments". If this link does not appear, there are no attachment files.]

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Association between Trypanosoma cruzi DTU TcII and chronic Chagas disease clinical presentation and outcome in an urban cohort in Brazil.

PONE-D-20-26324R2

Dear Dr. Saraiva,

We’re pleased to inform you that your manuscript has been judged scientifically suitable for publication and will be formally accepted for publication once it meets all outstanding technical requirements.

Within one week, you’ll receive an e-mail detailing the required amendments. When these have been addressed, you’ll receive a formal acceptance letter and your manuscript will be scheduled for publication.

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Kind regards,

Claudia Patricia Herrera, Ph.D.

Academic Editor

PLOS ONE

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