In this work, Abo-Zaid et al. focus on evaluating the host immune responses to Giardia lamblia in male Wistar rats. They follow the kinetics of both antibody and cytokine release in blood samples from naïve and G. lamblia-infected rats at 7, 14, 21, 28 and 35 days post-primary infection, as well as total white blood cell counts, trophozoite and cyst loads. Overall, the manuscript presents several major pitfalls and weaknesses, which the authors need to address in order to raise the manuscript to a higher publication standard.

Introduction: The authors have ignored a growing number of publications on anti-Giardia immune responses from the past years, which show convincing evidence of a key role for Th17, rather than Th1/Th2 responses for the control of Giardia infection. Please see: https://pubmed.ncbi.nlm.nih.gov/31889073/, https://pubmed.ncbi.nlm.nih.gov/26071205/, https://pubmed.ncbi.nlm.nih.gov/26376930/, https://pubmed.ncbi.nlm.nih.gov/24866800/, https://pubmed.ncbi.nlm.nih.gov/28819174/.

Manuscript formatting and English:

The line numbering throughout the manuscript restarts on every new page, making it difficult to easily compile a reviewer report and to comment on different sections or lines throughout the text. Moreover, the font sizes of the main text and the line numbers are very different and are completely mismatched, making it impossible to tell how the lines are numbered.

A well-intended recommendation to the authors would be to seek assistance from either a professional editor or a native English speaker to improve the quality of the written English throughout the manuscript. Numerous grammar and punctuation mistakes can be found within the text. Certain statements and interpretations are also written in a semi-incomprehensible manner and need re-phrasing.

Materials and Methods:

The description of how the rats were divided into groups is described in a very confusing manner for the reader.

The authors claim that they obtained a stock concentration of 10,000 cysts/mL and yet describe that the rats were infected with 2mL of the suspension. This would amount to 20,000 cysts/animal and not 10,000. The authors should double-check and clarify the infection dose per animal.

Results:

The results in Fig. 1,2 are inconsistently discussed: as pg/mL and ng/mL in the figure, while in the text they are discussed in percentage change.

Fig. 2: A significant decrease in IFNg is observed at later timepoints of infection, compared with earlier timepoints. This is not mentioned and not at all discussed by the authors in greater details.

Table 3: These results could be made much more understandable and easily interpretable if presented as bar graphs, rather than as a table.

Fig. 5-8 are cited in the Results before Fig. 3-4. Moreover, it appears that the authors have incorrectly interpreted some exemplary blood in Fig. 5-8. In the Fig. 5 legend it is unclear what is meant by “large granular lymphocytes” and “reactive lymphocytes” as neither statement can correctly be attributed to a typical lymphocyte phenotype by simply looking at blood smears.

The Discussion reaches a total of 9 full pages, which appears very unnecessary and unbalanced with the rest of the main text, where the combined introduction, methods and results reach only 7 pages. The authors should consider significantly trimming their Discussion section accordingly.

Several publications are incorrectly interpreted and cited in the text and some (eg. Yordanova et al. 2021) are listed in the References but are not cited anywhere in the text. Also, having looked up this reference, it was first published in 2020 and not 2021. Please see: https://onlinelibrary.wiley.com/doi/10.1111/pim.12791