Chlamydiaceae-Like Bacterium in Wild Magellanic Penguins (Spheniscus magellanicus)

Round 1

Reviewer 1 Report

Thanks authors for your good work and presentation.

However, some explanations may be required.

1. Are the obtained results recent? Samples were collected from 2014-2017? were they recently processed?

2. Samples were taken from apparently healthy penguins, why author specifically suspected presence of Chalmydia or like bacteria?

Best wishes

 

Author Response

Thank you for taking the time to review our study.

Concerning question 1, the samples were processed at the time of their collection, i.e. 2014-2017. Unfortunately, we failed to publish the study earlier.

Concerning question 2, all penguins were apparently healthy and we had no reason to suspect that these particular individuals were infected. However, in a previous study (published in 2020 but based on data collected in 1994-2008, https://doi.org/10.7589/2019-01-022) we had detected a high prevalence of antibodies in apparently healthy penguins (37.1% with complement fixation test with a 1:10 cut-off, remarkably close to the 36.5% qPCR prevalence in this study). This was what hinted us that healthy penguins might be hosts to Chlamydiales and motivated the study.

Reviewer 2 Report

Dear authors,

in this simple study conducted on a wild population of penguins, the possible presence of C. psittaci was investigated. The research is well conducted and described. While regretting that the multiplication of chlamydia on cell culture and the sequencing of a larger number of samples was not successful, it would be useful to examine the prey of penguins in order to possibly confirm the theory of finding similar microorganisms in the prey of penguins.

Specific comments:

L 125 and 132 and 140 – bracket after the year

Author Response

Thank you for taking the time to review our study.

Indeed it is unfortunate how difficult it was to study this organism (isolation in cell culture and most attempts to sequence the bacterium were unsuccessful), but we were fortunate to have one sample where sequencing was successful. We have plans to study this pathogen further, both by attempting new methods to isolate the organism and to detect it in the prey of penguins. We are hopeful that this will clarify the ecology and epidemiology of this organism.

Concerning the specific comments, we corrected the brackets as indicated.

Reviewer 3 Report

The manuscript describes a study of Chlamydiaceae-like bacterium in penguins, an attempt to catch more data than in previous studies. The harvest was low, thus although Chlamydiaceae-like bacterium was detected by qPCR at very low amounts in 36% of analysed specimens it was only one specimen that resulted in a sequence that enabled phylogenetic analysis.

Furthermore, the very low positive reactions in qPCR raises the question about laboratory contamination or unspecific reaction. However, the manuscript put the findings in relation to previous studies in a meaningful way and the data obtained is therefore reasonable. At the end the study contributes to the understanding of Chlamydiaceae-like bacterium in penguins and other sea birds.

Author Response

Thank you for taking the time to review our study.

Indeed, this bacterium was challenging to study. We do not feel that this was an issue relating to laboratory contamination, but rather to low DNA concentration in the samples (as indicated by the high CQ values in qPCR). The fact that the only sample where sequencing was successful had the lowest CQ value in this study corroborates the interpretation that DNA concentration was the limiting factor to our success. That being said, we have plans to conduct further studies about this pathogen, with renewed attempts to isolate and characterize this organism and attempting its detection in prey of penguins.