Review for 10.1186/1471-230X-10-44 (2010)

Reviewer's report
Title:Effective in vivo and ex vivo gene transfer to intestinal mucosa by
VSV-G-pseudotyped lentiviral vectors
Version: 4Date:11 February 2010
Reviewer: Steven Polyak
Reviewer's report:
Thank you for your clear responses to the initial comments and careful detailed
revisions to the manuscript. Nearly all comments were answered sufficiently and
I believe the manuscript is nearly ready for publication. Please see four
remaining comments. The comments are organized by Major and Minor per
journal specifications and each indicate which specific original comment is being
addressed.
Major revisions
1) Refer to author response to Major Comment #4 in the methods section and
Major Comment #3 in the results section: A significant observation in vector gene
transfer is the presence or lack of inflammation, which could be interpreted as a
safety concern or a confounder in experiments. You have provided Table 1
(which you reference for validation and how scoring is done) used to determine
gross pathology. You have also provided Table 2 used to determine histological
changes, but there is no reference; thus the question remains is this a validated
scoring system? Please add reference, otherwise experiments need to be shown
to validate it. Given the importance of, the presence or the lack of inflammation in
the tissues following vector treatment it is appropriate to provide the data
(numbers) to demonstrate lack of inflammation. Data comparing pathology of the
colon is provided but not the macroscopic or histological scoring data. This can
be simply stated in the text (paragraph 2 page 13 of pdf version). Alternatively, if
the histological scoring system is not validated, or there are no numbers
available to compare the experimental groups, then the histological scoring
methods and evaluations can be removed from the manuscript, but then this
weakness should be addressed in the discussion and conclusions. Lack of
inflammation is an important and relevant finding in the field of vector mediated
gene transfer.
2) Refer to author response to Major Comment #5 in the results section: Timing
and tissue structure disruption are provided as potential reasons for LV tropism
differences between murine and human mucosa (paragraph 2 page 18 of pdf
version). An additional uncontrolled experimental parameter is the ETOH in the in
vivo murine experiment vs. the polybrene used in the ex vivo human experiment.
The manuscript would be strengthened by briefly, discussing this potential
difference.
Minor revisions
1) Refer to author response to Minor Comment #5 in the methods section: The
term “quantitative morphometry” is misleading since it is typically reserved for
standardize digital imaging quantification techniques often using specialized
software. Since you state that this was not used please remove from text. Simply
state what you describe in the response, cells were manually counted.
2) Refer to author response to Minor Comment #1 in the results/discussion
section: “Additional figure 1” should be placed in the results section when
describing the immunofluorescence results. This figure should demonstrate to
the reader that a staining negative control was used to appropriately interpret the
images.
Level of interest: An article of importance in its field
Quality of written English: Acceptable
Statistical review: No, the manuscript does not need to be seen by a
statistician.
Declaration of competing interests:
I declare that I have no competing interests.