Cell Entry of Animal Coronaviruses

Round 1

Reviewer 1 Report

The review written by Cheng et al. is a good compilation of the information currently available about the cellular entry process of animal coronaviruses as well as the involved molecules and possible inhibitors. It is correctly written, in an understandable way and with up-to-date information.

Author Response

- Reviewer 1 does not have specific comment except saying that minor spell check required. 

Response: We have carefully examine the whole manuscript, and made dozens of changes as followings (changes are tracked):

1. Changed" Celling" to "cell" in line 17;
2. Added " and the" and changed "site" to "sites" in line 18;
3. Changed " factor" to "factors" in line 49;
4. Changed " retrovirus" to "retroviruses" in line 82;
5. Added "(S)" in line 91;
6. Deleted "S: spike. M: membrane. E: envelope. N: nucleocapsid. " in line 93;
7. Added "the" in line 100;
8. Added "*" behind "Species" in Table 1 and added "*" in line 123;
9. Added "The references are provided in bracket for the RBDs and attachment factors." in line 124-125;
10. Added ")" in line 127;
11. Added " domains and" and "s" in line 136;
12. Changed "abolishes" to "abolished" in line 137;
13. Changed " confers" to "conferred" in line 146 and 147;
14. Changed " supports" to "supported" in line 154;
15. Changed " to" to "be" in line 164;
16. Changed "betacoronaviruses" to "betacoronavirus" in line 165;
17. Changed the size of "neuraminic acid, a monosaccharide with a nine-carbon" from 12 to 10 in line 192 and 193;
18. Deleted " have" in line 195;
19. Changed " PRCoV" to "porcine respiratory coronavirus (PRCoV)" in line 205;
20. Deleted a space in line 207;
21. Deleted "the" in line 212;
22. Changed "betacoronaviruses" to italic in line 217;
23. Changed "receptor determinant" to "attachment factor " in line 219;
24. Added " ." in line 234;
25. Changed " due to" to " mediated by" in line 237;
26. Changed " S1-NTD" to "S1-NTDs" in line 238 and line 241; 
27. Changed " that" to "those" in line 239;
28. Changed the size of "polysaccharides" and "disaccharide" from 12 to 10 in line 244;
29. Changed " attachment/entry receptor" to "an attachment factor" in line 248;
30. Changed "becomes" to "became" in line 254;
31. Changed "results" to "resulted" in lin 255;
32. Changed "extends" to "extended" in line 256;
33. Changed "as entry receptor " to "for cell entry" in line 257;
34. Changed "can" to "could" in line 258; 
35. Deleted "also" in line 259; 
36. Changed "gammacoronaviruses" to italic in line 264;
37. Changed " species tropism" to "host range" in line 266;
38. Added "particles" in line 274;
39. Changed " show" to "showed" in line 281;
40. Added "the" in line 284;
41. Changed "does" to "do" in line 288;
42. Changed " play" to "plays" in line 301;
43. Changed "protein" to "proteins" in line 303;
44. Added "the" in line 304, 307, 320, 322, 333, and 357;
45. Added "the" and "individually" in line 321;
46. Added "region" in line 331;
47. Deleted "the" in line 337;
48. Deleted a space in line 341, 349 and 376;
49. Changed "alphacoronaviruses" to italic in line 343;
50. Deleted "," and added "and" in line 383;
51. Deleted "," in line 421;
52. Changed "Ly6E's" to "LY6E" in line 451;
53. Changed "control" to "controls" in line 452;
54. Changed " inhibit" to "inhibits" in line 459;
55. Deleted "Above of these implicate CD74 in host defense against a range of viruses, and identify an additional function of these proteins beyond their canonical roles in antigen presentation." in line 463-465.
56. Changed "shows" to "showed" in line 469;
57. Deleted "also" and changed "accumulates" to "accumulate" in line 486;
58. Changed "deplete" to "depletes" in line 489; 
59. Changed "SARA-CoV" to "SARS-CoV" in line 493;
60. Changed "in" to "is" in line 508;
61. Changed "need further investigation" to "thus further investigation is needed" in line 520.

Reviewer 2 Report

The authors wrote a useful review focusing on the cell entry of coronaviruses to their hosts. It compared and contrasted the mechanisms of entry of different animal viruses, including the involvement of different receptors. The better known mechanisms of cell binding between the coronaviral spike proteins and the receptors in their hosts were discussed in more detail. The roles of different attachment factors such as sialic acid, heparan sulfate, and C-type lectins were also introduced. The review also briefly outlined the participation of host restriction factors in coronavirus entry. Host restriction factors covered included the interferon-induced transmembrane proteins, lymphocyte antigen 6 family member E, CD74, Ezrin, gamma-interferon-inducible lysosomal thiol reductase, and cholesterol 25-hydroxylase. The review should provide a useful introduction to scientists just entering the field or just wanting to learn something about how coronaviruses enter host cells.

The paper was well written but please correct the following typos:

line 17: change “celling binding” to “cell binding”.

line 492: change “SARA-CoV” to “SARS-CoV”.

Author Response

- The reviewer 2 suggests correction of two typos. One is at line 17: change “celling binding” to “cell binding”. The other is at line 492: change “SARA-CoV” to “SARS-CoV”.

Response: both of them were corrected.

This manuscript is a resubmission of an earlier submission. The following is a list of the peer review reports and author responses from that submission.