Reviewer's report 
 Epidemiologic study of chronic hepatitis B virus infection in male volunteer blood donors in Title: 
Karachi, Pakistan 
 4  27 June 2005 Version: Date: 
 Keith Sabin Reviewer: 
Reviewer's report: 
General 
It seems that you have dealt with most of my major concerns about your interpretation of the results. 
However, I think you have misunderstood some of the citations you use to justify your choice of 
interpretation. While anti-HBc is not protective from infection in the way anti-HBs is, it is still 
indicative of prior infection and therefore there is virtually zero probability of re-infection by HBV. 
There are few case reports of such re-infection, but it is by no means typical and one cannot 
assume, in an epidemiologic survey, that anti-HBc(+) individuals are susceptible. Further, anti-HBc is less likely to wane to undetectable level than anti-HBs, so misclassification with anti-HBc is less 
than that with anti-HBs. 
In any case, I think it would help if you add a simple statement regarding the case-control study, that 
ascertainment of controls' serostatus may have non-differentially led to controls who are not 
susceptible to HB infection due to previous infection or immunization, thereby biasing results toward 
the null. 
------------------------------------------------------------------------------- 
Major Compulsory Revisions (that the author must respond to before a decision on publication can 
be reached) 
------------------------------------------------------------------------------- 
Minor Essential Revisions (such as missing labels on figures, or the wrong use of a term, which the 
author can be trusted to correct) 
------------------------------------------------------------------------------- 
Discretionary Revisions (which the author can choose to ignore) 
 Accept after minor essential revisions What next?: 
 An article whose findings are important to those with closely related research Level of interest: 
interests 
 Needs some language corrections before being published Quality of written English: 
 No Statistical review: 
Reviewer's report 
 Epidemiologic study of chronic hepatitis B virus infection in male volunteer blood donors in Title: 
Karachi, Pakistan 
 4  27 June 2005 Version: Date: 
 Keith Sabin Reviewer: 
Reviewer's report: 
General 
It seems that you have dealt with most of my major concerns about your interpretation of the results. 
However, I think you have misunderstood some of the citations you use to justify your choice of 
interpretation. While anti-HBc is not protective from infection in the way anti-HBs is, it is still 
indicative of prior infection and therefore there is virtually zero probability of re-infection by HBV. 
There are few case reports of such re-infection, but it is by no means typical and one cannot 
assume, in an epidemiologic survey, that anti-HBc(+) individuals are susceptible. Further, anti-HBc is less likely to wane to undetectable level than anti-HBs, so misclassification with anti-HBc is less 
than that with anti-HBs. 
In any case, I think it would help if you add a simple statement regarding the case-control study, that 
ascertainment of controls' serostatus may have non-differentially led to controls who are not 
susceptible to HB infection due to previous infection or immunization, thereby biasing results toward 
the null. 
------------------------------------------------------------------------------- 
Major Compulsory Revisions (that the author must respond to before a decision on publication can 
be reached) 
------------------------------------------------------------------------------- 
Minor Essential Revisions (such as missing labels on figures, or the wrong use of a term, which the 
author can be trusted to correct) 
------------------------------------------------------------------------------- 
Discretionary Revisions (which the author can choose to ignore) 
 Accept after minor essential revisions What next?: 
 An article whose findings are important to those with closely related research Level of interest: 
interests 
 Needs some language corrections before being published Quality of written English: 
 No Statistical review: 
Please review this paper.
user
Reviewer's report 
 Epidemiologic study of chronic hepatitis B virus infection in male volunteer blood donors in Title: 
Karachi, Pakistan 
 4  27 June 2005 Version: Date: 
 Keith Sabin Reviewer: 
Reviewer's report: 
General 
It seems that you have dealt with most of my major concerns about your interpretation of the results. 
However, I think you have misunderstood some of the citations you use to justify your choice of 
interpretation. While anti-HBc is not protective from infection in the way anti-HBs is, it is still 
indicative of prior infection and therefore there is virtually zero probability of re-infection by HBV. 
There are few case reports of such re-infection, but it is by no means typical and one cannot 
assume, in an epidemiologic survey, that anti-HBc(+) individuals are susceptible. Further, anti-HBc is less likely to wane to undetectable level than anti-HBs, so misclassification with anti-HBc is less 
than that with anti-HBs. 
In any case, I think it would help if you add a simple statement regarding the case-control study, that 
ascertainment of controls' serostatus may have non-differentially led to controls who are not 
susceptible to HB infection due to previous infection or immunization, thereby biasing results toward 
the null. 
------------------------------------------------------------------------------- 
Major Compulsory Revisions (that the author must respond to before a decision on publication can 
be reached) 
------------------------------------------------------------------------------- 
Minor Essential Revisions (such as missing labels on figures, or the wrong use of a term, which the 
author can be trusted to correct) 
------------------------------------------------------------------------------- 
Discretionary Revisions (which the author can choose to ignore) 
 Accept after minor essential revisions What next?: 
 An article whose findings are important to those with closely related research Level of interest: 
interests 
 Needs some language corrections before being published Quality of written English: 
 No Statistical review: 
assistant