Bovine Viral Diarrhea Virus: Recent Findings about Its Occurrence in Pigs

Round 1

Reviewer 1 Report

Overall, the manuscript needs help in terms of focus and organization.  That is, it touches on a lot of topics, but the logic for the order of presentation is difficult to follow and the information is too superficial.  For example, the abstract rightly says that "the presence of antibodies anti-BVDV in swine herds may interfere in the surveillance of CSF", but this topic is not fleshed out in the body of the reivew.  Of course, there is an massive body of literature on BVDV in pigs, cross reactions with CSFV tests, etc.  It is challenging to integrate this enormous body of information into a short review.  My suggestion would be to narrow the topic, e.g., Update on BVDV Infections in Pigs.  The "Update" could be on current estimates of BVDV infections in commercial pigs; recent experimental data; contemporary diagnostics and cross reactivity among pestiviruses.  

Author Response

Dear Viruses Editor and Reviewers,

We are very grateful for the opportunity of having our manuscript considered for publication in this important journal. We have accepted and corrected all items suggested by the Reviewers, and provided a better explanation of specific points for clarifying our idea.

We understand that there is plenty information regarding BVDV infection on pigs, and we wanted to bring data from recent experiments that contrast with the former ones. We have made a suggestion to narrow the manuscript title, which should better comprise the content of the work.

We are extremely thankful for all the suggestions, because we know that all of them were very important for improving the quality of this work. We also stated the changes made to the manuscript in response to the respective comment. Thank you for the opportunity to improve our work, we hope to receive a positive response.

Author Response File: Author Response.pdf

Reviewer 2 Report

The manuscript describes the review article of BVDV infections in pigs.

In general all important topics are included but not clearly and comprehensive  presented for reader in manuscript.

The statements from the literature are presented only as partial observation, not completely ''state of the art'' foe review article. This is difficult topics, but should be presented more comprehensive.

Some concerns:

Chapter 1 Update and general informations...

Lines 27-33 and 34-41: Old and new classification are presented one afer another-this should be explained properly

Lines 45-48: this statement can be moved down among reported countries (line 50).

Lines 54-69: Rather old references were used here: In general differential diagnosis of pestivirus antibodies can be obtained with VN test and using diffrent reference strains of CSFV, BVDV and Border disease virus, including field strains. The higher titer is obtained for homologus strain...

General data about cross reactivity in VN is missing

Lines  77-78: need revision, not clear

Line 79: Serological diagnostic (by ELISA test?)...

Lines 85; PSC vaccine (PSC?)

Line 88: RT-PCR -not celar (RT-reverse trascription or real-time PCR)

Chapter 2: Data collection...

Line 100: it is not clear the meaning of technified and non-technified pig herds

Line 104: not celar which strains were used for VN (reference of field strains)

Lines 103-107: nothing about titer of detected antibodies, also data about cohabitate of pigs and cattle is important.

Lines 112-118: What about Border disese virus antibodies

Table 2: Important data is mnissing-% of seroconverted pigs in different experimental infections, also data about titers for homologous strain and heterologos strains, if available should be presented

Author Response

Dear Viruses Editor and Reviewers,

We are very grateful for the opportunity of having our manuscript considered for publication in this important journal. We have accepted and corrected all items suggested by the Reviewers, and provided a better explanation of specific points for clarifying our idea.

We understand that there is plenty information regarding BVDV infection on pigs, and we wanted to bring data from recent experiments that contrast with the former ones. We have made a suggestion to narrow the manuscript title, which should better comprise the content of the work.

We are extremely thankful for all the suggestions, because we know that all of them were very important for improving the quality of this work. We also stated the changes made to the manuscript in response to the respective comment. Thank you for the opportunity to improve our work, we hope to receive a positive response.

Author Response File: Author Response.pdf

Reviewer 3 Report

The purpose of this generally well written manuscript is to review the current published literature on BVDV in swine. Controversy exists over the importance of BVDV infections swine that have been reported since the 1960s, and several studies have been published on this subject. These studies reported differing results about the ability of BVDV to cause infection and clinical signs in pigs. Clinical signs can range from completely asymptomatic, to signs of anemia, delayed development, rough hair coats, diarrhea, and others. Seroprevalence ranges dramatically in published reports, from less than 1% to 64% in different countries using different diagnostic techniques. BVDV infections in swine have been reported from both natural and experimental infections with a variety of methods of inoculation. As written, the manuscript focuses too much on the work by this group of authors, which likely has led to the conclusion that BVDV is not a threat to pigs – this is not the case based on other studies. Therefore the authors should discuss the conflicting results from previous studies, rather than omitting some of that work. While several improvements should be made to this manuscript, a review of the topic would be a valuable addition to the literature.

Specific comments:

1. In the abstract, authors state “Although BVDV does not pose a threat to pigs…”. However, many reports have demonstrated both experimental and natural infections resulting in clinical signs, this statement is not accurate. BVDV may not pose a similar threat to pigs as it does to ruminants, but there are certainly possible health effects. This statement should be revised…
2. As in comment 1, the same strong statement is made in the final considerations on line 233. As clinical signs can be observed under certain circumstances, we can’t definitively say that BVDV is not a threat to pig herds.
3. The abstract (and throughout) states that “this study aimed…” Please remove such language. The authors did not perform a study but wrote a review article.
4. Line 67- The reason for an absence of clinical signs in the studies conducted by your research group was postulated to only occur due to inadequate viremia. Is it not feasible that a low virulence strain in that species, serotype or biotype of the virus, host adaptation, or route of inoculation also be potential explanations for the lack of clinical signs?
5. Line 85- PSC is utilized, but no definition of the term is provided previously.
6. Line 86- PCR is utilized, but no definition of the term is provided previously.
7. Line 144- interspecies to interspecific
8. The entire manuscript is too focused on the work by this group of researchers. An example is the paragraph starting in line 157. Why did the authors omit work by Wieringa-Jelsma 2006, Paton and Done 1994, reports of clinical disease following use of contaminated vaccines etc. Much work has been done with BVDV in pigs and this previous work should be compared and contrasted, rather than omitted. Some of the other work contrast the research by this group of authors, and it is critical that it be discussed.
9. Line 205. In the cited work, pigs were inoculated on day 45 of gestation, which is likely outside of the window of susceptibility for creation of PI piglets. This should be discussed.
10. Section 3, lines 214-228 discuss of absence or presence of virus in semen in infected boars. As referenced #49, Terpstra and Wensvoort detail a persistently infected boar piglet that had virus present in the ejaculate, but no sperm were present. As no sperm was present in the ejaculate in this boar, it is speculative if horizontal transfer through insemination could occur, but vertical transmission would be possible.
11. Line 231- “maybe” needs to be changed to “may be”

Author Response

Dear Viruses Editor and Reviewers,

We are very grateful for the opportunity of having our manuscript considered for publication in this important journal. We have accepted and corrected all items suggested by the Reviewers, and provided a better explanation of specific points for clarifying our idea.

We understand that there is plenty information regarding BVDV infection on pigs, and we wanted to bring data from recent experiments that contrast with the former ones. We have made a suggestion to narrow the manuscript title, which should better comprise the content of the work.

We are extremely thankful for all the suggestions, because we know that all of them were very important for improving the quality of this work. We also stated the changes made to the manuscript in response to the respective comment. Thank you for the opportunity to improve our work, we hope to receive a positive response.

Author Response File: Author Response.pdf

Round 2

Reviewer 2 Report

The manuscript was significantly improved after revision and is now suitable for poblication. However, som minore remarks need to be implemented before publication.

1. Line 20: correct ''two dots'' at the end of sentece.
2. Line 59: Classical Swine Fever (CSF) already explained in line 55: correct into ''CSF''.
3. Line 84: Revise this sentence, specific RT-PCR methods are nowdays widely used for detection of viruses (PCR is not any more ''good alternative''), also direct sequencing from PCR product (eg in 5'NTR) should be metioned as an option for differentilal diagnosis between different pestivirus strains.
4. Line 94: Into chapter 2; Add also somewhere what is the titer, which is consider positive in VNT for BVD, when you are using VNT for differentioal disagnosis.
5. Also few sentences should bee added about possible effect of Border disese virus infection and other atipical pestiviruses for differential diagnosis in infected herds (maybe for Brasil this is not so important, but for other part of the world should be considered as an option, if different animal species are keept close together in the same holding)
6. Line 100: I will suggest use rether (Singer strain) instead only (Singer).
7. Line 101: I will suggest use (VS-253 strain) ....
8. Line 112: change into (Singer strain)
9. Line 113: change into (VS-253 strain)
10. Line 119: I will suggest to use ''The Netherlands'' instead of Holland
11. Line 120: Check aggain this sentence, is not clear...for finishing animals ELISA.
12. Line 130: use ''The Netherlans''
13. Line 134: Check anggain this sentence, if no exact data is presented in sentence, two time mentioned ''Germany'' is not necessary.
14. Line 200: delete ''(PI)'', here is enough ''congenital persistent infection''
15. Line 204: explain the meaning of ''CT''- first mentioned
16. Line 210: explain the meaning of APPV-first mentioned
17. Line 217: APPV is enough

I hope that my remarks are acceptable for you and will be considered as valuable and implemeted into reviesed version to improve manuscript before publication.

Author Response

Author Response File: Author Response.pdf