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Assessment of the rabbit as a wildlife reservoir of bovine viral diarrhea virus: serological analysis and generation of trans-placentally infected offspring.

Grant DM, Dagleish MP, Bachofen C, Boag B, Deane D, Percival A, Zadoks RN, Russell GC - Front Microbiol (2015)

Bottom Line: This did not lead to any clinical signs in the infected animals or obvious increases in abortion or stillbirth in the infected dams.Samples from the dams, placental material and ∼130 offspring were tested by BVDV-specific RT-PCR and antibody ELISA.Many of the offspring had BVDV-specific antibodies.

View Article: PubMed Central - PubMed

Affiliation: Vaccines and Diagnostics, Moredun Research Institute, Pentlands Science Park Midlothian, UK.

ABSTRACT
Eradication of bovine viral diarrhea virus (BVDV) is ongoing in many European countries and is based on removal of persistently infected (PI) cattle. In this context, low-level risks, including alternative reservoirs of infection, may become more important as the number of BVDV-free herds increases. Alternative reservoirs include livestock, such as sheep and goats, as well as wildlife, including deer and rabbits. Due to the extensive nature of the beef industry in Scotland, where an eradication program started in 2010, contact between cattle and alternative reservoir hosts is common. Seroprevalence to BVDV in rabbit populations can be high. In addition, rabbits can be infected with BVDV by natural routes, indicating that they could be a wildlife reservoir of infection. We analyzed the potential risk to livestock from rabbit populations in the UK by two approaches. First, ∼260 serum samples from free-ranging wild rabbits in Scotland and northern England were tested for BVDV-specific antibodies by ELISA. Only three samples exhibited low level BVDV-specific reactivity, suggesting that BVDV infection of rabbits was not frequent. Second, rabbits were challenged with BVDV at day 7 or 12 of pregnancy. This did not lead to any clinical signs in the infected animals or obvious increases in abortion or stillbirth in the infected dams. Samples from the dams, placental material and ∼130 offspring were tested by BVDV-specific RT-PCR and antibody ELISA. Positive PCR results in the placentas and in the tissues and body fluids of rabbits up to 10 days old showed that trans-placental infection of rabbits with BVDV had occurred. Many of the offspring had BVDV-specific antibodies. These data support the view that a wildlife reservoir of BVDV in rabbit poses a small but non-zero risk of re-infection for BVDV-free cattle herds. Rabbits are susceptible to infection with BVDV but only a small proportion of free-living rabbits in the UK appear to have been infected.

No MeSH data available.


Related in: MedlinePlus

Reactivity of BVDV-infected rabbits and their offspring to BVDV antigen. S/P values (vertical axis) of terminal serum samples from all tested dams and offspring (horizontal axis) are plotted. Dams are identified by their four-letter ear-tag codes, while the tested offspring follow the respective dams, identified by single letters or numbers depending on their survival, as described in Table 2. Experimental group is indicated within each chart. The position of the S/P value cut-off for these samples (0.2) is indicated by a horizontal line on each chart. All offspring tested here by ELISA were also tested by RT-PCR and positive RT-PCR results are indicated by an asterisk above the relevant column (∗).
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Figure 2: Reactivity of BVDV-infected rabbits and their offspring to BVDV antigen. S/P values (vertical axis) of terminal serum samples from all tested dams and offspring (horizontal axis) are plotted. Dams are identified by their four-letter ear-tag codes, while the tested offspring follow the respective dams, identified by single letters or numbers depending on their survival, as described in Table 2. Experimental group is indicated within each chart. The position of the S/P value cut-off for these samples (0.2) is indicated by a horizontal line on each chart. All offspring tested here by ELISA were also tested by RT-PCR and positive RT-PCR results are indicated by an asterisk above the relevant column (∗).

Mentions: Terminal serum samples from all dams were tested by BVDV-specific ELISA to demonstrate seroconversion (compared to seronegative pre-infection samples), which was used as indicator of successful infection. All offspring, where a terminal serum sample could be obtained, were tested in the same way to demonstrate presence of BVDV-specific antibodies, without distinction between maternal antibodies or antibodies generated by the offspring. The S/P values of the terminal samples are shown in Figure 2 and summarized in Table 2. A cut-off for samples to be considered positive was calculated from Group 3 as the mean S/P value plus three standard deviations (0.2). The data show that dams in Groups 1 and 2 responded to BVDV infection with a mean S/P value of 0.57. The timing of infection did not have a significant effect on the terminal titre, although the Group 1 dams (infected at day 7 after mating) appeared to have a lower mean S/P value (0.40) than dams in Group 2 (0.75) that were infected 5 days later.


Assessment of the rabbit as a wildlife reservoir of bovine viral diarrhea virus: serological analysis and generation of trans-placentally infected offspring.

Grant DM, Dagleish MP, Bachofen C, Boag B, Deane D, Percival A, Zadoks RN, Russell GC - Front Microbiol (2015)

Reactivity of BVDV-infected rabbits and their offspring to BVDV antigen. S/P values (vertical axis) of terminal serum samples from all tested dams and offspring (horizontal axis) are plotted. Dams are identified by their four-letter ear-tag codes, while the tested offspring follow the respective dams, identified by single letters or numbers depending on their survival, as described in Table 2. Experimental group is indicated within each chart. The position of the S/P value cut-off for these samples (0.2) is indicated by a horizontal line on each chart. All offspring tested here by ELISA were also tested by RT-PCR and positive RT-PCR results are indicated by an asterisk above the relevant column (∗).
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4585287&req=5

Figure 2: Reactivity of BVDV-infected rabbits and their offspring to BVDV antigen. S/P values (vertical axis) of terminal serum samples from all tested dams and offspring (horizontal axis) are plotted. Dams are identified by their four-letter ear-tag codes, while the tested offspring follow the respective dams, identified by single letters or numbers depending on their survival, as described in Table 2. Experimental group is indicated within each chart. The position of the S/P value cut-off for these samples (0.2) is indicated by a horizontal line on each chart. All offspring tested here by ELISA were also tested by RT-PCR and positive RT-PCR results are indicated by an asterisk above the relevant column (∗).
Mentions: Terminal serum samples from all dams were tested by BVDV-specific ELISA to demonstrate seroconversion (compared to seronegative pre-infection samples), which was used as indicator of successful infection. All offspring, where a terminal serum sample could be obtained, were tested in the same way to demonstrate presence of BVDV-specific antibodies, without distinction between maternal antibodies or antibodies generated by the offspring. The S/P values of the terminal samples are shown in Figure 2 and summarized in Table 2. A cut-off for samples to be considered positive was calculated from Group 3 as the mean S/P value plus three standard deviations (0.2). The data show that dams in Groups 1 and 2 responded to BVDV infection with a mean S/P value of 0.57. The timing of infection did not have a significant effect on the terminal titre, although the Group 1 dams (infected at day 7 after mating) appeared to have a lower mean S/P value (0.40) than dams in Group 2 (0.75) that were infected 5 days later.

Bottom Line: This did not lead to any clinical signs in the infected animals or obvious increases in abortion or stillbirth in the infected dams.Samples from the dams, placental material and ∼130 offspring were tested by BVDV-specific RT-PCR and antibody ELISA.Many of the offspring had BVDV-specific antibodies.

View Article: PubMed Central - PubMed

Affiliation: Vaccines and Diagnostics, Moredun Research Institute, Pentlands Science Park Midlothian, UK.

ABSTRACT
Eradication of bovine viral diarrhea virus (BVDV) is ongoing in many European countries and is based on removal of persistently infected (PI) cattle. In this context, low-level risks, including alternative reservoirs of infection, may become more important as the number of BVDV-free herds increases. Alternative reservoirs include livestock, such as sheep and goats, as well as wildlife, including deer and rabbits. Due to the extensive nature of the beef industry in Scotland, where an eradication program started in 2010, contact between cattle and alternative reservoir hosts is common. Seroprevalence to BVDV in rabbit populations can be high. In addition, rabbits can be infected with BVDV by natural routes, indicating that they could be a wildlife reservoir of infection. We analyzed the potential risk to livestock from rabbit populations in the UK by two approaches. First, ∼260 serum samples from free-ranging wild rabbits in Scotland and northern England were tested for BVDV-specific antibodies by ELISA. Only three samples exhibited low level BVDV-specific reactivity, suggesting that BVDV infection of rabbits was not frequent. Second, rabbits were challenged with BVDV at day 7 or 12 of pregnancy. This did not lead to any clinical signs in the infected animals or obvious increases in abortion or stillbirth in the infected dams. Samples from the dams, placental material and ∼130 offspring were tested by BVDV-specific RT-PCR and antibody ELISA. Positive PCR results in the placentas and in the tissues and body fluids of rabbits up to 10 days old showed that trans-placental infection of rabbits with BVDV had occurred. Many of the offspring had BVDV-specific antibodies. These data support the view that a wildlife reservoir of BVDV in rabbit poses a small but non-zero risk of re-infection for BVDV-free cattle herds. Rabbits are susceptible to infection with BVDV but only a small proportion of free-living rabbits in the UK appear to have been infected.

No MeSH data available.


Related in: MedlinePlus