Influence of border disease virus (BDV) on serological surveillance within the bovine virus diarrhea (BVD) eradication program in Switzerland

Novel Pestiviruses Detected in Cattle Interfere with Bovine Viral Diarrhea Virus Diagnostics

Since the start of the mandatory nationwide bovine viral diarrhea (BVD) eradication program in Germany in 2011, the number of persistently infected (PI) animals has decreased considerably, resulting in a continuous decrease in seroprevalence. The increasingly BVD-naive cattle population could facilitate spillover infections with non-BVDV ruminant pestiviruses. Here, we report two cases in which novel pestiviruses were isolated from cattle; in both cases, the whole genome sequence showed the highest level of identity to strain "Pestivirus reindeer-1". Both novel viruses gave positive results in BVDV diagnostic test systems, confirming that cross-reactivity is an important issue in pestivirus diagnostics. In the first case, the pestivirus was probably transmitted from sheep kept with the affected cattle, suggesting that the co-housing of small ruminants and cattle is a risk factor. The source of infection could not be determined in the second case. The occurrence of these two cases in independent cattle holdings within a relatively short time frame suggests that it would be useful to determine the presence of pestiviruses in small ruminants or even wild ruminants to better assess risk factors, especially for BVDV-free populations.

High Exposure to Livestock Pathogens in Southern Pudu (Pudu puda) from Chile

A significant gap in exposure data for most livestock and zoonotic pathogens is common for several Latin America deer species. This study examined the seroprevalence against 13 pathogens in 164 wild and captive southern pudu from Chile between 2011 and 2023. Livestock and zoonotic pathogen antibodies were detected in 22 of 109 wild pudus (20.18%; 95% CI: 13.34-29.18) and 17 of 55 captive pudus (30.91%; 95% CI: 19.52-44.96), including five Leptospira interrogans serovars (15.38% and 10.71%), Toxoplasma gondii (8.57% and 37.50%), Chlamydia abortus (3.03% and 12.82%), Neospora caninum (0.00% and 9.52%), and Pestivirus (8.00% and 6.67%). Risk factors were detected for Leptospira spp., showing that fawn pudu have statistically significantly higher risk of positivity than adults. In the case of T. gondii, pudu living in "free-range" have a lower risk of being positive for this parasite. In under-human-care pudu, a Pestivirus outbreak is the most strongly suspected as the cause of abortions in a zoo in the past. This study presents the first evidence of Chlamydia abortus in wildlife in South America and exposure to T. gondii, L. interrogans, and N. caninum in wild ungulate species in Chile. High seroprevalence of livestock pathogens such as Pestivirus and Leptospira Hardjo in wild animals suggests a livestock transmission in Chilean template forest.

Circulation of Pestiviruses in Small Ruminants from Greece: First Molecular Identification of Border Disease Virus

The incidence of small ruminant pestivirus infections in Greece remains unknown as they have not been diagnosed in the country since 1974 when the most recent Border Disease Virus (BDV) outbreak was reported. The objective of our study was to explore the possible occurrence of pestiviral infections among sheep and goat farms in Greece and to further determine the variants of major concern. Thus, serum samples were collected from 470 randomly selected animals belonging to 28 different flocks/herds. ELISA on p80 antibody revealed the existence of seropositive animals in four out of the 24 studied sheep flocks, whereas all the goats in the four studied herds were seronegative. Viral RNA and antigens were detected in two sheep out of the four seropositive flocks by RT-PCR and ELISA, respectively. Sequencing and phylogenetic analysis showed that the newly identified Greek variants were closely related to the strains of the BDV-4 genotype. One of the BDV-positive sheep demonstrated the diagnostic profile of a persistently infected (PI) animal, providing additional information regarding the source of the infection. This is the first molecular identification of BDV isolates in Greece. Our findings indicate that BDV infections are likely to remain undiagnosed, highlighting the need for further epidemiological studies and active surveillance programs to determine the prevalence and impact of BDV infections on a countrywide level.

Identification of border disease virus in naturally infected pigs in Mexico

Border disease virus (BDV) is a pathogen primarily infecting sheep and goats; however, infections in cattle, pigs, and wild ruminants have also been reported. Interspecies transmission of BDV occurs through close contact among infected animals. In this case report, we describe the detection of BDV in tonsil, mesenteric ganglia, and blood samples from piglets with severe clinical disease. Genetic characterization of evaluated samples resulted in the identification of BDV genotype 1 in Mexico. This represents the first report of BDV detected in pig populations in Mexico. Therefore, circulation of this virus in nonruminant populations should not be discarded.

Estimating the Effect of a Bovine Viral Diarrhea Virus Control Program: An Empirical Study on the Performance of Dutch Dairy Herds

More and more European countries have implemented a bovine viral diarrhea virus (BVDV) control program. The economic effects of such programs have been evaluated in simulations, but empirical studies are lacking, especially in the final stage of the program. We investigated the economic (gross margin) and production effects (milk yield, somatic cell count, and calving interval) of the herds obtaining BVDV-free certification based on longitudinal annual accounting and herd performance data from Dutch dairy herds between 2014 and 2019, the final stages of the Dutch national BVDV-free program. This study was designed as a case-control study: two types of case herds were defined for two analyses. The case herds in the first analysis are herds where the BVDV status changed from “BVDV not free” to “BVDV free” during the study period. The not-free status refers to a herd that participated in the BVDV-free program but had not yet obtained the BVDV-free certification. In the second analysis, the case herds started participating in the Dutch BVDV-free program during the study period and obtained the BVDV-free certification. Control herds in both analyses were BVDV-free during the entire study period. Potential bias between the covariates of the two herd groups was reduced by matching case and control herds using the propensity score matching method. To compare the differences between case and control herds before and after BVDV-free certification, we used the time-varying Difference-in-Differences estimation (DID) methodology. The results indicate that there was no significant change in milk yield, somatic cell count, calving interval, and gross margin upon BVDV-free certification. There are several possible explanations for the non-significant effects observed in our study, such as the final stage of the BVDV control program, not knowing the true BVDV infection situation in case herds and not knowing if control measures were implemented in case herds prior to participating in the BVDV-free program. In our study, the effects of BVDV-free certification might have been underestimated, given that the Dutch BVDV control program became mandatory during the study period, and some of the case herds might have never experienced any BVDV infection. The results of this study suggest that in the final stage of the BVDV control program, the program may no longer have a clear benefit to the herd performance of participating dairy herds. When designing national programs to eradicate BVDV, it is therefore important to include incentives for such farms to motivate them to join the program.

Evaluation of antibody and antigen cross-reaction in Kenyan dairy cattle naturally infected with two pestiviruses: Bovine viral diarrhea virus and classical swine fever virus

Background and Aim:

Bovine viral diarrhea virus (BVDV) and classical swine fever virus (CSFV) are important pathogens of cattle and pigs, respectively, and belong to the genus Pestivirus. As CSFV has been shown to infect cattle, it can create diagnostic challenges of BVDV results through possible cross-reactivity where cattle could be exposed to pigs and CSFV. This study aimed to determine the possible cross-reactivity of BVDV and CSFV enzyme-linked immunosorbent assay (ELISA) results for antigen (Ag) and antibody (Ab) among smallholder dairy cattle in Kenya.

Materials and Methods:

This was a cross-sectional study based on a single visit to farms to collect serum samples and other descriptive farm-level and animal-level information. Testing for BVDV Ag and Ab was conducted on serum samples from 320 dairy cows and heifers, with CSFV Ag and Ab testing conducted on a subset of 133 and 74 serum samples, respectively. CSFV testing was based on BVDV test results and the availability of enough sample volume from farms that kept pigs. The Ag and Ab tests utilized IDEXX ELISA for both BVDV and CSFV.

Results:

For the 74 samples with Ab tests for both viruses, 40 (54.0%) were BVDV Ab positive, while 63 (85.1%) were CSFV Ab positive. Of the 40 BVDV Ab positive samples, 36 cattle (90.0%) tested positive for CSFV Ab. However, of the 34 BVDV Ab negative samples, 27 (79.4%) were CSFV Ab test-positive. For the 133 samples with Ag tests for both viruses, 125 (94.0%) were BVDV Ag positive, while 2 (1.5%) samples were CSFV Ag positive. None of the eight BVDV Ag negative samples was positive for CSFV Ag and only two (1.6%) of the 125 BVDV Ag positive samples were positive for CSFV Ag.

Conclusion:

The results indicate either substantial cross-reactivity of the two Ab ELISA tests, or reactivity with some other protein in the samples that led to the positive Ab test results. There was only limited evidence for cross-reactivity of the two Ag ELISA tests. We recommend that Pestivirus genus cross-reactivity be considered when interpreting BVDV ELISA results in cattle, more for Ab than Ag tests. Further research is needed to clarify the levels of cross-reactivity between BVDV and other Pestivirus Ag and Ab tests from animals on mixed-species farms.

International proficiency trial for bovine viral diarrhea virus (BVDV) antibody detection: limitations of milk serology

Background

Control programs were implemented in several countries against bovine viral diarrhea (BVD), one of the most significant cattle diseases worldwide. Most of the programs rely on serological diagnostics in any phase of the program. For the detection of antibodies against BVD virus (BVDV), neutralization tests as well as a variety of (commercially available) ELISAs are used. Here, test systems applied in various laboratories were evaluated in the context of an international interlaboratory proficiency trial. A panel of standardized samples comprising five sera and five milk samples was sent to veterinary diagnostic laboratories (n=51) and test kit manufacturers (n=3).

Results

The ring trial sample panel was investigated by nine commercially available antibody ELISAs as well as by neutralization tests against diverse BVDV-1, BVDV-2 and/or border disease virus (BDV) strains. The negative serum and milk sample as well as a serum collected after BVDV-2 infection were mostly correctly tested regardless of the applied test system. A serum sample obtained from an animal immunized with an inactivated BVDV-1 vaccine tested positive by neutralization tests or by total antibody or E^rns-based ELISAs, while all applied NS3-based ELISAs gave negative results. A further serum, containing antibodies against the ovine BDV, reacted positive in all applied BVDV ELISAs, a differentiation between anti-BDV and anti-BVDV antibodies was only enabled by parallel application of neutralization tests against BVDV and BDV isolates. For the BVDV antibody-positive milk samples (n=4), which mimicked prevalences of 20% (n=2) or 50% (n=2), considerable differences in the number of positive results were observed, which mainly depended on the ELISA kit and the sample incubation protocols used. These 4 milk samples tested negative in 43.6%, 50.9%, 3.6% and 56.4%, respectively, of all investigations. Overall, negative results occurred more often, when a short sample incubation protocol instead of an over-night protocol was applied.

Conclusions

While the seronegative samples were correctly evaluated in most cases, there were considerable differences in the number of correct evaluations for the seropositive samples, most notably when pooled milk samples were tested. Hence, thorough validation and careful selection of ELISA tests are necessary, especially when applied during surveillance programs in BVD-free regions.

Fifty Shades of Erns: Innate Immune Evasion by the Viral Endonucleases of All Pestivirus Species

The genus Pestivirus, family Flaviviridae, includes four historically accepted species, i.e., bovine viral diarrhea virus (BVDV)-1 and -2, classical swine fever virus (CSFV), and border disease virus (BDV). A large number of new pestivirus species were identified in recent years. A common feature of most members is the presence of two unique proteins, N^pro and E^rns, that pestiviruses evolved to regulate the host’s innate immune response. In addition to its function as a structural envelope glycoprotein, E^rns is also released in the extracellular space, where it is endocytosed by neighboring cells. As an endoribonuclease, E^rns is able to cleave viral ss- and dsRNAs, thus preventing the stimulation of the host’s interferon (IFN) response. Here, we characterize the basic features of soluble E^rns of a large variety of classified and unassigned pestiviruses that have not yet been described. Its ability to form homodimers, its RNase activity, and the ability to inhibit dsRNA-induced IFN synthesis were investigated. Overall, we found large differences between the various E^rns proteins that cannot be predicted solely based on their primary amino acid sequences, and that might be the consequence of different virus-host co-evolution histories. This provides valuable information to delineate the structure-function relationship of pestiviral endoribonucleases.

Benefit of Bovine Viral Diarrhoea (BVD) Eradication in Cattle on Pestivirus Seroprevalence in Sheep

Bovine viral diarrhoea virus (BVDV) and Border disease virus (BDV) are closely related pestiviruses of cattle and sheep, respectively. Both viruses may be transmitted between either species, but control programs are restricted to BVDV in cattle. In 2008, a program to eradicate bovine viral diarrhoea (BVD) in cattle was started in Switzerland. As vaccination is prohibited, the cattle population is now widely naïve to pestivirus infections. In a recent study, we determined that nearly 10% of cattle are positive for antibodies to BDV. Here, we show that despite this regular transmission of BDV from small ruminants to cattle, we could only identify 25 cattle that were persistently infected with BDV during the last 12 years of the eradication program. In addition, by determining the BVDV and BDV seroprevalence in sheep in Central Switzerland before and after the start of the eradication, we provide evidence that BVDV is transmitted from cattle to sheep, and that the BVDV seroprevalence in sheep significantly decreased after its eradication in cattle. While BDV remains endemic in sheep, the population thus profited at least partially from BVD eradication in cattle. Importantly, on a national level, BVD eradication does not appear to be generally derailed by the presence of pestiviruses in sheep. However, with every single virus-positive cow, it is necessary to consider small ruminants as a potential source of infection, resulting in costly but essential investigations in the final stages of the eradication program.

The Long Journey to BVD Eradication

This paper provides a short review of bovine virus diarrhoea (BVD) control programmes across Europe, with a particular focus on current efforts from a stakeholder perspective. Using outputs gained from a global, virtual congress on BVD control, the theory of the journey from BVD control to possible eradication is enriched with insight from stakeholders representing the major parts of the cattle industry. Current control programmes were presented by Javier Dieguez (Galicia), Neil Shand (England), Neil Paton (Wales), Jenny Purcell (Scotland), Maria Guelbenzu (Ireland), Jörn Gethmann (Germany), and Matthias Schweizer (Switzerland).

Non-Bovine Species and the Risk to Effective Control of Bovine Viral Diarrhoea (BVD) in Cattle

Bovine viral diarrhoea virus (BVDV) is an economically important and highly prevalent virus of domestic cattle. Infections with BVDV may lead to both, reproductive and immunological effects that can result in widespread calf losses and increased susceptibility to diseases, such as mastitis and respiratory disease. While BVDV is generally considered to be host specific, it and other Pestivirus species, such as Border disease virus (BDV) in sheep, have been shown to be infecting species other than those from which they were originally isolated from. Recently BVDV was placed on the OIE’s list of notifiable disease and control and eradication programmes for BVDV have been developed throughout much of Europe, the United States, and the United Kingdom. While some countries, including Sweden and Ireland have successfully implemented eradication programmes, other countries such as New Zealand and Australia are still in the early stages of BVDV control. Despite effective control methods, incursions of BVDV into previously cleared herds still occur. While the cause of these incursions is often due to lapses in control methods, the ability of ruminant pestiviruses to infect species other than cattle poses the question as to whether non-bovine species could be impeding the success of BVDV eradication and control. As such, the aim of this review is to make mention of what is known about the cross-species transmission of BVDV, BDV and other pestiviruses between cattle and non-bovine ungulate species and draw conclusions as to the risk non-bovine species pose to the successful control and eradication of BVDV from cattle.

Eradication of Bovine Viral Diarrhoea (BVD) in Cattle in Switzerland: Lessons Taught by the Complex Biology of the Virus

Bovine viral diarrhoea virus (BVDV) and related ruminant pestiviruses occur worldwide and cause considerable economic losses in livestock and severely impair animal welfare. Switzerland started a national mandatory control programme in 2008 aiming to eradicate BVD from the Swiss cattle population. The peculiar biology of pestiviruses with the birth of persistently infected (PI) animals upon in utero infection in addition to transient infection of naïve animals requires vertical and horizontal transmission to be taken into account. Initially, every animal was tested for PI within the first year, followed by testing for the presence of virus in all newborn calves for the next four years. Prevalence of calves being born PI thus diminished substantially from around 1.4% to <0.02%, which enabled broad testing for the virus to be abandoned and switching to economically more favourable serological surveillance with vaccination being prohibited. By the end of 2020, more than 99.5% of all cattle farms in Switzerland were free of BVDV but eliminating the last remaining PI animals turned out to be a tougher nut to crack. In this review, we describe the Swiss BVD eradication scheme and the hurdles that were encountered and still remain during the implementation of the programme. The main challenge is to rapidly identify the source of infection in case of a positive result during antibody surveillance, and to efficiently protect the cattle population from re-infection, particularly in light of the endemic presence of the related pestivirus border disease virus (BDV) in sheep. As a consequence of these measures, complete eradication will (hopefully) soon be achieved, and the final step will then be the continuous documentation of freedom of disease.

Do modified live virus vaccines against bovine viral diarrhea induce fetal cross-protection against HoBi-like Pestivirus?

Bovine Pestivirus heterogeneity is a major challenge for vaccines against bovine viral diarrhea (BVD). In breeding herds, fetal protection is a high priority issue. To some degree, fetal infections in vaccinated heifers have been attributed to the antigenic diversity of bovine Pestiviruses. The purpose of this study was to assess fetal protection against a divergent bovine Pestivirus (Hobi-like Pestivirus, HoBiPeV) with a commercially available modified live vaccine (MLV) claiming fetal protection against BVDV 1 and BVDV 2 up to one year after the first inoculation. Five vaccinated and four unvaccinated heifers were challenged by intranasal inoculation with the HoBiPeV Italy-1/10-1 strain between 82 and 89 days after insemination, i.e. between 4 and 6 months after vaccination. At challenge, neutralizing antibody titers to HoBiPeV in vaccinated heifers were low or even undetectable. Of the four unvaccinated heifers, one control animal aborted (fetus not available) and the remaining three gave birth to HoBiPeV positive calves. Among the heifers of the vaccinated group, one aborted the fetus in the sixth month of pregnancy, which tested Pestivirus negative, while three others gave birth to healthy, HoBiPeV negative calves; the remaining heifer delivered one HoBiPeV positive calf. The results suggest that the BVDV vaccine might be able to elicit a partial fetal protection against HobiPeV, even in absence of a strong specific antibody response.

Viral infections shared between water buffaloes and small ruminants in Switzerland

Importation of exotic animals that may harbor infectious agents poses risks for native species with potentially severe impacts on animal health and animal production. Although the Asian water buffalo (Bubalus bubalis) population in Europe is steadily increasing, its susceptibility to viral infections and its role for interspecies transmission is largely unknown. To identify viral infections that are shared between exotic water buffaloes and native small ruminants, we collected blood samples from 3 Swiss farms on which water buffaloes were kept either without, or together with, sheep or goats. These samples were analyzed by next-generation sequencing (NGS) as well as by selected conventional tests, including PCR, ELISA, and in some cases a virus neutralization test. By NGS, a novel virus of the genus Gemykrogvirus (GyKV; Genomoviridae) was first detected in the buffaloes on one farm, and subsequently confirmed by PCR, and was also detected in the co-housed sheep. In contrast, this virus was not detected in buffaloes on the farms without sheep. Moreover, conventional methods identified a number of viral infections that were not shared between the exotic and the native animals, and provided evidence for potential roles of water buffaloes in the epidemiology of ruminant pestiviruses, especially bovine viral diarrhea virus, bluetongue virus, and possibly bovine alphaherpesvirus 2. Our results clearly indicate that water buffaloes are susceptible to interspecies viral transmission and may act as intermediate hosts, or even as reservoirs, for these viruses.

Detection of Pestivirus in small ruminants in Central Java, Indonesia

Background and Aim:

Globally, pestiviruses are among the most economically important viral pathogens of livestock. The genus Pestivirus comprises four species, including bovine viral diarrhea virus type 1 and 2 (BVDV-1 and BVDV-2), which infect cattle, border disease virus and classical swine fever virus which infect small ruminants and pigs, respectively. Accumulating evidence suggests that pestiviruses are no longer species-specific, creating new challenges for disease control. In Indonesia, investigations related to pestiviruses remain focused on cattle as the primary host and no research has been conducted on small ruminants (sheep and goats). Therefore, the present study aimed to study the possible occurrence of pestivirus (BVDV or BVD) infections in small ruminants in Indonesia, particularly in Central Java.

Materials and Methods:

We used 46 blood samples consisting of 26 sheep’s blood and 20 goat’s blood. Samples were selected from 247 small ruminant blood collected between July and October 2020 in Central Java, Indonesia, which met the following criteria: Female, local species, approximately 1-2 years old, never been pregnant, raised in the backyard, and had no close contact with cattle in either shelter or grazing area. We tested plasma samples from sheep and goats using competitive antibody enzyme-linked immunosorbent assay to detect specific antibodies against pestivirus followed by reverse transcription-polymerase chain reaction (RT-PCR) analysis for all positive samples to differentiate the species of pestivirus.

Results:

Two of the 20 samples collected from goats were positive for pestivirus at the serological and molecular levels, whereas 2 of 26 samples collected from sheep were doubtful but tested negative by RT-PCR. The genotyping test results obtained using nested PCR revealed that the positive samples collected from goats had a BVDV-1 genotype.

Conclusion:

The results of the present study demonstrated that BVDV-1 can infect species other than bovines, in Central Java, Indonesia. Further studies involving a larger number of samples are required to: (1) Determine the actual seroprevalence of pestiviruses in small ruminants and (2) Determine the potency of small ruminants as reservoirs for pestiviruses, both of which are important for the identification of the appropriate control program for pestiviruses in Indonesia.

An outbreak of abortions, stillbirths and malformations in a Spanish sheep flock associated with a bovine viral diarrhoea virus 2-contaminated orf vaccine

Bovine viral diarrhoea virus (BVDV) is a pestivirus that affects both cattle and sheep, causing an array of clinical signs, which include abortions and malformations in the offspring. Manufacturing of modified live virus (MLV) vaccines often includes the use of bovine-derived products, which implies a risk of contamination with viable BVDV. Recently, the circulation of a specific strain of BVDV 2b among Spanish sheep flocks, associated with outbreaks of abortions and malformations, and whose origin was not determined, has been observed. On February 2018, a MLV orf vaccine was applied to a 1,600 highly prolific sheep flock in the Northeast of Spain that included 550 pregnant ewes. In May 2018, during the lambing season, an unusual high rate (72.7%) of abortions, stillbirths, congenital malformations and neurological signs in the offspring was observed. It was estimated that about 1,000 lambs were lost. Three 1- to 3-day-old affected lambs and a sealed vial of the applied vaccine were studied. Lambs showed variable degrees of central nervous system malformations and presence of pestiviral antigen in the brain. Molecular studies demonstrated the presence of exactly the same BVDV 2b in the tissues of the three lambs and in the orf vaccine, thus pointing to a pestivirus contamination in the applied vaccine as the cause of the outbreak. Interestingly, sequencing at the 5'-untranslated region-(UTR) of the contaminating virus showed a complete match with the virus described in the previously reported outbreaks in Spain, thus indicating that the same contaminated vaccine could have also played a role in those cases. This communication provides a clear example of the effects of the application of this contaminated product in a sheep flock. The information presented here can be of interest in putative future cases of suspected circulation of this or other BVDV strains in ruminants.

Risk factors associated with the within-farm transmission of bovine viral diarrhea virus and the incidence of persistently infected cattle on dairy farms from Ibaraki prefecture of Japan

For understanding the factors affecting bovine viral diarrhea virus (BVDV) transmission, this study investigated the distribution of BVDV and the epidemiological features of persistently infected (PI) cattle in Ibaraki Prefecture of Japan, and identified farm-level risk factors associated with BVDV infection, with a focus on within-farm transmission and PI animal detection. Among all 377 dairy farms, forty-four PI cattle were identified on 22 farms. Thirty-eight and six PI cattle were born on their current farms or purchased, respectively. Twenty-six PI cattle were born from pregnancies on their current farms, seven from pregnancies in summer pastures, and eight from pregnancies on other farms. The within-farm seroprevalence on farms with PI animals was significantly higher than that on farms without PI cattle. Of 333 farms holding homebred cattle without movement records, antibody-positivity in homebred cattle was observed on 194 farms; these cattle were likely infected by within-farm transmission. Herd size, summer pasturing, and BVDV infection status of the nearest dairy farm were risk factors associated with within-farm transmission. Likewise, herd size, summer pasturing, and the proportion of purchased cattle were related to PI animal occurrence. This study shows the risk of within-farm transmission and occurrence of PI animals after the introduction of BVDV via purchasing and summer pasturing, and illustrates the significant role of PI cattle in circulating BVDV. More effective measures for screening BVDV infection and PI animals, including intensive tests targeting moved cattle and newborn calves, and bulk milk surveillance, are required to control the spread of BVDV in Japan.

Epidemiological factors and mitigation measures influencing production losses in cattle due to bovine viral diarrhoea virus infection: A meta-analysis

Infection with bovine viral diarrhoea virus (BVDV) is associated with a loss in productivity in cattle farms. Determining which factors influence monetary losses due to BVDV could facilitate the implementation of mitigation measures to reduce the burden of BVDV. Mixed‐effect meta‐analysis models were performed to estimate the extent to which the costs of mean annual BVDV production losses per animal may be influenced by epidemiological factors such as BVDV introduction risk, initial prevalence, viral circulation intensity and circulation duration (trial 1). Additionally, changes in mean annual BVDV production losses per animal due to specific mitigation measures (i.e., biosecurity, vaccination, testing and culling, cattle introduction or contact with neighbouring cattle herds) were analysed (trial 2). In total, 19 studies were included in the meta‐analysis to assess mean annual BVDV production losses. The mean annual direct losses were determined to be €42.14 per animal (trial 1). The multivariate meta‐regression showed that four of the previously mentioned epidemiological factors significantly influenced the mean annual BVDV production losses per animal. Indeed, the per animal costs increased to €67.19 when these four factors (trial 1) were considered as “high or moderate” compared to “low”. The meta‐regression analysis revealed that implementation of vaccination and biosecurity measures were associated with an 8%–12% and 28%–29% decrease in BVDV production losses on average, respectively, when simulated herds were compared with or without such mitigation measures (trial 2). This reduction of mean annual BVDV production losses per animal due to mitigation measures was partially counteracted when farmers brought new cattle on to farm or allowed contact with neighbouring cattle herds. The influencing mitigation factors presented here could help to guide farmers in their decision to implement mitigation strategies for the control of BVDV at farm level.

Pathogen spread and globalization: The case of Pestivirus heterogeneity in southern Italy

Pestiviruses are responsible for widespread diseases affecting cattle, pigs and other ruminants, presenting a wide range of clinical manifestations, with significant impact on animal production. Given the recent various reports of a relatively high number of new strains and atypical genomic variants, in the present study, ninety-seven genomic sequences from southern Italy have been evaluated applying the palindromic nucleotide substitutions method, based on 5'-UTR secondary structure alignment and computing genetic distance among strains in the internal ribosome entry site. Sequence analysis revealed a highly heterogeneous virus population, indicating the introduction of virus variants of Bovine viral diarrhea virus and Border disease virus species from foreign countries. The application of different analytical procedures was useful to avoid interpretation difficulties. Circulation of heterogeneous virus populations showed the need for more accurate epidemiological investigations and stringent veterinary controls to protect animal health and welfare.

Experimental infection with high- and low-virulence strains of border disease virus (BDV) in Pyrenean chamois (Rupicapra p. pyrenaica) sheds light on the epidemiological diversity of the disease

Since 2001, Pyrenean chamois (Rupicapra pyrenaica pyrenaica) populations have been affected by border disease virus (BDV) causing mortalities of more than 80% in some areas. Field studies carried out in France, Andorra, and Spain have shown different epidemiological scenarios in chamois populations. This study was designed to confirm the presence of BDV strains of a high and low virulence in free-ranging chamois populations from Pyrenees and to understand the implications of these findings to the diverse epidemiological scenarios. An experimental infection of Pyrenean chamois with a high-virulence (Cadí-6) and low-virulence (Freser-5) BDV strains was performed. Pregnant and non-pregnant animals with and without antibodies against BDV were included in each group. Cadí-6 BDV strain was confirmed to be of high virulence for seronegative adults and their foetuses. The antibody negative chamois infected with Freser-5 BDV strain did not show symptoms, presented less viral distribution and RNA load in tissues than Cadí-6 group, and cleared the virus from the serum. However, foetuses died before the end of the experiment and RNA virus was detected in sera and tissues although with lower RNA load than the Cadí-6 group. Chamois from both groups presented lesions in brain but the ones infected with the low-virulence Freser-5 BDV strain were mild and most likely transient. In both groups, seropositive pregnant females and all but one of their foetuses did not present viraemia or viral RNA in tissues. The existence of a low-virulence strain has been confirmed experimentally and related to chamois population infection dynamics in the area where it was isolated. Such strain may persist in the chamois population through PI animals and may induce cross-protection in chamois against high-virulence strains. This study demonstrates that viral strain diversity is a significant factor in the heterogeneity of epidemiological scenarios in Pyrenean chamois populations.

Border disease in cattle

Within the family Flaviviridae, viruses within the genus Pestivirus, such as Border disease virus (BDV) of sheep, can cause great economic losses in farm animals. Originally, the taxonomic classification of pestiviruses was based on the host species they were isolated from, but today, it is known that many pestiviruses exhibit a broad species tropism. This review provides an overview of BDV infection in cattle. The clinical, hematological and pathological-anatomical findings in bovines that were transiently or persistently infected with BDV largely resemble those in cattle infected with the closely related pestivirus bovine viral diarrhoea virus (BVDV). Accordingly, the diagnosis of BDV infection can be challenging, as it must be differentiated from various pestiviruses in cattle. The latter is very relevant in countries with control programs to eradicate BVDV in Bovidae, as in most circumstances, pestivirus infections in sheep, which act as reservoir for BDV, are not included in the eradication scheme. Interspecies transmission of BDV between sheep and cattle occurs regularly, but BDV in cattle appears to be of minor general importance. Nevertheless, BDV outbreaks at farm or local level can be very costly.

Traces of history conserved over 600 years in the geographic distribution of genetic variants of an RNA virus: Bovine viral diarrhea virus in Switzerland

The first records of smallpox and rabies date back thousands of years and foot-and-mouth disease in cattle was described in the 16th century. These diseases stood out by their distinct signs, dramatic way of transmission from rabid dogs to humans, and sudden appearance in cattle herds. By contrast, infectious diseases that show variable signs and affect few individuals were identified only much later. Bovine viral diarrhea (BVD), endemic in cattle worldwide, was first described in 1946, together with the eponymous RNA virus as its cause. There is general agreement that BVD was not newly emerging at that time, but its history remains unknown. A search for associations between the nucleotide sequences of over 7,000 BVD viral strains obtained during a national campaign to eradicate BVD and features common to the hosts of these strains enabled us to trace back in time the presence of BVD in the Swiss cattle population. We found that animals of the two major traditional cattle breeds, Fleckvieh and Swiss Brown, were infected with strains of only four different subgenotypes of BVDV-1. The history of these cattle breeds and the events that determined the current distribution of the two populations are well documented. Specifically, Fleckvieh originates from the Bernese and Swiss Brown from the central Alps. The spread to their current geographic distribution was determined by historic events during a major expansion of the Swiss Confederation during the 15th and 16th centuries. The association of the two cattle populations with different BVD viral subgenotypes may have been preserved by a lack of cattle imports, trade barriers within the country, and unique virus-host interactions. The congruent traces of history in the distribution of the two cattle breeds and distinct viral subgenotypes suggests that BVD may have been endemic in Switzerland for at least 600 years.

Seroprevalence of border disease virus and other pestiviruses in sheep in Algeria and associated risk factors

BACKGROUND

Border disease virus (BDV) is a pestivirus responsible for significant economic losses in sheep industry. The present study was conducted between 2015 and 2016 to determine the flock seroprevalence of the disease in Algeria and to identify associated risk factors. 56 flocks from nine departments were visited and 689 blood samples were collected from adult sheep between 6 and 24 months of age (n = 576) and from lambs younger than 6 months (n = 113). All samples were tested by RT-PCR as well as by Ag-ELISA, to detect Persistently Infected (PI) animals. Serum samples from adults were tested by Ab-ELISA (Enzyme Linked Immuno-Sorbent Assay), to detect specific antibodies against pestivirus and 197 of them were further characterized by VNT (virus neutralization test) for the detection of neutralizing antibodies specific for BDV and for Bovine virus diarrhea virus (BVDV-1 and BVDV-2).

RESULTS

No PI animals were found among the 689 sheep tested. 144/197 sera were positive in VNT for BDV, and 2 sera were strongly positive BVDV-2. Fifty-five flocks (98%) had at least one seropositive animal and the apparent within-flock seroprevalence was estimated to be 60.17% (95% C.I.: 52.96-66.96). The true seroprevalence based on estimated sensitivity and specificity of the Ab-ELISA was 68.20% (95% C.I.; 60.2-76.3). Several risk factors were identified as linked to BDV such as climate, landscape, flock management and presence of other ruminant species in the farm.

CONCLUSION

These high seroprevalence rates suggest that BDV is widespread and is probably endemic all over the country. Further studies are needed to detect and isolate the virus strains circulating in the country and understand the distribution and impact of pestiviruses in the Algerian livestock.

The Small-Compound Inhibitor K22 Displays Broad Antiviral Activity against Different Members of the Family Flaviviridae and Offers Potential as a Panviral Inhibitor

The virus family Flaviviridae encompasses several viruses, including (re)emerging viruses which cause widespread morbidity and mortality throughout the world. Members of this virus family are positive-strand RNA viruses and replicate their genome in close association with reorganized intracellular host cell membrane compartments. This evolutionarily conserved strategy facilitates efficient viral genome replication and contributes to evasion from host cell cytosolic defense mechanisms. We have previously described the identification of a small-compound inhibitor, K22, which exerts a potent antiviral activity against a broad range of coronaviruses by targeting membrane-bound viral RNA replication. To analyze the antiviral spectrum of this inhibitor, we assessed the inhibitory potential of K22 against several members of the Flaviviridae family, including the reemerging Zika virus (ZIKV). We show that ZIKV is strongly affected by K22. Time-of-addition experiments revealed that K22 acts during a postentry phase of the ZIKV life cycle, and combination regimens of K22 together with ribavirin (RBV) or interferon alpha (IFN-α) further increased the extent of viral inhibition. Ultrastructural electron microscopy studies revealed severe alterations of ZIKV-induced intracellular replication compartments upon infection of K22-treated cells. Importantly, the antiviral activity of K22 was demonstrated against several other members of the Flaviviridae family. It is tempting to speculate that K22 exerts its broad antiviral activity against several positive-strand RNA viruses via a similar mechanism and thereby represents an attractive candidate for development as a panviral inhibitor.

Insemination with border disease virus-infected semen results in seroconversion in cows but not persistent infection in fetuses

BACKGROUND

This study examined various health variables in cows after artificial insemination with Border disease virus (BDV)-infected semen and the occurrence of persistent infection in ensuing fetuses. Five cows were inseminated (day 0) with BDV-infected semen as well as with semen from a fertile Eringer bull. One cow, inseminated with virus-free semen only, served as a control. Clinical examination, assessment of eating and rumination activities, measurement of intraruminal temperature and leukocyte count were used to monitor the health of the cows. Blood samples were collected at regular intervals for the detection of viral RNA and antibodies against BDV, and the cows were slaughtered on day 56. The uteri, placentae and fetuses were examined macroscopically, histologically, immunohistochemically and by means of molecular methods for the presence of pestiviruses.

RESULTS

The demeanour, eating and rumination activities and intraruminal temperature were not affected by insemination with BDV-infected semen, whereas the total leukocyte and lymphocyte counts dropped transiently and were significantly lower on day 6 than on day 0. Seroconversion occurred by day 28 in the five infected cows but not in the control cow. The uteri, placentae and fetuses had no macroscopic or histological lesions, and immunohistochemical examination and RT-PCR were negative for pestiviruses.

CONCLUSIONS

The findings showed that cows inseminated with BDV-infected semen seroconverted and fetuses thus produced were not persistently infected. Transmission of BDV to cattle through infected semen, therefore, seems to be of minor importance.

Decision support beyond total savings-Eligibility and potential savings for individual participants from changes in the national surveillance strategy for bovine viral diarrhoea (BVD) in Ireland

Surveillance and management of livestock diseases is often evaluated with reference to expected sector-wide costs. In contrast, we calculate losses or savings for individual herd owners of a change in monitoring strategy during a national cattle disease eradication programme: bovine viral diarrhoea (BVD) in Ireland. The alternative strategy differs in how the disease is identified; by its sample- rather than census-based approach; and by its greater cost per test. We examined the costs faced by each breeding herd if testing were conducted using serology on a sample of young stock, in contrast to the current method of tissue-tag testing of all newborn calves. Following best knowledge of the likely costs, the following input values were used: i) €2.50 per test for tissue-tag testing and €7.66 for serology, ii) serology conducted on a sample of 10 young stock per management group from either the 6-12 month or 9-18 month cohorts; iii) 3 scenarios for the number of management groups: one per herd (M∞), one per 100 cows (M100) and one per 50 cows (M50). We found that many herds would often not be able to supply a suitable sample of young stock for serology or would face higher testing costs than when using tissue tag testing. The largest number (25%) of herds would benefit from participating in the change if sampling were done in October. These could annually save between €2.1 million under M∞ and €0.8 million under M50 (€108 - €49 per herd). However, analysing herd-level data we found that 90% of all Irish breeding herds would save less than €1.42 per cow or €99 in total per annum under M∞, and €0.59 per cow or €36 in total under M50. In a sensitivity analysis, we allowed serology costs to vary between €2 and €10 per animal. Herds at the 10 t h percentile of most savings made from switching would save at most €155 (M∞ at €2 per serology test) but would not save anything under M50 at costs ≥ €10. We conclude that, under these assumptions, the expected reduction in testing costs for the majority of beneficiaries would barely outweigh the practical implications of the strategy switch or the risks to the eradication programme associated with sample based surveillance. This study does not assess the cost-effectiveness of alternatives post-eradication.

Factors associated with the bovine viral diarrhoea (BVD) status in cattle herds in Northwest Germany

In Germany, all calves are tested for the presence of bovine viral diarrhoea/mucosal disease virus (BVDV) virus since January 1, 2011. The basis for this compulsory investigation is the BVDV Federal Regulation (BVDVV), which demands testing of calves before the age of six months and according to the new regulation of June 2016 within four weeks or before entering another stock. In 2012, a questionnaire was sent to 7250 Lower Saxony cattle farmers to identify potential factors associated with the presence of BVDV. Completed questionnaires were received from 2542 farms for further analysis. For BVD status determination of these farms, the diagnostic results of 425,911 ear notch samples of calves as part of the BVD eradication period from June 2010 to December 2013 were used. For the analysis of the completed questionnaires, a univariable analysis was performed by the chi-square or Wilcoxon test for each variable studied. In addition, a multivariable logistic model was performed. Four potential risk factors remained after a backward selection in the final logistic regression model: the dairy production compared to the suckling and other types of production, the herd size, the purchase of animals and the location in western region in comparison with the central and eastern regions. In summary, according to the results of this study, the farm with the highest probability of a BVDV infection in Lower Saxony is a large dairy farm that purchases cattle and is located in a cattle-dense region. When the complete eradication of the virus will be achieved, the results of the present study may help to conduct a risk-oriented monitoring programme.

Complete Genome Sequences of Three Border Disease Virus Strains of the Same Subgenotype, BDSwiss, Isolated from Sheep, Cattle, and Pigs in Switzerland

We report here the complete genome sequences of three border disease virus (BDV) strains of the same subgenotype isolated in Switzerland from a sheep, a cow, and a pig, respectively. This is the first report of full-length sequences of a tentatively new subgenotype isolated from three different species of cloven-hoofed farm animals.

Assessment of listing and categorisation of animal diseases within the framework of the Animal Health Law (Regulation (EU) No 2016/429): Border disease

Border disease has been assessed according to the criteria of the Animal Health Law (AHL), in particular criteria of Article 7 on disease profile and impacts, Article 5 on the eligibility of Border disease to be listed, Article 9 for the categorisation of Border disease according to disease prevention and control rules as in Annex IV and Article 8 on the list of animal species concerned by Border disease. The assessment has been performed following a methodology composed of information collection and compilation, expert judgement on each criterion at individual and, if no consensus was reached before, also at collective level. The output is composed of the categorical answer, and for the questions where no consensus was reached, the different supporting views are reported. Details on the methodology used for this assessment are explained in a separate opinion. According to the assessment performed, Border disease can be considered eligible to be listed for Union intervention as laid down in Article 5(3) of the AHL. The disease would comply with the criteria as in Sections 3, 4 and 5 of Annex IV of the AHL, for the application of the disease prevention and control rules referred to in points (c), (d) and (e) of Article 9(1). The animal species to be listed for Border disease according to Article 8(3) criteria are mainly sheep and other species of the family Bovidae as susceptible and reservoirs.