Bovine viral diarrhea virus: global status

Two thiosemicarbazones derived from 1-indanone as potent non-nucleoside inhibitors of bovine viral diarrhea virus of different genotypes and biotypes

Bovine viral diarrhea virus (BVDV) is a widespread pathogen of cattle and other mammals that causes major economic losses in the livestock industry. N4-TSC and 6NO2-TSC are two thiosemicarbazones derived from 1-indanone that exhibit anti-BVDV activity in vitro. These compounds selectively inhibit BVDV and are effective against both cytopathic and non-cytopathic BVDV-1 and BVDV-2 strains. We confirmed that N4-TSC acts at the onset of viral RNA synthesis, as previously reported for 6NO2-TSC. Moreover, resistance selection and characterization showed that N4-TSCR mutants were highly resistant to N4-TSC but remained susceptible to 6NO2-TSC. In contrast, 6NO2-TSCR mutants were resistant to both compounds. Additionally, mutations N264D and A392E were found in the viral RNA-dependent RNA polymerase (RdRp) of N4-TSCR mutants, whereas I261 M was found in 6NO2-TSCR mutants. These mutations lay in a hydrophobic pocket within the fingertips region of BVDV RdRp that has been described as a "hot spot" for BVDV non-nucleoside inhibitors.

Coding-complete genome sequence of a bovine viral diarrhea virus isolate NX2023 from a calf in China

The coding-complete genome sequence of bovine viral diarrhea virus (BVDV) isolate NX2023 that originated from a calf in China was determined. Phylogenetic analysis showed that the NX2023 strain belongs to the BVDV-1d subgenotype.

Outbreak of persistently infected heifer calves with bovine viral diarrhea virus subgenotypes 1b and 1d in a BVDV-vaccinated open dairy herd

Bovine viral diarrhea virus (BVDV) infection has a significant economic impact on beef and dairy industries worldwide. Fetal infection with a non-cytopathic strain may lead to the birth of persistently infected (PI) offspring, which is the main event in the epidemiological chain of BVDV infection. This report describes the birth of 99 BVDV-PI heifer calves within 52 days of birth in a regular BVDV-vaccinated Brazilian dairy cattle herd and the subgenotypes of the infecting field strains. This study was conducted in a high-yielding open dairy cattle herd that frequently acquired heifers from neighboring areas for replacement. The farm monitors the birth of PI calves by screening all calves born using an ELISA (IDEXX) for BVDV antigen detection. All calves aged 1-7 days were evaluated. For positive and suspected results, the ELISA was repeated when the calves were close to one month old. A total of 294 heifer calves were evaluated between February and March 2021. Of these, 99 (33.7 %) had positive ELISA results and were considered PI calves. To evaluate the predominant BVDV species and subgenotypes in this outbreak, whole blood samples were collected from 31 calves born during the study period. All samples were submitted to the RT-PCR assay for the partial amplification of the BVDV 5'-UTR region, and these amplicons were subjected to nucleotide sequencing. Phylogenetic analysis identified BVDV-1b and BVDV-1d in 16 and 13 heifer calves, respectively. In two calves, it was not possible to determine the BVDV-1 subgenotype. Detection of PI animals and monitoring of circulating BVDV subgenotype strains are central to disease control. This study shows that regular BVDV vaccination alone may be insufficient to prevent BVDV infection in high-yielding open dairy cattle herds. Other biosecurity measures must be adopted to avoid the purchase of cattle with acute infections by BVDV or BVDV-PI, which can cause a break in the health profile of the herd and economic losses.

In Vitro Virucidal Activity of Different Essential Oils against Bovine Viral Diarrhea Virus Used as Surrogate of Human Hepatitis C Virus

The hepatitis C virus (HCV) is a major hepatotropic virus that affects humans with increased risk of developing hepatocellular carcinoma. The bovine viral diarrhea virus (BVDV) causes abortion, calf mortality and poor reproductive performance in cattle. Due the difficulties of in vitro cultivation for HCV, BVDV has been used as surrogate for in vitro assessment of the efficacy of antivirals. Essential oils (EOs) display antiviral and virucidal activity on several viral pathogens. In this study, the virucidal activity of five EOs, Salvia officinalis L. EO (SEO), Melissa officinalis L. EO (MEO), Citrus lemon EO (LEO), Rosmarinus officinalis L. EO (REO) and Thymus vulgaris L. EO (TEO) against BVDV was evaluated in vitro at different concentrations for several time contacts. MEO and LEO were able to considerably inactivate BVDV with a time- and dose-dependent fashion. MEO and LEO at the highest concentrations decreased viral titer by 2.00 and 2.25 log10 TCID50/50 μL at 8 h contact time, respectively. SEO, REO and TEO displayed mild virucidal activity at the highest concentrations for 8 h contact times. In this study, the virucidal efficacies of MEO and LEO against BVDV were observed regardless of compound concentration and contact time. Further studies are needed to confirm the potential use of MEO and LEO as surface disinfectants.

Serological Profile for Major Respiratory Viruses in Unvaccinated Cows from High-Yielding Dairy Herds

This study aims to determine the serological profile of high-yielding dairy cows for four main viruses (bovine alphaherpesvirus 1 (BoAHV1), bovine viral diarrhea virus (BVDV), bovine parainfluenza virus 3 (BPIV3), and bovine respiratory syncytial virus (BRSV)) related to bovine respiratory disease (BRD) in cattle herds worldwide. In this survey, 497 blood serum samples were collected from non-vaccinated dairy cows without clinical respiratory signs in 39 herds in the central-eastern mesoregion of Paraná State, South Brazil. The presence of neutralizing antibodies was determined by virus neutralization (VN) tests. VN antibodies against BoAHV1, BVDV, BPIV3, and BRSV were detected in 355 (71.4%), 280 (56.3%), 481 (96.8%), and 315 (63.4%) serum samples, respectively. The frequencies of seropositive herds for BoAHV1, BVDV, BPIV3, and BRSV were 79.5 (n = 31), 82.0 (n = 32), 100 (n = 39), and 84.6% (n = 33), respectively. The frequencies of seropositive cows varied according to the type of herd management and the number of cows in the herd. The detection of VN antibodies in unvaccinated dairy cattle herds demonstrated the endemic circulation of the four viruses in the herds evaluated. For BRD prevention, it is recommended to implement a vaccination program for cows that provides passive immunity in calves and active immunity in cows.

[Persistent form of bovine viral diarrhea]

The review provides an analysis of literature data on the persistent form of Bovine Viral diarrhea/Mucosal disease (BVD) and is focused on virus and host factors, including those related to immune response, that contribute the persistence of the virus. BVD is a cattle disease widespread throughout the world that causes significant economic damage to dairy and beef cattle. The disease is characterized by a variety of clinical signs, including damage to the digestive and respiratory organs, abortions, stillbirths and other failures of reproductive functions.

A longitudinal study of bovine viral diarrhea virus in a semi-closed management dairy cattle herd, 2020-2022

Introduction

Bovine viral diarrhea virus (BVDV) brings great economic loss to the cattle industry worldwide. Developing a control/prevention strategy requires the prior assessment of certain epidemiological parameters. To determine the BVD incidence rate and associated risk factors, a dairy cattle herd in the eastern region of Saudi Arabia was monitored between 2020 and 2022.

Methods

Nasal swabs (n = 190), rectal swabs (n = 190), and sera (n = 190) were collected from 79 cows in this herd. Collected sera and swabs were tested using the commercially available ELISAs for the BVDV antibodies and antigens, respectively. Collected sera were also tested for the presence of BVDV nucleic acids using commercial real-time RT-PCR kits.

Results and discussion

Our data show BVDV seroprevalence (18.8%, 15%, and 8.2%) in the tested animals in 2020-2022, respectively. None of the collected nasal swabs, rectal swabs, or sera tested positive for the BVDV antigen, whereas 10.1%, 10%, and 18.1% of the tested sera were positive for BVDV nucleic acid in 2020-2022, respectively. The incidence rate was estimated at 0.02446 new cases/year despite the detection of BVDV in seronegative animals on single or two occasions at ≥6-month intervals. Young calves and bulls remained apparently unexposed to BVDV despite their presence with BVDV-infected females, with no significant physical separation. Both seropositivity and nucleic acid detectability showed significant positive and negative correlations, respectively, with reproductive performance. Collectively, the present study provides useful clues about the transmissibility of BVDV in the presence of possibly persistently infected animals. To the best of our knowledge, this is the first longitudinal study of BVDV in the Eastern Region of Saudi Arabia. Further detailed characterization of the circulating BVDVs is encouraged.

Molecular Characteristics of Bovine Viral Diarrhea Virus Strains Isolated from Persistently Infected Cattle

In this study, we reported the isolation, identification, and molecular characteristics of nine BVDV strains that were isolated from the serum of persistently infected cattle. The new strains were designated as BVDV TJ2101, TJ2102, TJ2103, TJ2104, TJ2105, TJ2106, TJ2107, TJ2108 and TJ2109. The TJ2102 and TJ2104 strains were found to be cytopathic BVDV, and the other strains were non-cytopathic BVDV. An alignment and phylogenetic analysis showed that the new isolates share 92.2-96.3% homology with the CP7 strain and, thus, were classified as the BVDV-1b subgenotype. A recombination analysis of the genome sequences showed that the new strains could be recombined by the major parent BVDV-1a NADL strain and the minor parent BVDV-1m SD-15 strain. Some genome variations or unique amino acid mutations were found in 5'-UTR, E0 and E2 of these new isolates. In addition, a potential linear B cell epitopes prediction showed that the potential linear B cell epitope at positions 56-61 is highly variable in BVDV-1b. In conclusion, the present study has identified nine strains of BVDV from persistently infected cattle in China. Further studies on the virulence and pathogenesis of these new strains are recommended.

Immune protection induced by E2 recombinant glycoprotein of bovine viral diarrhea virus in a murine model

Bovine viral diarrhea virus (BVDV) is considered the most important viral pathogen in ruminants worldwide due to the broad range of clinical manifestations displayed by infected animals. Therefore, infection with BVDV leads to severe economic losses in several countries' beef and dairy industries. Vaccination prevents reproductive failure and gastrointestinal and respiratory disorders caused by BVDV infection. However, considering their limitations, conventional vaccines such as live, attenuated, and killed viruses have been applied. Hence, different studies have described subunit vaccines as an effective and safe alternative for BVDV protection. Therefore, in this study, the ectodomain of E2 (E2e) glycoprotein from NADL BVDV strain was expressed in mammalian cells and used in two vaccine formulations to evaluate immunogenicity and protection against BVDV conferred in a murine model. Formulations consisted of solo E2e glycoprotein and E2e glycoprotein emulsified in adjuvant ISA 61 VG. Five groups of 6 mice of 6-to-8-week-old were immunized thrice on days 1, 15, and 30 by intraperitoneal injection with the mentioned formulations and controls. To evaluate the conferred protection against BVDV, mice were challenged six weeks after the third immunization. In addition, the humoral immune response was evaluated after vaccination and challenge. Mice groups inoculated with solo E2e and the E2e + ISA 61 VG displayed neutralizing titers; however, the E2 antibody titers in the E2e + ISA 61 VG group were significantly higher than the mice group immunized with the solo E2e glycoprotein. In addition, immunization using E2e + ISA 61 VG prevents animals from developing severe lesions in surveyed tissues. Moreover, this group acquired protection against the BVDV challenge, evidenced by a significant reduction of positive staining for BVDV antigen in the lungs, liver, and brain between the experimental groups. Our findings demonstrated that using E2e + ISA 61 VG induces greater BVDV protection by an early humoral response and reduced histopathological lesions and BVDV antigen detection in affected organs, indicating that E2e + ISA 61 VG subunit formulation can be considered as a putative vaccine candidate against BVDV. The efficacy and safety of this vaccine candidate in cattle requires further investigation.

Ethyl Gallate Inhibits Bovine Viral Diarrhea Virus by Promoting IFITM3 Expression, Lysosomal Acidification and Protease Activity

Bovine viral diarrhea virus (BVDV) is a highly contagious viral disease which causes economic losses to the cattle industry. Ethyl gallate (EG) is a phenolic acid derivative which has various potentials to modulate the host response to pathogens, such as via antioxidant activity, antibacterial activity, inhibition of the production of cell adhesion factors, and so on. This study aimed to evaluate if EG influences BVDV infection in Madin-Darby Bovine Kidney (MDBK) cells, and to understand the antiviral mechanism. Data indicated that EG effectively inhibited BVDV infection by co-treatment and post-treatment in MDBK cells with noncytotoxic doses. In addition, EG suppressed BVDV infection at an early stage of the viral life cycle by blocking entry and replication steps but not viral attachment and release. Moreover, EG strongly inhibited BVDV infection by promoting interferon-induced transmembrane protein 3 (IFITM3) expression, which localized to the cytoplasm. The protein level of cathepsin B was significantly reduced by BVDV infection, whereas with treatment with EG, it was significantly enhanced. The fluorescence intensities of acridine orange (AO) staining were significantly decreased in BVDV-infected cells but increased in EG-treated cells. Finally, Western blot and immunofluorescence analyses demonstrated that EG treatment significantly enhanced the protein levels of autophagy markers LC3 and p62. Chloroquine (CQ) significantly increased IFITM3 expression, and Rapamycin significantly decreased it. Thus, EG may regulate IFITM3 expression through autophagy. Our results showed that EG could have a solid antiviral activity on BVDV replication in MDBK cells via increased IFITM3 expression, lysosomal acidification, protease activity, and regulated autophagy. EG might have value for further development as an antiviral agent.

Temporal and geographic dynamics of bovine viral diarrhea virus in American countries

Bovine viral diarrhea virus (BVDV) is a worldwide distributed pathogen of livestock classified into three species, BVDV-1 (Pestivirus A), BVDV-2 (Pestivirus B), and HoBi-like pestivirus (HoBiPeV; Pestivirus H). Despite being considered endemic in several regions of the Americas, the spatiotemporal distribution of BVDV is scarcely known. This study aimed to reconstruct the population dynamics of BVDV in American countries. The analyses performed with the partial 5´UTR gene showed that BVDV-1 and -2 would have started their diversification in the 1670s and 1790s in the United States, whereas HoBiPeV probably emerged in the 1980s in Brazil. No evident geographic clustering was observed in the Bayesian trees, which may indicate that multiple introductions events would have occurred following the first introduction. This study provides new insights into BVDV dynamics, although further analyses including sequences from other American countries and continents will help to expand the knowledge of BVDV evolution and transmission.

Bovine viral diarrhea virus in China: A comparative genomic and phylogenetic analysis with complete genome sequences

Bovine viral diarrhea virus (BVDV), causing bovine viral diarrhea (BVD) in cattle, is one of the highly contagious and devastating diseases of cattle. Since 1980, BVDV has been identified all-over China in a variety of animal species including cattle, camels, yaks, sheep, water buffalo, goats, Sika deer and pigs. In this study, 31 BVDV complete genomes reported in China (from 2004 to 2020) with other 112 genomes reported around the world were comparatively analyzed. Phylogenetic analysis shows that BVDV genomes reported worldwide clustered in three major clades i.e., BVDV-1, BVDV-2, and BVDV-3. The BVDV-1 is genetically the most diverged genotype and phylogenetically classified into 7 sub-clades in our study based on full-length genomes. The China BVDV genomes fall into all three major clades, e.g., BVDV-1, BVDV-2 and BVDV-3. China BVDV-1 clustered into five sub-clades, e.g., 1, 2, 3, 6 and 7, where sub-clade 7 clustered as a separate sub-clade. Full-length genome recombination analysis reveals that the BVDV-1 reported in China appears to be mainly involved in recombination events. In addition, comparative analysis of E2 proteins between BVDV-1, BVDV-2, and BVDV-3 reveals that the amino acid variations could affect 12 potential linear B cell epitopes, demonstrating a dramatic antigen drift in the E2 protein. These results provide a thorough view of the information about the genetic and antigenic diversity of BVDVs circulating in China and therefore could benefit the development of suitable strategies for disease control.

The Epidemiology of Bovine Viral Diarrhea Virus in Low- and Middle-Income Countries: A Systematic Review and Meta-Analysis

Introduction

Bovine viral diarrhea virus (BVDV) causes reproductive inefficiencies and negatively impacts the economy of low- and middle-income countries (LMICs). It is characterized by a combination of syndromes that result in poor production performance and calf morbidity and mortality. BVDV control is possible by introduction of biosecurity measures, test-and-cull, and vaccination programs as accomplished in high-income countries. Knowledge of BVDV epidemiology is limited in many LMICs, which hinders implementation of effective control programs. We carried out a systematic review and meta-analysis to estimate the burden of BVDV, identify risk factors related to its occurrence, and health and economic impacts on production systems.

Materials and Methods

Relevant BVD articles were collated from library databases; 690 abstracts and full texts were found in an initial search followed by filtering of 59 manuscripts. We accounted for quality and risk of bias in the meta-analysis. Prevalence, exposure, and current infection at regional, production, and farming system levels were estimated using logistic random-effects meta-regression models. Finally, we calculated the proportion of studies that addressed risk factors and health and economic impacts across different production systems to inform future preventative strategies in LMICs.

Results

Seroprevalence was high and varied between regions. Mean weighted prevalence was 39.5% (95% CI 25-56.1), 45.2% (95% CI 35.9-54.8), 49.9% (95% CI 25.5-74.3), and 21.6% (95% CI 0.5-56) for sub-Saharan Africa, South America, Middle East, and Asia, respectively. Seroprevalence varied across farming systems, with smallholder farming showing the highest values. Herdsize was the most frequently reported risk factor, and the percentage of articles that reported herdsize as a risk factor were 20.6%, 33.3%, and 38.4% for dairy, beef and mixed systems respectively. Abortion (13.7% of articles) was the main reported health impact in dairy systems. Some articles reported milk drop (4.6% of articles), but no article investigated the economic cost of BVDV in farming systems.

Conclusion

Animal-level seroprevalence varied across all regions. Most of the studies focused on BVDV seroprevalence. There were some articles that investigated risk factors and health impacts, and there were even less that investigated economic impacts. Future studies should focus on identifying risk factors and quantifying health and economic impacts across systems. Understanding these aspects is crucial to develop management strategies to apply across diverse production systems in LMICs.

Investigation into an outbreak of Border disease virus in pigs in England

Border disease (BD) was first reported in 1959 in lambs from the border region of England and Wales. The causative virus (BD virus; BDV) has since been identified in several other ruminant species and pigs. The virus is prevalent in sheep flocks of UK, Europe and USA and has potential to inflict substantial economic losses. Natural BDV infection of pigs was first reported in the UK in 1992 from pigs with haemorrhagic lesions and more recently from healthy pigs in Spain and Japan. Here, a persistent problem of poor growth and anaemia in a small proportion of growing pigs on a mixed pig and sheep holding was investigated and tissues were tested in a pan viral microarray. The microarray detected BDV RNA in several tissues which was further confirmed by sequencing, specific BDV PCR and immunohistochemistry. Phylogenetically, the virus clustered with other BDVs in the sub‐genotype 1b. This investigation highlights likely interspecies transmission of pestiviruses and their impact on pestivirus detection and eradication programs.

Congenital Neurological Disease Associated With HoBi-like Pestivirus Infection in a Newborn Dairy Calf From Brazil

HoBi-like pestivirus (HoBiPeV) has been reported in several biological samples from cattle worldwide, but there are no descriptions of this virus associated with neurological symptoms. This report described the first occurrence of neurological disease associated with HoBiPeV in a newborn dairy calf. A mixed-breed Holstein calf had severe neurological symptoms at birth and died at 21 days old. The tissue fragments (central nervous system (CNS), myocardium, liver, kidney, lung, intestine, and spleen) were submitted to reverse transcription (RT)–PCR assay for the partial 5'-untranslated region (5'UTR) and N-terminal autoprotease (Npro) gene of the pestivirus genome, and the CNS tissue fragments were submitted to histopathological and immunohistochemical evaluation. The RT–PCR assay indicated that the kidney, CNS, and intestinal tissue fragments were positive for the pestivirus 5'UTR, and the CNS and intestinal tissue fragments were positive for the pestivirus Npro gene. Amplicons with high DNA quantification in the 5'UTR (CNS—cerebral cortex) and Npro (CNS—cerebral cortex and intestine) RT–PCR assays were sequenced. The nucleotide (nt) sequence and phylogenetic analysis of the 5'UTR strain exhibited 93.6 to 99.4%, 85%, 89.4 to 89.9%, 85.1%, and 90.5 to 91.5% nt identity with HoBiPeV strains from clades a, b, c, d, and e, respectively. The Npro amplicons showed 99.7% nt identity to each other and 90.4 to 96.5%, 85.1 to 85.3%, 79.2 to 79.7%, and 85.8 to 86.5% nt identity with HoBiPeV strains from clades a, c, d, and e, respectively. A histopathology revealed neuronal necrosis at the cerebrum, cerebellum, and brain stem. An immunohistochemical assay designed to identify antigens of bovine viral diarrhea virus revealed positive intracytoplasmic immunoreactivity within neurons at the cerebral cortex, cerebrum, cerebellum, and spinal cord. Thus, this report provides information about the first identification of HoBiPeV in tissues of the CNS in a newborn dairy calf with neurological symptoms.

[Genetic diversity and distribution of bovine pestiviruses (Flaviviridae: Pestivirus) in the world and in the Russian Federation]

The genus Pestivirus of the family Flaviviridae includes 11 species. Bovine pestiviruses are the causative agents of viral diarrhea/mucosal disease and include three genetically distinct species: pestivirus A (BVDV-1), B (BVDV-2), and H (BVDV-3). The number of BVDV-1 subtypes is 21, BVDV-2 - 4, and BVDV-3 - 4, which complicates the diagnosis of associated diseases, reduces the effectiveness of vaccination and control programs.We performed the search in the PubMed, Web of Science, Scopus, eLIBRARY.RU databases for articles published in 2000-2021.Pestivirus A is distributed everywhere, although the largest number of subtypes was found in cattle in Italy and China. The virus is widespread in the Central region of the Russia (subtypes 1a and 1m). In Siberia, eleven subtypes circulate among native and imported animals: 1a (5%), 1b (35%), 1c (5%), 1d (10%), 1f (20%), 1g, 1i (both 2.5%), 1j, 1k, 1p, and 1r (all for 5%). Pestivirus B subtype is more virulent, found less frequently and mainly in the North and South America, in some European countries, and in Asia. Three subtypes have been identified in Siberia: 2a (25%), 2b (10%), and 2c (5%). Pestivirus H circulates in Europe, Asia and South America. The main route of entry is contaminated biological products. In Russia, BVDV-3 of the Italian-Brazilian group (3a) was detected in 7 lots of fetal bovine serum.The role of the virus in the occurrence of respiratory diseases in calves, abortion, systemic infection and enteritis in calves and adult animals has been established. The source of the virus in such cases was a contaminated modified live vaccine.

Epigenomic and Proteomic Changes in Fetal Spleens Persistently Infected with Bovine Viral Diarrhea Virus: Repercussions for the Developing Immune System, Bone, Brain, and Heart

Bovine viral diarrhea virus (BVDV) infection during early gestation results in persistently infected (PI) immunotolerant calves that are the primary reservoirs of the virus. Pathologies observed in PI cattle include congenital defects of the brain, heart, and bone as well as marked functional defects in their immune system. It was hypothesized that fetal BVDV infection alters T cell activation and signaling genes by epigenetic mechanisms. To test this, PI and control fetal splenic tissues were collected on day 245 of gestation, 170 days post maternal infection. DNA was isolated for reduced representation bisulfite sequencing, protein was isolated for proteomics, both were analyzed with appropriate bioinformatic methods. Within set parameters, 1951 hypermethylated and 691 hypomethylated DNA regions were identified in PI compared to control fetuses. Pathways associated with immune system, neural, cardiac, and bone development were associated with heavily methylated DNA. The proteomic analysis revealed 12 differentially expressed proteins in PI vs. control animals. Upregulated proteins were associated with protein processing, whereas downregulated proteins were associated with lymphocyte migration and development in PI compared to control fetal spleens. The epigenetic changes in DNA may explain the immune dysfunctions, abnormal bone formation, and brain and heart defects observed in PI animals.

Prevalence of Bovine Viral Diarrhea Virus in Ovine and Caprine Flocks: A Global Systematic Review and Meta-Analysis

Background: Bovine viral diarrhea virus (BVDV) is the causative agent of bovine viral diarrhea. It can infect cattle, sheep, pigs, and other animals, causing diarrhea, miscarriage, and stillbirth, among other symptoms, and it can result in huge economic losses to animal husbandry. There are reports on BVDV infection rates in sheep and goat herds from all over the world and this meta-analysis aimed to evaluate the prevalence of and risk factors for BVDV in sheep and goats. Results: Using the data of 41,297 sheep and goats in 24 countries/regions to calculate a comprehensive prevalence rate for BVDV. The overall prevalence of BVDV infection in sheep and goats was estimated to be 8.6% (95% CI: 5.2-12.7) by immunological methods and 7.3% (95% CI: 2.7-13.7) by molecular methods. Analysis by national income level revealed that prevalence is higher in middle-income countries than in high-income countries (P < 0.05). The study also compared prevalence rates by species of BVDV, sampling year, and test species, but did not find significant differences. Conclusion: This systematic review and meta-analysis is the first to determine the global prevalence of BVDV in ovine and caprine flocks. The prevalence of BVDV in sheep and goat populations varies from region to region, and the situation is not optimistic in some countries.

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.

Genomic diversity and phylodynamic of bovine viral diarrhea virus in Argentina

Bovine viral diarrhea virus (BVDV) is an important pathogen of ruminants worldwide and is characterized by high genetic diversity and a wide range of clinical presentations. In Argentina, several studies have evaluated the genetic diversity of BVDV but no phylodynamic study has been published yet. In this study, a comprehensive compilation and update of Argentinean BVDV sequences were performed, and the evolutionary history of BVDV was characterized by phylodynamic analyses based on the 5´UTR. Although BVDV-1b and BVDV-1a were the most frequent subtypes, novel subtypes for Argentina, 1e and 1i, were identified. The phylodynamic analysis suggested that BVDV started its diversification in the mid-1650s with an exponential increase in viral diversity since the late 1990s, possibly related to the livestock expansion and intensification in the country. Evolutionary rate in the 5´UTR was faster for BVDV-1a than for BVDV-1b, and both subtypes presented an endemic nature according to the demographic reconstructions. The current study contributes to clarify the evolutionary history of BVDV in the main cattle region of the country and provides useful information about the epidemiology and future development of diagnostic and control tools in Argentina.

Seroprevalence of bovine viral diarrhea virus (BVDV) infection in cattle population in Iran: a systematic review and meta-analysis

Bovine viral diarrhea virus (BVDV) is an important pathogen correlated with reproductive, respiratory, and gastrointestinal disorders in cattle. Furthermore, it causes endemic infections and significant economic losses in cattle herds worldwide. This review was performed to determine the pooled seroprevalence of BVDV infection and related risk factors among cattle in Iran. Data were systematically gathered without time limitation until 1 December 2020 in the Islamic Republic of Iran from the following electronic databases: PubMed, Google Scholar, Science Direct, Scopus, Web of Science, Elmnet, Magiran, Irandoc, Scientific Information Database (SID), and Civilica. According to the preferred reporting items for systematic reviews and meta-analyses (PRISMA) and inclusion criteria, 28 eligible studies were obtained from various Iran areas. In total, the pooled seroprevalence of BVDV infection, using random-effect model, was estimated 52% (95% CI, 40.1-63.9) in cattle. According to serological detection methods, pooled seroprevalence was as follows: based on ELISA 53.9% and SVN 25.1%. The highest pooled seroprevalence of BVDV infection was in the southeast provinces of Iran (78.4%) and lowest pooled seroprevalence was in Southwest provinces of the country (28.5%). The pooled seroprevalence of BVDV infection in cattle ≤ 2 years was significantly lower than cattle > 2 years (OR = 0.606; 95% CI, 0.397-0.925), whereas the pooled seroprevalence had no significant difference according to other factors such as gender, herd size, and herd types. In conclusion, the pooled seroprevalence of BVDV infection among cattle in Iran is relatively high. The seroprevalence was different among geographical regions of the country. These results are desirable for managing the control programs of this infection in Iran.

Bovine Viral Diarrhea Virus in Cattle From Mexico: Current Status

Bovine viral diarrhea (BVD) is an infectious disease, globally-distributed, caused by bovine Pestiviruses, endemic of cattle and other ruminant populations. BVD leads to significant economic losses to the cattle industry due to the wide range of clinical manifestations, including respiratory and gastrointestinal diseases and reproductive disorders. Within the Pestivirus genus of the family Flaviviridae three viral species are associated with BVD; Pestivirus A (Bovine viral diarrhea virus 1, BVDV-1), Pestivirus B (Bovine viral diarrhea virus 2, BVDV-2), and Pestivirus H (HoBi-like pestivirus, atypical ruminant pestivirus). These species are subdivided into subgenotypes based on phylogenetic analysis. The extensive genetic diversity of BVDV has been reported for several countries, where the incidence and genetic variation are more developed in Europe than in the Americas. The first report of BVDV in Mexico was in 1975; this study revealed seropositivity of 75% in cows with a clinical history of infertility, abortions, and respiratory disease. Other studies have demonstrated the presence of antibodies against BVDV with a seroprevalence ranging from 7.4 to 100%. Recently, endemic BVDV strains affecting cattle populations started to be analyzed, providing evidence of the BVDV diversity in several states of the country, revealing that at least four subgenotypes (BVDV-1a, 1b, 1c, and 2a) are circulating in animal populations in Mexico. Little information regarding BVD epidemiological current status in Mexico is available. This review summarizes available information regarding the prevalence and genetic diversity viruses associated with BVD in cattle from Mexico.

A Herd Investigation Tool in Support of the Irish Bovine Viral Diarrhoea Eradication Programme

Bovine viral diarrhoea (BVD) is an important endemic disease of cattle. In Ireland, an industry-led compulsory eradication programme began in January 2013. The main elements of this programme are the identification and elimination of persistently infected (PI) calves by testing all new-borns, the implementation of biosecurity to prevent re-introduction of disease and continuous surveillance. In 2016, a standardised framework was developed to investigate herds with positive results. This is delivered by trained private veterinary practitioners (PVP). The investigation's aims are 3-fold: firstly, to identify plausible sources of infection; secondly, to ensure that no virus-positive animals remain on farm by resolving the BVD status of all animals in the herd; and thirdly, agreeing up to three biosecurity measures with the herd owner to prevent the re-introduction of the virus. Each investigation follows a common approach comprising four steps based on information from the programme database and collected on-farm: firstly, identifying the time period when each virus-positive calf was exposed in utero (window of susceptibility, taken as 30-120 days of gestation); secondly, determining the location of the dam of each positive calf during this period; thirdly, to investigate potential sources of exposure, either within the herd or external to it; and finally, based on the findings, the PVP and herdowner agree to implement up to three biosecurity measures to minimise the risk of reintroduction. Between 2016 and 2020, 4,105 investigations were completed. The biosecurity recommendations issued more frequently related to the risks of introduction of virus associated with contact with neighbouring cattle at pasture, personnel (including the farmer), the purchase of cattle and vaccination. Although each investigation generates farm-specific outcomes and advice, the aggregated results also provide an insight into the most commonly identified transmission pathways for these herds which inform overall programme communications on biosecurity. The most widely identified plausible sources of infection over these years included retained BVD-positive animals, Trojan births, contact at boundaries and indirect contact through herd owner and other personnel in the absence of appropriate hygiene measures. While generated in the context of BVD herd investigations, the findings also provide an insight into biosecurity practises more generally on Irish farms.

Severe outbreak of bovine neonatal diarrhea in a dairy calf rearing unit with multifactorial etiology

This study describes the etiological diversity observed in a severe neonatal diarrhea outbreak with morbidity and mortality rates of 80 and 20%, respectively, with detection of mixed infections with viral, bacterial, and protozoan disease agents in a dairy calf rearing unit. Diarrheic fecal samples were collected from eight 5 to 18 days of age calves and were submitted to the investigation of the presence of rotavirus A (RVA), bovine coronavirus (BCoV), bovine kobuvirus (BKV), bovine viral diarrhea virus 1 and 2 (BVDV-1 and BVDV-2), enteropathogenic Escherichia coli (ETEC), Salmonella sp., and Cryptosporidium spp. Fragments of the small intestine of one calf with diarrhea that spontaneously died were submitted for histopathological analyses. The most frequent infectious agent detected in diarrheic fecal samples was BKV (8/8—100%), followed by RVA (5/8—62.5%), BVDV (5/8—62.5%), Cryptosporidium parvum (5/8—62.5%), ETEC (4/8—50%), and Cryptosporidium ryanae (1/8—12.5%). These etiological agents were found in mixed infections with two or more pathogens per diarrheic fecal sample. The association of viral and protozoan pathogens was the most frequently identified (37.5%) in these samples, followed by viral and bacterial (25%); viral, bacterial, and protozoan (25%); and only viral agents (12.5%). BCoV and Salmonella sp. were not identified in the diarrheic fecal samples analyzed. Additionally, histopathology of the small intestine diagnosed chronic lymphocytic enteritis. In conclusion, in calf rearing units, the adoption and strict monitoring of health management practices are critical to the success of this calf creation system.

[Detection of bovine pestiviruses by a multiplex real-time polymerase chain reaction.]

INTRODUCTION

Pestiviruses are the cause of reproductive problems, diseases of the gastrointestinal and respiratory tracts of animals. Three species are important for cattle: Pestivirus A, B, and H. Fast and reliable methods of differentiation of these pathogens are currently needed. Aims and objectives of the study: the development of multiplex real time PCR for the simultaneous detection and differentiation of three viruses.

MATERIAL AND METHODS

The nucleotide sequences of the conserved regions of the 5´-UTR genes of pes tivirusesA, B, and H served as a target.

RESULTS

The reaction showed high specificity, sensitivity, reproducibility and was able to detect virus RNA at a concentration of not less than 0.6-1.2 lg TCID_50/cm³. Cross-reactions with other pestiviruses wer e not observed. Real time PCR confirmed the results obtained previously in RT-PCR with gel electrophoresis detection. In a parallel study of 1823 biological samples, the results of the two reactions were completely consistent. Pestivirus spp. was detectedin 76 samples, Pestivirus A was present in 73 samples, Pestivirus B - in 3 samples, and Pestivirus H was not detected.

DISCUSSION

A two-step real time PCR was developed for the simultaneous detection and differentiation of three pestiviruses. Modified pan primers of S. Vilcek et al. were used for the first reaction, and primers and probes of our own design were used for virus typing, which resulted in high reaction efficiency.

CONCLUSION

On the big dairy farms for livestock maintenance, there are favorable conditions for the circulation of pathogenic viruses. In this situation, rapid diagnostic methods are needed to quickly identify of several viruses. Real-time triplex analysis can be recommended as the rapid method for mass epidemiological studies, as well as for screening fetal calf serum used for virus cultivation in medicine and veterinary practice.

Detection of Pestivirus A (bovine viral diarrhea virus 1) in free-living wild boars in Brazil

Bovine viral diarrhea virus (BVDV) is a major pathogen in cattle herds. Considering the epidemiological importance of pestiviruses and the process of wild boar invasion in Brazil, this study aimed to investigate the presence of BVDV in free-living boars. Forty-nine free-living wild boars were collected by exotic wildlife controller agents in 2017 and 2018. The presence of BVDV antibodies was evaluated in 42 serum samples using the virus neutralization test, and the detection of BVDV RNA was performed from the 5'UTR genomic region by RT-PCR assay in 49 lung tissue samples followed by sequencing of amplicons. BVDV neutralizing antibodies in serum were not identified in any of the evaluated samples. However, 3/49 (6.12%) lung samples were positive for BVDV RNA and classified one as BVDV-1a and two as 1d subgenotype. This report identified BVDV RNA in free-living wild boars and these results should be considered in BVDV control programs, especially in extensive beef cattle rearing systems.

Effect of bovine viral diarrhea virus on subsequent infectivity of bovine gammaherpesvirus 4 in endometrial cells in primary culture: An in vitro model of viral co-infection

Bovine viral diarrhea virus (BVDV) and bovine gammaherpesvirus 4 (BoHV-4) infect the uterus of cattle, being responsible for huge economic losses. Most of the pathogenesis of BoHV-4 in the bovine reproductive tract has been elucidated by conducting tests on primary cultures. Thus, it is important to have optimal in vitro conditions, avoiding the presence of other pathogens that can alter the results. BVDV is one of the most frequent viral contaminants of cell cultures. Considering that non-cytopathic (NCP) BVDV biotype can generate persistently infected (PI) cattle, which are the major source for virus transmission in susceptible herds, it is important to check products derived from cattle that are intended to be used in research laboratories. The aim of this work was to evaluate how the natural infection of bovine endometrial cells (BEC) with a NCP BVDV strain (BEC + BVDV) affects BoHV-4 replication. We have demonstrated a delay in BoHV-4 gene expression and a decrease in viral load in the extracellular environment in BEC + BDVD cells compared to BEC (BVDV-free) cells. These results confirm that replication of BoHV-4 in BEC primary cultures is affected by previous infection with BVDV. This finding highlights the importance of ruling out BVDV infection in bovine primary cell cultures to avoid biological interference or misinterpretation of results at the time of performing in vitro studies with BoHV-4.

Identification and genotyping of a new subtype of bovine viral diarrhea virus 1 isolated from cattle with diarrhea

In 2019, diarrhea cases occurred on cattle farms in Qionglai and Guang'an, Sichuan Province. Two out of 20 (10%) serum and nasal swab samples were positive when tested using a bovine viral diarrhea virus (BVDV) antigen-capture ELISA kit. Two non-cytopathic strains of BVDV were isolated and named QL1903 and GA190608, respectively. The nucleotide sequences of the genomes of the two isolates were 89.52% identical. Phylogenetic analysis based on the 5'-UTR sequence revealed that the BVDV isolate QL1903 belonged to BVDV subtype 1b, whereas isolate GA190608 clustered with strains HN1814, EN-19, and BJ09_26 in a separate branch, which has tentatively been classified as a new genetic subtype, "1v".

Intestinal Viral Loads and Inactivation Kinetics of Livestock Viruses Relevant for Natural Casing Production: a Systematic Review and Meta-Analysis

Animal intestines are the source of edible sausage casings, which are traded worldwide and may come from areas where notifiable infectious animal diseases are prevalent. To estimate the risks of virus contamination, knowledge about the quantity of virus and decimal reduction values of the standard preservation method by salting is of great importance. A literature search, based on the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, was performed in search engine CAB Abstracts to determine the viral load of 14 relevant animal viruses in natural casings or intestines. Only a very limited number of scientific publications per virus were found and viral loads in the intestines varied from high for ASFV (five publications), BVDV (3), CSFV (6), PPRV (3), RPV (2) and TGEV (3) to moderate for PEDV (2) and SVDV (3), low for HEV (2) and FMDV (5), very low for VESV (1) and negative for PrV (2) and VSV (1). PRRSV was found in intestines, however, viral titers were not published. Three viruses (BVDV, CSFV and PPRV) with high viral loads were selected to search for their inactivation kinetics. For casings, no inactivation data were found, however, thermal inactivation data of these viruses were available, but differed in quantity, quality and matrices. In conclusion, important data gaps still exist when it comes to the quantitative inactivation of viruses in sausage casings or livestock intestines.

BoHV-1-Vectored BVDV-2 Subunit Vaccine Induces BVDV Cross-Reactive Cellular Immune Responses and Protects against BVDV-2 Challenge

The bovine respiratory disease complex (BRDC) remains a major problem for both beef and dairy cattle industries worldwide. BRDC frequently involves an initial viral respiratory infection resulting in immunosuppression, which creates a favorable condition for fatal secondary bacterial infection. Current polyvalent modified live vaccines against bovine herpesvirus type 1(BoHV-1) and bovine viral diarrhea virus (BVDV) have limitations concerning their safety and efficacy. To address these shortcomings and safety issues, we have constructed a quadruple gene mutated BoHV-1 vaccine vector (BoHV-1 QMV), which expresses BVDV type 2, chimeric E2 and Flag-tagged Erns-fused with bovine granulocyte monocyte colony-stimulating factor (GM-CSF) designated here as QMV-BVD2*. Here we compared the safety, immunogenicity, and protective efficacy of QMV-BVD2* vaccination in calves against BVDV-2 with Zoetis Bovi-shield Gold 3 trivalent (BoHV-1, BVDV types 1 and 2) vaccine. The QMV-BVD2* prototype subunit vaccine induced the BoHV-1 and BVDV-2 neutralizing antibody responses along with BVDV-1 and -2 cross-reactive cellular immune responses. Moreover, after a virulent BVDV-2 challenge, the QMV-BVD2* prototype subunit vaccine conferred a more rapid recall BVDV-2-specific neutralizing antibody response and considerably better recall BVDV types 1 and 2-cross protective cellular immune responses than that of the Zoetis Bovi-shield Gold 3.

Concurrent detection of bovine viral diarrhoea virus and bovine herpesvirus-1 in bulls' semen and their effect on semen quality

Reproductive diseases may have destructive effects on the fertility of cattle. Bovine viral diarrhoea virus (BVDV) and bovine herpes virus-1 (BoHV-1) are potent viral pathogens linked to reproduction. Thus, the aim of this study was to utilize raw semen samples for conventional and molecular detection of BVDV and BoHV-1, simultaneously. Additionally, the effect of virus infection on the semen quality of naturally infected bulls has been investigated. Therefore, 40 bulls were employed for semen collection, evaluation and testing for both viruses by virus isolation, direct fluorescent antibody technique (FAT) and SYBR Green real-time PCR assay. In virus isolation results, no cytopathic effect (CPE) was observed for BVDV on cell culture whereas, eight (20%) samples displayed characteristic grape-like clusters of cells for BoHV-1. By direct FAT, 12 (30%) positive BVDV and 8 (20%) positive BoHV-1 samples were confirmed. SYBR Green real-time PCR analysis using 48 h inoculated semen samples revealed 14 (35%) and 8 (20%) positive samples for BVDV and BoHV-1, respectively. Statistical analysis of semen evaluation parameters showed a significant difference between viral-infected and free groups represented by increased sperm abnormalities and decreased sperm motility, liveability and concentration. However, there was no significant difference among BVDV, BoHV-1 and mixed-infected groups. The study concluded that BVDV and/or BoHV- 1 infected bulls expressed low semen quality. Real-time PCR was confirmed to be the ideal laboratory assay for detection of both viruses in semen.

A novel MHC-II targeted BVDV subunit vaccine induces a neutralizing immunological response in guinea pigs and cattle

Bovine viral diarrhoea virus (BVDV) is a major cause of economic loss in the cattle industry, worldwide. Infection results in reduced productive performance, growth retardation, reduced milk production and increased susceptibility to other diseases leading to early culling of animals. There are two primary methods used to control the spread of BVDV: the elimination of persistently infected (PI) animals and vaccination. Currently, modified live or inactivated vaccines are used in BVDV vaccination programmes, but there are safety risks or insufficient protection, respectively, with these vaccines. Here, we report the development and efficacy of the first targeted subunit vaccine against BVDV. The core of the vaccine is the fusion of the BVDV structural protein, E2, to a single-chain antibody, APCH, together termed, APCH-E2. The APCH antibody targets the E2 antigen to the major histocompatibility type II molecule (MHC-II) present on antigen-presenting cells. Industrial production of the vaccine is carried out using the baculovirus expression vector system (BEVS) using single-use manufacturing technologies. This new subunit vaccine induces strong BVDV-specific neutralizing antibodies in guinea pigs and cattle. Importantly, in cattle with low levels of natural BVDV-specific neutralizing antibodies, the vaccine induced strong neutralizing antibody levels to above the protective threshold, as determined by a competition ELISA. The APCH-E2 vaccine induced a rapid and sustained neutralizing antibody response compared with a conventional vaccine in cattle.

Frequency of bovine viral diarrhea virus (BVDV) in Argentinean bovine herds and comparison of diagnostic tests for BVDV detection in bovine serum samples: a preliminary study

Bovine viral diarrhea (BVD) is a major worldwide disease with negative economic impact on cattle production. Successful control programs of BVD require the identification and culling of persistently infected (PI) animals with bovine viral diarrhea virus (BVDV). A variety of diagnostic tests are available to detect BVDV, but no comparison has been performed among those tests in Argentina. Sera collected from 2864 cattle, belonging to 55 herds from three Argentinean provinces, were analyzed by nested RT-PCR (RT-nPCR) to detect BVDV for diagnostic purposes. Additionally, this study evaluated the agreement of the RT-nPCR along with virus isolation, antigen-capture ELISA, and real-time RT-PCR for BVDV detection in archived bovine serum samples (n = 90). The RT-nPCR was useful for BVDV detection in pooled and individual serum samples. BVDV was detected in 1% (29/2864) of the cattle and in 20% (11/55) of the herds. The proportion of BVDV-positive sera was not statistically different among the tests. In addition, comparisons showed high agreement levels, with the highest values between both RT-PCR protocols. The frequency of BVDV infection at individual and herd level was lower than the reported values worldwide. Since follow-up testing was not performed, the frequency of PI cattle was unknown. Also, this study demonstrated that the four diagnostic tests can be used reliably for BVDV identification in individual serum samples. Further epidemiologically designed studies that address prevalence, risk factors, and economic impact of BVDV in Argentina will be necessary to implement effective control programs.

Interferon lambda protects cattle against bovine viral diarrhea virus infection

Interferon lambda (IFN-λ) plays an important role in inducing an antiviral state in mucosal surfaces and has been used as an effective biotherapeutic against several viral diseases. Here we performed a proof of concept study on the activity of a biologically active recombinant bovine IFN-λ (rIFN-λ) produced in eukaryotic cells against Bovine Viral Diarrhea Virus (BVDV) in cattle. We first confirmed the lack of toxicity of different concentrations of rIFN-λ in bovine peripheral blood cells and the safety of its subcutaneous application in calves in doses up to 12 IU/kg. The antiviral activity of the rIFN-λ against BVDV was assessed in calves that were inoculated with 6 IU/kg of rIFN-λ (n = 4) or mock-treated (n = 2) two days before and after challenge with a BVDV type-2 non-cytopathic strain. Mock-treated animals developed respiratory disease, shedded the virus from 4 to 7 days post-infection (dpi) and had viremia between 4 and 14 dpi. Conversely, calves treated with rIFN-λ did not develop clinical symptoms. The virus was not found in nasal secretions or sera. Only one animal had a positive viral RNA detection in serum at 7 dpi. All infected animals treated with rIFN-λ increased systemic type-I IFNs levels at 4 dpi. The antiviral treatment induced an earlier onset of the anti-BVDV neutralizing antibodies. Altogether, these results constitute the proof-of-principle of bovine IFN-λ as an antiviral biotherapeutic to protect cattle against the clinical disease caused by BVDV.

Cross-Reactivity Antibody Response after Vaccination with Modified Live and Killed Bovine Viral Diarrhoea Virus (BVD) Vaccines

Pestivirus A or bovine viral diarrhoea virus (BVDV) type 1 is responsible for cosmopolitan diseases affecting cattle and other ruminants, presenting a wide range of clinical manifestations, with relevant impact on zootechnic production. The objective of the present study was to verify whether animals immunised with four commercial vaccines also developed a protective humoral immunity against other viral subgenotypes than those contained in each vaccine. Four groups of 25 bovines each were formed and vaccinated according to the manufacturer’s instructions of the commercial vaccines. On sera collected 28 days after the last vaccination, virus neutralisation tests (VNT) were performed using homologous and heterologous viruses and enzyme-linked immunosorbent assay (ELISA) methods. Finally, the VNT results were comparatively evaluated through a statistical analysis. Serological results highlighted that, although with a different degree of efficiency, the four vaccines resulted in not developing a solid antibody-mediated cross-immunity against all the strains used.

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

Bovine viral diarrhea virus (BVDV) is an important pathogen belonging to the Pestivirus genus, Flaviviridae family, which comprises viral species that causes an economic impact in animal production. Cattle are the natural host of BVDV and the main source of infection for pigs and other animal species. Due to its antigenic and genetic similarity with other important pestiviruses such as Classical Swine Fever Virus (CSFV), several studies have been conducted to elucidate the real role of this virus in piglets, sows, and boars, not only in the field but also in experimental infections, which will be discussed in this paper. Although BVDV does not pose a threat to pigs as it does to ruminants, the occurrence of clinical signs is variable and may depend on several factors. Therefore, this study presents a survey of data on BVDV infection in pigs, comparing information on prevalence in different countries and the results of experimental infections to understand this type of infection in pigs better.

Detection methods and characterization of bovine viral diarrhea virus in aborted fetuses and neonatal calves over a 22-year period

Detection of bovine viral diarrhea virus (BVDV) in aborted fetus samples is often difficult due to tissue autolysis and inappropriate sampling. Studies assessing different methods for BVDV identification in fetal specimens are scarce. The present study evaluated the agreement between different diagnostic techniques to detect BVDV infections in specimens from a large number of bovine aborted fetuses and neonatal deaths over a period of 22 years. Additionally, genetic, serological, and pathological analyses were conducted in order to characterize BVDV strains of fetal origin. Samples from 95 selected cases from 1997 to 2018 were analyzed by antigen-capture ELISA (AgELISA), nested RT-PCR (RT-nPCR), and real-time RT-PCR (RT-qPCR). In addition, amplification and sequencing of the 5'UTR region were performed for phylogenetic purposes. Virus neutralization tests against the BVDV-1a, BVDV-1b, and BVDV-2b subtypes were conducted on 60 fetal fluids of the selected cases. Furthermore, the frequency and severity of histopathological lesions were evaluated in BVDV-positive cases. This study demonstrated that RT-nPCR and RT-qPCR were more suitable than AgELISA for BVDV detection in fetal specimens. However, the agreement between the two RT-PCR methods was moderate. The BVDV-1b subtype was more frequently detected than the BVDV-1a and BVDV-2b subtypes. Neutralizing antibodies to any of the three subtypes evaluated were present in 94% of the fetal fluids. Microscopically, half of the BVDV-positive cases showed a mild non-suppurative inflammatory response. These results emphasize the need to consider different methods for a diagnostic approach of BVDV associated to reproductive losses.

Microbial diversity involved in the etiology of a bovine respiratory disease outbreak in a dairy calf rearing unit

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BALF is a good biological sample for the molecular diagnosis of BRD in dairy calves.

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Mixed infections of viruses and bacteria were frequent in dairy calves with respiratory disease.

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BVDV 1d in BALF samples of dairy heifer calves in a BRD outbreak was characterized.

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The calf rearing unit without prophylactic measures for respiratory infections represent a risk factor for BRD.

The etiological agents involved in a bovine respiratory disease (BRD) outbreak were investigated in a dairy heifer calf rearing unit from southern Brazil. A battery of PCR assays was performed to detect the most common viruses and bacteria associated with BRD, such as bovine viral diarrhea virus (BVDV), bovine respiratory syncytial virus (BRSV), bovine alphaherpesvirus 1 (BoHV-1), bovine coronavirus (BCoV), bovine parainfluenza virus 3 (BPIV-3), Mannheimia haemolytica, Pasteurella multocida, Histophilus somni, and Mycoplasma bovis. Bronchoalveolar lavage fluid (BALF) samples were taken from 21 heifer calves (symptomatic n = 15; asymptomatic n = 6) that, during the occurrence of the BDR outbreak, were aged between 6 and 90 days. At least one microorganism was detected in 85.7 % (18/21) of the BALF samples. Mixed infections were more frequent (72.2 %) than single infections (27.7 %). The interactions between viruses and bacteria were the most common in coinfections (55.5 %). The frequencies of BRD agents were 38.1 % for BRSV, 28.6 % for BVDV, 33.3 % for BCoV, 42.85 % for P. multocida, 33.3 % for M. bovis, and 19 % for H. somni. BoHV-1, BPIV-3, and M. haemolytica were not identified in any of the 21 BALF samples. Considering that BALF and not nasal swabs were analyzed, these results demonstrate the etiological multiplicity that may be involved in BRD outbreaks in dairy calves.

Genetic Diversity of Bovine Pestiviruses Detected in Backyard Cattle Farms Between 2014 and 2019 in Henan Province, China

Bovine pestiviruses include Pestivirus A (BVDV-1), Pestivirus B (BVDV-2), and Pestivirus H, which was originally called HoBi-like pestivirus. We conducted an epidemiological investigation for pestiviruses circulating in backyard cattle farms in central China. RT-PCR assays and sequences analysis were conducted on 54 nasal swabs, 26 serum samples, and three lung samples from cattle with respiratory infections and identified 29 pestivirus strains, including 24 Pestivirus A and five Pestivirus H strains. Phylogenetic analysis based on partial 5'-UTR and Npro sequences showed that the genotypes of 24 Pestivirus A strains included Pestivirus A 1b (six isolates), Pestivirus A 1m (six isolates), Pestivirus A 1q (two isolates), Pestivirus A 1u (one isolates), and Pestivirus A 1o (nine isolates, a putative new sub-genotype). In addition, a single Pestivirus H agenotype included all five Pestivirus H strains. This study revealed extensive genetic variations within bovine pestivirus isolates derived from cattle in backyard farms in Central China, and this epidemiological information improves our understanding of the epidemics of bovine Pestiviruses, as well as will be useful in designing and evaluating diagnostic methods and developing more effective vaccines.

Serological survey of wild cervids in England and Wales for bovine viral diarrhoea virus

BACKGROUND

Bovine viral diarrhoea (BVD) is a production disease commonly found in British cattle herds. Species other than cattle have been shown to be infected with the virus, thereby providing a potential source of infection for livestock. This study surveyed serum samples taken from 596 culled wild deer from England and Wales, between 2009 and 2010, for the presence of BVD antibodies.

METHODS

596 samples were tested with the SVANOVIR BVDV p80-Ab ELISA and a subset of 64 were tested with the IDEXX BVDV p80-Ab ELISA. ELISA results were confirmed using serum neutralisation tests.

RESULTS

2/596 samples (0.35 per cent) tested positive for BVD antibodies using the Svanova test and one of these tested positive and the other inconclusive using the IDEXX test; both were confirmed positive with serum neutralisation tests. These were both red deer stags, one from Devon and the other from East Anglia.

CONCLUSIONS

The results indicate that it is unlikely that BVD virus is widely circulating within the wild deer population and particularly unlikely that persistently infected deer are present in the populations surveyed. These results suggest that wild deer are unlikely to be a significant reservoir of BVD infection in cattle.

Detection of bovine viral diarrhea virus in stable flies following consumption of blood from persistently infected cattle

Control of bovine viral diarrhea virus (BVDV) relies on resource-intensive sampling to detect and remove persistently infected (PI) cattle. Herd-level surveillance tools would be useful for herds with unknown BVDV status and for monitoring herds with BVDV-free status. Our objective was to determine the feasibility of using stable flies as a sampling tool to detect BVDV at the herd level. Stable flies (Stomoxys calcitrans) were fed citrated blood from either BVDV-PI or BVDV-free cattle to establish pools of 100 flies with various proportions of BVDV-fed flies (0%, 1%, 10%, 20%, 40%, or 100% in each pool). BVDV-fed flies in these pools were harvested either 1, 2, or 3 d after consuming BVDV-PI blood to determine the impact of time after feeding. Two replicates of a 3-d by 6-dilution level matrix were produced. BVDV RNA was consistently detected on day 1 when ≥10% of the flies in the pool consumed PI blood. On days 2 and 3, positive BVDV RNA detection was variable and became less consistent. Our results demonstrate that BVDV RNA can be detected in stable flies after feeding on blood from PI cattle. Successful use of stable flies as a surveillance tool will require validation under field conditions.

Herbal extracts as antiviral agents

Phytotherapy, or herbalism, is defined as the usage of plants or herbs as medication to treat or prevent diseases in human and animals. The usage is gaining more attention among medical practitioners as well as large-scale livestock producers. A number of reports have shown the positive effects of herbal extracts as an antiviral agent used in animal feed or as a prophylaxis and remedy. Besides being a cheaper and safer alternative, the use of herbs may reduce the incidence of drug resistance and may modulate the immune system in preventing viral-related diseases. In this chapter, the antiviral effects of several herbs and their extracts against viruses in terms of the mechanism of action in targeting viral replication steps, the effects in the host and the application in animals will be discussed. The information given may aid in improving the health and increase the production of animals.

Bovine Viral Diarrhoea Virus Infection Disrupts Uterine Interferon Stimulated Gene Regulatory Pathways During Pregnancy Recognition in Cows

In cattle, conceptus-derived interferon tau (IFNT) is the pregnancy recognition (PR) signal. Our previous studies showed that non-cytopathic bovine viral diarrhoea virus (ncpBVDV) infection inhibited IFNT-induced interferon stimulated gene (ISG) expression, potentially causing early embryonic death. This study investigated the effect of bovine viral diarrhoea virus (BVDV) infection on upstream regulatory pathways of ISG production using an established PR model. Uterine endometrial cells from 10 apparently healthy and BVDV free cows were cultured and treated with 0 or 100 ng/mL IFNT for 24 h in the presence or absence of ncpBVDV infection. Microarray and pathway analysis were used to determine the IFNT-induced upstream regulators. Expression of the genes associated with the identified pathways were quantified with qPCR. IFNT challenge activated the signalling pathways associated with IFN receptors, JAK1/TYK2, IRFs and STATs and ncpBVDV infection inhibited the activation of IFNT on this pathway. Inhibition of this upstream signalling pathway may thus reduce ISG production to disrupt maternal PR. In addition, the reduction of uterine immunity by ncpBVDV infection may predispose the animals to uterine infection, which in turn impairs their reproductive performance. This provides a mechanism of how BVDV infection leads to early pregnancy failure in cows.

Genetic analysis of bovine viral diarrhea virus in pre-weaned native Korean calves

Bovine viral diarrhea virus (BVDV), a prominent viral pathogen worldwide, causes substantial economic losses in the cattle industry. BVDV comprises two recognized species, BVDV-1 and BVDV-2, and at least 21 subtypes (1a-1u) for BVDV-1 and four subtypes (2a-2d) for BVDV-2 based on its 5'-untranslated region. This study aimed at investigating the prevalence and genetic analysis of BVDV in calf feces in the Republic of Korea (ROK). We collected fecal samples from 635 pre-weaned native Korean calves aged 1-60 days, regardless of diarrhea, and subjected them to RT-PCR and phylogenetic analysis. Thirty-five (5.5%) of the 635 samples were positive for BVDV infection. BVDV was detected in 20, 10, and 5 calves aged 1-20 days, 21-40 days, and 41-60 days, respectively. BVDV was the most frequent in 17 normal feces, followed by 16 diarrheic feces, and 2 hemorrhagic feces. Phylogenetic analysis revealed that 25 samples belonged to BVDV-1b; 1 sample, BVDV-1c; and 9 samples, BVDV-2a. Moreover, the BVDV-1b and BVDV-2a isolates showed genetic variations. BVDV-1b was detected in diarrheic, hemorrhagic, and normal fecal samples. Thus, BVDV-1b is the most prevalent in calves and causes enteric disease with differing severity. BVDV-1c was newly identified in diarrheic calves. Further studies are warranted to elucidate the pathogenesis of BVDV-1c infection and its clinical manifestations. Our results indicate that effective vaccines and control programs against BVDV are required in the ROK.

Molecular detection and phylogeny of bovine viral diarrhea virus 1 among cattle herds from Northeast, Southeast, and Midwest regions, Brazil

We examined the circulating BVDV species and genotypes among cattle herds from Northeast, Southeast, and Midwest regions in Brazil. A total of 77 animals tested positive through standard PCR. Phylogenetic analyses revealed the presence of BVDV-1a, highlighting the need for better surveillance strategies to prevent BVDV spread in the country.

A systematic review and meta-analysis of the epidemiology of bovine viral diarrhea virus (BVDV) infection in dairy cattle in China

Bovine viral diarrhea virus (BVDV) infection causes significantly economic losses to cattle industry worldwide, also including China. The epidemiological prevalence of infection associated with BVDV in dairy cattle has not been systematically assessed in China. Therefore, we undertook this study to evaluate prevalent of BVDV infection. We conducted a systematic review and meta-analysis of data from papers on the BVDV incidence and prevalence in dairy cattle in China by searching China Science and Technology Journal Database, China National Knowledge Infrastructure (CNKI), Wan Fang Database and PubMed for publication from March 2003 to March 2018. The 41 studies reporting the prevalence of BVDV in cattle in China were selected upon our inclusion criterion. The pooled BVDV prevalence in dairy cattle in China was estimated to 53.0% (95% CI 40.2-65.7) based on the data obtained from the 27,530 cows tested using serological or virological assay in the qualified papers published during the periods (χ² = 51,861.0, I² = 99.9%). The highest BVDV positive rate in dairy flocks reached 90.0% in Fujian province of China, followed by Shaanxi (88.9%) and Shandong (83.3%). The prevalence in the six administrative districts of China was validated to be highly variable (25.7%-72.2%) and reached 72.2% in dairy cattle flocks of Northern China. Besides, the BVDV-RNA positive rate was estimated 27.1% (95% CI 17.3-37.0) based on 6 studies, comparatively, the pooled BVDV seroprevalence based on 35 studies was about 57.0% (95% CI 44.4-69.5) in China. This systematic review and meta-analysis firstly established an estimated prevalence of BVDV in dairy herds in China, indicating that the BVDV infection is escalating, though there is a bias in the number of studies between 2003-2009 and 2010-2018 timescales. This study may help understand the status of BVDV infection in dairy herds in China. Further extensive and comprehensive investigation is recommended, and effective intervention measures for preventing and controlling BVDV spread in dairy herds should be deployed, especially herds that have been exposed to BVDV.

High prevalence of persistently infected animals from bovine viral diarrhea in Colombian cattle

Background

Bovine Viral Diarrhea Virus (BVDV) is associated with gastrointestinal, respiratory and reproductive diseases of livestock across the world that causes continuous economic losses in the cattle industry. This virus can establish a persistent infection (PI) in calves after the fetal infection, making BVDV positive catle carriers and primary reservoirs which will constantly transmit the virus to healthy and new-born animals. For this reason, the detection of the PI animals in herds is the first line of prevention of the viral infection.

Results

In this study, PI animals were detected in five different regions of Colombia through RT-PCR techniques and confirmed by sequencing. BVDV genotypes were determined using one fragment of the 5’UTR. It was found a 7% BVDV prevalence in animals and 22% in farms; and genotype 1 was identified as a single genotype for all of the samples. All samples were BVDV 1a.

Conclusion

This is the first report in Colombia with higher prevalence rates compared with other places in the world, turned out to be of great importance for the ranchers, the vaccine producers and animal health control parties.

Genetic Diversity of Bovine Viral Diarrhea Virus Infection in Goats in Southwestern China

Bovine viral diarrhea virus (BVDV) affects cows, pigs, sheep, goats, and other ruminants, as well as some wild animals. BVDV causes considerable economic losses every year and many countries have developed programs aimed at the eradication of this disease. The genetic diversity of BVDV in diseased goats has never been described in southwestern China. Thus, in this study, we applied antigen-capture ELISA and RT-PCR to survey the infection rate of BVDV in diseased goats in this region. Our results demonstrated that the average BVDV infection rate in goats was 17.51%, with all positive samples indicating infection by BVDV-1 and not BVDV-2, BVDV-3, or Border disease virus. The molecular characteristics of the 5′-untranslated region (5′-UTR) of BVDV-1 were recognized as belonging predominantly to the BVDV-1a, 1b, 1c, 1m, and 1p subtypes. BVDV-1b and 1m were the most abundant subtypes identified in this region, similar to the BVDV epidemics in cattle in other regions of China. This is the first study that describes the genetic characterization of BVDV in sick goats from southwestern China and is important for future studies and control programs.

Evidence of bovine viral diarrhea virus transmission by back pond water in experimentally infected piglets

ABSTRACT: Swine can be infected by bovine viral diarrhea virus (BVDV). However, transmission routes among pigs are still unknown. The objective of the present study was to induce experimental infection of BVDV-1 in weaned piglets and to assess the potential transmission through pen back pond water, used to facilitate heat exchange of the pigs housed in barns. Two repetitions (BP1 and BP 2) were performed using 12 piglets proven to be free BVDV (n=6 per repetition) allocated into three groups: control, sentinels and infected with two piglets each. The piglets were placed in stainless steel isolators. The infected group received an inoculum containing BVDV-1, Singer strain. The piglets remained in the cabinets for 25 days, during which samples of nasal swab were collected daily and blood sampled weekly. At the end, the piglets were euthanized, necropsied and organ fragments were collected for histopathology, immunohistochemistry and RT-PCR. In the first experiment (BP1) the infected animals shed the virus between days 6 and 21 post-infection. Regarding the sentinel group, shedding occurred in only one piglet, on the 20th day after infection, and seroconversion was observed on the 25th day post-infection. In BP2, infected piglets I3 and I4 shed the virus on days 4 and 21 post-infection, respectively. Only one sentinel piglet (S3) she the virus on day 13 post-infection. Therefore, it was concluded that pigs can become infected with BVDV-1 and shed potentially infectious viral particles consequently, being able to transmit the virus to other pigs through back pond water.