Mechanisms linking bovine viral diarrhea virus (BVDV) infection with infertility in cattle

The host protein CALCOCO2 interacts with bovine viral diarrhoea virus Npro, inhibiting type I interferon production and thereby promoting viral replication

Bovine viral diarrhoea-mucosal disease caused by bovine viral diarrhoea virus (BVDV) is a major infectious disease that affects the cattle industry. The nonstructural protein Npro of BVDV antagonizes the type I interferon (IFN-I) pathway, thereby escaping the host immune response. The exact mechanism by which Npro uses host proteins to inhibit IFN-I production is unclear. The host protein CALCOCO2 was identified as a binding partner of Npro using a yeast two-hybrid screen. The interaction between Npro and CALCOCO2 was confirmed by yeast co-transformation, co-immunoprecipitation assays, and GST pull-down assays. The stable overexpression of CALCOCO2 markedly promoted BVDV propagation, while the knockdown of CALCOCO2 significantly inhibited BVDV replication in MDBK cells. Interestingly, CALCOCO2 inhibited IFN-I and IFN-stimulated gene production in BVDV-infected cells. Ectopic expression of CALCOCO2 effectively reduced IRF3 protein levels via the proteasome pathway. CALCOCO2 was found to promote Npro-mediated ubiquitination degradation of IRF3 by interacting with IRF3. Our results demonstrate the molecular mechanism by which Npro recruits the CALCOCO2 protein to regulate IRF3 degradation to inhibit IFN-I production.

Exploring viral diversity and metagenomics in livestock: insights into disease emergence and spillover risks in cattle

Cattle have a significant impact on human societies in terms of both economics and health. Viral infections pose a relevant problem as they directly or indirectly disrupt the balance within cattle populations. This has negative consequences at the economic level for producers and territories, and also jeopardizes human health through the transmission of zoonotic diseases that can escalate into outbreaks or pandemics. To establish prevention strategies and control measures at various levels (animal, farm, region, or global), it is crucial to identify the viral agents present in animals. Various techniques, including virus isolation, serological tests, and molecular techniques like PCR, are typically employed for this purpose. However, these techniques have two major drawbacks: they are ineffective for non-culturable viruses, and they only detect a small fraction of the viruses present. In contrast, metagenomics offers a promising approach by providing a comprehensive and unbiased analysis for detecting all viruses in a given sample. It has the potential to identify rare or novel infectious agents promptly and establish a baseline of healthy animals. Nevertheless, the routine application of viral metagenomics for epidemiological surveillance and diagnostics faces challenges related to socioeconomic variables, such as resource availability and space dedicated to metagenomics, as well as the lack of standardized protocols and resulting heterogeneity in presenting results. This review aims to provide an overview of the current knowledge and prospects for using viral metagenomics to detect and identify viruses in cattle raised for livestock, while discussing the epidemiological and clinical implications.

Diagnosis of bovine viral diarrhea virus: an overview of currently available methods

Bovine viral diarrhea virus (BVDV) is the causative agent of bovine viral diarrhea (BVD), which results in significant economic losses in the global cattle industry. Fortunately, various diagnostic methods available for BVDV have been established. They include etiological methods, such as virus isolation (VI); serological methods, such as enzyme-linked immunosorbent assay (ELISA), immunofluorescence assay (IFA), and immunohistochemistry (IHC); molecular methods, such as reverse transcription-polymerase chain reaction (RT-PCR), real-time PCR, digital droplet PCR (ddPCR), loop-mediated isothermal amplification (LAMP), recombinase polymerase amplification (RPA), and CRISPR-Cas system; and biosensors. This review summarizes the current diagnostic methods for BVDV, discussing their advantages and disadvantages, and proposes future perspectives for the diagnosis of BVDV, with the intention of providing valuable guidance for effective diagnosis and control of BVD disease.

Development and application of one-step multiplex Real-Time PCR for detection of three main pathogens associated with bovine neonatal diarrhea

Introduction

Neonatal calf diarrhea (NCD) is one of the most common diseases in calves, causing huge economic and productivity losses to the bovine industry worldwide. The main pathogens include bovine rotavirus (BRV), bovine coronavirus (BCoV), and Enterotoxigenic Escherichia coli (ETEC) K99. Since multiple infectious agents can be involved in calf diarrhea, detecting each causative agent by traditional methods is laborious and expensive.

Methods

In this study, we developed a one-step multiplex Real-Time PCR assay to simultaneously detect BRV, BCoV, and E. coli K99+. The assay performance on field samples was evaluated on 1100 rectal swabs of diseased cattle with diarrhea symptoms and compared with the conventional gel-based RT-PCR assay detect BRV, BCoV, and E. coli K99+.

Results

The established assay could specifically detect the target pathogens without cross-reactivity with other pathogens. A single real-time PCR can detect ~1 copy/µL for each pathogen, and multiplex real-time PCR has a detection limit of 10 copies/µL. Reproducibility as measured by standard deviation and coefficient of variation were desirable. The triple real-time PCR method established in this study was compared with gel-based PT-PCR. Both methods are reasonably consistent, while the real-time PCR assay was more sensitive and could rapidly distinguish these three pathogens in one tube. Analysis of surveillance data showed that BRV and BCoV are major enteric viral pathogens accounting for calves' diarrhea in China.

Discussion

The established assay has excellent specificity and sensitivity and was suitable for clinical application. The robustness and high-throughput performance of the developed assay make it a powerful tool in diagnostic applications and calf diarrhea research. ​.

PI3K/AKT mediated De novo fatty acid synthesis regulates RIG-1/MDA-5-dependent type I IFN responses in BVDV-infected CD8+T cells

Bovine viral diarrhea virus (BVDV) has caused massive economic losses in the cattle business worldwide. Fatty acid synthase (FASN), a key enzyme of the fatty acid synthesis (FAS) pathway, has been shown to support virus replication. To investigate the role of fatty acids (FAs) in BVDV infection, we infected CD8+T lymphocytes obtained from healthy cattle with BVDV in vitro. During early cytopathic (CP) and noncytopathic (NCP) BVDV infection in CD8+ T cells, there is an increase in de novo lipid biosynthesis, resulting in elevated levels of free fatty acids (FFAs) and triglycerides (TG). BVDV infection promotes de novo lipid biosynthesis in a dose-dependent manner. Treatment with the FASN inhibitor C75 significantly reduces the phosphorylation of PI3K and AKT in BVDV-infected CD8+ T cells, while inhibition of PI3K with LY294002 decreases FASN expression. Both CP and NCP BVDV strains promote de novo fatty acid synthesis by activating the PI3K/AKT pathway. Further investigation shows that pharmacological inhibitors targeting FASN and PI3K concurrently reduce FFAs, TG levels, and ATP production, effectively inhibiting BVDV replication. Conversely, the in vitro supplementation of oleic acid (OA) to replace fatty acids successfully restored BVDV replication, underscoring the impact of abnormal de novo fatty acid metabolism on BVDV replication. Intriguingly, during BVDV infection of CD8+T cells, the use of FASN inhibitors prompted the production of IFN-α and IFN-β, as well as the expression of interferon-stimulated genes (ISGs). Moreover, FASN inhibitors induce TBK-1 phosphorylation through the activation of RIG-1 and MDA-5, subsequently activating IRF-3 and ultimately enhancing the IFN-1 response. In conclusion, our study demonstrates that BVDV infection activates the PI3K/AKT pathway to boost de novo fatty acid synthesis, and inhibition of FASN suppresses BVDV replication by activating the RIG-1/MDA-5-dependent IFN response.

Identification of Genomic Instability in Cows Infected with BVD Virus

An important factor for dairy cattle farmers is the profitability of cattle rearing, which is influenced by the animals' health and reproductive parameters, as well as their genomic stability and integrity. Bovine viral diarrhea (BVD) negatively affects the health of dairy cattle and causes reproductive problems. The aim of the study was to identify genomic instability in cows with reproductive disorders following infection with the BVD virus. The material for analysis was peripheral blood from Holstein-Friesian cows with reproductive problems, which had tested positive for BVD, and from healthy cows with no reproductive problems, which had tested negative for BVD. Three cytogenetic tests were used: the sister chromatid exchange assay, fragile sites assay, and comet assay. Statistically significant differences were noted between the groups and between the individual cows in the average frequency of damage. The assays were good biomarkers of genomic stability and enabled the identification of individuals with an increased frequency of damage to genetic material that posed a negative impact on their health. The assays can be used to prevent disease during its course and evaluate the genetic resistance of animals. This is especially important for the breeder, both for economic and breeding reasons. Of the three assays, the comet assay proved to be the most sensitive for identifying DNA damage in the animals.

Immune evasion strategies of bovine viral diarrhea virus

Bovine viral diarrhea virus (BVDV) is a significant pathogen that causes great economic losses in the global livestock industry. During the long-term interactions between BVDV and its hosts, the virus has evolved multiple strategies to evade the host's innate immunity and adaptive immunity, thereby promoting viral survival and replication. This review focuses on the most recent research on immune evasion strategies employed by BVDV, including evading type I IFN signaling pathway, evading host adaptive immunity, mediating NF-κB signaling pathway, mediating cell apoptosis and inducing autophagy. Unraveling BVDV's immune evasion strategies will enhance our understanding of the pathogenesis of BVDV and contribute to the development of more effective therapies for the prevention, control and eradication of BVDV.

Bovine Airway Models: Approaches for Investigating Bovine Respiratory Disease

Bovine respiratory disease (BRD) is a multifactorial condition where different genera of bacteria, such as Mannheimia haemolytica, Histophilus somni, Pasteurella multocida, and Mycoplasma bovis, and viruses, like bovine respiratory syncytial virus, bovine viral diarrhea virus, and bovine herpes virus-1, infect the lower respiratory tract of cattle. These pathogens can co-infect cells in the respiratory system, thereby making specific treatment very difficult. Currently, the most common models for studying BRD include a submerged tissue culture (STC), where monolayers of epithelial cells are typically covered either in cellular or spent biofilm culture medium. Another model is an air-liquid interface (ALI), where epithelial cells are exposed on their apical side and allowed to differentiate. However, limited work has been reported on the study of three-dimensional (3D) bovine models that incorporate multiple cell types to represent the architecture of the respiratory tract. The roles of different defense mechanisms in an infected bovine respiratory system, such as mucin production, tight junction barriers, and the production of antimicrobial peptides in in vitro cultures require further investigation in order to provide a comprehensive understanding of the disease pathogenesis. In this report, we describe the different aspects of BRD, including the most implicated pathogens and the respiratory tract, which are important to incorporate in disease models assembled in vitro. Although current advancements of bovine respiratory cultures have led to knowledge of the disease, 3D multicellular organoids that better recapitulate the in vivo environment exhibit potential for future investigations.

A serological survey of pathogens associated with the respiratory and digestive system in the Polish European bison (Bison bonasus) population in 2017-2022

BACKGROUND

The European bison (Bison bonasus) is a near threatened species and requires health monitoring. The aim of the present study was to determine the prevalence of antibodies to pathogens known to cause respiratory and digestive illness in ruminants.

RESULTS

In the studied 328 European bison, the highest seroprevalence was observed for Bovine herpesvirus-1 (BoHV-1) (50.27%), Bovine Coronavirus (BCoV) (26.36%), and Bluetongue Virus (BTV) (12.83%). For Mycoplasma bovis strains and Bovine Viral Diarrhea Virus (BVDV), positive results were rare. Interestingly, a higher prevalence of BTV antibodies was noted in the northeastern populations and older animals.

CONCLUSIONS

Our findings indicate that the Polish European bison population appears to have considerable contact with BoHV-1; however, this does not appear to be of great significance, as clinical symptoms and post-mortem lesions are rarely noted in Polish European bison population. The high seroprevalence of BTV in the north-east of Poland is an ongoing trend, also noted in previous studies. It is possible that European bison may perpetuate the virus in this region. This is the first report of antibodies for BCoV in European bison.

Development and application of an indirect ELISA for the serological detection of bovine viral diarrhea virus infection based on the protein E2 antigen

BACKGROUND

Bovine viral diarrhea virus (BVDV) causes continuous economic losses to the livestock industry. Monitoring antibodies with enzyme-linked immunosorbent assay (ELISA) is a valuable tool to ensure the purification of BVDV in cattle. However, currently available ELISA kits based on the whole BVDV virion are both costly and time-consuming. The E2 protein has good immunogenicity, induces the secretion of neutralizing antibodies and is an essential immunogen for serological detection.

METHODS AND RESULTS

We developed a novel recombinant E2 protein-based indirect ELISA (rE2-iELISA) and conducted a serological survey for BVDV antibodies in 2021-2022 in Beijing, China. The results showed that E2 protein was successfully expressed with high immunogenicity and the optimal rE2-iELISA displayed high sensitivity, reproducibility and specificity. Clinical testing of 566 serum specimens indicated that 318 BVDV positive samples and 194 BVDV negative samples were tested by rE2-iELISA and the IDEXX BVDV ELISA-Ab kit, with a positive coincidence rate of 93.3%, a negative coincidence rate of 86.3%, and an overall coincidence rate of 90.5%.

CONCLUSION

This study established an rE2-iELISA method, which is a highly sensitive, specific and robust ELISA-test validated to detect anti-BVDV antibodies. These findings indicate that the newly developed rE2-iELISA method has the potential to be used as a rapid, reliable and cost-effective screening tool for BVDV infection and provides technical support for the evaluation of vaccine efficacy in cattle herds in the future.

Pestiviruses infection: Interferon-virus mutual regulation

Pestiviruses are a class of viruses that in some cases can cause persistent infection of the host, thus posing a threat to the livestock industry. Interferons (IFNs) are a group of secreted proteins that play a crucial role in antiviral defense. In this review, on the one hand, we elaborate on how pestiviruses are recognized by the host retinoic acid-inducible gene-I (RIG-I), melanoma-differentiation-associated protein 5 (MDA5), and Toll-like receptor 3 (TLR3) proteins to induce the synthesis of IFNs. On the other hand, we focus on reviewing how pestiviruses antagonize the production of IFNs utilizing various strategies mediated by self-encoded proteins, such as the structural envelope protein (E^rns) and non-structural protein (N^pro). Hence, the IFN signal transduction pathway induced by pestiviruses infection and the process of pestiviruses blockade on the production of IFNs intertwines into an intricate regulatory network. By reviewing the interaction between IFN and pestiviruses (based on studies on BVDV and CSFV), we expect to provide a theoretical basis and reference for a better understanding of the mechanisms of induction and evasion of the innate immune response during infection with these viruses.

Characterization of gut microbiota dysbiosis of diarrheic adult yaks through 16S rRNA gene sequences

The ruminant gut microbial community has a strong impact on host health and can be altered during diarrhea disease. As an indigenous breed of the Tibetan Plateau, domestic yak displays a high diarrhea rate, but little research has been done to characterize the bacterial microbial structure in diarrheic yaks. In the present study, a total of 30 adult yaks, assigned to diarrhea (case, N = 15) and healthy (control, N = 15) groups, were subjected to gut microbiota profiling using the V3–V4 regions of the 16S rRNA gene. The results showed that the gut microbiome of the case group had a significant decrease in alpha diversity. Additionally, differences in beta diversity were consistently observed for the case and control groups, indicating that the microbial community structure was changed due to diarrhea. Bacterial taxonomic analysis indicated that the Bacteroidetes, Firmicutes, and Proteobacteria were the three most dominant phyla in both groups but different in relative abundance. Especially, the proportion of Proteobacteria in the case group was increased as compared with the control group, whereas Spirochaetota and Firmicutes were significantly decreased. At the genus level, the relative abundance of Escherichia-Shigella and Prevotellaceae_UCG-003 were dramatically increased, whereas that of Treponema, p-2534-18B5_gut_group, and Prevotellaceae_UCG-001 were observably decreased with the effect of diarrhea. Furthermore, based on our linear discriminant analysis (LDA) effect size (LEfSe) results, Alistipes, Solibacillus, Bacteroides, Prevotellaceae_UCG_003, and Bacillus were significantly enriched in the case group, while the other five genera, such as Alloprevotella, RF39, Muribaculaceae, Treponema, and Enterococcus, were the most preponderant in the control group. In conclusion, alterations in gut microbiota community composition were associated with yak diarrhea, differentially represented bacterial species enriched in case animals providing a theoretical basis for establishing a prevention and treatment system for yak diarrhea.

Non-structural proteins of bovine viral diarrhea virus

Bovine viral diarrhea virus (BVDV) belongs to the family Flaviviridae genus pestivirus. The viral genome is a single-stranded, positive-sense RNA that encodes four structural proteins (i.e., C, Erns, E1, and E2) and eight non-structural proteins (NSPs) (i.e., Npro, p7, NS2, NS3, NS4A, NS4B, NS5A, and NS5B). Cattle infected with BVDV exhibit a number of different clinical signs including diarrhea, abortion, and other reproductive disorders which have a serious impact on the cattle industry worldwide. Research on BVDV mainly focuses on its structural protein, however, progress in understanding the functions of the NSPs of BVDV has also been made in recent decades. The knowledge gained on the BVDV non-structural proteins is helpful to more fully understand the viral replication process and the molecular mechanism of viral persistent infection. This review focuses on the functions of BVDV NSPs and provides references for the identification of BVDV, the diagnosis and prevention of Bovine viral diarrhea mucosal disease (BVD-MD), and the development of vaccines.

Development of a One-Step Multiplex Real-Time PCR Assay for the Detection of Viral Pathogens Associated With the Bovine Respiratory Disease Complex

Bovine respiratory disease complex (BRDC) occurs widely in cattle farms. The main viral pathogens include bovine viral diarrhea virus (BVDV), Bovine herpesvirus 1 (BoHV-1), bovine parainfluenza virus type 3 (BPIV3), and bovine respiratory syncytial virus (BRSV), and the newly emerged influenza D virus (IDV). In this study, we have developed a one-step multiplex real-time Polymerase Chain Reaction (PCR) capable of simultaneously detecting these five viral pathogens causing BRDC. The established assay could specifically detect targeted viruses without cross-reaction with others. The detection limit was ~10 copies/reaction for single real-time PCR and 100 copies/ reaction for multiplex real-time PCR assay. A total of 213 nasal samples from cattle with signs of respiratory tract disease were then collected for performance evaluation of the established platform, proving that the method has good specificity and sensitivity. The surveillance data suggested that BVDV and BoHV-1 infections are the dominant cause of BRDC in the herd, whereas the detection rate of IDV, BIPV3, and BRSV is relatively lower. In summary, the established assay provides technical support for rapid clinical detection of BRDC associated viral pathogens to guide the formulation of BRDC prevention and control measures.

Bovine viral diarrhea virus (BVDV) infection: Effect on reproductive performance and milk yield in dairy herds

The impact of an outbreak of bovine viral diarrhea (BVD) on reproductive performance and milk production was investigated in 28 Spanish dairy herds using an observational study design. Mean calving to conception interval (CCI), mean number of inseminations per conception (AI/P) and mean daily milk yield were recorded from herds affected by outbreaks. Infection was confirmed by evidence of viral transmission to young stock (heifers 9-24 months) and persistently infected animals, after previous BVD-free status. Fifteen herds did not use vaccines (G1) whereas the remaining 13 received modified live BVD virus (BVDV) vaccines (G2). In G1 herds, a significant increase in CCI (13.8 days; 95% CI, 0.4-27.3 days; P = 0.050) was observed during the BVD outbreak compared to the year before the outbreak. In G2 herds, there was a not a significant increase in CCI (3.0 days; 95% CI, -1.2-7.2 days; P = 0.558). Changes in AI/P between periods were not significant in any of the herds. In G1 herds, there was an increase of 0.09 units (P > 0.05) during the outbreak, whereas in G2 herds, AI/P decreased 0.08 units (P > 0.05). Compared to milk production in the year before the BVD outbreak, there was no significant change in G1 herds throughout the study period (P > 0.05), but there were significant increases in G2 herds over the study period (P1-P2, 1.4 kg/day increase, P = 0.019; P1-P3, 2.0 kg/day increase, P = 0.007). These results indicate that BVDV infection affected reproductive performance, which is critical in maintaining dairy herd profitability.

Lipopolysaccharide endotoxin injections elevated salivary TNFα and corneal temperatures and induced dynamic changes in circulating leukocytes, inflammatory cytokines, and metabolic indicators in wether lambs

Pathogenic infections increase morbidity and reduce performance in livestock, and thus understanding the comprehensive physiological changes associated with infections can benefit production sustainability. In this study, we sought to investigate such physiological responses to an acute immune challenge in lambs. Polypay wethers received single IV injections of 1.5 µg/kg lipopolysaccharide endotoxin (LPS-injected; n = 6) or saline (controls; n = 6). Corneal temperatures (via infrared thermography), rectal temperatures, blood, plasma, and saliva were assessed every 2 hr for 10 hr after injections. Blood was also assessed at 24 hr. LPS-injected lambs exhibited elevated (P < 0.05) corneal and rectal temperatures that peaked at 4 hr but were still slightly greater (P < 0.05) than controls at 10 hr. Circulating total white blood cells, monocytes, and granulocytes were reduced (P < 0.05) in LPS-injected lambs within the first 4 hr but were subsequently greater (P < 0.05) than in controls. Lymphocytes were reduced (P < 0.05) in LPS-injected lambs over the first 8 hr and did not differ from controls thereafter. Red blood cells, hematocrit, and hemoglobin were increased (P < 0.05) in LPS-injected lambs over the first 6 hr, indicating mild dehydration. Blood glucose briefly increased (P < 0.05) in LPS-injected lambs at 2 hr but was less (P < 0.05) than in controls thereafter. Blood lactate was greater (P < 0.05) in LPS-injected lambs between 6 and 10 hr after injections, which together with reduced (P < 0.05) CO2 partial pressure indicated a metabolic shift toward glycolysis. LPS-injected lambs exhibited a transient increase (P < 0.05) in plasma TNFα at 2 and 4 hr only and sustained increases (P < 0.05) in CXCL9 and CXCL10 beginning at 6 and 4 hr, respectively. They also exhibited a mild, paradoxical increase (P < 0.05) in the anti-inflammatory sFRP3. Salivary TNFα was increased (P < 0.05) in LPS-injected lambs at 2 hr only. Regression analyses indicated that rectal temperatures were a generally poor predictor of the other inflammatory components in this study, with the exception of circulating leukocyte populations. Likewise, correlations among the 10 cytokines measured in this study were generally weak, with notable exceptions between CXCL9 and CXCL10 and between IL-21 and IFNγ. These findings demonstrate that physiological changes to even short-lived immune challenges are dynamic in nature and persist beyond the time frame of febrile responses and other common assessments.

Comparison of the Ability of High and Low Virulence Strains of Non-cytopathic Bovine Viral Diarrhea Virus-1 to Modulate Expression of Interferon Tau Stimulated Genes in Bovine Endometrium

Bovine Viral Diarrhea virus (BVDV) is a pestivirus with a single-stranded, positive sense RNA genome. It is endemic in many cattle populations, causing major economic losses in part due to reduced fertility. BVDV exhibits great genetic diversity and is classified as type 1 or 2 (BVDV-1, BVDV-2) with either non-cytopathogenic (ncp) or cytopathogenic (cp) biotypes. Differing strains of ncpBVDV differ in virulence, affecting clinical outcome. BVDV replicates in the reproductive tract, affecting host immunity and embryo survival. This study used an in vitro model of primary bovine endometrial cell cultures to compare the effects of two BVDV ncp type 1a strains of differing virulence (termed HO and KY) on endometrial transcription of candidate interferon stimulated genes (ISG) using qPCR. Half the cultures were stimulated with interferon tau (IFNT, the conceptus produced pregnancy recognition factor) in the presence or absence of viral infection. Cultures were replicated on cells from 10 BVDV-free cows. IFNT treatment stimulated transcription of 10 candidate ISGs, whereas both ncpBVDV-1 strains alone inhibited transcription of 8/10 ISGs. In combined BVDV-1+IFNT cultures, the stimulatory effect of IFNT on expression of GBP4, ISG15, HERC5, RSAD2, IFIH1, IFIT3, and MX1 was significantly inhibited by HO, but only ISG15, RSAD2, IFI27, and IFIT3 were decreased by KY. Inhibition by HO was generally greater. The IFNT-induced expression of TRIM56 was, however, increased by HO. These data show that HO, the more virulent ncpBVDV-1 strain, has a greater capacity to inhibit key antiviral pathways. These differences need confirmation at the protein level but may influence immune tolerance of the host. They could also reduce fertility by increasing uterine susceptibility to bacterial infection and disrupting IFNT-mediated pregnancy recognition.

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.

Upregulation of interferon-alpha gene in bovine embryos produced in vitro in response to experimental infection with noncytophatic bovine-viral-diarrhea virus

In-vitro fertilization is a routine livestock-breeding technique widely used around the world. Several studies have reported the interaction of bovine viral-diarrhea virus (BVDV) with gametes and in-vitro-produced (IVP) bovine embryos. Since, gene expression in BVDV-infected IVP bovine embryos is scarcely addressed. The aim of this work was to evaluate the differential expression of genes involved in immune and inflammatory response. Groups of 20-25 embryos on Day 6 (morula stage) were exposed (infected) or not (control) to an NCP-BVDV strain in SOF medium. After 24 h, embryos that reached expanded blastocyst stage were washed. Total RNA of each embryo group was extracted to determine the transcription levels of 9 specific transcripts related with antiviral and inflammatory response by SYBR Green real time quantitative (RT-qPCR). Culture media and an aliquot of the last embryos wash on Day 7 were analyzed by titration and virus isolation, respectively. A conventional PCR confirmed BVDV presence in IVP embryos. A significantly higher expression of interferon-α was observed in blastocysts exposed to NCP-BVDV compared to the controls (p < 0.05). In this study, the upregulation of INFα and TLR7 genes involved in inflammatory and immune response in BVDV-infected IVP bovine embryos is a new finding in this field. This differential expression suggest that embryonic cells could function in a manner like immune cells by recognizing and responding early to interaction with viral pathogens. These results provide new insights into the action of BVDV on the complex molecular pathways controlling bovine early embryonic development.

The Effect of Stress on Reproduction and Reproductive Technologies in Beef Cattle-A Review

Researchers have contributed by increasing our understanding of the factors affecting reproduction in beef, mainly physical health and nutrition aspects, which have been main concerns during decades. Animal welfare is of outmost relevance in all animal production systems and it is strongly associated to stress. Stress responses involve endocrine, paracrine and neural systems and the consequences of this stress on the reproductive efficiency of specifically, beef cattle and bulls, need to be highlighted. We, therefore, describe the fundamentals of stress and its quantification, focusing in beef herds, reviewing the highly valuable pieces of research, already implemented in this field. We examine major factors (stressors) contributing to stress in beef cattle and their effects on the animals, their reproductive performance and the success of reproductive biotechnologies. We include terms such as acclimatization, acclimation or temperament, very relevant in beef systems. We examine specifically the management stress due to handling, social environment and hierarchy or weaning effects; nutritional stress; and thermal stress (not only heat stress) and also review the influence of these stressors on reproductive performance and effectiveness of reproductive biotechnologies in beef herds. A final message on the attention that should be devoted to these factors is highlighted.

Comparison of milk production of dairy cows vaccinated with a live double deleted BVDV vaccine and non-vaccinated dairy cows cohabitating in commercial herds endemically infected with BVD virus

Daily milk production and reproductive performance of cows vaccinated with a live double-deleted Bovine Viral Diarrhoea Virus (BVDV) vaccine were compared to those of non-vaccinated cows, cohabitating in endemic BVDV herds. All animals in the treatment group were vaccinated on study day 0 irrespective of lactation or gestation status, while control animals did not receive any treatment. 1463 animals were enrolled in the study from four different farms in three different countries (UK, Italy, France). Endemic presence of BVDV in study herds was demonstrated by the detection of BVDV in the bulk tank milk, and seroconversion was evaluated at the beginning of the study. For individual animals, the day of calving was taken to be the start of lactation for the calculation of days in milk (DIM). The standard lactation period of 305 days was divided into three periods: early lactation (EL, from DIM 8 to DIM 102), mid lactation (ML, from DIM 103 to DIM 204 and late lactation (LL, from DIM 205 to DIM 305). For each farm and each lactation period, a mixed model statistical analysis was performed with daily milk production as response, and group, day as well as the interaction between those two factors as fixed factors. Chi-square test was used to compare abortion rate and prolonged inter-oestrous interval rate between treatment and control groups. A significant increase in milk production in the vaccinated group was observed in farms 1 (1.023 L/day) and 3 (0.611 L/day) during EL (p<0.001) and in farm 2 (1.799 L/day) during ML (P<0.001). In addition, at farm 2, vaccinated cows produced more milk than non-vaccinated cows starting from 80 DIM. No differences were found between groups in abortion rates or prolonged inter-oestrous interval rates. Data demonstrate that cows in herds endemically infected with BVDV and vaccinated with live double-deleted BVDV vaccine produce more milk; the difference in milk production occurs during early lactation.

Anti-BVDV Activity Evaluation of Naphthoimidazole Derivatives Compared with Parental Imidazoquinoline Compounds

Background:

Pestivirus genus includes animal pathogens which are involved in economic impact for the livestock industry. Among others, Bovine Viral Diarrhoea Virus (BVDV) establish a persistent infection in cattle causing a long list of symptoms and a high mortality rate. In the last decades, we synthesised and reported a certain number of anti-BVDV compounds.

Methods:

In them, imidazoquinoline derivatives turned out as the most active. Their mechanism of actions has been deeply investigated, BVDV RNA-dependent RNA polymerase (RpRd) resulted as target and the way of binding was predicted in silico through three main H-bond interaction with the target.

The prediction could be confirmed by target or ligand mutation. The first approach has already been performed and published confirming the in silico prediction.

Results:

Here, we present how the ligand chemical modification affects the anti-BVDV activity. The designed compounds were synthesised and tested against BVDV as in silico assay negative control.

Conclusion:

The antiviral results confirmed the predicted mechanism of action, as the newly synthesised compounds resulted not active in the in vitro BVDV infection inhibition.

The emerging role and significance of circular RNAs in viral infections and antiviral immune responses: possible implication as theranostic agents

Circular RNAs (circRNAs) are ubiquitously expressed, covalently closed rings, produced by pre-mRNA splicing in a reversed order during post-transcriptional processing. Circularity endows 3'-5'-linked circRNAs with stability and resistance to exonucleolytic degradation which raises the question whether circRNAs may be relevant as potential therapeutic targets or agents. High stability in biological systems is the most remarkable property and a major criterion for why circRNAs could be exploited for a range of RNA-centred medical applications. Even though various biological roles and regulatory functions of circRNAs have been reported, their in-depth study is challenging because of their circular structure and sequence-overlap with linear mRNA counterparts. Moreover, little is known about their role in viral infections and in antiviral immune responses. We believe that an in-depth and detailed understanding of circRNA mediated viral protein regulations will increase our knowledge of the biology of these novel molecules. In this review, we aimed to provide a comprehensive basis and overview on the biogenesis, significance and regulatory roles of circRNAs in the context of antiviral immune responses and viral infections including hepatitis C virus infection, hepatitis B virus infection, hepatitis delta virus infection, influenza A virus infection, Epstein-Barr virus infection, kaposi's sarcoma herpesvirus infection, human cytomegalovirus infection, herpes simplex virus infection, human immunodeficiency virus infection, porcine epidemic diarrhoea virus infection, ORF virus infection, avian leukosis virus infection, simian vacuolating virus 40 infection, transmissible gastroenteritis coronavirus infection, and bovine viral diarrhoea virus infection. We have also discussed the critical regulatory role of circRNAs in provoking antiviral immunity, providing evidence for implications as therapeutic agents and as diagnostic markers.