Clinical and reproductive consequences of using BVDV-contaminated semen in artificial insemination in a beef herd in Argentina

Infectious sporadic bovine abortions: retrospective analysis

Infectious sporadic abortions in cattle are mainly caused by opportunistic bacteria and fungi usually present in environmental or gastrointestinal and reproductive microbiota of healthy animals. A retrospective analysis was carried out to evaluate the main opportunistic microorganisms involved in bovine abortions recorded at INTA Balcarce (Argentina) from 1997 to 2023, accounting for 2.2% of the total diagnosed etiologies of bovine abortion. The opportunistic agents identified as the cause of abortion in 29 fetuses were bacteria (90%) and fungi (10%). Escherichia coli (n = 8), Trueperella pyogenes (n = 5), and Histophilus somni (n = 4) were the bacterial species most often identified as causing infectious abortions, whereas Aspergillus spp. (n = 3) was implicated in all fungal abortions identified. Pure culture of bacteria or fungus was achieved from abomasal content and/or lung essential. Main microscopic findings were bronchopneumonia, myo- and epicarditis, meningitis, and portal hepatitis. Herein, we highlight the importance of detecting potential infectious bacteria in cultures to improve etiological diagnosis of bovine abortions associated with compatible microscopic findings to confirm the etiology.

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.

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.

Occurrence of BVDV Infection and the Presence of Potential Risk Factors in Dairy Cattle Herds in Poland

Simple Summary

The bovine viral diarrhea virus (BVDV) causes one of the most common and economically important viral diseases of cattle. It affected cattle reproductive disorders in breeding cattle as well as decreased productivity through increased forced culling, morbidity, and mortality, all of which can be observed on the herd level. The aim of our study was the estimation of the occurrence of BVDV infection in different regions of Poland and the analysis of the different factors that could be correlated with the productive results. We evaluated 354 cattle herds. The presence of antibodies against the BVD virus was found in 33.3% of examined herds, and the heterogenous distribution of BVDV-positive herds in all regions of Poland was confirmed. We found that the rate of BVDV infection was strongly correlated with the geographical location of the examined cattle populations in Poland, the grazing of the animals, and the purchasing of new animals to be introduced to herds.

Abstract

The aim of the study was to analyze the risk factors of BVDV infection, in different regions of Poland, with respect to certain parameters of animal health, including productivity, herd management practices, the presence of BVDV, and the effect of non-vaccination. A total of 354 cattle herds were estimated and linked to the analysis of the different factors that might be correlated with productive results. The presence of antibodies against BVDV was found in 33.3% of examined herds, and the heterogenous distribution of BVDV-positive herds in all regions of Poland (p = 0.001) was confirmed. We found statistical correlations between BVDV infection and pasture (p = 0.004) and the number of grazing animals (p < 0.001), and also the purchase of animals for replacement (p = 0.004) was observed. Production or clear clinical outcomes potentially linked to BVDV infection in the herd have not been observed. The results of this study indicate that the rate of BVDV infection was most strongly correlated with the geographical location of the examined cattle populations in Poland. The second most significant factors were the grazing of animals and the purchasing of new animals to be introduced to herds. The strengthened procedures of management, as well as the implementation of eradication programs, should be considered in the examined herds.

Diseases associated with bovine viral diarrhea virus subtypes 1a and 2b in beef and dairy cattle in Uruguay

Bovine viral diarrhea virus (BVDV, Pestivirus) causes significant economic losses to the livestock industry worldwide. Although serological surveys show that BVDV exposure is widespread in cattle in Uruguay, BVDV-associated diseases are greatly underreported. The aim of this work is to describe the epidemiological, clinical, pathological, and virological findings from spontaneous outbreaks of BVDV-associated diseases in cattle in Uruguay. Diagnostic investigations were performed during 6 spontaneous disease outbreaks on beef and dairy cattle farms in the departments of Colonia, Rio Negro, and Soriano between November 2016 and April 2018. Carcasses of 8 naturally deceased cattle from these outbreaks were necropsied and subjected to histological examination and immunohistochemistry to detect BVDV antigen in the tissues. Reverse transcription real-time PCR and genomic sequencing were also performed to identify BVDV at the species and subtype levels. Other ancillary diagnostic tests, including bacterial cultures, were performed on a case-by-case basis to rule in/out differential diagnoses based on initial clinicopathological presumptive diagnoses. BVDV-associated conditions that were diagnosed in the 8 cases included mucosal disease, transient postnatal BVDV infections associated with digestive/septicemic salmonellosis by Salmonella serovar typhimurium, Histophilus somni bronchopneumonia, urinary tract coinfections with Escherichia coli and Streptococcus sp., enteric coinfection with coccidia, and transplacental fetal infections and abortions with Neospora caninum coinfection. BVDV-1a and BVDV-2b were each identified in four of the eight cases. We conclude that BVDV-1a and BVDV-2b contribute significantly to disease and mortality in cattle in Uruguay. Future research should estimate the economic impact of BVDV in the Uruguayan livestock sector.

Comparative study in the control of bovine viral diarrhea

Bovine viral diarrhea virus (BVDV) is an important infectious agent affecting herd productivity and reproduction, and leading to massive economic losses. As such, BVD is the subject of a number of control and eradication schemes globally. The key elements of such schemes are: diagnosis and removal of persistently infected animals from herds; implementation of biosecurity practices aimed at preventing the introduction or re-introduction of BVDV in free herds; and ongoing surveillance to monitor the progress of the program and to detect new infections. The objective of this review is to examine the impact of BVD and the management of the disease in three countries: Scotland, Spain, and Argentina, where BVD control programs are in distinct phases: established, developing, and yet to be initiated. This work also sets out to highlight potential difficulties and formulate recommendations for successful BVD control. It concludes that a systematic, countrywide approach is needed to achieve a sustainable decrease in BVD prevalence. The role of vaccines in control programs is concluded to be a valuable additional biosecurity measure. This study also concludes that there are potential wider benefits to a systematic BVD control program, such as a reduction in antimicrobial use and increases in the competitiveness of the cattle industry.

Synthesis, antiviral evaluation and molecular docking studies of N4-aryl substituted/unsubstituted thiosemicarbazones derived from 1-indanones as potent anti-bovine viral diarrhea virus agents

A series of N⁴-arylsubstituted thiosemicarbazones derived from 1-indanones and a set of compounds lacking such substitution in the N⁴ position of the thiosemicarbazone moiety were synthesized and evaluated for their anti-bovine viral diarrhea virus (BVDV) activity. Among these, derivatives 2 and 15 displayed high activity (EC₅₀=2.7±0.4 and 0.7±0.1µM, respectively) as inhibitors of BVDV replication. Novel key structural features related to the anti-BVDV activity were identified by structure-activity relationship (SAR) analysis. In a previous study, the thiosemicarbazone of 5,6-dimethoxy-1-indanone (5,6-TSC) was characterized as a non-nucleoside inhibitor (NNI) of the BVDV RNA-dependent RNA polymerase. In the present work, cross-resistance assays were performed with the most active compounds. Such studies were carried out on 5,6-TSC resistant BVDV (BVDV-TSC^r T1) carrying mutations in the viral polymerase. This BVDV mutant was also resistant to compound 15. Molecular docking studies and MM/PBSA calculations were performed to assess the most active derivatives at the 5,6-TSC viral polymerase binding site. The differences in the interaction pattern and the binding affinity of derivative 15 either to the wild type or BVDV-TSC^r T1 polymerase were key factors to define the mode of action of this compound.

What variables are important in predicting bovine viral diarrhea virus? A random forest approach

Bovine viral diarrhea virus (BVDV) causes one of the most economically important diseases in cattle, and the virus is found worldwide. A better understanding of the disease associated factors is a crucial step towards the definition of strategies for control and eradication. In this study we trained a random forest (RF) prediction model and performed variable importance analysis to identify factors associated with BVDV occurrence. In addition, we assessed the influence of features selection on RF performance and evaluated its predictive power relative to other popular classifiers and to logistic regression. We found that RF classification model resulted in an average error rate of 32.03% for the negative class (negative for BVDV) and 36.78% for the positive class (positive for BVDV).The RF model presented area under the ROC curve equal to 0.702. Variable importance analysis revealed that important predictors of BVDV occurrence were: a) who inseminates the animals, b) number of neighboring farms that have cattle and c) rectal palpation performed routinely. Our results suggest that the use of machine learning algorithms, especially RF, is a promising methodology for the analysis of cross-sectional studies, presenting a satisfactory predictive power and the ability to identify predictors that represent potential risk factors for BVDV investigation. We examined classical predictors and found some new and hard to control practices that may lead to the spread of this disease within and among farms, mainly regarding poor or neglected reproduction management, which should be considered for disease control and eradication.