Pathogenetic aspects of rabbits’ experimental infection caused by bovine leukemia virus

Bovine leukemia virus (BLV) is an infectious disease of cattle, causing high economic losses worldwide, especially in the field of dairy farming. There is no common vision on the problem of interspecies transmission of BLV. Therefore, a detailed study of the etiologic relationship between leukemia in cattle and other animal species is relevant. Various laboratory animal models provide insight into the pathogenesis of viral infections. The article presents the research results of two series rabbits’ intravenous infection with bovine leukemia virus (BLV) using the culture antigen FLK-BLV and the blood of rabbits with clinical, hematological and immunological signs of viral tumor growth. Blood from all animals was taken from the ear vein after 14, 21, 30 days, and then monthly for six months: to study the morphological parameters of blood and to determine the titer of antibodies to BLV. Blood serum for the presence of antibodies to BLV was examined using a diagnostic kit for the indication of animals infected with the leukemia virus in an immunodiffusion reaction produced by LLC “SRE Veterinary Medicine”, Kharkiv. It was found that the stage of the BLV provirus in the blood leukogram of infected animals was characterized by pronounced lymphocytosis on the 21st day of the experiment. The highest concentration of antibodies to BLV in the blood serum was found on the 90th day after the administration of the virus-containing material, which disappeared from the blood on the 150–180th day after infection. In experimental rabbits, after five months for thirty days, in the absence of antibodies to leukemia in the blood serum, multiple tumors of a dense consistency began to develop throughout the body. Such clinical signs and changes in the of rabbits’ blood of the experimental group are characteristic of serologically positive cows on the hematological development stage of leukemic process and correlate with the results of domestic and foreign authors. The presence of a large number of lymphoblasts, as well as leukolysis cells, in the histological preparation of lymph nodes, lungs, heart and the accumulation of lymphocytes’ immature forms around the interlobular vessels of the liver, which were found in pathohistological studies of the experimental rabbits’ organs, may indicate the development of the leukemia process on early stage in them. The results obtained indicate the ability of BLV to overcome successfully the interspecies barrier upon parenteral ingestion of heterologous individuals from infected lymphocytes and in the form of a culture antigen.

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Quantitative Risk Assessment for the Introduction of Bovine Leukemia Virus-Infected Cattle Using a Cattle Movement Network Analysis

Pathogens ◽

10.3390/pathogens9110903 ◽

2020 ◽

Vol 9 (11) ◽

pp. 903

Author(s):

Kosuke Notsu ◽

Anuwat Wiratsudakul ◽

Shuya Mitoma ◽

Hala El Daous ◽

Chiho Kaneko ◽

...

Keyword(s):

Bovine Leukemia Virus ◽

Linear Mixed Model ◽

Leukemia Virus ◽

Clinical Signs ◽

Quantitative Risk Assessment ◽

Economic Losses ◽

Degree Centrality ◽

Infected Cattle ◽

Worst Case ◽

Cattle Movement

The cattle industry is suffering economic losses caused by bovine leukemia virus (BLV) and enzootic bovine leukosis (EBL), the clinical condition associated with BLV infection. This pathogen spreads easily without detection by farmers and veterinarians due to the lack of obvious clinical signs. Cattle movement strongly contributes to the inter-farm transmission of BLV. This study quantified the farm-level risk of BLV introduction using a cattle movement analysis. A generalized linear mixed model predicting the proportion of BLV-infected cattle was constructed based on weighted in-degree centrality. Our results suggest a positive association between weighted in-degree centrality and the estimated number of introduced BLV-infected cattle. Remarkably, the introduction of approximately six cattle allowed at least one BLV-infected animal to be added to the farm in the worst-case scenario. These data suggest a high risk of BLV infection on farms with a high number of cattle being introduced. Our findings indicate the need to strengthen BLV control strategies, especially along the chain of cattle movement.

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Early Detection of Encroaching Woody Juniperus virginiana and Its Classification in Multi-Species Forest Using UAS Imagery and Semantic Segmentation Algorithms

Remote Sensing ◽

10.3390/rs13101975 ◽

2021 ◽

Vol 13 (10) ◽

pp. 1975

Author(s):

Lin Wang ◽

Yuzhen Zhou ◽

Qiao Hu ◽

Zhenghong Tang ◽

Yufeng Ge ◽

...

Keyword(s):

Early Detection ◽

Early Development ◽

Spatial Resolution ◽

Early Stage ◽

Semantic Segmentation ◽

Development Stage ◽

Unmanned Aircraft ◽

Economic Losses ◽

Juniperus Virginiana ◽

Segmentation Algorithms

Woody plant encroachment into grasslands ecosystems causes significantly ecological destruction and economic losses. Effective and efficient management largely benefits from accurate and timely detection of encroaching species at an early development stage. Recent advances in unmanned aircraft systems (UAS) enabled easier access to ultra-high spatial resolution images at a centimeter level, together with the latest machine learning based image segmentation algorithms, making it possible to detect small-sized individuals of target species at early development stage and identify them when mixed with other species. However, few studies have investigated the optimal practical spatial resolution of early encroaching species detection. Hence, we investigated the performance of four popular semantic segmentation algorithms (decision tree, DT; random forest, RF; AlexNet; and ResNet) on a multi-species forest classification case with UAS-collected RGB images in original and down-sampled coarser spatial resolutions. The objective of this study was to explore the optimal segmentation algorithm and spatial resolution for eastern redcedar (Juniperus virginiana, ERC) early detection and its classification within a multi-species forest context. To be specific, firstly, we implemented and compared the performance of the four semantic segmentation algorithms with images in the original spatial resolution (0.694 cm). The highest overall accuracy was 0.918 achieved by ResNet with a mean interaction over union at 85.0%. Secondly, we evaluated the performance of ResNet algorithm with images in down-sampled spatial resolutions (1 cm to 5 cm with 0.5 cm interval). When applied on the down-sampled images, ERC segmentation performance decreased with decreasing spatial resolution, especially for those images coarser than 3 cm spatial resolution. The UAS together with the state-of-the-art semantic segmentation algorithms provides a promising tool for early-stage detection and localization of ERC and the development of effective management strategies for mixed-species forest management.

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MASKED GENOTYPE 6 OF BOVINE LEUKEMIA VIRUS IS FOUND IN COLOMBIAN CATTLE

10.21203/rs.2.11155/v1 ◽

2019 ◽

Author(s):

Adriana Patricia Corredor-Figueroa ◽

Nury Nathalia Olaya-Galán ◽

Sandra Patricia Salas ◽

Juan Sebastián Quintero ◽

Álvaro Fajardo ◽

...

Keyword(s):

Genetic Variability ◽

Bovine Leukemia Virus ◽

Phylogenetic Analyses ◽

Leukemia Virus ◽

Gene Analysis ◽

Economic Losses ◽

Envelope Gene ◽

Genotype 1 ◽

Global Epidemiology ◽

Bovine Leukosis

Abstract Background Viral diseases such as bovine leukosis are a major cause of health problems associated with economic losses in the livestock industry worldwide. The prevalence of bovine leukosis ranges between 4% and 90%, and this disease is considered endemic. The etiological agent is bovine leukemia virus (BLV). Ten BLV genotypes have been reported based on analysis of complete or partial envelope gene sequences, of which genotype 1 is the most prevalent. However, the genetic variability of BLV variants circulating in Colombia remains unexplored. Therefore, in the present study, we analyzed blood samples collected from 289 cows distributed in 75 farms across the country. PCR amplification of env, gag and tax gene segments was performed. The obtained amplicons were sequenced and then subjected to phylogenetic analyses. Results A total of 62% of the cows present at 92% of the farms were BLV-positive. Genotype 1 was exclusively detected by env and gag gene segments when analyzed using previously reported primers. However, tax gene analysis revealed circulation of genotype 6 variants, which were also detected based on env gene analysis with newly designed primers. These results indicate that current genotyping approaches based on partial env sequencing may bias BLV genetic variability approaches and underestimate the diversity of the detected BLV genotypes. Conclusions This report is the first molecular and epidemiological study of BLV conducted in Colombia and contributes to the global epidemiology of the virus; it also reinforces the great impact of BLV on the country’s livestock and thus is a useful resource for farmers and government entities.

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Persistent viral infections in farm and companion animals: mechanisms of establishment and maintenance of viral persistence

Journal of the Hellenic Veterinary Medical Society ◽

10.12681/jhvms.15146 ◽

2017 ◽

Vol 55 (4) ◽

pp. 353

Author(s):

M. PAPANASTASOPOULOU (Μ. ΠΑΠΑΝΑΣΤΑΣΟΠΟΥΛΟΥ)

Keyword(s):

Viral Infections ◽

National Level ◽

Companion Animals ◽

Clinical Signs ◽

Host Cells ◽

Animal Origin ◽

Economic Losses ◽

Neoplastic Disease ◽

Persistent Infections ◽

Persistent Viral Infections

In persistent viral infections the responsible virus is not eliminated by the host's immune system, but it is maintained in infected cells for months, years or lifetime and it is excreted periodically or continuously. The carrier animal may either appear healthy or show clinical signs. The epizootiologic importance of persistent infections is of compelling interest, since the asymptomatic carriers become a permanent source of viral dissemination that can transport the virus across long-distances and reintroduce it into a given herd, region or country, where the disease had been eliminated. Moreover, a persistent viral infection may be reactivated and cause recrudescent episodes of disease, may lead to immunopathologic or neoplastic disease in the individual host and yet may be transmitted to other animals or to the humans via contaminated materials of animal origin. The economic losses are significant at both farm and national level. Fifty four RNA or DNA viruses induce persistent infections in farm and companion animals. In particular, 14 viruses cause persistent infections in bovines, 7 in small ruminants, 9 in swine, 11 in equines, 8 in cats and 5 in dogs. The majority of these infections are caused by retroviruses and herpesviruses. For a virus to establish and maintain persistent infection, it should have limited cytolytic action, it should be able to maintain its genome within host cells over time and to evade the immune defence mechanisms of the host. The preventive measures are largely based either on the immunization of susceptible animals or on the eradication of the disease by stamping-out policy. The currendy available vaccines are inactivated or live attenuated. Most of them are prepared by conventional methods, but they also exist those that are biotechnologicaUy engineered, such as vector vaccines marker vaccines or subunit vaccines. A major advantage related to the use of marker vaccines is that vaccinated animals can potentially be differentiated from the naturally infected ones by this process.

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B220 expression as an immunological marker for differentiation of Feline Leukemia Virus carrying cats

Ciência Rural ◽

10.1590/0103-8478cr20190467 ◽

2020 ◽

Vol 50 (12) ◽

Author(s):

Isadora Duarte Santos Frota ◽

Jéssica de Oliveira Souza ◽

Fernanda de Oliveira Busato ◽

Cristina Abreu de Araujo ◽

Flávio Curbani ◽

...

Keyword(s):

B Cells ◽

B Cell ◽

Feline Immunodeficiency Virus ◽

Peripheral Blood ◽

Mononuclear Cells ◽

Viral Infections ◽

Leukemia Virus ◽

Clinical Signs ◽

Feline Leukemia Virus ◽

Immunodeficiency Virus

ABSTRACT: Feline leukemia virus (FeLV) causes an infection in cats that, in some cases, can also be reported with other pathologies, such as infection with feline immunodeficiency virus (FIV), feline infectious peritonitis (FIP), and lymphoma. Although, a compromised immune response is reported in these animals, little is known about the immunological state of their cells. To shed some light in this area, we studied peripheral blood samples from both infected and non-infected cats with FeLV, with or without FIV, FIP, and lymphoma. We tested a panel of monoclonal antibodies (n=11) against mouse and human antigens and we reported that cat leukocytes can be stained with anti-mouse B220 monoclonal antibody; therefore, percentages of B cells were evaluated in different cat groups. Our results showed that cats with FeLV and FIP, or with leukemia, presented a large decrease in B220+ mononuclear cells. However, FeLV+ cats without clinical signs, or with unspecific clinical signs, had the same amount of B220+ mononuclear cells as healthy cats (control cats). Since the expression of B220 is exclusively restricted to the naïve B cell population, we inferred that the absence of these B cells in FeLV+ cats is related to other conditions that affect B cell numbers, such as viral infections and leukemias. Therefore, the amount of naïve B cells in peripheral blood (i.e., B220+ cells) can be used to identify FeLV+ cats concomitantly carrying FIP or leukemia, from FeLV+ cats with lymphoma or without any clinical signs.

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ВМІСТ ЛІПІДІВ У СИРОВАТЦІ КРОВІ КОРІВ ЗА СПОНТАННОГО ІНФІКУВАННЯ ВІРУСОМ ЛЕЙКОЗУ ВЕЛИКОЇ РОГАТОЇ ХУДОБИ

Scientific Messenger of LNU of Veterinary Medicine and Biotechnology ◽

10.15421/nvlvet7028 ◽

2016 ◽

Vol 18 (3(70)) ◽

pp. 119-123

Author(s):

L.M. Ishchenko ◽

V.D. Ishchenko ◽

V.G. Spyrydonov

Keyword(s):

Blood Serum ◽

Bovine Leukemia Virus ◽

Plastic Material ◽

Total Phospholipid ◽

Leukemia Virus ◽

Blood System ◽

Control Group ◽

Quantitative Composition ◽

Animal Blood ◽

Lactating Cows

Lipids take part in the biological cycle of retroviruses and regulation of their expression. In particular, in the processes associated with the interaction with the lipid bilayer of the host cell (virus penetration into the cell), and budding of newly synthesized viral particles. To study the effect bovine leukemia virus on lipid metabolism in the host organism is very important for veterinary medicine, because of its effect on animal blood system. At the same time, changes in the blood system of lactating cows have a significant impact on the biochemical indicators of quantitative composition of the milk and therefore its quality, nutritional value and safety for consumers. Investigated the lipid composition of blood serum of cattle spontaneous infected with the virus leukemia. For study was formed by two groups of cows black–and–white breed in 3 years of age on 3 – 4 months of lactation, body weight were 400 – 450 kg, 6 animals in each. In the first (control) group was clinically healthy animals, free from bovine leukemia virus (according to the RID, ELISA and PCR studies), the second (experimental) was animals which infected by virus bovine leukemia. Established that in the infected animals significantly increases the content of total phospholipid by 6.0%, total and esterified cholesterol by 4.3 and 4.2%, respectively. Thus, the correlation of total cholesterol to total phospholipids was unchanged in both groups of animals. Also, in the blood serum of cows research groups noted increase of free fatty acids content by 83.3%. Thus, at the spontaneous infection the bovine leukemia virus in animals is a disturbance qualitative and quantitative composition of blood serum lipids owing to disturbance of synthetic processes in liver, caused by the necessity in the plastic material for build lipid layer of shell pathogen.

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Current Developments in the Epidemiology and Control of Enzootic Bovine Leukosis as Caused by Bovine Leukemia Virus

Pathogens ◽

10.3390/pathogens9121058 ◽

2020 ◽

Vol 9 (12) ◽

pp. 1058

Author(s):

Paul C. Bartlett ◽

Vickie J. Ruggiero ◽

Holden C. Hutchinson ◽

Casey J. Droscha ◽

Bo Norby ◽

...

Keyword(s):

Bovine Leukemia Virus ◽

Leukemia Virus ◽

Research Priorities ◽

Economic Losses ◽

Antibody Testing ◽

Enzootic Bovine Leukosis ◽

Cellular And Humoral Immunity ◽

Bovine Leukosis ◽

And Control

Enzootic Bovine Leukosis (EBL) caused by the bovine leukemia virus (BLV) has been eradicated in over 20 countries. In contrast, the U.S. and many other nations are experiencing increasing prevalence in the absence of efforts to control transmission. Recent studies have shown that BLV infection in dairy cattle has a greater impact beyond the long-recognized lymphoma development that occurs in <5% of infected cattle. Like other retroviruses, BLV appears to cause multiple immune system disruptions, affecting both cellular and humoral immunity, which are likely responsible for increasingly documented associations with decreased dairy production and decreased productive lifespan. Realization of these economic losses has increased interest in controlling BLV using technology that was unavailable decades ago, when many nations eradicated BLV via traditional antibody testing and slaughter methods. This traditional control is not economically feasible for many nations where the average herd antibody prevalence is rapidly approaching 50%. The ELISA screening of cattle with follow-up testing via qPCR for proviral load helps prioritize the most infectious cattle for segregation or culling. The efficacy of this approach has been demonstrated in at least four herds. Breeding cattle for resistance to BLV disease progression also appears to hold promise, and several laboratories are working on BLV vaccines. There are many research priorities for a wide variety of disciplines, especially including the need to investigate the reports linking BLV and human breast cancer.

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Seroprevalence, Risk Factors and Molecular Identification of Bovine Leukemia Virus in Egyptian Cattle

Animals ◽

10.3390/ani11020319 ◽

2021 ◽

Vol 11 (2) ◽

pp. 319

Author(s):

Abdelfattah Selim ◽

Eman A. Manaa ◽

Abdullah D. Alanazi ◽

Mohamed S. Alyousif

Keyword(s):

Risk Factors ◽

Dairy Cattle ◽

Bovine Leukemia Virus ◽

Leukemia Virus ◽

Significant Risk ◽

Control Program ◽

Effective Control ◽

Economic Losses ◽

Genetic Classification ◽

Associated Risk Factors

Bovine leukemia virus (BLV) is distributed worldwide and affects dairy cattle causing severe economic losses. The BLV has been serologically reported in Egypt, but few studies have evaluated its associated risk factors and genetic classification. Therefore, this study assessed risk factors associated with BLV infection and identified the genetic diversity of the Egyptian strain. The study was conducted on 500 dairy cattle distributed in four Governorates located in Northern Egypt. Overall, the seroprevalence of BLV infection among Egyptian dairy cattle was 18.2%. The grazing cattle in the losing house system had higher odds for BLV seropositivity, and bad practice such as the use of a single needle or one plastic glove for more than one animal was considered a significant risk factor for BLV infection. Besides, the sequencing and phylogenetic analysis for one Egyptian BLV strain was performed, and the obtained results confirmed the clustering of Egyptian BLV strain into genotype-1. The assessment of associated risk factors for BLV infection and determination of its genetic classification are essential to implement an effective control program.

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Necrotizing pneumonia caused Staphylococcus aureus

Epidemiology and Infectious Diseases (Russian Journal) ◽

10.17816/eid40758 ◽

2014 ◽

Vol 19 (2) ◽

pp. 4-10

Author(s):

V. B. Beloborodov

Keyword(s):

Virus Infection ◽

Antibacterial Therapy ◽

Early Stage ◽

Clinical Signs ◽

Empirical Therapy ◽

Community Acquired Pneumonia ◽

The Body ◽

Necrotizing Pneumonia ◽

Children And Young Adults ◽

Respiratory Virus Infection

Necrotizing pneumonia caused by S. aureus is infrequent, but very serious illness with a high mortality. Pneumonia arises mainly in children and young adults, develops within several days is accompanied with multiple necroses in lung tissue, often leads to a lethal outcome. The feature ofpathogen is ability to formation ofpore-forming toxin destroying different cells in the body including polymorphonuclear leukocytes. The previous virus infection, for example flu, is considered a contributing factor or the co-infection which creates prerequisites for destruction ofneutrophils in lungs with appearance ofnecroses. S. aureus is not the most frequent causative agent of community-acquired pneumonia therefore empirical therapy does not include antibiotics with the activity against staphylococci which are sensitive or resistant to oxacyllin/meticyllin. As a result empirical regimen of antibacterial therapy appears not to be effective. Early clinical signs are a high fever, blood in the sputum, the presence of cavities in the lungs, a rapid increase in respiratory failure. The microscopy of sputum with detection o a large number of staphylococci allows to establish pathogen at an early stage, before obtaining results oif microbiological tests to prove application ofantibiotics active against staphylococci, and after receiving microbiological data to carry out the final correction ovf antibacterial therapy. Respiratory virus infection preceding peumonia or adverse epidemiological situation (flu epidemic) also is the justification for empiric application of anti-staphylococcal antibiotics in community acquired pneumonia.

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