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Enzootic Bovine Leukosis (EBL), caused by the bovine leukosis virus (BLV), is a global infectious disease affecting livestock. This study focuses on studying the frequency and genetic traits of BLV in three Creole breeds including Chino Santandereano (Chino), Casanareño (CAS), and Sanmartinero (SM) in Eastern Colombia. We implemented a cross-sectional survey between 2019 and 2020 across four departments (Arauca, Casanare, Santander and Meta) in Eastern Colombia to assess the molecular characteristics of BLV infection in these breeds. A total of 253 cattle were analyzed, of which 42.6 %, 28.8 %, and 28.4 % belonged to the Chino, CAS, and SM breeds, respectively. BLV provirus was detected using nested polymerase chain reaction (n-PCR) targeting the conserved region of the env viral gene. Subsequently, the obtained amplicons were sequenced and subjected to phylogenetic analyses. The overall BLV infection frequency was 26.48 % (95 % CI: 21.01 - 31.98 %), with Chino exhibiting the highest frequency (35.1 %) following by SAM and CAS, respectively (P < 0.05). Other epidemiological variables associated with the infection included age, department, and season (P < 0.05). BLV-positive animals exhibited elevated levels of total serum proteins (P < 0.05), while molecular characterization revealed the exclusive circulation of BLV genotype 1 within these breeds. This study provides an updated assessment of BLV infection in Creole breeds from the eastern of Colombia, underscoring their lower infection frequency compared to introduced breeds and their reduced susceptibility to developing clinical signs. The epidemiological and molecular characteristics observed should be considered in developing control programs aimed at improving genetic resistance to BLV in Colombian cattle.

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Slaughterhouse inspections play a crucial role in the sanitary control of zoonoses and foodborne diseases. This study aimed to identify and analyze the frequencies of lymph node diseases in cattle slaughtered for human consumption, using the samples sent to the anatomic pathology service of the Federal Laboratory for Agricultural Defense (Laboratório Federal de Defesa Agropecuária), Minas Gerais, Brazil, from January 2015 to September 2022. In total, 2000 lymph node samples were analyzed, and additional information was individually retrieved. Lesions were most frequently identified in thoracic lymph nodes. Bacterial isolation and quantitative polymerase chain reaction (qPCR) were performed using samples suspected of tuberculosis. Tuberculosis cases accounted for 89.3% of the samples. Histopathology was more sensitive than other ancillary tests for diagnosing tuberculosis. Paraffin-embedded tissues from lymphoma cases were subjected to immunophenotyping using anti-CD3 and anti-CD79a immunohistochemistry. Frozen and/or paraffin-embedded tissues from lymphoma cases were used to identify the enzootic bovine leukosis (EBL) retrovirus through qPCR. Other diagnoses included primary (T- and B-cell lymphoma) and metastatic neoplasms (squamous cell carcinoma, pulmonary adenocarcinoma, undifferentiated carcinoma, undifferentiated adenocarcinoma, undifferentiated sarcoma, undifferentiated round cell tumor, mesothelioma, hepatic carcinoid, meningioma, and seminoma), actinogranulomas (pyogranulomatous lymphadenitis [actinobacillosis and actinomycosis]), idiopathic lymphadenitis (neutrophilic and/or histiocytic, granulomatous, and suppurative), and miscellaneous nonspecific lymphadenopathies (depletion/lymphoid atrophy, lymphangiectasia, erythrocyte drainage, parasitic eosinophilic lymphadenitis, follicular hyperplasia, and toxic granulomatous lymphadenitis). The combination of histopathology with complementary techniques is important for successful diagnosis, especially in complex cases of high epidemiological, economic, and zoosanitary importance, such as tuberculosis and EBL.

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A black skimmer (Rynchops niger) and a brown booby (Sula leucogaster) were rescued and gross, histopathological, immunohistochemical and polymerase chain reaction evaluations were conducted to investigate the cause of death. There were neoplastic infiltrations of CD3+ PAX5- lymphocytes in the black skimmer and CD3- PAX5+ lymphocytes in the brown booby. Molecular assays for viral agents were negative in both cases. This is the first report of disseminated lymphoma as the cause of stranding and death in these species in Brazil.

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OBJECTIVE: The objective of this study was to determine the seroprevalence of reproductive and infectious diseases in tropical cattle in the Tambopata and Tahuamanu Provinces in the department of Madre de Dios, Peru. SAMPLE: 156 bovines from 7 cattle farms were sampled. These farms used exclusive grazing for food and natural mating for reproduction and did not have sanitary or vaccination programs. METHODS: The serum of blood samples was subjected to ELISA with commercial kits for the detection of antibodies against Neospora caninum, Mycobacterium avium subsp paratuberculosis (MAP), Leptospira interrogans, pestivirus bovine viral diarrhea virus-1, retrovirus bovine leukemia virus (BLV), orbivirus bluetongue virus (BTV), and herpesvirus bovine herpes virus-1 (BHV). The data were analyzed by means of association tests with χ2 (P < .05) and Spearman rank correlation (P < .05) in the SPSS v.15.0 software (IBM Corp). RESULTS: A low prevalence of antibodies to L interrogans, N caninum, M avium subsp paratuberculosis, bovine viral diarrhea virus-1 was found, but it was high to BTV, BLV, and BHV (100%, 53.85%, and 72.44%, respectively). The presence of BLV and BHV was higher in the Las Piedras District, bovines less than 5 years old, and cattle with breed characteristics of zebu and crossbred (P < .01). In addition, there was a significant correlation between both infections, showing 83.3% of BLV positivity that were also BHV positive (P < .01). CLINICAL RELEVANCE: The high prevalence of antibodies to BTV, BHV, and BLV could be due to livestock management practices, direct contact with infected animals, and variation of the presence of vectors and natural reservoirs in the context of climate change in the tropics.

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The objective of this study was to determine the prevalence of bovine leukosis virus (BLV) in specialized and dual-purpose dairy cows located in the central zone of Veracruz state in Mexico, using endpoint polymerase chain reaction (PCR). The study population consisted of 307 specialized dairy cows and 95 dual-purpose cows from 13 municipalities located in the study area. All cows were apparently healthy and ≥ 3 years old. Cows were stratified by age (3 - 5, 6 - 8 and ≥ 9 years). The overall prevalence of infection was 6.96%; the calculated prevalence in dairy cows was 7.82% and in dual-purpose cows it was 4.21%. The municipality with the highest proportion was Acajete (14.28%), followed by Huatusco and Tomatlán (11.53%). The association analysis confirms the infection's independence to the cows' productive purpose. The results by age strata were 3 - 5 (4.60%), 6 - 8 (8.00%) and ≥ 9 (18.40%) with X2 = 9.96, with an odds ratio of 4.68 for the stratum ≥ 9 years with a significant difference. The present study determined the prevalence of proviral DNA of BLV in dairy and dual-purpose cows in six municipalities in the central zone of Veracruz state, Mexico, using endpoint PCR.

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Background: Enzootic bovine leukosis (EBL) is a lymphoproliferative disorder caused by the bovine leukemia virus (BLV), a virus of the Retroviridae family. The infection is distributed worldwide, and a high percentage of animals infected by the BLV are asymptomatic and act as carriers of the virus in many cattle populations. Aim: To identify the risk factors associated with EBL in the municipalities of Boyacá and Cundinamarca (Colombia). Methods: A simple descriptive cross-sectional study with random sampling was conducted. A total of 1,140 blood samples were taken from cattle (females and males) from the municipalities of Chiquinquirá, Ubaté, and San Miguel de Sema of different breeds and age groups. The samples were processed using the commercial ELISA SERELISA® BLV Ab Mono Blocking kit (sensitivity 97%, specificity 98%). The data were processed with the statistical programs WinEpi and Epi Info® version 7.2.4.0, estimating the prevalence ratio, implementing the chi-square test (p ≤ 0.05) and logistic regression. Results: A true prevalence (TP) and apparent prevalence (AP) of 23.61% and 22.7% in Ubaté, 19.22% and 18.1% in Chiquinquirá, and 15.61% and 14.3% in San Miguel de Sema, respectively, were established. Bovines 2-4 years old were the most prevalent in Ubaté and Chiquinquirá (37.5% and 21.21%, respectively), while in San Miguel de Sema individuals >4 years had the highest percentage of antibodies (18.3%). The Holstein breed had a higher prevalence in Ubaté and San Miguel de Sema (26.02% and 19.67%), and crossbreeds were more BLV-seroprevalence in Chiquinquirá (20.20%). In Ubaté, re-use of needles was identified as a risk factor, contaminated blood in needles is considered one of the main routes of transmission. On the other hand, manual milking was identified as a risk factor in San Miguel de Sema. Conclusion: The non-implementation of an individual needle per animal in Ubaté; the Holstein breed and manual milking in San Miguel de Sema were identified as risk factors for the presence of antibodies against the disease. EBL prevention and control plans should be established that focus on the implementation of management and sanitary practices based on herd biosecurity.

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Bovine leukosis is caused by an oncogenic virus of the genus Deltaretrovirus, causing losses associated with decreased production indicators and restrictions on exports of cattle and cattle products. The disease has a prolonged incubation period of between 1-5 years and the antibodies can be detected 2-3 weeks post infection. The disease can present asymptomatically, and develop persistent lymphocytosis or lymphosarcoma. The objective of this study was to estimate the prevalence and risk factors associated with bovine leukosis in Villavicencio, Colombia. Blood samples were taken from 636 animals, and obtained randomly from 24 herds. The samples were analysed using a Competition ELISA kit for the detection of anti-gp51 antibodies. Information on possible risk factors was collected, then OR and X2 were calculated, and statistically significant with p < 0.05 variables were included in a linear regression multivariate analysis. The general seroprevalence was 24.6% and the herd seroprevalence was 83.3%. The seroprevalence was 21.3% in males and 25.0% in females. The risk factors identified were abortion, non-bearing cows, artificial insemination, and use of common needles, Creole breed and participation in cattle exhibitions. The study confirmed the presence of bovine leukosis associated with reproductive and management factors.(AU)

A leucose bovina é causada por um vírus oncogênico do gênero Deltaretrovirus, causando prejuízos associados à queda dos indicadores produtivos e restrições à exportação de bovinos e derivados.Adoença tem um período de incubação prolongado entre 1 e 5 anos e os anticorpos podem ser detectados 2 a 3 semanas após a infecção. A doença pode se apresentar de forma assintomática, e evoluir para linfocitose persistente ou linfossarcoma. O objetivo do estudo foi estimar a prevalência e os fatores de risco associados à leucose bovina em Villavicencio, Colômbia. Amostras de sangue foram coletadas de 636 animais, obtidos aleatoriamente de 24 rebanhos.As amostras foram analisadas com o kit Competition ELISA para detecção de anticorpos anti-gp51. Foram coletadas informações sobre possíveis fatores de risco, se realizo um analise univariado entre as variáveis e a presença da seropositividad a leukosis bovina mediante o cálculo do OR e X2, as variáveis estatisticamente significativas com p<0,05 foram incluídas em uma análise multivariada de regressão linear. A soroprevalência geral foi de 24,6% e a soroprevalência do rebanho foi de 83,3%.Asoroprevalência foi de 21,3% em machos e 25,0% em fêmeas. Os fatores de risco identificados foram: aborto, vacas não reprodutivas, inseminação artificial e uso de agulha comum, raça crioula e exposições de gado. O estudo confirmou a presença de leucose bovina associada a fatores reprodutivos e de manejo.(AU)

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Droplet digital PCR (ddPCR) is a highly sensitive tool developed for the detection and quantification of short-sequence variants-a tool that offers unparalleled precision enabling measurement of smaller-fold changes. We describe here the use of ddPCR for the detection of Bovine leukemia virus (BLV) DNA provirus. Serum samples and whole blood from experimentally infected sheep and naturally infected cattle were analyzed through ddPCR to detect the BLV gp51 gene, and then compared with serologic and molecular tests. The ddPCR assay was significantly more accurate and sensitive than AGID, ELISA, nested PCR, and quantitative PCR. The limit of detection of ddPCR was 3.3 copies/µL, detecting positive experimentally infected sheep beginning at 6 d post-infection. The ddPCR methodology offers a promising tool for evaluating the BLV proviral load, particularly for the detection of low viral loads.

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This study demonstrates the influence of pregnancy on serum diagnosis of enzootic bovine leukosis (EBL), emphasizing the importance of routine testing to maintain herd health. For this, 143 pregnant cows were sampled in duplicate (30 days before and 15 days after calving). For EBL diagnosis, samples were submitted to agar gel immunodiffusion testing (AGID). Different results were observed before and after delivery in seventy-six serum samples (53.15%), indicating variations in the levels of serum globulins in the blood during the peripartum period. Therefore, using a single sample for serological diagnosis during the birth season might not represent the correct infection status of animal health due to physiological variations in antibody concentrations.

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Pooled samples are used in veterinary and human medicine as a cost-effective approach to monitor disease prevalence. Nonetheless, there is limited information on the effect of pooling on test performance, and research is required to determine the appropriate number of samples which can be pooled. Therefore, this study aimed to evaluate the use of pooled serum samples as a herd-level surveillance tool for infectious production-limiting diseases: bovine viral diarrhoea (BVD), infectious bovine rhinotracheitis (IBR), enzootic bovine leukosis (EBL) and Neospora caninum (NC), by investigating the maximum number of samples one can pool to identify one positive animal, using commercial antibody-detection ELISAs. Four positive field standards (PFS), one for each disease, were prepared by pooling highly positive herd-level samples diagnosed using commercially available ELISA tests. These PFS were used to simulate 18 pooled samples ranging from undiluted PFS to a dilution representing 1 positive in 1,000 animals using phosphate-buffered saline as diluent. A 1:10 dilution of the PFS resulted in positive results for IBR, BVD and EBL. Moreover, for IBR and BVD, results were still positive at 1:100 and 1:30 dilutions, respectively. However, for NC, a lower dilution (8:10) was required for a seropositive result. This study indicates that, at herd-level, the use of pooled serum is a useful strategy for monitoring infectious diseases (BVD, IBR and EBL) but not NC, using readily available diagnostic assays.

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BACKGROUND AND AIM: Enzootic bovine leukosis is a disease economically important to the dairy farming industry worldwide. The virus is of the Deltaretrovirus genus and is primarily transmitted iatrogenically. Most bovines infected with the virus remain asymptomatic with only 5-10% of cattle having lymphomas. This study aimed to determine the seroprevalence of bovine leukosis virus (BLV) in Sotaquirá, Boyacá, Colombia. MATERIALS AND METHODS: We conducted a descriptive, observational epidemiological cross-sectional study using the simple random sampling method with a sample size of 1000. Blood samples from random bovine were processed using the SERELISA® BLV Ab Mono Blocking indirect enzyme-linked immunosorbent assay kit (Zoetis, USA). The assay had a sensitivity of 97% and a specificity of 98%. The collected data were processed using Epi Info® (Centers for Disease Control and Prevention; Atlanta, Georgia). From the study, we could determine a high seroprevalence of BLV in Sotaquirá. RESULTS: We established a high seroprevalence on BLV in the municipality, with 31.1% apparent seroprevalence and 30.6% real seroprevalence rate. We found that male cattle more than 4 years old (39.4%) and the Ayrshire breed (45.5%) had the highest prevalence rates of the virus. In this study, we could establish statistically significant associations according to breed, age, and gender of the cattle under study. Moreover, we identified the risk factors for BLV infection. We found that in cattle aged <1 year and those older than 4 years of age and those of the Holstein breed, the presentation of infectious bovine rhinotracheitis, mucosal secretions, mastitis, fetal death, the presence of a corral, and the implementation of artificial insemination practices were risk factors for BLV infection. CONCLUSION: Determining the prevalence of BLV within the herd and identifying the associated risk factors for the disease are fundamental in developing efficient programs for the control and eradication of BLV within herds.

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Abstract Background: Bovine leukemia virus (BLV) is the causative agent of enzootic bovine leukosis (EBL). This disease mainly affects cattle, causing severe economic losses to producers. Objective: To establish individual and herd seroprevalence and determine the risk factors associated with BLV seropositivity for dairy and dual-purpose cattle herds in Ecuador. Methods: A total of 2,668 serum samples from 386 herds were collected. A questionnaire, including variables related to cattle health, management and the environment was completed by each herd. A commercial blocking enzyme-linked immunosorbent assay (ELISA) test was used to determine seropositivity. A generalized estimating equation model (GEE) was developed to determine the factors associated with BLV seropositivity. Results: Individual seroprevalence of BLV infection in Ecuador was 17.3% (CI95% = 15.86-18.74%). Herd prevalence was 37.8% (CI95% = 33.0-42.6%), and intra-herd prevalence ranged between 12.5 and 100% (median: 37.5%). The risk factors associated with BLV seropositivity were artificial insemination (OR: 2,215; CI95% =1.402-3.501), concrete floors (OR: 2.178; CI95% = 1.217-3.889), presence of wild ruminants (OR: 2.998; CI95% = 1.788-5.027), and sampling season (wet; OR: 1.996; CI95% = 1.140-3.497). Conclusions: Results indicate that BLV is widespread in cattle herds in Ecuador. In addition, the study suggests that a control program to fight BLV infection should focus on controlling the risk factors identified.

Resumen Antecedentes: El virus de la leucosis bovina (BLV) es el principal agente etiológico causante de la leucosis enzoótica bovina (EBL). Esta enfermedad afecta a los bovinos causando grandes pérdidas económicas a los productores. Objetivo: Establecer la seroprevalencia y dispersión del BLV, así como los factores de riesgo asociados a la seropositividad en explotaciones lecheras y de doble propósito en Ecuador. Métodos: Se recolectó un total de 2.668 muestras de suero de 386 explotaciones. Se aplicó un cuestionario que incluyó variables relacionadas con la salud del hato, medidas de manejo, y características ambientales de cada explotación. Para los análisis serológicos se utilizó un test inmunológico ligado a enzimas (ELISA). Para definir los factores de riesgo asociados a la seropositividad a BLV se desarrolló un modelo utilizando ecuaciones de estimación generalizadas (GEE). Resultados: La seroprevalencia de BLV en Ecuador fue de 17,3% (IC95% = 15,86-18,74%). La dispersión fue de 37,8% (IC95%= 33,0-42,6%), y la prevalencia intra-hato alcanzó rangos entre 12,5-100% (media: 37,5%). Los factores de riesgo asociados a la seropositividad a BLV fueron: inseminación artificial (OR: 2,215; IC95% = 1,402-3,501), piso de concreto (OR: 2,178; IC95% = 1,217-3,889), presencia de rumiantes salvajes (OR: 2,998; IC95% = 1,788-5,027), y temporada de muestreo (húmeda; OR: 1,996; IC95% = 1,140-3,497). Conclusiones: Los resultados indican que el BLV se encuentra disperso en las explotaciones de Ecuador. Adicionalmente, se sugiere la implementación de un programa de control para la lucha contra el BLV, debiéndose considerar medidas que se enfoquen al control de los factores de riesgo identificados en esta investigación.

Resumo Antecedentes: O vírus da leucemia bovina (BLV) é o principal agente causador da leucose enzoótica bovina (EBL). Esta doença afeta o gado causando graves prejuízos econômicos aos produtores. Objetivo: Estabelecer a soroprevalência e dispersão do BLV, assim como os fatores de risco associados à soropositividade nas produções leiteiras e de duplo propósito no Equador. Métodos: Um total de 2.668 amostras de soro de 386 explorações foram coletadas. Foi aplicado um questionário que incluía variáveis relacionadas à saúde do rebanho, medidas de manejo e ambiente para cada exploração. Para a análise sorológica foi utilizado um teste imunológico sobre enzimas (ELISA) para determinação da soropositividade. Para definir os fatores de risco associados à soropositividade a BLV, foi utilizado um modelo de equações estimativas generalizadas (GEE). Resultados: A soroprevalência de BLVno Equador é de 17,3% (IC95% = 15,86-18,74%). La dispersão de 37,8% (IC95% = 33,0-42,6%), e a prevalência intra-rebanho alcançou entre 12,5-100% (media: 37,5%). Os fatores de risco associados à soropositividade a BLV foram inseminação artificial (OR: 2,215; IC95% = 1,402-3,501), chão de concreto (OR: 2,178; IC95% = 1,217-3,889), presença de ruminantes selvagens (OR: 2,998; IC95% = 1,788-5,027) e época da amostragem (úmida; OR: 1,996; IC95% = 1,140-3,497). Conclusões: Os resultados indicam que o BLV se encontra disseminado nas explorações no Equador. Adicionalmente, o estudo pode contribuir para a implementação de um programa de controle para a luta contra o BLV, devendo-se considerar ações de controle dos fatores de risco identificados nesta investigação.

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The implications of bovine leukemia virus (BLV) on innate and adaptive immune responses have been widely investigated; however, the effects of BLV on mammary gland immunity require further investigation. The present study investigated the viability, phagocytic capacity, and intracellular production of reactive oxygen and nitrogen species (RONS) by macrophages in milk samples from dairy cows naturally infected with BLV with or without persistent lymphocytosis (PL). No effect of BLV infection in the overall number of macrophages per milliliter and in the percentage of viable macrophages among overall milk viable cells was found. Furthermore, BLV-infected dairy cows had a higher frequency of viable milk macrophages, while healthy animals had a tendency toward a higher percentage of apoptotic milk macrophages. The percentage of milk macrophages that phagocytosed Staphylococcus aureus in seronegative animals was higher than that in BLV-infected dairy cows. No effect of BLV infection on the intracellular RONS production and the intensity of phagocytosis by milk macrophages was observed. Thus, this study provides new insights into the implications of BLV infections in the bovine mammary gland.

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Epidemiological surveys that investigate infectious diseases such as enzootic bovine leukosis (EBL) are important. Furthermore, estimating the prevalence of such infectious diseases and associated factors is key to assess the disease impact and design control programs. In this study, we identified a high herd-level seroprevalence of EBL in cattle from the semi-arid Paraíba state, Northeast Region of Brazil, using a planned cross-sectional survey. Herd-level and animal-level prevalence were estimated using a two-stage random sampling survey. In total, 2067 cows aged ≥24 months from 400 herds were sampled. An enzyme-linked immunosorbent assay was used to detect specific antibodies directed to the bovine leukosis virus gp51 antigen in both individual and pooled sera. The herd-level and animal-level prevalence was 23.4 % (95 % CI = 19.2-28.1 %) and 10.8 % (95 % CI = 7.5 %-15.3 %), respectively. There were no significant clusters of positive herds (within a radius of 2 km). The factors associated with herd-level prevalence were the exclusive use of hand milking (prevalence ratio [PR] = 1.88), herd size (PR = 1.005), artificial insemination (PR = 2.03), purchase of animals in the previous year (PR = 1.87), and peri-urban farms (PR = 2.09). Prevention measures should be applied at the herd-level, particularly for farms located in peri-urban areas, focusing on good hygiene in hand milking, robust practices and standards for artificial insemination, and serological testing of animals prior to purchase.

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Background: The enzootic bovine leukosis (EBL) is a viral disease with a chronic aspect and its etiological agent is anoncogenic deltaretrovirus called bovine leukemia virus (VLB). It has a wide distribution in dairy cattle herds, and it maytake several years before the first clinical manifestations occur. Animals seropositive for VLB are more susceptible todeveloping infectious diseases such as mastitis. The objective of this study was to evaluate the seroprevalence of EBL, theprevalence of mastitis, the possible association between leukosis and mastitis, and the risk factors related to leukosis inmunicipalities of the Caparaó region of Espírito Santo, Brazil.Materials, Methods & Results: The prevalence of enzootic bovine leukosis and its association with mastitis were evaluatedin an 854 clinically healthy crossbred (Bos tauros tauros x Bos taurus indicus) dairy cows were used, in different lactationphases, from farms located in the 12 municipalities that compose the Caparaó Capixaba micro-region, in the southernpart of Espírito Santo, Brazil, in the period from February to December 2015. The seroprevalence of EBL was determinedby the agar gel immunodiffusion test, the presence of clinical mastitis was ascertained by the black background mug testand of subclinical mastitis by the CMT. The reuse of needles, type of milking, reproductive management, calf mortality,presence of reproductive problems and milk yield were the risk factors assessed. The association between the variableswas estimated by the odds ratio (95% confidence interval). The significance of the associations was determined by theChi-square test. The prevalence of EBL, clinical and subclinical mastitis was 56.79%, 5.50% and 43.55%, respectively.There was a positive association between the EBL virus and the presence of...(AU)

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O linfoma maligno bovino, também conhecido por linfossarcoma ou leucemia bovina, é uma neoplasia linfóide que acomete preferencialmente animais adultos, evoluindo de forma enzoótica. Esse trabalho teve como objetivo relatar um caso de linfoma bovino em um animal abatido em abatedouro frigorifico sob Serviço de Inspeção Federal (SIF) no estado do Maranhão. O animal apresentava, no post-mortem, lesões compatíveis com a enfermidade, como: aumento generalizado dos linfonodos de diferentes regiões, acompanhado de perda no padrão morfológico, não sendo possível a distinção do córtex e da medula. No exame histopatológico, foi evidenciada a infiltração de células neoplásicas redondas no parênquima do nodo linfático. As alterações histológicas associadas as lesões multicêntricas e características do animal (adulto) sugerem etiologia infecciosa associada ao Vírus da Leucemia Bovina (leucose enzoótica bovina) permitindo o diagnóstico de Linfoma Bovino.

Bovine lymphosarcoma, also known as malignant lymphoma and bovine leukemia, is a lymphoid neoplasm that affects adult animals, evolving in an enzootic way. This work reports a case of bovine lymphoma in an animal slaughtered in a slaughterhouse with a Federal Inspection Service (SIF) in the state of Maranhão. The animal presented post-mortem signs that are compatible with the disease, such as: generalized enlargement of lymph nodes in different regions, accompanied by a loss in the morphological pattern, making it impossible to distinguish the cortex and spinal cord. In the histopathological examination, histopathology showed evidence of infiltration of round neoplastic cells in the lymph node parenchyma. The histological changes associated with multicentric lesions and characteristics of the animal (adult) suggest an infectious etiology associated with the Bovine Leukemia Virus (bovine enzootic leukosis) allowing the diagnosis of Bovine Lymphoma.

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Background: The enzootic bovine leukosis (EBL) is a viral disease with a chronic aspect and its etiological agent is anoncogenic deltaretrovirus called bovine leukemia virus (VLB). It has a wide distribution in dairy cattle herds, and it maytake several years before the first clinical manifestations occur. Animals seropositive for VLB are more susceptible todeveloping infectious diseases such as mastitis. The objective of this study was to evaluate the seroprevalence of EBL, theprevalence of mastitis, the possible association between leukosis and mastitis, and the risk factors related to leukosis inmunicipalities of the Caparaó region of Espírito Santo, Brazil.Materials, Methods & Results: The prevalence of enzootic bovine leukosis and its association with mastitis were evaluatedin an 854 clinically healthy crossbred (Bos tauros tauros x Bos taurus indicus) dairy cows were used, in different lactationphases, from farms located in the 12 municipalities that compose the Caparaó Capixaba micro-region, in the southernpart of Espírito Santo, Brazil, in the period from February to December 2015. The seroprevalence of EBL was determinedby the agar gel immunodiffusion test, the presence of clinical mastitis was ascertained by the black background mug testand of subclinical mastitis by the CMT. The reuse of needles, type of milking, reproductive management, calf mortality,presence of reproductive problems and milk yield were the risk factors assessed. The association between the variableswas estimated by the odds ratio (95% confidence interval). The significance of the associations was determined by theChi-square test. The prevalence of EBL, clinical and subclinical mastitis was 56.79%, 5.50% and 43.55%, respectively.There was a positive association between the EBL virus and the presence of...

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RESUMO

Enzootic bovine leukosis (EBL) is an infectious disease caused by bovine leukemia virus (BLV) that affects cattle worldwide. Agar gel immunodiffusion (AGID) was the reference test for EBL diagnosis for many years, but enzyme-linked immunosorbent assay (ELISA) showed higher sensitivity, was faster to perform, and resulted in an objective reading. However, the importation of ELISA kits is lengthy and expensive, and currently, no AGID kits are available in Brazil. The aim of this work was to standardize an indirect ELISA (iELISA) for EBL diagnosis using BLV antigens produced in Tadarida brasiliensis lung (Tb1Lu) cells, which are Bovine viral diarrhea virus (BVDV) free, unlike fetal lamb kidney (FLK) cells, currently used for this purpose. Following standardization, iELISA results were compared with those obtained by AGID and the commercial Chekit Leucose-Serum ELISA. Compared to AGID, iELISA had 94,44% sensitivity, 75.68% specificity, 79.10% positive predictive value (PPV) and 93.30% negative predictive value (NPV), with 84% concordance and a Kappa index of 0.699. Compared to the Chekit Leucose-Serum ELISA, iELISA showed 92.60% sensitivity, 87.09% specificity, 90.27% PPV and 90,00% NPV, with 90.27% concordance and a Kappa index of 0.801. Taking into account the high agreement with the traditional tests and the absence of non-specific reactions with BVDV, the developed assay could be used as diagnostic method to control EBL in Brazil.(AU)

A leucose enzoótica bovina (LEB) é uma doença infecciosa natural dos bovinos com distribuição mundial causada pelo "bovine leukemia virus" (BLV). A imunodifusão em gel de ágar (IDGA) foi considerada por muitos anos o teste de eleição, porém ensaios imunoenzimáticos (ELISA) apresentam sensibilidade mais elevada e leitura mais rápida e objetiva. No entanto, a importação de kits de ELISA é um processo dispendioso e demorado, e atualmente não há kits de IDGA comercialmente disponíveis no Brasil. Desta forma, o objetivo deste trabalho foi padronizar um ELISA indireto (iELISA) para diagnóstico da LEB utilizando antígenos produzidos a partir do cultivo do BLV em linhagem celular Tadarida brasiliensis "lung" (Tb1Lu) livre de "bovine viral diarrhea virus" (BVDV), diferentemente do que acontece com as linhagens "fetal lamb kidney" (FLK) atualmente utilizadas na produção desses antígenos para uso em ensaios sorológicos. Após a padronização do iELISA, os resultados foram comparados com aqueles obtidos por IDGA e pelo ELISA comercial "Chekit Leucose-Serum". Comparado ao IDGA, o iELISA apresentou 94,44% de sensibilidade, 75,68% de especificidade, valor preditivo positivo (VPP) de 79,1% e valor preditivo negativo (VPN) de 93,3%, com concordância entre os testes de 84% e o índice Kappa 0,699. Quando comparado ao ELISA "Chekit Leucose-Serum", o iELISA apresentou sensibilidade de 92,6%, especificidade de 87,09%, VPP de 90,27% e VPN de 90%, com concordância de 90,27% e o índice Kappa 0,801. Portanto, devido à alta concordância com os testes tradicionais e ausência da ocorrência de reações inespecíficas com BVDV, o ensaio desenvolvido pode ser utilizado como ferramenta diagnóstica para o controle da LEB no Brasil.(AU)

Assuntos

RESUMO

Enzootic bovine leukosis (EBL) is an infectious disease caused by bovine leukemia virus (BLV) that affects cattle worldwide. Agar gel immunodiffusion (AGID) was the reference test for EBL diagnosis for many years, but enzyme-linked immunosorbent assay (ELISA) showed higher sensitivity, was faster to perform, and resulted in an objective reading. However, the importation of ELISA kits is lengthy and expensive, and currently, no AGID kits are available in Brazil. The aim of this work was to standardize an indirect ELISA (iELISA) for EBL diagnosis using BLV antigens produced in Tadarida brasiliensis lung (Tb1Lu) cells, which are Bovine viral diarrhea virus (BVDV) free, unlike fetal lamb kidney (FLK) cells, currently used for this purpose. Following standardization, iELISA results were compared with those obtained by AGID and the commercial Chekit Leucose-Serum ELISA. Compared to AGID, iELISA had 94,44% sensitivity, 75.68% specificity, 79.10% positive predictive value (PPV) and 93.30% negative predictive value (NPV), with 84% concordance and a Kappa index of 0.699. Compared to the Chekit Leucose-Serum ELISA, iELISA showed 92.60% sensitivity, 87.09% specificity, 90.27% PPV and 90,00% NPV, with 90.27% concordance and a Kappa index of 0.801. Taking into account the high agreement with the traditional tests and the absence of non-specific reactions with BVDV, the developed assay could be used as diagnostic method to control EBL in Brazil.(AU)

A leucose enzoótica bovina (LEB) é uma doença infecciosa natural dos bovinos com distribuição mundial causada pelo "bovine leukemia virus" (BLV). A imunodifusão em gel de ágar (IDGA) foi considerada por muitos anos o teste de eleição, porém ensaios imunoenzimáticos (ELISA) apresentam sensibilidade mais elevada e leitura mais rápida e objetiva. No entanto, a importação de kits de ELISA é um processo dispendioso e demorado, e atualmente não há kits de IDGA comercialmente disponíveis no Brasil. Desta forma, o objetivo deste trabalho foi padronizar um ELISA indireto (iELISA) para diagnóstico da LEB utilizando antígenos produzidos a partir do cultivo do BLV em linhagem celular Tadarida brasiliensis "lung" (Tb1Lu) livre de "bovine viral diarrhea virus" (BVDV), diferentemente do que acontece com as linhagens "fetal lamb kidney" (FLK) atualmente utilizadas na produção desses antígenos para uso em ensaios sorológicos. Após a padronização do iELISA, os resultados foram comparados com aqueles obtidos por IDGA e pelo ELISA comercial "Chekit Leucose-Serum". Comparado ao IDGA, o iELISA apresentou 94,44% de sensibilidade, 75,68% de especificidade, valor preditivo positivo (VPP) de 79,1% e valor preditivo negativo (VPN) de 93,3%, com concordância entre os testes de 84% e o índice Kappa 0,699. Quando comparado ao ELISA "Chekit Leucose-Serum", o iELISA apresentou sensibilidade de 92,6%, especificidade de 87,09%, VPP de 90,27% e VPN de 90%, com concordância de 90,27% e o índice Kappa 0,801. Portanto, devido à alta concordância com os testes tradicionais e ausência da ocorrência de reações inespecíficas com BVDV, o ensaio desenvolvido pode ser utilizado como ferramenta diagnóstica para o controle da LEB no Brasil.(AU)

Assuntos

RESUMO

Bovine leukemia virus (BLV) is one of the five agents considered most significant for cattle. It is important to determine the prevalence and molecular epidemiology of BLV throughout the country in order to gain a more thorough understanding of the current situation of BLV and to reveal the possibility of masked genotypes that the primers used by OIE are unable to identify. Blood samples were collected at random 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. A total of 62% of the cows present at 92% of the farms were BLV-positive for gag fragment. Genotype 1 was exclusively detected by env gene segment 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. This report is one of the first molecular and epidemiological studies of BLV conducted in Colombia, which contributes to the global epidemiology of the virus; it also highlights the substantial impact of BLV on the country's livestock and thus is a useful resource for farmers and government entities.

Assuntos