RESUMO
The Bovine Leukemia Virus (BLV) affects mainly cattle, is transmitted by exposure to contaminated biological fluids, and generates lymphomas in 5 % of infected animals. The zoonotic potential of BLV has been studied, and it is currently unknown if it circulates in human workers on dairy herds in Antioquia. Objective: To determine the frequency of BLV detection, the genotypes of the virus, and the factors associated with its detection in workers for dairy herds in Antioquia, Colombia. Through a cross-sectional study in 51 dairy herds, 164 adults were recruited. A peripheral blood sample was collected from each participant for molecular detection of the BLV env and tax genes, and associated factors were explored through bivariate and multivariate mixed Poisson model analyses. The analysis showed that 82 % (134/164) of the participants were men, with an average age of 40. Using qPCR, the constitutive gene GAPDH was amplified to evaluate the presence of amplification inhibitors in the DNA samples. Using nested PCR, the amplification of the env viral gene was obtained in 13 % (22/164) of the total samples analyzed, while all the samples tested negative for tax. The amplicons of the env gene were sequenced, and the identity compatible with BLV was verified by BLAST analysis (NCBI). Using molecular phylogeny analysis, based on maximum likelihood and haplotype network analysis, it was identified that BLV genotype 1 is present in the evaluated population. 16 % (26/164) of the participants reported having ever had an accident with surgical material during work with cattle; this variable was associated with BLV positivity even after adjusting for other variables (PRa =2.70, 95 % CI= 1.01- 7.21). Considering that other studies have reported the circulation of BLV genotype 1 in cattle from this same region and the present report in humans from dairy herds, the results suggest a possible zoonotic transmission of BLV genotype 1 in Antioquia, reinforcing the need to continue investigating to determine the potential role of this virus as an etiological agent of disease in livestock farmers in the department.
Assuntos
Indústria de Laticínios , Leucose Enzoótica Bovina , Genótipo , Vírus da Leucemia Bovina , Vírus da Leucemia Bovina/genética , Vírus da Leucemia Bovina/isolamento & purificação , Vírus da Leucemia Bovina/classificação , Colômbia/epidemiologia , Humanos , Feminino , Estudos Transversais , Adulto , Animais , Masculino , Bovinos , Pessoa de Meia-Idade , Leucose Enzoótica Bovina/virologia , Leucose Enzoótica Bovina/epidemiologia , Adulto Jovem , Filogenia , Zoonoses/virologia , Zoonoses/transmissão , Fazendeiros/estatística & dados numéricosRESUMO
The Bovine Leukemia Virus (BLV) Envelope (Env) glycoprotein complex is instrumental in viral infectivity and shapes the host's immune response. This study presents the production and characterization of a soluble furin-mutated BLV Env ectodomain (sBLV-EnvFm) expressed in a stable S2 insect cell line. We purified a 63 kDa soluble protein, corresponding to the monomeric sBLV-EnvFm, which predominantly presented oligomannose and paucimannose N-glycans, with a high content of core fucose structures. Our results demonstrate that our recombinant protein can be recognized from specific antibodies in BLV infected cattle, suggesting its potential as a powerful diagnostic tool. Moreover, the robust humoral immune response it elicited in mice shows its potential contribution to the development of subunit-based vaccines against BLV.
Assuntos
Anticorpos Antivirais , Vírus da Leucemia Bovina , Proteínas Recombinantes , Proteínas do Envelope Viral , Animais , Vírus da Leucemia Bovina/genética , Vírus da Leucemia Bovina/imunologia , Bovinos , Proteínas Recombinantes/genética , Camundongos , Proteínas do Envelope Viral/genética , Proteínas do Envelope Viral/imunologia , Proteínas do Envelope Viral/metabolismo , Anticorpos Antivirais/imunologia , Leucose Enzoótica Bovina/virologia , Linhagem Celular , Produtos do Gene env/genética , Produtos do Gene env/metabolismo , Produtos do Gene env/imunologiaRESUMO
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.
Assuntos
Doença das Mucosas por Vírus da Diarreia Viral Bovina , Doenças dos Bovinos , Doenças Transmissíveis , Vírus da Diarreia Viral Bovina Tipo 1 , Vírus da Diarreia Viral Bovina , Leucose Enzoótica Bovina , Vírus da Leucemia Bovina , Paratuberculose , Bovinos , Animais , Paratuberculose/epidemiologia , Doenças dos Bovinos/epidemiologia , Leucose Enzoótica Bovina/epidemiologia , Peru/epidemiologia , Estudos Soroepidemiológicos , Anticorpos Antivirais , Anticorpos Antibacterianos , Doenças Transmissíveis/veterinária , Reprodução , Diarreia/veterináriaRESUMO
Bovines infected by bovine leukemia virus (BLV) are characterized by presenting low proviral load (LPL) or high proviral load (HPL). It is reported that animals with HPL in peripheral blood mononuclear cells (PBMCs) present a decrease in apoptosis, an increase in viability and the proliferation rate, while animals that maintain an LPL have an intrinsic ability to control the infection, presenting an increased apoptosis rate of their PBMCs. However, there is little information on the effect of BLV on these mechanisms when the virus infects somatic milk cells (SC). This study investigates the mechanisms underlying apoptosis in milk and blood from BLV-infected animals with HPL and LPL. Relative levels of mRNA of tumor necrosis factor-α (TNF-α), TNF receptor 1 (TNF-RI), TNF receptor 2 (TNF-RII), anti-apoptotic B-cell lymphoma 2 protein (Bcl-2), and pro-apoptotic Bcl-2-like protein 4 (Bax) were measured in SC and PBMCs using quantitative reverse transcription-polymerase chain reaction (RT-qPCR) assay. A significant decrease in the expression of TNF-α in SC from HPL animals vs non-infected bovines was observed, but the infection in SC with BLV did not show a modulation on the expression of TNF receptors. A significant increase in TNF-RI expression in PBMCs from HPL bovines compared to LPL bovines was observed. No significant differences in PBMCs between HPL and LPL compared to non-infected animals concerning TNF-α, TNF-RI, and TNF-RII expression were found. There was a significant increase of both Bcl-2 and Bax in SC from LPL compared to non-infected bovines, but the Bcl-2/Bax ratio showed an anti-apoptotic profile in LPL and HPL bovines compared to non-infected ones. Reduced mRNA expression levels of Bax were determined in the PBMCs from HPL compared to LPL subjects. In contrast, BLV-infected bovines did not differ significantly in the mRNA expression of Bax compared to non-infected bovines. Our data suggest that the increased mRNA expression of Bax corresponds to the late lactation state of bovine evaluated and the exacerbated increase of mRNA expression of Bcl-2 may be one of the mechanisms for the negative apoptosis regulation in the mammary gland induced by BLV infection. These results provide new insights into the mechanism of mammary cell death in HPL and LPL BLV-infected bovine mammary gland cells during lactation.
Assuntos
Doenças dos Bovinos , Leucose Enzoótica Bovina , Vírus da Leucemia Bovina , Animais , Bovinos , Feminino , Apoptose , Proteína X Associada a bcl-2/metabolismo , Proliferação de Células , Leucócitos Mononucleares/metabolismo , Leite , Provírus/genética , Provírus/metabolismo , Receptores Tipo II do Fator de Necrose Tumoral/metabolismo , RNA Mensageiro/metabolismo , Fator de Necrose Tumoral alfa/genética , Fator de Necrose Tumoral alfa/metabolismoRESUMO
Enzootic bovine leukosis virus (BLV) and bovine herpesvirus 1 (BHV-1) are very important infectious agents for the livestock industry worldwide. The present study aimed to explore the association between natural exposure to BLV and BHV-1 with sperm quality analyzed by Computer-Assisted Semen Analysis (CASA) systems. Ten sexually mature Brahman bulls, with sanitary status BLV+/BHV-1+ (n = 2), BLV-/BHV-1+ (n = 6) and BLV-/BHV-1- (n = 2) were evaluated twice, 30 days apart. Results showed that sanitary status of each bull was not associated with semen quality. It was found that the quality of the semen from the second collection was better due to the interruption of sexual rest. The evidence thus revealed that a bull infected with BLV generated good-quality contaminated semen and, therefore, that it is essential to detect contaminated seminal samples to prevent the spread of BLV. A multivariate analysis showed the presence of four sperm subpopulations in Brahman bulls that differ significantly in their kinematic patterns and with respect to sanitary status (P < 0.05), indicating that infection-free and seronegative bulls present the best kinematic parameters, which improved discrimination of sperm quality according to sanitary status. Overall, the analyses indicate that the seropositive-infected bulls with BLV and BHV-1 should be excluded from beef cattle farms.
Assuntos
Doenças dos Bovinos , Herpesvirus Bovino 1 , Vírus da Leucemia Bovina , Masculino , Animais , Bovinos , Análise do Sêmen , SêmenRESUMO
Bovine leukemia virus (BLV) causes enzootic bovine leukosis, a persistent infection and the most important neoplastic disease in cattle. It is spread primarily by transferring infected lymphocytes through blood from carriers to healthy animals. The present study is aimed at determining the seropositivity of BLV in breeding bulls from Costa Rica and at detecting for the first time in the country BLV DNA in bull semen. Between May 2011 and August 2018, 379 blood and 133 semen samples were collected from bulls distributed in 118 farms. The serum was analyzed by an enzymatic immunoassay and the semen by polymerase chain reaction and sequencing. BLV seropositivity was 43.5% (165/379), while 64.4% (76/118) of the farms had positive reactors. Holstein (75.7%) and Jersey (73.0%) breeds showed the highest seropositivity. In addition, Bos taurus bulls (68.1%), older than seven years (50.0%), and those belonging to dairy farms (75.5%) had higher seropositivity compared to Bos indicus (17.7%), younger than seven years (42.2%), and those from beef farms (15.5%), respectively. Moreover, Bos taurus bulls had a higher risk of being seropositive than Bos indicus (OR = 3.4; 95% CI: 1.7-6.8). BLV DNA was found in one semen sample (2.5%; 1/40) from a seropositive bull. The importance of serum and molecular BLV screening in semen samples and the potential role of some risk factors associated with the disease, such as the bull's age, genotype, and type of livestock productive system, is argued in the present report.
Assuntos
Doenças dos Bovinos , Leucose Enzoótica Bovina , Vírus da Leucemia Bovina , Bovinos , Animais , Masculino , Sêmen , Leucose Enzoótica Bovina/epidemiologia , Costa Rica/epidemiologia , Estudos SoroepidemiológicosRESUMO
Enzootic bovine leukosis (EBL) is a chronic infectious disease caused by the bovine leukosis virus (BLV), a Deltaretrovirus. Bovine viral diarrhea (BVD) is an infectious disease caused by a pestivirus. Bovine neosporosis is caused by the obligate intracellular parasite Neospora caninum (Nc). These pathogens can have horizontal (postnatal) or vertical (transplacental) transmissions and affect the productive and reproductive performance of infected bovines. This work aimed to detect BLV, BVD, and Nc seroprevalence in specialized dairy cattle from the north, east, and Aburrá Valley regions of the Department of Antioquia, the highest in milk production regions in Antioquia. A total of 599 blood samples, obtained from 53 specialized dairy cattle herds, were evaluated by the ELISA test. The results revealed a seroprevalence of 41.13% for BLV (242/599), 28.48% (163/599) for Nc, and 22.7% (132/599) for BVD. Regarding the regional seroprevalence evaluation, BLV was found in 47.02% of the samples from the east, 36.87% from the north, and 46.02% from the Aburrá Valley. Nc was found in 31.03% of the samples from the east, 24.26% from the north, and 36.63% from Aburrá Valley. BVD was found in 21.62% of the samples from the east, 25.03% from the north region, and 10.39% of the samples from the Aburrá Valley. It is highlighted by these results that the north region, with the highest milk production in Antioquia, had the lowest BLV and Nc seroprevalences but the highest seroprevalence of BVD. BLV has increased in Antioquia in recent years, and as an immunosuppressive infection, opportunities for other pathogens are created by it. A significant statistical difference was found in the average prevalence of the pathogens according to the municipality, cattle breed, and region of origin of the sample. The seroprevalence of these pathogens in specialized dairy herds in Antioquia can be classified as medium-low. However, it is recommended that biosecurity practices should be maximized to avoid the spread of these pathogens due to the variability detected in the region, municipality, breed group, and herd age. The rapid and efficient diagnosis of these three pathogens through reliable methodologies will allow for the control of dissemination in dairy herds.
Assuntos
Doenças dos Bovinos , Doenças Transmissíveis , Leucose Enzoótica Bovina , Vírus da Leucemia Bovina , Neospora , Animais , Bovinos , Colômbia , Leucose Enzoótica Bovina/epidemiologia , Estudos Soroepidemiológicos , Doenças Transmissíveis/veterinária , Diarreia/veterináriaRESUMO
Bovine leukemia virus (BLV) is the causative agent of enzootic bovine leukosis, an endemic disease in dairy cattle of Argentina. However, little is known about the seroprevalence of BLV in beef cattle. In this study, we conducted a cross-sectional study including farms from thirteen provinces of Argentina. A total of 5827 bovine serum samples were collected from 76 farms and analyzed using an in-house developed enzyme-linked immunosorbent assay. Information about herd management was collected through a questionnaire, and univariate and multivariate analyses were performed to detect risk factors associated with BLV infection. Herd-level seroprevalence was 71.05%, while the mean animal-level seroprevalence was 7.23% (median = 2.69%; min = 0, max = 75). Only two provinces had no positive BLV samples. The other eleven provinces showed more than 50% of their farms infected with BLV. The multivariate model revealed that BLV prevalence was significantly associated with the use of animals raised in the same farm for cattle replacement (P = 0.005), breeding cows by natural mating with a bull (P < 0.001), and weaning calves after 6 months of age (P = 0.011). This extensive study revealed that BLV seroprevalence in Argentine beef farms has increased during the last years and allowed identifying some management practices associated with BLV prevalence. These data deserve special attention because BLV infection in beef cattle seems to lead to a dissemination pattern similar to that observed during the last decades in dairy cattle, especially considering that Argentina is the sixth beef producer in the world, with about 5% of global beef production.
Assuntos
Doenças dos Bovinos , Leucose Enzoótica Bovina , Vírus da Leucemia Bovina , Feminino , Bovinos , Animais , Masculino , Estudos Soroepidemiológicos , Estudos Transversais , Anticorpos Antivirais , Leucose Enzoótica Bovina/epidemiologia , Fatores de Risco , Ensaio de Imunoadsorção Enzimática/veterinária , Doenças dos Bovinos/epidemiologiaRESUMO
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.
Assuntos
Doenças dos Bovinos , Leucose Enzoótica Bovina , Vírus da Leucemia Bovina , Animais , Bovinos , Feminino , Masculino , Colômbia/epidemiologia , Cidades , Estudos Transversais , Leucose Enzoótica Bovina/epidemiologia , Estudos Soroepidemiológicos , Fatores de Risco , Doenças dos Bovinos/epidemiologia , Doenças dos Bovinos/etiologiaRESUMO
To review the available studies on the frequency of detection of the bovine leukemia virus in human samples, a systematic review with meta-analysis of the scientific literature was carried out, including papers published in English, Spanish, and Portuguese in 5 multidisciplinary databases. We collected information from different populations following a detailed and reproducible search protocol in which two researchers verified the inclusion and exclusion criteria. We identified 759 articles, of which only 33 met the inclusion criteria. Analyzed studies reported that the presence of the virus was measured in human samples, such as paraffin-embedded breast tissue and peripheral blood from 10,398 individuals, through serological and molecular techniques. An overall virus frequency of 27% (Ranging between 17 and 37%) was observed, with a high-frequency data heterogeneity between studies. The presence of this virus in different human biological samples suggests the need to investigate further its transmission route to humans and its potential role in developing and progressing diseases.
Assuntos
Vírus da Leucemia Bovina , Humanos , Vírus da Leucemia Bovina/isolamento & purificaçãoRESUMO
The aim of this study was molecular identification of bovine leukemia virus and possible co-infection with bovine respiratory disease complex (BRDC) viral agents in Mexican dairy herds. We collected 533 blood samples from cattle vaccinated against the BRDC virus in 9 states across Mexico. Peripheral blood leukocytes were removed and genetic material was extracted to detect bovine leukemia virus (BLV), bovine herpesvirus 1 (BoHV-1), bovine viral diarrhea virus (BVDV), bovine parainfluenza virus 3 (BPIV-3), and bovine respiratory syncytial virus (BRSV) infection using polymerase chain reaction. We identified high BLV infection rates in 270 cattle (50.65%). One hundred and thirty-three cows (24.95%) tested positive for BoHV-1, of which 65 samples were positive for both viruses (BoHV-1 and BLV) and 68 were only positive for BoHV-1. Only 4 samples tested positive for BPIV-3 and no sample was positive for BVDV or BRSV. Relative risk and odds ratio analyses did not identify that the presence of BLV infection favors BoHV-1 co-infection in vaccinated herds.
Le but de cette étude était l'identification moléculaire du virus de la leucémie bovine et une éventuelle co-infection par des agents viraux du complexe des maladies respiratoires bovines (BRDC) dans des troupeaux laitiers mexicains. Nous avons recueilli 533 échantillons de sang de bovins vaccinés contre le virus BRDC dans neuf états du Mexique. Les leucocytes du sang périphérique ont été prélevés et le matériel génétique a été extrait pour détecter le virus de la leucémie bovine (BLV), le virus de l'herpès bovin 1 (BoHV-1), le virus de la diarrhée virale bovine (BVDV), le virus parainfluenza bovin 3 (BPIV-3), et le virus respiratoire syncytial bovin (BRSV) par réaction d'amplification en chaîne par la polymérase. Nous avons identifié des taux élevés d'infection par le BLV chez 270 bovins (50,65 %). Cent trente-trois bovins (24,95 %) ont été testés positifs pour le BoHV-1, desquels 65 échantillons étaient positifs pour les deux virus (BoHV-1 et BLV) et 68 étaient uniquement positifs pour le BoHV-1. Seuls quatre échantillons ont été testés positifs pour le BPIV-3 et aucun échantillon n'a été positif pour le BVDV ou le BRSV. Les analyses du risque relatif et des rapports de cotes n'ont pas identifié que la présence d'une infection par le BLV favorise la co-infection par le BoHV-1 dans les troupeaux vaccinés.(Traduit par les auteurs).
Assuntos
Leucose Enzoótica Bovina , Herpesvirus Bovino 1 , Rinotraqueíte Infecciosa Bovina , Vírus da Leucemia Bovina , Vacinação , Animais , Bovinos , Complexo Respiratório Bovino/prevenção & controle , Coinfecção/epidemiologia , Coinfecção/veterinária , Leucose Enzoótica Bovina/epidemiologia , Herpesvirus Bovino 1/isolamento & purificação , Rinotraqueíte Infecciosa Bovina/epidemiologia , Vírus da Leucemia Bovina/isolamento & purificação , México/epidemiologia , Vacinação/estatística & dados numéricos , Vacinação/veterinária , FemininoRESUMO
Bovine leukemia virus (BLV) is a retrovirus that causes malignant B-cell lymphoma in up to ten-percent of infected cattle. To date, the mechanisms of BLV linked to malignant transformation remain elusive. Although BLV-encoded miRNAs have been associated with the regulation of different genes involved in oncogenic pathways, this association has not been evaluated in cattle naturally infected with BLV. The objective of this study was to determine the relative expression of BLV-encoded miRNA blv-miR-b4-3p, the host analogous miRNA bo-miR-29a and a couple of potential target mRNAs (HBP-1 and PXDN, with anti-tumorigenic function in B-cells), in cattle naturally infected with BLV compared to uninfected animals (control group). We observed that PXDN was significantly downregulated in BLV-infected cattle (P = 0.03). Considering the similar expression of endogenous bo-miR-29a in both animal groups, the downregulation of PXDN in BLV-naturally infected cattle could be linked to blv-miR-b4-3p expression in these animals. Knowing that PXDN is involved in anti-tumoral pathways in B-cells, the results presented here suggest that blv-miR-b4-3p might be involved in BLV tumorigenesis during natural infection with BLV in cattle.
Assuntos
Leucose Enzoótica Bovina , Vírus da Leucemia Bovina , Linfoma de Células B , MicroRNAs , Neoplasias , Animais , Bovinos , MicroRNAs/genética , Vírus da Leucemia Bovina/genética , Linfócitos B , Leucose Enzoótica Bovina/genéticaRESUMO
Background: Enzootic bovine leukosis (EBL) is a widespread infectious disease caused by the bovine leukemia virus (BLV), which results in immune system dysfunction. The resulting immunosuppression may lead to an increased prevalence of other diseases. Dairy cows infected have altered immune function associated with decreased milk production and shortened lifespan and decreased immune response to immunization. BLV infection, however, is often asymptomatic, so any connection between subclinical infection and common reproductive diseases remains unknown. This study aimed to describe the relationship between naturally occurring subclinical BLV and infectious reproductive diseases seroconversion in the field. Materials, Methods & Results: The diseases investigated included Bovine viral diarrhoea (BVD), Bovine alfaherpesvirus 1 (BoHV-1), Bovine gammaherpesvirus 4 (BoHV-4), Chlamydiosis, Leptospirosis, Brucellosis and Neosporosis in dairy cattle. Six hundred fifty-five sera samples from the northern and south-central regions of Uruguay, from asymptomatic female Holstein and Holstein crosses without a history of vaccination against reproductive diseases were processed using reference diagnostic methods (Seronautalization, ELISA, MAT, Rose Bengal Plate test). The seroprevalence of BLV was 20.0%. Seroprevalence of reproductive diseases BVD, BoHV-1 and BoHV-4 were 99.3%, 41.2% and 27.3% of the populations, respectively, and the total seroprevalence of Leptospirosis, bovine Neospora caninum and Chlamydiosis were 19.8%, 29.8% and 33.0% respectively. The results revealed positive associations between naturally contracted BLV and the presence of antibodies against BoHV-1 (P = 0.002), as well as between naturally contracted BLV and presence of antibodies against Leptospira spp. (P = 0.028). Discussion: BLV infection can impact innate and adaptive immune system cells and alter the proper functioning of uninfected cells. BLV infection may also induce changes in the complex balance of cytokine expression, cell proliferation, and programmed cell death in T- and B-lymphocytes, which is critical for immune competence and effective response to infectious challenges. The progression of BLV infection has a substantial effect on host defense mechanisms. Indeed, lowmagnitude serologic responses to a commercial foot-and-mouth disease vaccine and a J5 Escherichia coli vaccine have been observed. These results are supported by recent trial studies showing a reduced immune response to vaccination against BoHV-1 and Leptospira spp. in asymptomatic animals infected with BLV. These are 2 of the most prevalent infectious reproductive diseases in cattle worldwide, and our results provide evidence that a link between BLV and susceptibility to these diseases may exist. Although there is evidence of the co-occurrence of these diseases, it remains unknown whether there is a direct or indirect effect of BLV on infertility, embryonic loss, or abortion. Another possibility is that natural infection with these reproductive pathogens (BoHV-1, Leptospira, or others) promotes BLV expression, negatively affecting the farms where these pathogens are endemic. Considering the high seroprevalence of BLV in dairy herds in North and South America where the infection is endemic, it was explored BLV's role as an immunosuppressant by quantifying its co-occurrence with diseases that affect reproductive performance in breeding herds. Future work should clarify the role of BLV and the co-occurring pathogens in causing infertility or abortions.
Assuntos
Animais , Feminino , Bovinos , Leucose Enzoótica Bovina/complicações , Vírus da Leucemia Bovina , Doenças dos Genitais Femininos/veterinária , Rinotraqueíte Infecciosa Bovina , Leptospirose/veterinária , Infecções do Sistema Genital/veterináriaRESUMO
Clinical History: A 5-year-old, Holstein-Friesian dairy cow was evaluated by a veterinary practitioner for a 30-day history of unilateral exophthalmos (Fig. 1). After 15 days, the cow presented lameness followed by progressive weight loss and pelvic limbs paresis, culminating in persistent sternal recumbency (Fig. 2). The superficial inguinal lymph nodes were enlarged. Due to the poor prognosis, the cow was euthanized and submitted to a postmortem examination. Gross Findings: The cow was in poor body condition with mild amounts of subcutaneous and visceral fat stores. The oral and conjunctival mucous membranes were pale. There was severe exophthalmos in the right eye, caused by a soft, homogenous, white to yellow mass (6 cm in diameter) (Fig. 3) in the retrobulbar space. Similar irregular masses were seen in the left renal pelvis, partially effacing the renal parenchyma, and in the epidural space, circumferentially surrounding the pachymeninges (extradural location) (Fig. 4) of the lumbar segment of the spinal cord. The superficial inguinal lymph nodes (supramammary) were markedly enlarged and, on the cut surface, had homogenous white to yellow discoloration and loss of the corticomedullary junction. Multifocal areas of the abomasum wall were moderately thickened and expanded by a soft, homogenous, white to yellow masses. No significant alterations were observed in other organs. Follow-up questions: Morphologic diagnosis? Etiological agent? Name of the condition? Probable pathogenesis pathways?
Assuntos
Animais , Feminino , Bovinos , Leucose Enzoótica Bovina/diagnóstico , Bovinos/virologia , Vírus da Leucemia Bovina/patogenicidadeRESUMO
Bovine leukemia virus (BLV) subclinical infection promotes persistent lymphocytosis (PL), which is related to susceptibility and progression to lymphoma. Moreover, lymphocyte counts directly correlate with BLV antibody titers and proviral load, and cell immune responses are considered atypical due to immune suppression. In order to determine the relationship of PL, antibody titers, and proviral load with interleukin (IL)-12, interferon (IFN)-γ, IL-2, IL-4, IL-10, and transforming growth factor (TGF)-ß expression in a 3-month interval, 58 cows were selected (30 BLV+ and 28 BLV-) from a high-prevalence dairy herd to complete 3 monthly blood samplings for the assessment of PL, BLV antibody titers, BLV proviral load, and IL-12, IFN-γ, IL-2, IL-4, IL-10, and TGF-ß expression. At sampling conclusion, the BLV-infected cows were grouped according to PL, BLV proviral load, and BLV antibody titers as follows: BLV+PL+ (n = 16) and BLV+PL- (n = 14); high proviral load (HPL) (n = 18) and low proviral load (LPL) (n = 13); high antibody titers (HAT) (n = 17) and low antibody titers (LAT) (n = 14). The BLV+PL+ cows showed significantly higher proviral load and antibody titers than the BLV+PL- group; however, the former suggested spread presumably unrelated to lymphoma outcome, because HPL was observed in PL- cows in the last sampling. Consistent with the data, a higher antibody response strongly indicated BLV susceptibility since it was linked to PL+ occurrence and a cytokine profile compatible with immune suppression. Furthermore, a reversion to lower antibody titers was observed in cows with HPL far ahead of time, most likely due to long-term immune suppression. In addition, high expression of IL-10 and TGF-ß was associated with reduced IL-12, IFN-γ, IL-2, and IL-4 expression alongside PL, HAT, and HPL in BLV-infected cows, suggesting an IL-10- and TGF-ß-induced immune suppression. The IL-10 expression was increasing throughout, implying disease progression, as described. In conclusion, the proliferative expansion of lymphocytes known as PL might enhance a regulatory-rich cell population (Bregs and/or Tregs) that secretes IL-10 and TGF-ß, leading to immune suppression. Further studies must be conducted regarding the types of regulatory cells involved in BLV-induced immune suppression.
L'infection subclinique par le virus de la leucémie bovine (BLV) favorise une lymphocytose persistante (PL), qui est liée à la susceptibilité et à la progression vers le lymphome. De plus, le nombre de lymphocytes est directement corrélé aux titres d'anticorps BLV et à la charge provirale, et les réponses immunitaires cellulaires sont considérées comme atypiques en raison de la suppression immunitaire. Afin de déterminer la relation entre PL, les titres d'anticorps et la charge provirale avec l'interleukine (IL)-12, l'interféron (IFN)-γ, l'IL-2, l'IL-4, l'IL-10 et l'expression du facteur de croissance transformant (TGF)-ß dans un intervalle de 3 mois, 58 vaches ont été sélectionnées (30 BLV+ et 28 BLV−) à partir d'un troupeau laitier à forte prévalence pour compléter trois prélèvements sanguins mensuels pour l'évaluation de PL, des titres d'anticorps BLV, de la charge provirale BLV et l'expression d'IL-12, IFN-γ, d'IL-2, d'IL-4, d'IL-10 et TGF-ß. À la fin de l'échantillonnage, les vaches infectées par le BLV ont été regroupées en fonction du PL, de la charge provirale du BLV et des titres d'anticorps du BLV comme suit : BLV+PL+ (n = 16) et BLV+PL− (n = 14); charge provirale élevée (HPL) (n = 18) et charge provirale faible (LPL) (n = 13); titres d'anticorps élevés (HAT) (n = 17) et titres d'anticorps faibles (LAT) (n = 14). Les vaches BLV+PL+ ont montré une charge provirale et des titres d'anticorps significativement plus élevés que le groupe BLV+PL−; cependant, le premier suggère une propagation vraisemblablement sans rapport avec l'issue du lymphome, car HPL a été observé chez les vaches PL− lors du dernier échantillonnage. Conformément aux données, une réponse anticorps plus élevée indiquait fortement une sensibilité au BLV puisqu'elle était liée à l'apparition de PL+ et à un profil de cytokines compatible avec la suppression immunitaire. De plus, un retour à des titres d'anticorps plus faibles a été observé chez les vaches atteintes de HPL bien avant le temps, probablement en raison d'une immunosuppression à long terme. De plus, une expression élevée d'IL-10 et de TGF-ß était associée à une expression réduite d'IL-12, d'IFN-γ, d'IL-2 et d'IL-4 aux côtés de PL, HAT et HPL chez les vaches infectées par le BLV, suggérant une immunosuppression induite par IL-10 et le TGF-ß. L'expression d'IL-10 augmentait tout au long, impliquant une progression de la maladie, comme décrit. En conclusion, l'expansion proliférative des lymphocytes connus sous le nom de PL pourrait renforcer une population de cellules riches en régulation (Bregs et/ou Tregs) qui sécrète d'IL-10 et du TGF-ß, conduisant à une suppression immunitaire. D'autres études doivent être menées sur les types de cellules régulatrices impliquées dans la suppression immunitaire induite par le BLV.(Traduit par Docteur Serge Messier).
Assuntos
Doenças dos Bovinos , Leucose Enzoótica Bovina , Vírus da Leucemia Bovina , Linfocitose , Animais , Bovinos , Citocinas , Leucose Enzoótica Bovina/epidemiologia , Feminino , Interferon gama/genética , Interleucina-10 , Interleucina-12 , Interleucina-2 , Interleucina-4/genética , Vírus da Leucemia Bovina/fisiologia , Linfocitose/veterinária , Prevalência , Provírus/genética , Fator de Crescimento Transformador beta , Fatores de Crescimento TransformadoresRESUMO
Previous attempts to develop a vaccine against bovine leukemia virus (BLV) have not been successful because of inadequate or short-lived stimulation of all immunity components. In this study, we designed an approach based on an attenuated BLV provirus by deleting genes dispensable for infectivity but required for efficient replication. The ability of the vaccine to protect from natural BLV infection was investigated in the context of dairy productive conditions in an endemic region. The attenuated vaccine was tested in a farm in which the prevalence rose from 16.7% in young cattle at the beginning of the study to more than 90% in adult individuals. Sterilizing immunity was obtained in 28 out of 29 vaccinated heifers over a period of 48 months, demonstrating the effectiveness of the vaccine. As indicated by the antiviral antibody titers, the humoral response was slightly reduced compared to wild-type infection. After initial post-vaccination bursts, the proviral loads of the attenuated vaccine remained most frequently undetectable. During the first dairy cycle, proviral DNA was not detected by nested-PCR in milk samples from vaccinated cows. During the second dairy cycle, provirus was sporadically detected in milk of two vaccinated cows. Forty-two calves born from vaccinated cows were negative for proviral DNA but had antiviral antibodies in their peripheral blood. The attenuated strain was not transmitted to sentinels, further supporting the safety of the vaccine. Altogether, these data thus demonstrate that the vaccine against BLV is safe and effective in herd conditions characterized by a very high incidence. This cost-effective approach will thus decrease the prevalence of BLV without modification of production practices. After facing a series of challenges pertaining to effectiveness and biosafety, the vaccine is now available for further large-scale delivery. The different challenges and hurdles that were bypassed may be informative for the development of a vaccine against HTLV-1.
Assuntos
Leucose Enzoótica Bovina , Vírus da Leucemia Bovina , Animais , Antivirais , Bovinos , Feminino , Provírus , Vacinas AtenuadasRESUMO
The retropepsin (PR) of the Bovine leukemia virus (BLV) plays, as in other retroviruses, a crucial role in the transition from the non-infective viral particle to the infective virion by processing the polyprotein Gag. PR is expressed as an immature precursor associated with Gag, after an occasional -1 ribosomal frameshifting event. Self-hydrolysis of PR at specific N- and C-terminal sites releases the monomer that dimerizes giving rise to the active protease. We designed a strategy to express BLV PR in E. coli as a fusion protein with maltose binding protein, with a six-histidine tag at its N-terminal end, and bearing a tobacco etch virus protease hydrolysis site. This allowed us to obtain soluble and mature recombinant PR in relatively good yields, with exactly the same amino acid composition as the native protein. As PR presents relative promiscuity for the hydrolysis sites we designed four fluorogenic peptide substrates based on Förster resonance energy transfer (FRET) in order to characterize the activity of the recombinant enzyme. These substrates opened the way to perform kinetic studies, allowing us to characterize the dimer-monomer equilibrium. Furthermore, we obtained kinetic evidence for the existence of a conformational change that enables the interaction with the substrate. These results constitute a starting point for the elucidation of the kinetic properties of BLV-PR, and may be relevant not only to improve the chemical warfare against this virus but also to better understand other viral PRs.
Assuntos
Ácido Aspártico Proteases , Vírus da Leucemia Bovina , Dimerização , Escherichia coli/genética , Escherichia coli/metabolismo , Protease de HIV/metabolismo , Cinética , Vírus da Leucemia Bovina/genética , Vírus da Leucemia Bovina/metabolismo , Peptídeo Hidrolases/metabolismoRESUMO
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.
Assuntos
Doenças dos Bovinos , Leucose Enzoótica Bovina , Vírus da Leucemia Bovina , Doenças dos Ovinos , Animais , Bovinos , Leucose Enzoótica Bovina/diagnóstico , Ensaio de Imunoadsorção Enzimática/veterinária , Vírus da Leucemia Bovina/genética , Provírus/genética , Reação em Cadeia da Polimerase em Tempo Real/veterinária , OvinosRESUMO
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.
Assuntos
Leucose Enzoótica Bovina , Vírus da Leucemia Bovina , Animais , Anticorpos Antivirais , Bovinos , Ensaio de Imunoadsorção Enzimática/métodos , Feminino , Imunodifusão/métodos , Imunodifusão/veterinária , Período Periparto , GravidezRESUMO
Bovine leukemia virus (BLV) is the causative agent of leukemia/lymphoma in cattle. However, previous evidence has shown its presence in other species of livestock as well as in humans, suggesting that other species can be accidental hosts of the virus. In viral infections, receptors that are common to different animal species are proposed to be involved in cross-species infections. For BLV, AP3D1 has been proposed to be its receptor, and this protein is conserved in most mammalian species. In Colombia, BLV has been reported in cattle with high prevalence rates, but there has been no evidence of BLV infections in other animal species. In this study, we tested for the virus in sheep (n = 44) and buffaloes (n = 61) from different regions of Colombia by nested PCR, using peripheral blood samples collected from the animals. BLV was found in 25.7% of the animals tested (12 buffaloes and 15 sheep), and the results were confirmed by Sanger sequencing. In addition, to gain more information about the capacity of the virus to infect these species, the predicted interactions of AP3D1 of sheep and buffaloes with the BLV-gp51 protein were analyzed in silico. Conserved amino acids in the binding domains of the proteins were identified. The detection of BLV in sheep and buffaloes suggests circulation of the virus in multiple species, which could be involved in dissemination of the virus in mixed livestock production settings. Due to the presence of the virus in multiple species and the high prevalence rates observed, integrated prevention and control strategies in the livestock industry should be considered to decrease the spread of BLV.