Mycobacterium avium subspecies paratuberculosis and bovine leukemia virus seroprevalence and associated risk factors in dairy herds in Minas Gerais state, Brazil / [Soroprevalência do Mycobacterium avium subespécie paratuberculosis e vírus da leucemia bovina e fatores de risco associados em rebanhos leiteiros de Minas Gerais, Brasil]

Mycobacterium avium subesp. paratuberculosis (MAP) e o vírus da leucemia bovina (BLV) são agentes que causam grandes perdas econômicas nos rebanhos. O objetivo deste estudo foi avaliar a situação epidemiológica da paratuberculose bovina (PTB) e leucose enzoótica bovina (EBL) em rebanhos leiteiros de Lagoa Formosa, Minas Gerais, Brasil. Foram coletadas 236 amostras de sangue de vacas, as quais foram submetidas aos testes ELISA e imunodifusão em gel de ágar para detecção de anticorpos contra MAP e BLV. A soroprevalência de anticorpos contra MAP e BVL foi de 20% para os rebanhos e 6% para os animais e de 85% para os rebanhos e 50,42% para os animais, respectivamente. A presença dessas enfermidades deve servir como um alerta para os produtores e veterinários, para que concentrem maior atenção na implementação de medidas higiênico-sanitárias, incorporando elementos de vigilância com base nos riscos identificados no estudo.(AU)

Development of an indirect ELISA based on recombinant capsid protein to detect antibodies to bovine leukemia virus

Abstract Serological testing and culling infected animals are key management practices aiming eradication of bovine leukemia virus infection. Here, we report the development of an indirect ELISA based on BLV recombinant capsid protein (BLVp24r) to detect anti-BLV antibodies in cattle serum. The BLVp24r was expressed in Escherichia coli and purified by affinity chromatography, and then used to set up the ELISA parameters. The Polysorp ® plate coated with 50 ng of antigen/well and bovine serum diluted 1:100 gave the best results during standardization. Using sera from infected and non-infected cattle we set up the cutoff point at 0.320 (OD450 nm) with a sensitivity of 98.5% and specificity of 100.0%. Then, we tested 1.187 serum samples from dairy (736 samples) and beef cattle (451 samples) with unknown status to BLV. We found that 31.1% (229/736) and 9.5% (43/451) of samples amongst dairy and beef cattle, respectively, had IgGs to BLV. The rate of agreement with a commercial competitive ELISA was 84.3% with a κ value of 0.68. Thus, our BLVp24r iELISA is suitable to detect BLV infected animals and should be a useful tool to control BLV infection in cattle.

Intercorrência entre leucose enzoótica e tuberculose em bovinos leiteiros do estado de Pernambuco / Assessment of intercurrence of enzootic leucosis and bovine tuberculosis in dairy cows in the state of Pernambuco, Brazil

Objetivou-se com este estudo avaliar a intercorrência entre leucose enzoótica e tuberculose em rebanhos bovinos leiteiros em oito municípios do Estado de Pernambuco, pelo estabelecimento da prevalência de bovinos reagentes às provas diagnósticas específicas. Foram analisados sorologicamente 662 animais, pela técnica de imunodifusão dupla em gel de agarose e 612 foram avaliados imunoalergicamente, por meio do teste de tuberculinização. Nos 15 rebanhos examinados, as prevalências de bovinos que apresentaram positividade aos testes IDGA e tuberculina foram 32,2% (213/662) e 14,1% (86/612), respectivamente. Os resultados obtidos nesta pesquisa permitiram concluir que as doenças estudadas encontram-se amplamente disseminadas na população avaliada, com crescimento em níveis significativos da leucose, e as infecções pelo vírus da leucose bovina (VLB) e Mycobacterium bovis encontram-se ativas e em expansão, com risco do comprometimento da saúde dos rebanhos bovinos e, pelo caráter zoonótico da tuberculose bovina, das pessoas que lidam com os bovinos.

We carried out this study to evaluate the intercurrence of tuberculosis and enzootic leukosis in dairy cattle herds in 8 districts of the State of Pernambuco, Brazil, by establishing the prevalence of bovines reagent to specific diagnostic tests, and to also verify the correlation between enzootic leucosis, cattle tuberculosis, the leukocytes count and lymphocytes count among the cattle studied. A total of 662 animals were tested serologically and hematologically, by the techniques of double immunodiffusion in agarose gel and the white blood cell count with the total and differential leukocyte count, respectively, and 612 were evaluated immunoallergically by the tuberculin test. In the 15 herds examined, the prevalence of cattle that were positive to the AGID and tuberculin tests were 32.2% (213/662) and 14.1% (86/612), respectively. Analyzing the correlation between the variables total leukocytes and lymphocytes, we found that total leukocyte is highly related to the variable lymphocytes (72%). The results in this study indicated that the diseases studied are widespread in the population studied, with significant levels of growth in leukemia, and infections of bovine leukosis virus (VLB) and Mycobacterium bovis are active and growing, with risk of impairment of the health of cattle herds, and, due to the zoonotic nature of bovine tuberculosis, of the health of people who work with cattle.

Soroprevalência de anticorpos para o Vírus da Leucose Enzoótica em bovinos criados na região metropolitana de Curitiba, Paraná / Seroprevalence for Bovine Leukosis Virus (BLV) in dairy cattle of Curitiba and the surrounding area, Paraná, Brazil

A Leucose Enzoótica Bovina (LEB) é uma doença infecto-contagiosa causada pelo Vírus da Leucemia Bovina (VLB), um retrovírus oncogênico da família Retroviridae. O presente estudo teve como objetivo avaliar a soroprevalência e a respectiva influência de fatores etários da LEB em bovinos leiteiros das raças Holandesa Preta e Branca, Jersey, Pardo-Suíço e mestiços, criados na região metropolitana de Curitiba, PR. Foram testadas 268 amostras de soros sanguíneos pela prova de Imunodifusão em gel de Agar (IDGA), colhidas em cinco propriedades situadas nos municípios de São José dos Pinhais, Campina Grande do Sul, Pinhais e Fazenda Rio Grande. Foram encontrados 151/268 (56,34%) animais positivos e 117/268 (43,66%) negativos. Animais mais velhos mostraram um aumento estatisticamente significativo de soropositividade. Pode-se concluir que a LEB está amplamente disseminada em bovinos leiteiros da região metropolitana de Curitiba e há necessidade de adequada aplicação de medidas de controle e prevenção da LEB.

Enzootic bovine leukosis (EBL) is aninfectious and contagious disease caused by bovine leukemia virus (BLV), an oncogenic retrovirus of the family Retroviridae. The present study aimed to evaluate the seroprevalence and respective age influence of BLV in Holstein, Jersey, Brown Swiss and mixed-breed dairy cattle raised in Curitiba and the surrounding area, Paraná, Brazil. A total of 268 samples of bovine serum from five different herds in the counties of São José dos Pinhais, Campina Grande do Sul, Pinhais and Fazenda Rio Grande were tested with immunodiffusion (ID). A total of 151/268 (56.34%) testedseropositive, while 117/268 (43.66%) were considered seronegative. Older animals prsented a significant rise in seropositivity. In conclusion, BLV is widely distributed among dairy cattle of Curitiba and the surrounding area, present in all tested herds, thus requiring adequate application of measures in EBL control and prevention.

Serological and genomic detection of bovine leukemia virus in human and cattle samples

Bovine leukemia virus [BLV] is a retro virus responsible for lymphoproliferative disorders in cattle. Although infections of BLV in animals are well known, little is known about its capacity to infect humans. This study investigated the presence of anti-BLV antibodies and BLV pro viruses in human and cattle samples. An indirect enzyme-linked immunosorbent assay [ELISA] was used to detect anti-BLV antibodies while nested PCR was employed to identify BLV provirus sequences. The overall prevalence of anti-BLV antibodies in human and cattle samples were 12.50% and 16.73%, respectively. When using ELISA as a reference test, sensitivity and specificity for nested PCR were 0.625 and 0.970, respectively. The predictive value of a positive test was 0.862 and the predictive value of a negative test was 0.897. The percentage of cattle correctly classified by nested PCR assay was 89.1%. Nested PCR and Southern blot analysis, using primers specific for BLV gag sequences, revealed that BLV pro viruses were detectable in cattle and human samples. Our results highlight the risk of human exposure to BLV and the need for further investigations to determine whether BLV infection poses a health hazard for humans

Simultaneous presence of bovine papillomavirus and bovine leukemia virus in different bovine tissues: in situ hybridization and cytogenetic analysis

Bovine papillomavirus (BPV) DNA sequences were detected in different tissues, in addition to epithelium. Cytogenetic abnormalities were observed in blood lymphocytes. The presence of more than one virus in a single tissue is a difficult aspect to evaluate, especially when the DNA sequences are detected in tissues that are not specifically targeted by the virus. BPV and bovine leukemia virus (BLV) are clastogenic, causing chromosome aberrations in peripheral blood lymphocytes. In the present study, we investigated the simultaneous presence of DNA sequences of both viruses and the possibility of vertical transmission and compared the types of chromosome aberrations related to viral action. BPV 1, 2, and 4 DNA sequences were found in three females of the herd and in their offspring. BLV DNA sequences were not detected in their progeny. A newborn calf that was negative for BLV infection showed specific chromosome rearrangements possibly related to the effect of infection with BPV.