Natural Transmission of Bovine Leukemia Virus in Dairy and Beef Cattle

Hopkins, Sharon G.; Rf, DiGiacomo

doi:10.1016/s0749-0720(15)30367-4

Cited by 134 publications

(131 citation statements)

References 52 publications

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“…Our analysis suggests that reduction of vertical transmission will be relatively ineffective since most cases arise through horizontal transmission, as has been suggested before [21].…”

Section: Discussionsupporting

confidence: 65%

Transmission of bovine leukaemia virus within dairy herds by simulation modelling

2006

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SUMMARYIn Argentina, bovine leukaemia virus (BLV) infection is common in dairy herds. The country currently has a National Voluntary Control Programme but relatively few farms have enrolled. However, there is increased interest from authorities and farmers to implement regional compulsory programmes but there is scarce quantitative information of the transmission of BLV in cattle herds. This information is a prerequisite to develop effective BLV control strategies. Mathematical modelling offers ways of integrating population-level knowledge and epidemiological data to predict the outcomes of intervention scenarios. The purpose of the current paper is to gain understanding about the dynamics of the transmission of BLV in dairy herds from Argentina by simulation and to compare various BLV transmission models and select the one that is most appropriate. The hypothetical herd is conceptually described in terms of BLV status as a population of individuals that are protected by maternal antibodies (M), that are susceptible (S), that are in the latent period (E) or that are infectious (I). BLV is spread by horizontal and vertical transmission. We used an age-structured population model and withinherd transmission was simulated by Monte Carlo techniques. The next-generation approach has been used for the systematic computation of the basic reproduction ratio (R 0 ). Parameter values for disease transmission were derived from previously published data; rates of entry, exit or transition between age groups were calculated based on our previous study, observational data, expert opinions and literature. With these parameter values the probability of a minor outbreak was estimated to be 10 %, the probability of extinction was estimated as <0 . 001 % and the expected time to extinction as more than 80 years. The probability of a minor outbreak and changes in prevalence were different when the index case was an adult cow compared to introduction by a heifer. Prediction of prevalences from MSI models fit the data satisfactorily. R 0 was estimated as 9 . 5. The sensitivity analysis on R 0 showed that all measures directed to reduce the transmission rate are potentially effective given operational control measures. An important prediction of these models is that, even in a relatively small, closed dairy herd, the time-scale for a BLV outbreak may be as long as several years and within-herd control of BLV requires intensive efforts.

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“…Our analysis suggests that reduction of vertical transmission will be relatively ineffective since most cases arise through horizontal transmission, as has been suggested before [21].…”

Section: Discussionsupporting

confidence: 65%

Transmission of bovine leukaemia virus within dairy herds by simulation modelling

2006

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“…After a latency period of 1-8 years, less than 10% of infected cattle develop EBL, which is a malignant CD5 + B-cell lymphoma (FERRER, 1980;GILLET et al, 2007). BLV has a silent dissemination in the herd due to infected cell exchange (HOPKINS; DIGIACOMO, 1997), thus the concentration of BLV-infected cells in blood should play a major role in the success of viral transmission. Even though PL cattle are considered the most risky for transmission, asymptomatic animals may also play a role depending on their proviral load (JULIARENA et al, 2007).…”

Section: Introductionmentioning

confidence: 99%

A novel association of BoLA DRB3 alleles in BLV infected cattle with different proviral loads

Farías

Caffaro

Lendez

et al. 2017

Braz. J. Vet. Res. Anim. Sci.

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Bovine leukemia virus (BLV) is associated with the most common neoplastic disease of cattle. BLV has a silent dissemination in the herd due to infected cell exchange, thus the concentration of BLV-infected cells in blood should play a major role in the success of viral transmission. Genes from Bovine leukocyte antigen (BoLA), the MHC system of cattle, are associated with genetic resistance and susceptibility to a wide range of diseases, and also with production traits. Some BoLA DRB3.2 allele polymorphisms in Holstein cattle have been associated with resistance or susceptibility to BLV-disease development, or with proviral load (PVL). This investigation studied 107 BLV-infected Argentinean Holstein dairy cows, all of them belonging to one herd. PVL was analysed by qPCR and animals were classified as high proviral load (HPVL, N = 88) and low proviral load (LPVL, N = 19), and BoLA DRB3.2 alleles were genotyped. Alleles BoLA DRB3.2*1501 and *1201 were significantly associated with HPVL (p = 0.0230 and p = 0.0111 respectively), while allele BoLA DRB3.2*0201 was significantly associated with LPVL (p = 0.0030). The present study aims at contributing to the knowledge of the association between BoLA polymorphism and development of a BLV infection profile. Genes that best explain the PVL in this population resulted BoLA DRB3.2*0201 (as a protection factor) and *1501 (as a risk factor). Allelic differences may play an important role in the development of effective immune responses. A better understanding of how BoLA polymorphism contributes to these responses and the establishment of a BLV status is desirable to schedule and evaluate control measures. Keywords: BLV. Proviral load. BoLA DRB3 polymorphism. ResumoO vírus da leucemia bovina (BLV) está associado à doença neoplásica mais comum do gado bovino. O BLV tem uma disseminação silenciosa no rebanho devido à troca de células infectadas, assim, a concentração de células BLV infectadas no sangue deve desempenhar um papel importante no sucesso da transmissão viral. Os genes do antígeno leucocitário bovino (BoLA), sistema MHC do gado bovino, estão associados à resistência genética e à susceptibilidade a uma ampla gama de doenças, bem como às características da produção. Alguns polimorfismos de alelos de BoLA DRB3.2 em bovinos Holstein têm sido associados à resistência ou susceptibilidade ao desenvolvimento da doença BLV, ou com carga proviral (PVL). Esta investigação avaliou 107 vacas leiteiras da raça Holstein argentina infectadas com BLV e pertencentes a um único rebanho. A PVL foi analisada por qPCR, os animais foram classificados em alta carga proviral (HPVL, N = 88) e baixa carga proviral (LPVL, N = 19) | 216Braz.

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“…Enzootic Bovine Leukosis (EBL), caused by bovine leukemia virus (BLV), is a highly disseminated disease in Brazilian dairy herds, with infection rates of up to 56% (BIRGEL JUNIOR et al, 1995;D´ANGELINO et al, 1998a;MOLNÁR et al, 1999;MATOS;BIRGEL JÚNIOR;BIRGEL, 2005;BARROS FILHO et al, 2010), which is a result of management techniques common to this kind of production (HOPKINS; DIGIACOMO, 1997;FERNANDES et al, 2009). …”

Section: Introductionmentioning

confidence: 99%

Effects of bovine leukemia virus infection on crossbred and purebred dairy cattle productive performance in Brazil

et al. 2014

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The aim of this study was to evaluate the effects of bovine leukemia virus (BLV) infection on productive performance of dairy cattle in Brazil. A total of 158 blood samples from lactating adult cows, purebred Holstein and crossbred Holstein X Zebu, were analyzed by Agar Gel Immunodifusion Test (AGID) and leukogram. According to AGID and leukogram results, animals were grouped into three categories: seronegative, seropositive without persistent lymphocytosis, and seropositive with persistent lymphocytosis. Milk production data were compared between groups, according to breed. BLV infected females showed lower milk yield than uninfected ones, both purebred and crossbred ones. There was no difference between milk yield of seropositive cows with or without persistent lymphocytosis. These results indicate an association between BLV infection and reduction of milk production, and this study is the first one to show these effects in crossbred Holstein X Zebu cows. Key words: Bovine leukemia virus, milk production, purebred, crossbred, cow ResumoO objetivo desse estudo foi avaliar os efeitos da infecção pelo vírus da leucose bovina (VLB) na produção de vacas leiteiras no Brasil. Foram analisadas 158 amostras de sangue de vacas adultas em lactação puras da raça Holandesa e mestiças Holandês X Zebu. As amostras foram testadas pela Imunodifusão em Gel de Ágar (IDGA) e pelo leucograma. De acordo com os resultados da IDGA e do leucograma, os animais estudados foram agrupados em três categorias: soronegativos, soropositivos sem linfocitose persistente e soropositivos com linfocitose persistente. Os dados de produção leiteira foram comparados entre os grupos, de acordo com a raça. Vacas infectadas com o VLB apresentaram produção de leite inferior que de vacas não infectadas, tanto puras como mestiças. Não houve diferença na produção de leite de vacas positivas com e sem linfocitose persistente. Esses resultados indicam a associação da infecção pelo VLB com a queda na produção de leite, e esse é o primeiro estudo a mostrar tais efeitos em vacas mestiças Holandês X Zebu. Palavras-chave: Vírus da leucose bovina, produção de leite, pura, mestiça, vaca

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Natural Transmission of Bovine Leukemia Virus in Dairy and Beef Cattle

Cited by 134 publications

References 52 publications

Transmission of bovine leukaemia virus within dairy herds by simulation modelling

Transmission of bovine leukaemia virus within dairy herds by simulation modelling

A novel association of BoLA DRB3 alleles in BLV infected cattle with different proviral loads

Effects of bovine leukemia virus infection on crossbred and purebred dairy cattle productive performance in Brazil

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