Hot topic: Bovine leukemia virus (BLV)-infected cows with low proviral load are not a source of infection for BLV-free cattle

Juliarena, Marcela Alicia; Barrios, Clarisa Natalia; Ceriani, María Carolina; Esteban, Eduardo

doi:10.3168/jds.2015-10480

Cited by 80 publications

(72 citation statements)

References 14 publications

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“…Genetic selection for BoLA DRB3.2*0902 allele has been proposed to breed cattle that are resistant to HPVL development (JULIARENA et al, 2016 (JULIARENA et al, 2008). It must be considered that expression of BoLA DRB3 might be influenced by polymorphisms in other surrounding genes.…”

Section: Discussionmentioning

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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Section: Discussionmentioning

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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“…While no BLV-free cattle became infected in this experimental herd, new infections occurred in other herds of the region. 48 This situation simulates the second step of the proposed control plan.…”

Section: Control Of Blv Infection By Genetic Selection Of Resistant Cmentioning

confidence: 99%

“…On the other hand, LPL cattle, carrying an exiguous number of infected lymphocytes in peripheral blood, have been proven not to transmit the infection to adjacent uninfected cattle in natural conditions of management. 48 Evidence has been reported on the role of blood sucking insects in the transmission of BLV, and the beneficial effect of insect vector control. 49 …”

Section: Transmissionmentioning

confidence: 99%

“…143,[147][148][149][150][151][152] BoLA-DRB3*0902 animals with LPL phenotype did not transmit the infection at herd level in natural conditions, 48 and under experimental conditions, it was necessary to inoculate a large volume of blood in order to infect sheep. 145,147 Furthermore, to date, the BoLA-DRB3*0902 allele has not been associated with susceptibility to other infectious agent, nor has it negatively affected production or reproduction traits.…”

Section: Control Of Blv Infection By Genetic Selection Of Resistant Cmentioning

confidence: 99%

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Bovine leukemia virus: current perspectives

Juliarena¹,

Barrios²,

Lützelschwab³

et al. 2017

VAAT

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Enzootic bovine leukosis, caused by bovine leukemia virus (BLV), is the most common neoplasm of dairy cattle. Although beef and dairy cattle are susceptible to BLV infection and BLV-associated lymphosarcoma, the disease is more commonly detected in dairy herds, mostly because of the management practices in dairy farms. The pathogenicity of BLV in its natural host, the bovine, depends mainly on the resistance/susceptibility genetics of the animal. The majority of infected cattle are asymptomatic, promoting the extremely high dissemination rate of BLV in many bovine populations. The important productive losses caused by the BLV, added to the health risk of maintaining populations with a high prevalence of infection with a retrovirus, generates the need to implement control measures. Different strategies to control the virus have been attempted. The most effective approach is to identify and cull the totality of infected cattle in the herd. However, this approach is not suitable for herds with high prevalence of infection. At present, no treatment or vaccine has proven effective for the control of BLV. Thus far, the genetic selection of resistant animals emerges as a natural strategy for the containment of the BLV dissemination. In natural conditions, most of the infected, resistant cattle can control the infection, and therefore do not pass the virus to other animals, gradually decreasing the prevalence of the herd.

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“…Thus, BLV-infected BoLA-DRB3*0902 cows incorporated into a BLV-negative dairy herd did not cause infection of the latter for a long time. The infected individuals were positive for BLV antibodies, though in low titers, and contained BLV proviral DNA in the genome [20].…”

Section: Introductionmentioning

confidence: 99%

The Infection Hazard of Carriers of Proviral Bovine Leukemia Virus and Its Evaluation With Regard to Leukocytosis

Kosovskii¹,

Glazko²,

Andreichenko³

et al. 2016

S-h. biol.

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A b s t r a c tThe spread of the bovine leukemia virus (BLV) brings significant economic damage to dairy and beef cattle still due to the problems to develop the optimal methods for its prevention. The situation is compounded by the fact that the clinical manifestation of lymphocytic leukemia has been observed in animals during 5 to 10 years after infection in approximately 5-7 % of animals. Subdivision of BLV infected B cells on the producers of mature viral particles and precursors of the formation of lymphomas necessitates of separately consideration of the risk of infecting animals and forecast for development of lymphocytic leukemia. Testing antibodies to viral antigens, or provirus DNA insertion into the host genomes does not allow to reveal the most dangerous animals in view of their role in the infection spread, which is most essential for its control. In this regard, the particular urgency is the method development to assess the infection hazard from carriers of provirus DNA of bovine leukemia virus, associated with a large number of B lymphocytes, producing mature viral particles. In order to evaluate the possibility of using in these purposes not only testing individual animals on the quantity of viral RNA in blood samples, but the proliferative activity of leucocytes, these two characteristics were compared in the present work. The presence or absence of genome integrated provirus DNA in Black-and-White Holstein cows (n = 57, commercial herd) was evaluated and the group of infected animals was revealed when using primers designed by us for BLV gag and pol genes (G.Yu. Kosovoskii et al., 2013). The relative quantity expression of provirus in individual infected cows using RT-PCR analysis and primers to the fragment of the BLV pol gene were assessed. The counting of leukocytes in blood samples of all cows, included in the analysis, was performed. The number of leucocytes in cows free from infection, with the exception of one cow, was less than 1210 9 cells/l. This indicator in infected animals divided the investigated cows into two subgroupsin the first subgroup the leucocyte values did not exceed 1710 9 cells/l, in the second subgroup the number of leukocytes was significantly higher, reaching 2810 9 cells/l in some animals. It was important to note, that the amount (above 2010 9 cells/l) of BLV RNA, sufficient to detect by RT-PCR, was revealed only in the second subgroup. The coincidence of the increased leucocyte amount and the BLV RNA in blood of infected animals indicates that particular these cows represent the greatest infection hazard and suggests that the combination of estimates of the number of leukocytes and RNA BLV can be quite a reliable approach for the herd recovery by priority of their liquidation.

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Hot topic: Bovine leukemia virus (BLV)-infected cows with low proviral load are not a source of infection for BLV-free cattle

Cited by 80 publications

References 14 publications

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

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

Bovine leukemia virus: current perspectives

The Infection Hazard of Carriers of Proviral Bovine Leukemia Virus and Its Evaluation With Regard to Leukocytosis

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