Analysis of risk factors associated with bovine leukemia virus seropositivity within dairy and beef breeding farms in Japan: A nationwide survey

Kobayashi, Sota; Hidano, Arata; Tsutsui, Toshiyuki; Yamamoto, Takehisa; Hayama, Yoko; Nishida, Takeshi; Muroga, Norihiko; Konishi, Misako; Kameyama, Ken-ichiro; Murakami, Kenji

doi:10.1016/j.rvsc.2013.11.014

Cited by 47 publications

(41 citation statements)

References 16 publications

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“…The majority of BLV-positive samples detected in this study were collected from relatively large dairy farms where milking is the most common activity. A tendency towards high rates of BLV infection on dairy farms was also found in a Japanese study [39]. Thompson and Miller [40] demonstrated that pathogens can be transmitted during the milking process.…”

Section: Discussionmentioning

confidence: 55%

“…By contrast, cattle that were negative for the BLV provirus were raised on small farms. Previous studies focusing on risk factors for BLV transmission revealed that loose housing systems, the presence of hematophagous insects, blood-contaminated dehorning devices [41], physical contact [42], common use of needles and/or the introduction of infected animals [39] are the predominant risk factors. Therefore, we believe that the extremely high level of BLV present in farms in ''V'' City may be the result of cattle management procedures that involve transfer of infected blood, such as common use of needles, ear tattooing, physical contact and/or cattle exchange from one farm to another, as well as infection through milking.…”

Section: Discussionmentioning

confidence: 99%

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Detection and molecular characterization of bovine leukemia virus in Philippine cattle

et al. 2014

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Bovine leukemia virus (BLV) is the etiological agent of enzootic bovine leukosis, which is the most common neoplastic disease of cattle. BLV infects cattle worldwide, imposing a severe economic impact on the dairy cattle industry. However, there are no comprehensive studies on the distribution of BLV in the Philippines, and the genetic characteristics of Philippine BLV strains are unknown. Therefore, the aim of this study was to detect BLV infections in the Philippines and determined their genetic variability. Blood samples were obtained from 1116 cattle from different farms on five Philippine islands, and BLV provirus was detected by BLV-CoCoMo-qPCR-2 and nested PCR targeting BLV long terminal repeats. Out of 1116 samples, 108 (9.7 %) and 54 (4.8 %) were positive for BLV provirus, as determined by BLV-CoCoMo-qPCR-2 and nested PCR, respectively. Of the five islands, Luzon Island showed the highest prevalence of BLV infection (23.1 %). Partial env gp51 genes from 43 samples, which were positive for BLV provirus by both methods, were sequenced for phylogenetic analysis. Phylogenetic analysis based on a 423-bp fragment of the env gene revealed that Philippine BLV strains clustered into either genotype 1 or genotype 6. Substitutions were mainly found in antigenic determinants, such as the CD4(+) T-cell epitope, the CD8(+) T-cell epitope, the second neutralizing domain, B and E epitopes, and these substitutions varied according to genotype. This study provides comprehensive information regarding BLV infection levels in the Philippines and documents the presence of two BLV genotypes, genotypes 1 and 6, in this population.

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Section: Discussionmentioning

confidence: 55%

Section: Discussionmentioning

confidence: 99%

Detection and molecular characterization of bovine leukemia virus in Philippine cattle

et al. 2014

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“…Furthermore, the lack of insect control program has been recognized as a risk factor for BLV infection [82,83]. In warm regions, the animals may be exposed to a high density of hematophagous insects that continuously fed on them; hence, the control of bloodsucking insects by pesticides has been reported to prevent the transmission in a model farm [84].…”

Section: Transmission Of Blv and Economic Impact Of The Infectionmentioning

confidence: 99%

Major Histocompatibility Complex-Associated Resistance to Infectious Diseases: The Case of Bovine Leukemia Virus Infection

Gutiérrez¹,

Esteban²,

Lützelschwab³

et al. 2017

Trends and Advances in Veterinary Genetics

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The major histocompatibility complex (MHC) is a polymorphic gene cluster of about 150 genes, present in all vertebrates. Many of these genes contribute to immunity. Particularly, MHC-encoded class I and class II molecules, which are typically highly polymorphic and polygenic, are central in defining the specificity of the adaptive immune response. Among the diversity of genes associated with disease resistance, MHC genes are particularly interesting as they are associated with resistance and susceptibility to a wide range of diseases, some of which produce important economic losses in livestock. Enzootic bovine leukosis is an infectious disease caused by the retrovirus bovine leukemia virus (BLV), with an important economic impact, mainly in dairy herds. In this chapter, MHC-associated genetic resistance to BLV is revised. Certain alleles of the bovine MHC (BoLA) class II locus have been found strongly associated with resistance to viral dissemination. Genetic selection of resistant animals emerges as a natural strategy for the control of infectious diseases, especially when there is no other alternative of control or prevention, as vaccines. Founded on this knowledge, a BLV control program based on selection of genetically resistant cattle was designed. The proof of concept indicates that this strategy is feasible to implement in dairy herds.

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“…Therefore, detection of host anti-BLV antibodies may indicate the presence of the infection source (Kobayashi et al, 2014).…”

Section: Introductionmentioning

confidence: 99%

“…However, BLV has been detected at various frequencies on farms worldwide. For instance, it was estimated that in the United States 89.0% of dairy herds were infected with BLV in 1996 and 83.9% in 2007 (Kobayashi et al, 2014).…”

Section: Introductionmentioning

confidence: 99%

Seroprevalence and risk factors associated with bovine leukemia virus in Colombia

Ortega¹,

SÃ¡nchez²,

TobÃ3n³

et al. 2016

J. Vet. Med. Anim. Health

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An epidemiological study was conducted to establish the prevalence of the Bovine Leukemia Virus (BLV) in Colombia and to describe risk and protecting factors associated with this infection disease. The study was performed with an observational descriptive cross-sectional process in twelve Colombian regions, by collecting blood samples from 8150 bovines in 390 cattle farms between February and September 2014. The seroprevalence obtained by enzyme-linked immunosorbent assay (ELISA) tests was 42.7% in animals and 67.7% in farms. The highest seroprevalence was found in Villavicencio with 91% in animals. The infection with blood parasites and another virus was attributed to be among the main risk factors associated to BLV. The use of individual needles during veterinary procedures was found to be the main source of protection against the virus. Climate data and ecological groups were recorded at sampling sites in order to elaborate geo-referencing maps by using analyzes of viral distribution around the country. Results obtained showed that there is a probability of an increase on the incidence of this pathology as well as a predictive issue associated with places and climate variables. It was found that developing epidemiological analyzes aiming to report and monitor the presence of this disease and its risk factors is the only alternative to generate prevention and control strategies.

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Analysis of risk factors associated with bovine leukemia virus seropositivity within dairy and beef breeding farms in Japan: A nationwide survey

Cited by 47 publications

References 16 publications

Detection and molecular characterization of bovine leukemia virus in Philippine cattle

Detection and molecular characterization of bovine leukemia virus in Philippine cattle

Major Histocompatibility Complex-Associated Resistance to Infectious Diseases: The Case of Bovine Leukemia Virus Infection

Seroprevalence and risk factors associated with bovine leukemia virus in Colombia

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