Detection of bovine leukemia virus and identification of its genotype in Mongolian cattle

Ochirkhuu, Nyamsuren; Konnai, Satoru; Odbileg, Raadan; Nishimori, Asami; Okagawa, Tomohiro; Shiro, Motoo; Ohashi, Kazuhiko

doi:10.1007/s00705-015-2676-8

Cited by 30 publications

(33 citation statements)

References 25 publications

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“…The variation of EBL seroprevalence among Brazilian states is due to the different environmental conditions, herd size, cattle management, and genetics, as well as the particularities of the diagnostic techniques employed [14,24,37]. This scenario is also repeated in different countries [32] such as Mongolia [26], Iraq [14], China [39], and Japan [15,27], which reported varied prevalences of 3.9%, 7.75%, 18.3%, and 66.8%, respectively.…”

Section: Discussionmentioning

confidence: 99%

Risk Factors for Enzootic Leukosis in Dairy Cattle from the Brazilian Amazon

Silva

Melchior

Reckziegel

et al. 2019

Acta Scientiae. Vet.

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Background: Enzootic bovine leukosis (EBL) is a viral and lymphoproliferative disease that attributes negative economic impacts to dairy farming. The immunosuppressive condition of these bovines favors the development of bacterial diseases such as tuberculosis, brucellosis, and bovine leptospirosis, which implications to the public health given that they are zoonosis. Diagnosis and control of EBL are neglected in cattle rearing, allowing their dissemination, especially in developing countries. In this sense, the objective of this study was to analyze the risk factors of EBL in dairy cattle from the Brazilian Amazon. Materials, Methods & Results:In order to identify the BLV-infected animals (527 serological samples), we used the agarose gel immunodiffusion serological test (IDGA) to diagnose the EBL and characterize the risk factors through the application of epidemiological questionnaires. We used the logistic regression test to evaluate the existence of a significant association between the variables. The EBL frequency in the study area was 14.42%. We detected seroreagent bovines in all municipalities evaluated with 95% of the properties showing outbreaks of the disease. The reuse of needles was the risk factor with the most significant statistical association (P < 0.01; OR = 2.16). Discussion: The origin of EBL in the Brazilian Amazon is probably related to the expansion of dairy cattle in the 1980s, which, at first, demanded the importation of cattle for the fast formation of the herds, without complying with the sanitary criteria of animal commercialization. The frequency of EBL in the Rio Branco microregion is below the estimated national average, as well as the regional level. The reduced influx of animals due to the geographical situation of Acre, since it is an area of greater physical isolation due to forest and river barriers, may influence the observed frequency. Different environmental conditions, herd size, cattle management, genetics and particularities of the diagnostic techniques should also be considered. The Rio Branco microregion can currently be considered as an area of medium frequency for BLV infection, a situation that ranges from 11 to 30% in the occurrence rate. When compared to herds with low infection frequency (<10%), the elimination of seroreagent animals and their respective outbreaks become more expensive in areas of medium or high frequency. As for the number of outbreaks detected, the finding reflects the degree of negligence regarding the prophylactic measures of EBL since it is a silent propagation disease, as well as the implications for the absence of official control and eradication programs in Brazil. According to the final logistic regression model, the reuse of needles for vaccinations, deworming, and for applying other drugs in different animals was the risk factor of greater association in the region, explaining the widespread occurrence of EBL in the studied farms. In Canadian herds, this practice also was associated with an increase in clinical cases. It is known that ...

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Section: Discussionmentioning

confidence: 99%

Risk Factors for Enzootic Leukosis in Dairy Cattle from the Brazilian Amazon

Silva

Melchior

Reckziegel

et al. 2019

Acta Scientiae. Vet.

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show abstract

Section: Discussionmentioning

confidence: 99%

“…This genotype, along with genotype 3, is common in the USA and Japan while genotypes 2, 5 and 6 have only been found in South America and genotypes 4 and 7 are common in Russia and Eastern Europe [36]. Genotype 1 has also been described in Costa Rica in Central America [17], along with genotype 5 [36]. Of the 5 nucleotide substitutions we identified in the Caribbean strains, two were silent substitutions (G87C and T534C), two were conservative substitutions (A161G and T896C) and one was a non-conservative substitution (C1505T).…”

Section: Discussionmentioning

confidence: 99%

First Molecular Characterization of Bovine Leukemia Virus Infections in the Caribbean

et al. 2016

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Bovine leukemia virus (BLV) is a retrovirus that causes enzootic bovine leucosis. To investigate the presence and genetic variability of BLV in the Caribbean for the first time, we preformed fluorescence resonance energy transfer (FRET)-PCR for the pol of BLV on DNA from whole blood of cattle from Dominica, Montserrat, Nevis and St. Kitts. Standard PCRs with primers for the env were used for phylogenetic analysis of BLV in positive animals. We found FRET-PCR positive cattle (12.6%, 41/325) on Dominica (5.2%; 4/77) and St. Kitts (19.2%; 37/193) but not on Montserrat (0%, 0/12) or Nevis (0%, 0/43). Positive animals were cows on farms where animals were raised intensively. Phylogenetic analysis using the neighbor-joining (NJ) method on partial and full-length env sequences obtained for strains from Dominica (n = 2) and St. Kitts (n = 5) and those available in GenBank (n = 90) (genotypes 1–10) revealed the Caribbean strains belonged to genotype 1 (98–100% sequence homology). Ours is the first molecular characterization of BLV infections in the Caribbean and the first description of genotype 1 in the region.

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“…and -10 in Thailand (Lee et al 2016);genotype-1, -4 and -7 in Mongolia (Ochirkhuu et al 2016); genotype-10 in samples from Myanmar (Polat et al 2016b); and genotype-1 and -6 in Jordan (Ababneh et al 2012). (Rodriguez et al 2011;EPAHW 2015).…”

Section: G E O G R a P H I C A L D I S T R I B U T I O N O F B L V Gementioning

confidence: 99%

“…In addition, infected-cattle were also reintroduced into some of European countries; Take an example, BLV was introduced into the UK through breeding animals from Canada in 1968and 1973(EPAHW 2015 and -10 (in Thailand and Myanmar) are observed only in geographically close areas, probably due to exchange of animals between these countries (Lee et al 2016;Polat et al 2016b). Genotype-6 and -7 are also widely distributed, possibly via cattle importation and animal trading between countries (Polat et al 2015;Ochirkhuu et al 2016). …”

Section: G E O G R a P H I C A L D I S T R I B U T I O N O F B L V Gementioning

confidence: 99%