Genetic heterogeneity among bovine leukemia viruses in Japan and their relationship to leukemogenicity

Abstract

Bovine leukemia virus (BLV) infection in cattle causes persistent lymphocytosis, and a few percent of infected animals develop lymphoid tumors, namely enzootic bovine leukosis (EBL). In this study, a 440-bp fragment of the env gene was amplified from 204 tumor samples collected from different regions of Japan and analyzed by restriction fragment length polymorphism (RFLP) to determine the association of BLV with EBL. Of the seven RFLP types defined, types I, II, and III were dominant and found in 12.7, 75.0, and 8.3% of tumor samples, respectively. Cattle harboring type III virus were significantly older than other animals at the time of diagnosis of EBL. Type III viruses were found in approximately 33% and 5.5% of Japanese Black and Holstein cattle, respectively, with EBL. These findings indicate that genetically distinct BLV was associated with EBL in Japan and that the genetic profile may influence the leukemogenicity of the virus.

Detection of Bovine Leukemia Virus in Brains of Cattle with a Neurological Syndrome: Pathological and Molecular Studies

“…Its topology confirmed the separate genotypes reported by these cited authors. Discussions and controversies have been generated concerning the number of genotypes of BLV but have evolved to consensus on the existence of at least seven genotypes, based both on studies using PCR-RFLP and those employing sequencing analyzes [24, 30, 32]. However, evidence for an eighth genotype was reported by Hemmatzadeh [33] and suggested by Matsumura et al [31], which is why it was considered by this study.…”

Prevalence and Risk Factor Analysis of Bovine Hemoplasma Infection by Direct PCR in Eastern Hokkaido, Japan

“…Vertical transmission of BLV in cattle across the placenta or through colostrums has been previously reported [16]. Horizontal transmission of BLV has also been reported, which can occur with hematophagous insect bites or inappropriate medical treatment [12,14]. One report described the use of molecular techniques to show how hemoplasma could be transmitted vertically and horizontally in cattle [11].…”

The Molecular Characterization of Bovine Leukaemia Virus Isolates from Eastern Europe and Siberia and Its Impact on Phylogeny

“…These mutations conferred some differences in restriction enzyme sites allowing the classification of BLV isolates into three [14] and six [15] genotypes by RFLP analysis. It was also demonstrated that some genotypes can influence the leukomogenecity of a virus [16]. Fechner et al [14] reported the association between some BLV variants and the failure of antibody detection in infected cattle; however, Licursi et al [15] and Asfaw et al [17], did not observe a relationship between particular genotypes and the serological status of infected animals.…”