Bovine leukemia virus (BLV), a retrovirus related to human T-cell leukemia virus types 1 and 2, can induce persistent nonneoplastic expansion of the CD5(+) B-cell population, termed persistent lymphocytosis (PL). As in human CD5(+) B cells, we report here that CD5 was physically associated with the B-cell receptor (BCR) in normal bovine CD5(+) B cells. In contrast, in CD5(+) B cells from BLV-in...

The most important task of the dairy cattle industry is to obtain high quality raw milk. To achieve it, a set measures required, including aimed at increasing biological safety produced materials. aim study was create scientific and methodological basis for Bovine leukemia virus (BLV) gene diagnostics in combined format pathogen indication identification. This required updating strategy BLV PCR...

Bovine leukemia virus (BLV) is silent in most cells detectable in vivo, and the repression of its expression allows BLV to evade the host's immune response. In this study, we examined whether CpG methylation of DNA might be involved in the regulation of the expression of BLV in vivo. To investigate the effects of CpG methylation on the activity of the long terminal repeat (LTR) of BLV, we measu...

Bovine leukemia virus (BLV) is a retrovirus that is highly prevalent in US dairy herds: over 83% are BLV infected and the within-herd infection rate can be almost 50% on average. While BLV is known to cause lymphosarcomas, only 5% or fewer infected cattle will develop lymphoma; this low prevalence of cancer has historically not been a concern to dairy producers. However, more recent research ha...

A plasmid pLTR-DT which contained a gene for diphtheria toxin A-chain (DT-A) under the control of the long terminal repeat (LTR) of bovine leukemia virus (BLV) (BLV-LTR) in the multicloning site of pUC-18 was entrapped in cationic liposomes composed of N-(alpha-trimethylammonioacetyl)-didodecyl-D-glutamate chloride (TMAG), dioleoyl phosphatidylethanolamine (DOPE) and dilauroyl phosphatidylcholi...

by the immunodiffusion test was found to be the same as that detected by the IFA technique (5). Previous studies also showed that disruption of the virus is necessary for release of the antigen, suggesting that the antigen is an internal virion component (3, 6). The resistance of the BLV antigen to ether and acetone, and its presence in the cytoplasm of infected cells, are features which also c...

Efficient transcription and replication of the bovine leukemia virus (BLV) genome require both the viral long terminal repeat (LTR) and the virus-coded transcriptional activator Tax, which functions through a 21-bp sequence (Tax-responsive element [TxRE]) which is repeated three times within the LTR. Since Tax does not bind directly to DNA, host cell transcription factors play a central role in...

Retrovirus genomes have a conserved modular organization that consists of trans-acting gag, pol, and env genes that function through cis-acting sequences to replicate the RNA genome to the DNA provirus. Genetically more complex retroviruses also encode regulatory genes and cis-acting sequences that are essential for their replication. We sought to convert a more complex retrovirus into a simple...

The DNA from 17 lymphoid tumors induced by bovine leukemia virus (BLV) was digested with the restriction endonuclease EcoRI. Filter hybridization analysis using radioactive probes specific for the BLV genome showed that all tumors contained at least one or a portion of one provirus. Digestion of these proviruses with Sac I demonstrated that deletions occurred in about 25% of the cases and invol...