It is widely accepted that the majority of cancers result from multiple cellular events leading to malignancy after a prolonged period of clinical latency, and that the immune system plays a critical role in the control of cancer progression. Bovine leukemia virus (BLV) is an oncogenic member of the Retroviridae family. Complete genomic sequences of BLV strains isolated from peripheral blood mo...

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...

The effects of bovine leukemia virus (BLV) on the immune response have been extensively investigated; however, its effects on mammary gland immunity are only speculative. Although BLV has a tropism for B cells, it can affect both adaptive and innate immunities because these systems share many effector mechanisms. This scenario is the basis of this investigation of the effects of BLV on mammary ...

The role of colostrum and milk in the transmission of the bovine leukemia virus (BLV) was examined by monitoring the development of BLV infection in calves that were fed since birth on colostrum and milk from their BLV-positive dams and then reared in complete or partial isolation from infected cattle. Twenty-one of the 25 calves raised in complete isolation re mained negative for BLV until the...

Seroprevalence of bovine leukemia virus (BLV) infection was studied in replacement dairy heifers. Blood samples were collected from 80 pregnant heifers raised in 8 dairy farms in Saraburi province, the central part of Thailand and serum samples were tested for antibodies against BLV infection using commercially available ELISA test kits. The results revealed that 26 (32.5%) pregnant heifers wer...

For the further characterization of bovine leukemia virus (BLV)-induced leukemogenesis, we investigated the association between polymorphism of ovine leukocyte antigen (OLA)-DRB1 gene and tumor development after infection of sheep with BLV. We infected 28 sheep with BLV and cloned exon 2 of the OLA-DRB1 gene from asymptomatic animals and from animals with lymphoma Sequence analysis revealed tha...

Infection of cattle with bovine leukemia virus (BLV) has been observed and reported worldwide, including in Korea. The onsite identification of infected cattle would help decreasing and eradicating BLV infections on farms. Here, we present a new immunochromatographic assay that employs monoclonal antibodies (MAbs) for the detection of antibodies against BLV in the field. BLV envelope glycoprote...

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...

Bovine leukemia virus (BLV) is a deltaretrovirus that infects cattle worldwide. In agriculturally intensive regions, approximately 30% of dairy cows are BLV infected. Like the human T-cell leukemia virus (HTLV), there is a lengthy period of viral quiescence after initial infection with BLV. Unlike HTLV, BLV resides predominantly in B cells. Lymphoma is observed in less than 10% of BLV-infected ...

The relationship of cull rate to age was investigated retrospectively in dairy cows with and without antibodies to bovine leukemia virus (BLV). Banked sera from eight annual herd tests on one 200-cow herd were tested for presence of BLV antibodies by agar-gel immunodiffusion using the Mr 51,000 glycoprotein antigen of BLV. Age-specific cull rates were computed for BLV-antibody-positive and anti...