The bovine leukemia virus (BLV) is an oncogenic retrovirus that is associated with the development of persistent lymphocytosis (PL) and lymphoma in cattle. While B lymphocytes have been shown to be the primary cellular target of BLV, recent studies suggest that some T lymphocytes and monocytes may be infected by the virus. Because virally altered functions of monocytes and/or T cells could cont...

The prevalence of BHV-1 and BLV antibodies was studied in 313 serum samples collected from 5 dairy cattle herds. Serum samples were collected from both apparently healthy animals and animals with respiratory symptoms. The samples were tested for the presence of antibodies against BHV-1 and BLV using virus neutralization and agar gel immunodiffusion test, respectively. The results indicated that...

Programmed death-1 (PD-1) is a known immunoinhibitory receptor that contributes to immune evasion of various tumor cells and pathogens causing chronic infection, such as bovine leukemia virus (BLV) infection. First, in this study, to establish a method for the expression and functional analysis of bovine PD-1, hybridomas producing monoclonal antibodies (mAb) specific for bovine PD-1 were establ...

Bovine leukemia virus (BLV) is the etiologic agent of enzootic bovine leukosis. We previously identified several mutants of the BLV Tax protein with an ability to transactivate transcription via the BLV enhancer that is significantly greater than that of the wild-type Tax protein. Moreover, the mutant proteins also activated other viral enhancers, such as the enhancer of human T-cell leukemia v...

The gene encoding the major envelope glycoprotein (gp51) with its signal sequence, represented by an additional NH2-terminal 33-residue amino acid sequence of bovine leukemia virus (BLV), was inserted into a baculovirus transfer vector. A recombinant virus expressing a secreted gp51 protein in insect cells was isolated. The recombinant gp51 expressed was characterized by using an anti-BLV monoc...

The European Community's (EC) Key, which is also called Bendixen's Key, is a well-established bovine leukemia virus (BLV) diagnostic method that classifies cattle according to the absolute lymphocyte count and age. The EC Key was originally designed for dairy cattle and is not necessarily suitable for Japanese Black (JB) beef cattle. This study revealed the lymphocyte counts in the BLV-free and...

Human infections with Shiga toxin (Stx)-producing Escherichia coli (STEC) cause hemorrhagic colitis. The Stxs belong to a large family of ribosome-inactivating proteins (RIPs) that are found in a variety of higher plants and some bacteria. Many RIPs have potent antiviral activity for the plants that synthesize them. STEC strains, both virulent and nonvirulent to humans, are frequently isolated ...

The gag gene encoded protein, p24 of bovine leukemia virus (BLV), was cloned and expressed as thioredoxin-6xHis-p24 protein in Escherichia coli. The bacterial cells carrying plasmid pT7THis-p24 expressed the protein of 38 kDa that was detected by immunoblotting analysis using anti-p24 monoclonal antibodies and sera from BLV infected cattle and sheep. The purified p24 fusion protein was shown to...

Bovine leukemia virus (BLV) is a valuable model system for understanding human T-lymphotropic virus 1 (HTLV-1); the availability of an infectious BLV clone, together with animal-model systems, will help to explore anti-HTLV-1 strategies. Nevertheless, the specificity and inhibitor sensitivity of the BLV protease (PR) have not been characterized in detail. To facilitate such studies, a molecular...

Blood leukocytes of cattle characterized in terms of bovine leukemia virus (BLV) infection and persistent lymphocytosis (PL) were examined for the presence of lymphocyte subpopulation markers and viral antigens. The percentages of cells with surface and intracytoplasmic immunoglobulin M (IgM) and erythrocyteantibody-rosetting cells agreed closely in all infected cattle. This correlation and the...