Here, we used a sheep bioassay to determine the effect of freezing colostrum to prevent the transmission of bovine leukemia virus (BLV) among neonatal calves. Leukocytes were isolated from the colostrum of a BLV-infected Holstein cow and were then either left untreated (control) or freeze-thawed. A sheep inoculated intraperitoneally with the untreated leukocytes was infected with BLV at 3 weeks...

The nucleic acid-binding proteins of bovine leukemia virus (BLV) and feline leukemia virus (FeLV) were isolated in a high state of purity with chloroform-methanol extraction followed by reversed-phase liquid chromatography. Selective solubilization and purity of BLV p12 and FeLV p10 was confirmed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The compositions and molecular weight...

Bovine leukemia virus (BLV) envelope glycoprotein (gp51/ gp30(T-)), consisting of BLV gp51 and BLV gp30 that lacked its C-terminal transmembrane domain, was expressed in insect cells under the control of the baculovirus polyhedron promoter. Recombinant BLV gp51/gp30(T-) secreted from insect cells was determined by immunofluorescence, enzyme-linked immunosorbent and western blot assays using a B...

To further investigate the molecular basis underlying the dysregulation of B cell homeostasis associated with bovine leukemia virus disease progression in cattle, bovine bax was cDNA cloned and sequenced. The predicted amino acid sequence of bovine Bax revealed a 192-amino-acid protein having extensive identity with the human (97%), murine (93%), and rat (94%) homologues. Because the ratio of B...

This report describes the detailed procedures for Western blot analysis using fluorescent antibodies. After electrophoresis and subsequent electroblotting, the fluorescent-labeled antibodies were visible upon ultraviolet illumination of the polyvinylidene fluoride (PVDF) membranes and could then be photographed to give an accurate record of the blots. Fluorescent labeling allows for photographi...

A precipitating antigen of bovine leukemia virus was isolated by isoelectric focusing and Sephadex gel filtration. In SDS-polyacrylamide gel electrophoresis it was found to be a homogeneous protein with a relative molecular weight of 69000 daltons. Because of its relative molecular weight and staining characteristics it was designated as BLV gp69. A protein with the same molecular weight could ...

cDNA synthesized on the bovine leukemia virus RNA template has been cloned in the pBR322 Pst I site. Colony hybridization with BLV RNA fragments and oligo (dT) has revealed a clone with cDNA insert containing 660 3'-terminal nucleotides of the BLV genome. The nucleotide sequence of the insert corresponding to U3 and R regions of the long terminal repeats (LTR) of viral genome has been determine...

Bovine leukemia virus (BLV) is estimated to infect over 83% of dairy herds and over 40% of all dairy cows in the United States. While, BLV only causes leukemia in a small proportion of animals, research indicates that BLV+ cattle exhibit reduced milk production and longevity that is distinct from lymphoma development. It is hypothesized that BLV negatively affects production by interfering with...

Bovine leukemia virus (BLV) infection, endemic in North American dairy herds, has production-limiting effects. A literature review of available papers published since 1995 concerning BLV transmission and its control was conducted. Although confirmed routes were reviewed (blood, natural breeding, utero, colostrum, milk), there is still a lack detailed information on other specific risks for (e.g...

Bovine leukemia virus (BLV) from either persistently infected bat cells or fetal lamb kidney cells induced rapid syncytium formation in F81 indicator cells. Distinct syncytia were seen within 2 h after inoculation of cells with highly concentrated (500-fold) cell-free BLV preparations and within 4 to 8 h when unconcentrated cell-free BLV preparations were used. Indicator cell densities of 1 x 1...