Detection of bovine leukaemia virus (BLV) infection by DNA probe technology

Expression of bovine leukemia virus ENV glycoprotein in insect cells by recombinant baculovirus

The gp51-p30 glycoprotein constituting BLV envelope was expressed in Sf-21 insect cells by means of recombinant baculoviruses. Post-infection cell lysates were analyzed, in order to define the immunologic reactivity of recombinant products. Oligosaccharide chains, containing N-acetylglucosamine, mannose, galactose and sialic acid were found on recombinant gp51-p30. In order to investigate the timing of transcription and translation of the glycoprotein, kinetic assays were carried out on cell lysates and directly in situ on Sf-21 cells during the course of baculovirus infection. The use of different solubilizing reagents was also evaluated in order to rescue recombinant glycoprotein from its subcellular location.

Molecular characterization of a variant of proviral bovine leukaemia virus (BLV)

Southern-blot hybridization and partial sequencing of the pol and env genes were used to characterize BLV-integrated provirus of seropositive cattle from two dairy herds in northern Italy. Comparison of the data obtained with those of previously characterized BLV strains from other geographic areas (Australia, Belgium, Japan and USA) revealed the presence of a viral variant (BLV-12), which showed both conserved and unique features. Regarding the gp51 envelope glycoprotein, the BLV-12 variant showed: 1. A high extent of conservation, which included potential glycosylation sites and cysteine residues; 2. Three unique amino acid residues not present in any of the other BLV strains analysed; and 3. Some variability at the level of one (G) of the three (F, G and H) conformational epitopes, which is probably important in the process of infection. These results agree with the suggestion that the sequence variability of the gp51 glycoprotein preferentially involves structures whose change is thought to underlie the phenomenon of escape from immune surveillance.

In situ hybridization for the demonstration of bovine leukemia virus transcripts in lymphosarcoma cells using biotinylated probes

Bovine leukemia virus (BLV) RNA was demonstrated in peripheral blood lymphocytes treated with concanavalin A or phytohemagglutinin from a BLV-infected ox, and in lymphosarcoma cells cultured without mitogen from an enzootic bovine leukosis cow by in situ hybridization using biotinylated DNA probes.