[Preparative isolation of the glycosylated protein and the major core protein of bovine leukemia virus].

A technique for purifying intact bovine leukemia virus (BLV) and a procedure for preparing gag protein (p24) and envelope glycoprotein (gp 51) from intact BLV are described. The preparation method employs solubilization of BLV by n-octyl-beta-D-Glycopyranoside and sodium desoxycholate with following ultracentrifugation in a linear 10-60% sucrose gradient. The isolated components preserve their antigenicity.

[Biosynthesis of immunoglobulin G-binding factor in cattle lymphocytes].

Synthesis of the IgG-binding factor was estimated by the amount of labeled [14C]hydrolysate of proteins in the total synthesized de novo protein. The obtained data showed that the IgG binding factor which was synthesized by blood lymphocytes of the normal cattle and that suffered from chronic leukemia had a molecular weight of 72 kDa and was revealed before and after restoration of S-S bonds as one peptide.

[Segmental flexibility of Fc-region of spin labeled 2 subclasses of IgG molecule from cow blood and local conformational mobility of their carbohydrate components].

Spin-label was bound to carbohydrates of Fc-region of two subclasses of the IgG molecule from the blood serum of healthy and ill cows. By the value of rotational correlation time (10 nsec) internal flexibility of Fc-region of both IgG subclasses and by value of the order parameter (S = 0.9)--rigid attachment of oligosaccharide chains to protein parts of the molecules were found.

[Quantitative parameters of the IgG binding by Fc receptors and the functional activity of blood lymphocytes in healthy cattle and cattle with chronic lympholeukemia].

The binding of IgG to lymphocyte Fc receptors in the blood of healthy cattle and of cattle with chronic lympholeukemia has been studied by fluorometric techniques before and after the incubation of lymphocytes in a serum-free medium at 37 degrees C. The study has shown that changes in the intensity of binding of IgG to Fc receptors of normal and leukemic lymphocytes correlate with changes in the cell-mediated cytotoxic activity of the corresponding lymphocytes. Lower cell-mediated cytotoxic activity of leukemic lymphocytes in comparison with that of normal lymphocytes was parallelled by a lower association constant of IgG with leukemic lymphocytes Fc receptors.

[Isolation of immunoglobulin G-binding factor from blood lymphocytes of cows with lymphocytic leukemia].

Incubation of bovine blood lymphocytes in the medium without serum at 37 degrees C caused the spontaneous release of immunoglobulin G-binding factor (IBF-IgG), which was isolated from the medium by the affinity chromatography on IgG, immobilized on sepharose 4B. The electrophoretic analysis showed one polypeptide chain with a molecular weight of 72000 Dalton. The biological activity of IBF-IgG was tested using the EA-rosette inhibition technique.