BLV-p24 expression in BLV infected cattle and detection of BLV-p24 receptors in cattle afflicted with tumorous leukosis in vivo.

Noncultivated and short-term cultivated blood leukocytes of BLV-infected cattle both with and without tumorous leukosis have been investigated for BLV-p24 antigen expression and for their capacity to bind BLV-p24 antigen. In animals with persistent lymphocytosis using cell extracts of 3-6 X 10(8) non-short-term cultivated blood leukocytes, BLV-p24 antigen could be identified by means of competitive RIA. In cattle with tumorous leukosis, the antigen detection in non-short-term cultivated leukocytes may be masked by the presence of antigen-binding receptors.

Bovine leucosis virus challenge infection of calves following application of BL-3 cells.

8 calves were vaccinated 3 times with 1.5.10(7) BL-3 cells.

Antibody production against BLV-p24 in calves following application of cell extracts from tumorous lymph nodes of cattle with enzootic bovine leukosis.

In the cell extract from tumorous lymph nodes of bovine leukosis virus (BLV)-infected cattle (tumour cell extract) and from lymph nodes of BLV-free cattle (control cell extract) neither the gp51 nor the p24 antigens were detectable. The tumour cell extract contained receptors for the BLV antigens gp51 and p24. The immunogenicity of the cell extracts was tested in calves.

Demonstration of a thymus cell tumour in BLV-infected cattle.

Occurrence of thymus cell tumours was followed in cattle with enzootic leukosis using a thymus-specific antiserum. Among 32 tumorous lymph nodes investigated, one could be identified as a thymus cell tumour. In the DNA extract from this tumorous lymph node BLV-specific sequences have been demonstrated.

BLV receptor activity in plasma membranes from tumorous lymph nodes of BLV-infected cows.

Plasma membranes of cells from lymph nodes of bovine leukaemia virus (BLV)-free cattle and of cells from tumorous lymph nodes of BLV-infected cattle have been investigated for their reactivity with iodine labelled BLV antigens gp51 and p24. It has been found that only the plasma membranes from cells of tumorous lymph nodes bound gp51 and p24. The binding could be abolished by addition of nonlabelled antigens.

[Transplantation immunity to a UV-induced murine sarcoma by injection of a glycoprotein fraction from the tumor].

One single subcutaneous injection of 100 micrograms protein of a glycoprotein fraction from UV light-induced mouse sarcoma produces transplantation resistance against the same tumor. The glycoprotein fraction was isolated by 2% Triton X-100 and 3M KCl from enriched membranes. As measured by immunogenicity a tenfold enrichment of a tumor-associated antigen was obtained when compared with the 3M KCl extract on the basis of protein concentration.

Differences of the in vitro reactivity of lymphocytes from normal and persistently lymphocytotic cows to enzootic bovine leukosis tumour membrane extracts as detected with the macrophage-electrophoretic mobility test.

The response of peripheral blood lymphocytes from normal and persistently lymphocytotic cows to cell membranes and sodium cholate-extracted membrane proteins from normal and tumourous lymph nodes was tested with the macrophage-electrophoretic-mobility test with guinea pig peritoneal macrophages as indicator cells. Lymphocytes from 13 cows with persistent lymphocytosis (PL) showed a positive reaction with cholate extracts from tumour cell membranes. On the other hand, there was a negative reaction with corresponding extracts from normal lymph nodes for 11 animals.

[Demonstration and characterization of tumor-associated antigenic components from cell membranes of a UV-induced murine sarcoma using the MEM technic].

Purification of tumour-associated antigenic material from the ascites sarcoma cells was attempted by extraction with 3 M KCl and SDS-polyacrylamide gel electrophoresis (SDS-PAGE). The antigenic activity was assayed in the macrophage-electrophoretic-mobility (MEM) test. Extraction of whole tumour cells with 3 M KCl results in preparations with low antigenic activity which on SDS-PAGE show a very heterogenous composition of more than 20 protein bands.