Bovine lymphocytic leukemia: studies of etiology, pathogenesis, and mode of transmission. Progress report No. 19, June 1978-June 1979

Abstract

Bovine leukemia is believed to be caused by an oncogenic RNA virus designated bovine leukemia virus (BLV). The presence of BLV particles in lymphocyte cultures from leukemic cattle and cattle with a persistent lymphocytosis has been consistentily demonstrated. Concentrated, cell free, BLV preparations were used to inoculate 12 late stage bovine fetuses (in utero) and two newborn calves. Current studies involve extensive monitoring of these inoculated animals to detect precancerous changes and obtain a detailed description of the events preceding the development of lymphosarcoma. Ongoing monitoring studies will provide a complete record of all changes in the various leukemia associated parameters. We will then be able to detail when, in what sequence, and to what extent each parameter changes in the course of lymphosarcoma development. Fourteen animals were successfully inoculated during the study. Eleven remain alive, and comprise the current monitoring program. All eleven of these animals are definitely infected with BLV, and in nine the infection has substantially progressed with respect to the parameters being monitored. In addition to transmission and monitoring studies, various lymphocyte subpopulations were examined to determine which cell type(s) are involved in the pathogenesis of bovine lymphosarcoma. These studies have conclusively established that B-lymphocytes aremore » the target cells for BLV infection and that they carry the morphologic nuclear abnormality associated with this disease.« less