Bovine Lymphocytic Leukemia: Studies of Etiology, Pathogenesis and Mode of Transmission. Final Report, April 30, 1969-June 30, 1982

摘要

The primary objectives were to elucidate the cause(s) and early pathogenesis of the adult form of bovine lymphosarcoma through experimental transmission of the disease. Large quantities of bovine leukemia virus (BLV) were propagated in short-term mitogen stimulated, lymphocyte cultures. Cultures containing abundant BLV particles were pooled and further processed by continuous flow, density gradient, ultracentrifugation. This highly concentrated, cell free, BLV preparation was used as inoculum for 12 late stage bovine fetuses (inoculated in utero) and two newborn calves. Extensive monitoring of lymphosarcoma associated blood parameters such as BLV production, nuclear pocket incidence, B-cell percentage, anti-BLV serology titer, and complete blood count established that all inoculated animals became persistently BLV infected. However, after more than five years of incubation, no clinical cases of lymphosarcoma had developed. Consequently, five of these well-characterized animals received monthly injections of BLV infected lymphocytes in an attempt to accelerate tumor formation. One year following completion of this 15 month injection series, the experiment was terminated and each animal subjected to extensive physical and post-mortem examination. None of the 11 animals remaining, including the five repeatedly inoculated, showed clinical signs of leukemia. Necropsy examination, however, revealed one case of lymphosarcoma which was histologically confirmed. This animal had a six year history of persistent lymphocytosis and had received the supplemental series of inoculations. (ERA citation 08:001037)