Regional Specificity of the Mode of Transmission of Bovine Leukemia Virus and of Garcinogenecity of Viral Tumors

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During a two-year period 1991 - 1992, we made an international joint study on bovine leukemia with Changchun Veterinary College in China.For the 1st year : Hematological and bovine leukemia virus (BLV) antibody investigation were made on a total of 370 heads [257 of yellow cow (beef cattle) of Chinese origin and 113 of Holstein (dairy cattle)]. The antibody investigation was made on the basis of agar gel immunodiffusion reaction (AGID) using BLV diabnostic antigen (Kitasato antigen). As a result, BLV antibody proved to be negative in all dairy cattle, but positive in one of the beef cattle. Hematological investigation revealed lymphocytosis (according to the Bendixbnls leukemia diagnostic criteria) in 3 beef and 15 dairy cattle. All cases werd blood protozoa-negative.For the 2nd year : BLV antibody investigation using the AGID method was made on 180 heads of a Holstein pasture. Histological, immunohistochemical and electron microscopic examinations were also made of those bovine leukemic materials which had been preserved by Changchun Veterinary College. As a result, all dairy cattle proved to be BLV antibody-negative, indicating non-BLV contamination of the above pasture, and this was considered to be ascribable to that successful BLV antibody examination by AGID method which has been made upon introduction of new cows. Bovine leukemia now occurring in China was also revealed to be frequently of B lymphocytic origin and similar to epidemic (adult type) leukemia occurring in Japan.