2013 Volume 66 Issue 2 Pages 109-114
We investigated the conditions and factors associated with the onset of bovine leukosis in 18 Holstein cows from July to November 2009. Physical examinations revealed abnormalities in 22% cows, while blood tests revealed abnormal lymphocytes in the peripheral blood of 57% cows. Histological examinations revealed diffuse, large cell lymphosarcoma in all cows. T-cell lymphoma was detected in a 29-month-old cow without bovine leukemia virus (BLV) infection, while B-cell lymphoma was observed in the remaining 17 cows aged ≥45 months with BLV genotype I. Immunohistochemical examinations detected p53 proteins in 29% of leukemic cows with a significant difference compared with that in the control. PCR analysis did not detect bovine immunodeficiency virus (BIV) in any cow. Bovine leukocyte antigen (BoLA) DRB3 allele 1501 was detected in 75% of leukemic cows; allelic frequency was 41% and there was a significant difference compared with that in the control. These findings suggest that nearly all cases of bovine leukosis in this study were enzootic bovine leukosis with BLV genotype I, that onset of bovine leukosis does not necessarily require BIV infection, and that p53 and BoLA-DRB3 alleles play some role in the onset of bovine leukosis.