p53 mutation as a potential cellular factor for tumor development in enzootic bovine leukosis

Mutations of p53 in the lymphocytes from peripheral blood and from tumoral lymph nodes in six naturally occurring bovine leukemia virus (BLV)-infected cows were examined. A point mutation of the p53 gene was found in three of six (50%) BLV-infected cows. These p53 gene mutations resulted in amino acid substitutions of codons 144, 167 and 241. The BLV-infected cow in the tumor stage had abnormally proliferating monoclonal B-lymphocytes having the p53 mutation. However, the mutation was not found in somatic cells, except for tumor cells. These results show that p53 mutation plays an important role in the pathogenesis of BLV-induced neoplasms, and that the B-lymphocyte bearing p53 mutations may be a target cell for tumor formation of enzootic bovine leukosis.