Identification and Quantitative Determination of Myeloid Chloroleukæmia Virus with the Aid of the Resistance Phenomenon

Abstract

THE examination of viral leukæmias in mice is seriously hindered by the absence of reliable methods of identification and quantitative determination of leukæmogenic viruses. Titration of viruses in vivo by their leukæmogenic action is practically impossible because of the long latent period (the only exception is the Friend virus). After publication of Habel's¹, Sjögren's² and Sachs's^3,4 data on the resistance of the animals infected with oncogenic viruses against transplantation of neoplasms induced by the same virus, we attempted to use the resistance phenomenon for identification and titration of myeloid chloroleukæmia virus (MCLV). This virus, which we isolated in 1958s from our sub-line of Ehrlich tumour^5,6, is similar to or even identical with the Graffi virus⁷. Since its isolation the virus has been propagated in mice.