Isolement de particules virales intracytoplasmiques du type “A” a partir du lymphome murin induit par L'éthyluréthane

Abstract

Isolation of intracytoplasmic type “A” particles from murine lymphoma induced by ethyl‐urethan The significance of naked intracytoplasmic “A” particles present in many cases of murine leukemias and mammary tumors is still unsettled and will become meaningful only after isolating these particles in pure form. Unfortunately, till now, type “A” particles were always isolated mixed with B and mainly C forms. From an urethaninduced lymphoma in Swiss mice, we were able to isolate these “A” particles by means of isopyknic centrifugation in caesium chloride. This rapid technique without any altering detergent produces intact particles. Both in vitro and in vivo electron microscopic aspects are the same. In our first bio‐assays, intraperitoneal injections of A‐fraction into newborn mice gave rise to many malignant mesenchymomes with polymorphic differentiation which were never observed spontaneously in the colony of Swiss mice used by the authors.