Abstract
The discovery that many forms of murine leukemia are of virus etiology has provided scientific investigators with an animal model system in which the mechanisms of neoplastic transformation can be studied experimentally. Studies of this model have been stimulated by an increasing belief that viruses may either cause or be a necessary component in a multistage induction of human leukemia. For this reason, many investigators in recent years have directed their efforts towards developing effective ways of either preventing murine virus leukemia or curing the disease once it has become established. The approaches employed in these efforts have, in the main, consisted of stimulating natural host defense mechanisms against infectious agents. The use of formalinized virus as an immunoprophylactic agent has proved to be as effective in murine leukemia as in many nononcogenic viral infections of man. However, development of a vaccine against human leukemia must await the isolation and