10 The RNA Tumour Viruses: Morphology, Composition and Classification

Abstract

RNA tumour virology has a surprisingly long history, which has been discussed in Chapter 1 and exhaustively chronicled by Gross (1970). Readers interested in the details of the history of the subject cannot do better than read Gross’s book, Oncogenic Viruses.

In 1908 and 1909 Ellerman and Bang reported the transmission of erythromyeloblastic leukemia of chickens by cell-free filtrates of leukemia cells. Their experiments, which were the first transmission of a truly neoplastic disease by cell-free filtrates, led initially not to a search in other species for infectious agents which might cause leukemia, but to the classification of chicken leukemia apart from the leukemias of other species. The first transmission of a solid tumour by cell-free filtrates was reported three years later by Rous (1911), who isolated several filtrates capable of inducing a variety of sarcomas in chickens. In spite of independent confirmation of these results (Fujinami and Inamoto, 1914), the scientific and medical communities were by and large reluctant to concede the fundamental importance of these two sets of discoveries that proved that viruses can cause malignant diseases, and it was not until 1966 that Rous was awarded the Nobel prize for his work.

During the nineteen-twenties and thirties, however, Rous sarcoma viruses and avian leukemia viruses attracted the attention of increasing numbers of scientists, and the viruses and the diseases they cause were further characterized. At the same time a handful of biologists began systematically to inbreed mice, and work on inbred strains led to the discovery of...