[Cell transformation by viruses and the development of tumours (author's transl)]

The history of tumour virology and some main points of recent experimentation are described. First, a definition of the term virus is presented. Subsequently, four main topics are discussed: The tumour virus and the integration of its nucleic acid; The mechanism of transformation; The genes of the tumour virus and their products; The importance of the genetic background of animals and cells for transformation and tumour development. The mutual influence of cell and virus genomes is in the focus of consideration. The particulare tumour virus, at least for limited periods of time, comes under the influence of the cell genome. The theories about tumour development by viruses and the possibility of prophylactic measures are described.