UNIVERSITY OF SOUTHERN CALIFORNIA SCHOOL OF MEDICINE 2025 ZONAL AVENUE LOS ANGELES, CALIFORNIA 90033 DEPARTMENT OF MICKOBIOLOGY March 11, 1975 TELEPHONE: (213) 226-2142 Dr. Harold Varmus Department of Mi crobi 01 ogy University of California School of Medicine San Francisco, California 94122 Dear Harold: I am sending you the draft of a virus characterization prepared for the International Committee on Taxonomy of Viruses. The data, compiled by the RNA Tumor Virus Study Group of the ICTV, pertain to enveloped RNA viruses of vertebrates which replicate through a DNA provirus. sheets follow standard ICTV format. As chairman of the RNA Tumor Virus Study Group within the ICTV, I would appreciate receiving your conments and criticisms on this document before I submit it to the Vertebrate Virus Subcomnittee of the ICTV in April. I would be particularly interested in your reaction to the proposed nomenclature and taxonomic structure. My feeling is that a majority of workers in the field are in favor of the term retravirus as a family name including not only RNA tumor viruses but also foamy agents and slow viruses like visna. There also seems to be some sentiment in favor of oncornavirus to designate the genera of RNA tumor viruses. like these names -- oncorna also violates the ICTV rule that names made up of abbreviations may not be used -- and now is the last chance to make a better and perhaps a successful counterproposal. The ICTV will meet on the occasion of the International Congress of Virology in Madrid, September 9 - 17, 1975 and will vote on proposals of virus nomenclature and taxonomy. There will also be an open session on this subject orga- nized by the ICTV in Madrid. be found in the December 1974 issue of ViroZogy. The data However, there are many workers who for some reason dis- An announcement about these meetings may th all good wishes. Peter K. Vogt PKV : mdz Enclosures 2. Dr. Harold Varmus March 11, 1975 P.S. Harold, I would be very grateful for your reaction to nomenclature and virus terms. Do you think retraviruses and oncornaviruses are now unavoidable? Is the proposed taxonomic status of RNA tumor viruses (that of genus) sufficient or should it be a family? Have I omitted any important data on B-type viruses?