MEMORANDUM

TO :

FROM :

SUBJECT :

Dr. Harold Varmus

DEPARTMENT OF HEALTH, EDUCATION, AND WELFARE

PUBLIC HEALTH SERVICE

NATIONAL INSTITUTES OF HEALTH

Dr. Robert Huebner

MS. - Detection of new and additional virus-specific DNA sequences  in

chick embryo fibroblasts after infection by RSV.

This is a very interesting, useful and significant contribution. I think
what most needs to be determined is, what is RSV? It's been around 50-1-
years, is certainly a recombinant, and like MlV according to Rubin, a
mixture of several ALV phenotypes (RIF-1, 2, etc.). I would suggest
making DNA probes from natural ALV'S isolated from RIF-free colonies.
Both ecotropic and xenotropic viruses are certainly present and/or
activatable. RSV and MSV have not turned up in large numbers of sarcomas
in chickens and mice in my 10 years of extensive surveys for natural
sarcoma viruses.
species.  Existing RSV and MSV lab strains are laboratory-created
artifacts and could not represent faithfully natural virus or viral
genomes in natural host cells.  There are almost as many variants  of
RSV and MSV as there are investigators working with them.

There has never been one epidemic of sarcoma in any