McARDLE LABORATORY 
FOR CANCER RESEARCH 
DEPARTMENT OF ONCOLOGT 
MEDICAL SCHOOL, UNIVERSITY OF WISCONSIN 
July 22, 1986 
Dr. William J. Gartland, Jr. 
Recombinant DNA Advisory Committee 
Building 31, Room 3B10 
National Institutes of Health 
Bethesda, MD 20205 
Dear Bill: 
Thank you for your call. I have two concerns relating to 
B.l.B. (1) (B) . In this section about the purity of the virus, we 
should perhaps Indicate explicitly that there Is no contamination 
of the virus producing cells (as mentioned In my letter of March 
4), and that any contaminating materials Include molecules like the 
rodent VL30 sequences. 
VL30 sequences are endogenous sequences in rodent cells which 
produce an RNA that Is very efficiently packaged In retrovirus 
virions. In fact, Harvey and Kirsten sarcoma viruses are VL30 
recombinants. 
Another problem that might be considered in relation to effect- 
iveness of the vectors is the requirement of demonstration of good 
expression In a primate. The recent difficulties in getting expres- 
sion in animals as opposed to cell culture indicates that there may 
be difficulty In extrapolating to the human species from other 
species. 
I don't think that I shall be able to attend the August 8 
meeting. My summer has turned into a time busier than the rest of 
the year Instead of a let up. 
With best regards. 
Sincerely yours. 
Howard M. Temin 
[44] 
Recombinant DNA Research, Volume 11 
