Department ot Botany and Plant Pathology 
303/491-6524 
Colorado Stale University 
Fort Collins. Colorado 
80523 
November 10, 1977 
Dr. Donald S. Fredrickson, Director 
Department of Health, Education, and Welfare 
Public Health Service 
National Institutes of Health 
Bethesda, Maryland 20014 
Dear Dr. Fredrickson: 
This is in response to your memo of October 26, 1977 requesting 
review of proposed revisions of the NIH Guidelines. 
Section III A designates experiments that are not to be performed. 
One of these is "Deliberate creation by the use of recombinant DNA 
of a plant pathogen with increased virulence and host range beyond that 
which occurs by natural genetic enchange" (probably exchange). 
Virulence is usually defined as extent in time and severity of 
pathogenicity. It's a degree or measure of pathogenicity. In this 
context, pathogenicity is assumed even though virulence may be very 
low. Thus the wording in the guidelines appears to allow one to take 
an organism that is not a pathogen and convert it to a pathogen. This 
might be stretching a point but I gather the NIH Guidelines is at least 
a semilegal document (and may be adopted in legislation) and should 
contain wording that is not susceptible to misinterpretation. 
I hasten to add that the wording in the guidelines may be carefully 
designed to allow research on conversion of nonpathogens to pathogens. 
Benefits from such research may outweigh hazards. One could conjure 
up all kinds of exciting experiments using recombinant DNA to test the 
common antigen hypothesis, for example. 
It would seem that section III, A, iii has been violated already. 
Plasmids from a virulent isolate of the crown gall bacterium were trans- 
ferred to an avirulent strain rendering the latter virulent. This is 
increasing the virulence of a plant pathogen (as a separate entity) and 
not a species, however, and I see no reason to ban research of this 
nature. Perhaps it would be more lucid to use the phrase "species of 
plant pathogen" rather than "plant pathogen" alone. 
Sincerely, 
Ralph Baker 
Professor of Botany and Plant Pathology 
RB/cvh 
CC: Martin Alexander 
Peter R. Day 
Joel Fisher 
[Appendix A — 53] 
