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would be judged to be permissible. If the intent is to de-regulate such 
experiments, prohibition (i) is inconsistent. If, on the other hand, the 
intent is to prohibit such experiments, even when "novel" DNAs are not 
involved, the proposed deregulation paragraph should indicate specifically 
that deregulation does not apply to prohibition (i). 
Similar arguments could be presented with regard to prohibition (ii). 
5) Prohibition III, (a) In the original guidelines "The deliberate creation 
from plant pathogens of recombinant DNAs that might increase virulence and 
host range" was totally prohibited. In the revised Guidelines, this pro- 
hibition applies to "The deliberate creation by use of recombinant DNA of 
plant pathogens with increased virulence and host range beyond that which 
occurs by natural genetic exchange." This revision is a meaningful one. 
However, while I do not disagree with the spirit of prohibi tion III , I find 
it not entirely fair since it applies only to plant pathogens. Similar 
experiments are not totally prohibited with CDC class I or II organisms. 
To circumvent this problem two possible revisions can be suggested: (i) 
omit the word "plant" so that prohibition III applies equally to all pathogens 
not covered by prohibition; (ii) propose a classification of plant pathogens 
according to risk similar to the CDC classification (no such classification 
exists presently). Prohibition III could then be maintained as such for 
high-risk phytopathogens, but could be lifted for those which are judged to 
be of low risk. I personally favor the latter approach. 
(b) Another point concerning prohibition III should be made also. In- 
creases in virulence or host range may occur naturally by mutation, in addition 
to gene exchange. Strictly interpreted the revised prohibition III would 
require that the origin of a plant pathogenic strain different in varietal 
specificity should be traced to natural exchange. Strains which have acquired 
[Appendix A — 117] 
