19 
1 revised guidelines for recombinant DNA research is to 
2 support the general direction of the proposed changes, 
3 rather than to comment on specific provisions. I am a 
4 pediatrician who specializes in infectious diseases, and 
5 also a microbiologist whose primary focus has been mechan- 
6 isms of pathogenesis of microorganisms. As such, I have 
1 been concerned from the outset of the recombinant DNA 
8 debate with the relative lack of recourse to the substan- 
9 tial fund of knowledge concerning known pathogenetic 
10 mechanisms and genuinely virulent organisms. 
11 The inference has sometimes been that pathogenetic 
12 mechanisms of microbes are generally unknown and mysterious, 
13 and that once pathogenic, organisms are uniformly so in an 
14 all or none fashion. As I read the revised guidelines I 
15 was therefore pleased to note that the proposed changes 
16 move substantially toward a thoroughly rational, cautious 
17 approach to facilitating advances in research under condi- 
18 tions of sensible containment. 
19 Perhaps some consideration of known facts about 
20 pathogens will amplify my first point, that the revised 
21 guidelines are sensible in their emphasis on the human 
22 host, who would be the initial biologic target of an 
23 1 nadvertently released vector. A healthy adult who is 
24 not undergoing antimicrobial or immunosuppressive therapy 
25 is usually an effective barrier even against pathogenic 
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