May 21-23 - MINlfTES OF MEETING 
26 
XXIV. COOTAINMENT LEVELS FOR UNMODIFIED LABORATORY STRAINS OF NEUROSPORA 
CRASSA 
Based on extensive analysis of the fungus N. crassa, the NIH previously 
approved genetically modified strains of Neurospora crassa as HV1 as 
stated in the Federal Register of April 11, 19*7$. At its February 1979 
meeting, the RAC also reccrmended a limited use of unmodified laboratory 
strains of N. crassa . The NIH accepted the following conservative 
interpretation of the RAC's position based on the discussion at the time 
and until there was opportunity for further clarification by the RAC: 
"Unmodified laboratory strains of N. crassa 
are approved at the P3 level of containment 
for shotgun experiments with phages, plasmids, 
and DNA from Class 1 prokaryotes [1] and lower 
eukaryotes that do not produce polypeptide 
toxins (34] . " 
Based on the need for further clarification, the following alternate 
interpretation of the RAC's action was published in the Federal Register 
on April 13, 1979 for an additional 30-day comment period prior to its 
consideration at the May meeting. During the 30-day comment period 
no comments were received on this proposal: 
"Unmodified laboratory strains of Neurospora 
crassa can be used in all experiments for 
which HV1 N. crassa systems are approved 
provided that these are carried out at 
physical containment one level higher than 
required for HV1. However, if P3 contain- 
ment is specified for HV1 N. crassa , this 
level is considered adequate for unmodified 
N. crassa . For P2 physical containment, 
special care must be exercised to prevent 
aerial dispersal of macroconidia, including 
the use of a biological safety cabinet." 
The discussion on this issue at the meeting followed that which has been 
described in the Federal Register of April 11, 1979. Essentially, there 
was concern about the escape of N. crassa since it forms sporefi which 
are freely dispersed. As a result of this concern, it was recommended 
at the February 1979 meeting that all experiments with wild type N. crassa 
should require the use of a biological safety cabinet. Dr. Cottesman 
noted that the proposal would permit the cloning of intact viruses under 
P3 conditions in unmodified strains of N. crassa . This is the same con- 
tainment level required for cloning viruses in HV1 N. crassa systems. 
She asked whether the RAC is satisfied that P3 is adequate for unmodified 
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