Vhat tests have been used and vhat is the sensitivity 
of the tests? 
(b) -If a virus, how is it prepared from the ENA construct? In 
vhat cell is the virus grown (any special features)? vhat 
medium and serum are used? How is the virus purified? What 
is its structure and purity? Vhat steps are being taken 
(and assays used with their sensitivity) to detect and 
eliminate any contaminating materials (nucleic acids, pro- 
teins, etc.) or contaminating viruses or other organisms in 
the cells or serum used for preparation of the virus stock? 
(c) If co-cultivation of virus-producing cells with target 
cells is used, how is the absence of contamination by 
donor cells or by sequences packaged into infectious 
particles by the donor (e.g., VL30 sequences) demonstrated? 
What is the sensitivity of these tests? What cells were 
used for co-cultivation? 
(d) If methods other than those covered by a-c are used to 
introduce new genetic information into target cells, 
how is it demonstrated that the final target cells 
are free of contamination? Vhat are possible sources 
of contamination? What is the sensitivity of tests 
used to monitor contamination? 
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Recombinant DNA Research, Volume 1 1 
