Therefore, these concentrations were used in the following experiments as the 
maximal final concentration of inactivating reagent to which the cells were 
exposed. This assured that apparent reductions in infectious units of SFV resulted 
from virus inactivation, rather than interference with virus infection or toxicity 
for BHK-21 cells. 
Inactivation protocol : 
lxlO 6 infectious units of activated SFV3-lacZ/Helper 2 particles (50 /d) were 
combined with an equal volume of disinfectant reagent stock, or dilution of that 
reagent, for 5 minutes at room temperature. 20 p\ of the reagent/virus solution 
were then diluted into 6 mis PBS (Ca ++ , Mg ++ ) and 1 ml was added to each well 
of a 6- well plate. After a one-hour incubation at 37° C, the plate was washed once 
with PBS, and 3 ml of complete medium were added to each well. At 24 hr post- 
infection, the cells were stained in situ for /3-gal activity, using X-gal as a 
substrate (see protocol in Section in A). 
In each experiment, two controls were incorporated. In one, 2x10 s infectious units 
of SFV3-lacZ Helper 2 particles were incubated for 5 minutes in PBS, and diluted 
prior to plating. In the other control, 2x10 s infectious units were also incubated 
for 5 minutes in PBS, and then diluted into a concentration of inactivating reagent 
known not to interfere with virus infection of cells (see above) prior to plating. 
Results: 
BACDOWN DETERGENT DISINFECTANT 
Inactivation Cone. 
7.5 ml/L 
2.5 ml/L 
0.75 ml/L 
PBS control 
PBS control 
Final conc.on cells 
.025 ml/L 
.0083ml/L 
.0025 ml/L 
.025 ml/L 
No. of fl-gal positive 
cells/6 wells 
0 
7 
72 
-2x10 s 
-2x10 s 
Conclusion: 7.5 ml/L, or higher, of BACDOWN detergent completely inactivates 
2x10 s infectious units of SFV. 
[4781 
Recombinant DNA Research, Volume 18 
