0.2 vs 0.45um filter for clearing retro- or lentiviral supernatant? - (Mar/25/2014 )

When collecting the supernatant after packaging virus in a cell line such as 293T, why do most protocols ask for a 0.45um filter? I understand that filtering is done to eliminate cells and cellular debris so a 0.45um is all that is needed. Also, it should also be done with a filter that has low protein binding. However, what is the harm of using a 0.2um filter? It seems like a 0.2um filter would provide the added benefit of filtering out any bacteria if contamination did occur during the virus production. Any thoughts on this?

Thanks!

because 0.45 is sufficient and 0.2 will take more time to complete. it's for convenience.

mdfenko on Wed Mar 26 11:45:21 2014 said:

because 0.45 is sufficient and 0.2 will take more time to complete. it's for convenience.

Thanks! Never thought of it in the context of time efficiency. 

Does anyone know which size of filter will clear human or mouse cell debris?