help: virus purification problem

[Richard Van Frank]

In article <326DAA54.764E at bric.postech.ac.kr>,
   mhlee at BRIC.POSTECH.AC.KR (Min-Ho Lee) wrote:
>Hello!
>I have a problem in purification of an insect virus. 
>When viral particles were collected (as a white band) in sucrose 
>gradients (30%/60%), I transferred the band to a new ultracentrifuge
>tube.
>Then, I spun the tube at 100,000g for 1 hr. But, I have no get any 
>pellet. I thought that viruses have no spun down because of 
>sucrose buoyancy. 
>So, I allowed the solution at 4oC, overnight, stirred it roughly and
>ultracentrifuge at 100,000g for 1 hr. But, I have no any pellet, too!
>
>Is there anyone know about it?
>Why virus particles were spun down?
>What can I do for purification of the virus particles?
>
>Your Sincerely, Min-Ho Lee

Are you sure the "white band" was composed of virus?
Did you dilute the sucrose to reduce the concentration to <10% before trying to 
sediment the virus? It takes a lot of virus to get a visible pellet.
RMVF