Can you remove the serum proteins from viral particles without concentrating the virus?
Question: I am not planning on actually concentrating virus-but I would like to remove the serum proteins. In step five of the concentration protocol, the protocol says to centrifuge at full speed for 3-4 minutes. What is the rpm of "full speed"? Will this will still work if I haven't concentrated the virus? Should I adjust the rpm or time at all to account for the unconcentrated virus?Answer: This 3-4 min centrifugation step in a microfuge, to "remove serum proteins", is only applicable after the virus-containing supernatant has been ultracentrifuged to concentrate the viral particles. During the ultracentrifugation of the supernatant, the proteins found in the serum are pelleted at the bottom of the centrifuge tube along with the viral particles. When you resuspend the viral pellet, you also dislodge the serum protein pellet. However, since the serum proteins remain aggregated together, it can be simply removed from the resuspended viral particles by microfuging at full speed. We use a Eppendorf microfuge model 5415D. It will remove most of the serum proteins. I'm sure there is some protein that remains. Now it's important to realize that the removal of the serum proteins in this manner is only applicable following ultracentrifugation, which is needed to aggregate the serum proteins. One cannot simply remove serum proteins directly from virus-containing supernatant by microfuging for 3-4 minutes.