Dear fellow researchers,

We routinely concentrate BEI inactivated FMDV in TFF. On sucrose density gradient ultracentrifugation, we have observed considerable loss of virus as compared to virus concentration in the harvest. Is this due to virus aggregates? I don't think we lose virus in the permeate as we use the TFF cassette of right cut off value. If it is due to aggregates how to disperse it before ultra? Look forward to your help in resolving this.  Thanks