I want to isolate (preferably infectious) hepatitis C viral particles form infected patient's serum. I have reviewed some protocols which are based on PEG 8000, PEG 6000 with or without salt precipitation followed by centrifugation. Is there any optimized protocol for HCV isolation. Additionally I am interested in in-dept understanding the criteria/principles for selecting PEG type, slat concentration so that I can manipulate protocols optimized for other viruses to develop my own protocol.