Clarification of sap using organic solvents like chloroform or butanol or heat, or pH 5.0 exposure should be possible.  Followed by low speed centrifugation, discard the pellet, retain the virus containing supernatant. Then, have you acquainted yourself with the use of polyethylene glycol in the range of 3 to 8% in saline as a method to aggregate virions in clarified sap?  The smaller the viron the more PEG needed, in general.  Something like 4% for rod shapes and 6-8% for spherical ones.  The aggregated forms can be pelleted at low speed. Then re-suspended in an appropriate buffer to place virions back onto suspension.  Repeat at least once.  Be sure to do the same with healthy tissue to gauge how much plant material is in you final partially purified virus suspension.  The higher the PEG % the more plant products in fiinal prep.  Antisera raised using such viral preps can be cross-absorbed with anitera raised against  the plant proteins form the healthy plants.  A form of gradient centrifugation can be done with PEG.  10-40 %, sucrose lowest on top with 8-2% PEG, with PEG 'reversed', highest at the top of the gradient.  This way the virions are loaded in 8%PEG in the aggegated form, sediment down under low speed forces till they reach the sweet spot for going back into solution, and just sit there in the gradient.  Using a second separatory technique for the second round of purification is better of course, something like agarose bead chromatography?

I had a senior moment there.  The antiserum raised against the PEG product from the infected plants (virus prep) could be cross absorbed with the PEG product from the healthy plants before being used in tests for infected plants is what I should have said.

Thank you very much for the protocol. We will try to apply this protocol for our study. When you say 'low speed', is 11000-12000 rpm good enough or do we need more speed?