Protein purification method and kit

1. A method for combined virus inactivation and purification of a feed containing a protein of interest comprising the steps of:

(a) contacting the feed with negatively charged particles or media,

(b) conditioning the particles or media such that their pH is at least 2.5 and at most 4.3 for at least one minute after the particles or media contact the feed to inactivate one or more viruses present in said feed, and

(c) eluting said protein of interest from said particles or media.

2. The method according to claim 1 wherein, prior to step (a), the pH of said feed is adjusted such that it is below the isolectric point (pI) of said protein of interest.

3. The method according to claim 1 wherein prior to step (a) the feed is conditioned such that the conductivity of said feed is at most 25 mS/cm.

4. The method according to claim 1 , wherein elution of said protein occurs at a pH of 3 to 9.

5. The method according to claim 1 , wherein elution of said protein occurs at a conductivity of at least 0.1 mS/cm.

6. The method according to claim 1 ,

wherein the conditioning step includes conditioning the feed such that its conductivity is at least 5 mS/cm and at most 15 mS/cm and its pH is at least 3.

7. The method according to claim 1 , wherein the feed is conditioned prior to contacting said feed with said particles or media such that the conductivity is at least 0.1 mS/cm and at most 25 mS/cm and/or such that its pH is at least 3 and at most 9.

8. The method according to claim 1 , wherein during step (b), the pH of at least 2.5 and at most 4.3 of the particles or media is maintained for at least 1 min and at most 4 hours after the particles or media contacts the feed.

9. The method according to claim 1 , wherein the particles or media during elution are conditioned such that their conductivity is at least 1 mS/cm and at most 50 mS/cm.

10. The method according to claim 1 , wherein the feed is a clarified feed.

11. The method according to claim 10 wherein the clarification of said feed comprises adding to the feed at least one fatty acid having 7 to 10 carbon atoms and/or allantoin; at least one electropositive compound selected from the group comprising electropositive polysaccharide, electropositive polymer, chitosan, a chitosan derivative, a synthetic polymer, polydiallyl dimethylammonium chloride (pDADMAC), a cationic surfactant; and diatomaceous earth or any combination thereof.

12. The method according to claim 1 further comprising:

removing non-target molecules from said particles or media, and/or

conditioning the pH of the particles or media by dilution, buffer exchange, titration or any combination thereof.

13. The method of claim 1 wherein the contacting step comprises introducing the feed into a separation device having negatively charged particles and media.