Method for purifying a target substance with viral inactivation

A method for purifying a target substance from a fluid to be treated comprising at least one impurity, in an installation comprising:

• a first separation unit comprising at least a chromatography column, a fluid inlet, and a fluid outlet;
• a second separation unit comprising at least one or more chromatography columns, one or more fluid inlets, one or more fluid outlets, and a bypass line, the bypass line being connected to at least one fluid inlet of the second separation unit at a first end of the bypass line and connected to at least one fluid outlet of the second separation unit at a second end of the bypass line, the bypass line bypassing each of the chromatography columns of the second separation unit;
• a first reservoir in fluid connection with a fluid outlet of the first separation unit and a fluid inlet of the second separation unit;
• and
• a second reservoir in fluid connection with at least a fluid inlet and a fluid outlet of the second separation unit;
• wherein the method comprises the following steps:
• providing a flow of fluid to be treated;
• treating the flow of fluid to be treated by means of a chromatography step in the first separation unit;
• collecting a fraction enriched in the target substance in the first reservoir;
• viral inactivation of the fraction enriched in the target substance, wherein the viral inactivation comprises:
• passing the fraction enriched in the target substance collected in the first reservoir through the second separation unit via the bypass line;
• passing a viral inactivation solution through the second separation unit via the bypass line;
• mixing the fraction enriched in the target substance and the viral inactivation solution;
• and
• collecting the mixture of the fraction enriched in the target substance and the viral inactivation solution in the second reservoir;
• so as to obtain a fraction depleted of active virus;
• treating the fraction depleted of active virus by means of a chromatography step in the second separation unit;
• and
• collecting a fraction more enriched in the target substance at the outlet of the second separation unit.