The present invention provides methods and systems for recovering an essentially cell-associated expression product from a host cell comprising (a) culturing said host cell under conditions that allow expression of said expression product； (b) collecting said host cell in/on a filter unit； (c) disrupting said host cell in/on the filter unit； and (d) separating said expression product from said disrupted host cell. The present invention also provides an expression product obtainable by the methods or systems, wherein the expression product is a poxvirus.
