INACTIVATION OF VIRUS

PROBLEM TO BE SOLVED: To inactivate virus in a plasma protein solution by incubating the plasma protein solution at room temperature in an added state with a specific concentration of an ammonium salt, separating the precipitate, removing the ammonium salt, and by performing pasteurization to obtain its pharmaceutical preparations. SOLUTION: By incubating a plasma protein solution, which is e.g. a plasma protein solution purified by affinity chromatography, at room temperature in an added state with an ammonium salt (e.g. ammonium sulfate, or the like) having 13-22 wt.% concentration, separating the precipitate, incubating the mixture again in a state that the ammonium concentration is increased up to 24-27 wt.%, removing the ammonium salt down to a residual content of