Virus removal membrane

A virus removal membrane for removing viruses from a protein-containing solution,

• the virus removal membrane comprising:
• a primary surface configured to have the protein-containing solution applied thereto, and
• a secondary surface configured to allow a liquid that permeates through a thickness of the virus removal membrane to flow therefrom, wherein,
• a body of the virus removal membrane is configured such that,
• i) a value obtained by dividing a standard deviation of a value of an area of a spectrum of variation in brightness by an average of the value of the area of the spectrum of variation in the brightness is 0.01 or more and 1.50 or less, wherein the brightness is measured for a cross section of the virus removal membrane after 40 mL of a solution containing gold colloids having a diameter of 20 nm is applied to a filtration area of 0.001 m2 of the primary surface, filtered under a pressure of 196 kPa, and penetrates into the body of the virus removal membrane to allow the virus removal membrane to capture the gold colloids for measurement of brightness;
• and
• ii) a thickness of a portion where gold colloids having a diameter of 20 nm or more and 30 nm or less are captured in the cross section of the virus removal membrane in a wet state is 10 μm or more and 28.0 μm or less, wherein the thickness is measured after 40 mL of a solution containing gold colloids having a diameter of 20 nm or more and 30 nm or less is applied to the filtration area of 0.001 m2 of the primary surface, filtered under a pressure of 196 kPa, and penetrates into the body of the virus removal membrane,
• wherein
• the body of the virus removal membrane is configured such that
• a portion where gold colloids having a diameter of 30 nm are captured is located at a place corresponding to 15% or more and 60% or less of a thickness of the virus removal membrane from the primary surface in the cross section of the virus removal membrane in a wet state after 40 mL of a solution containing the gold colloids having a diameter of 30 nm is applied to the filtration area of 0.001 m2 of the primary surface, filtered under a pressure of 196 kPa, and penetrates into the body of the virus removal membrane,
• a portion where gold colloids having a diameter of 20 nm are captured is located at a place corresponding to 25% or more and 85% or less of the membrane thickness from the primary surface in the cross section of the virus removal membrane in a wet state after 40 mL of a solution containing the gold colloids having a diameter of 20 nm is applied to the filtration area of 0.001 m2 of the primary surface, filtered under a pressure of 196 kPa, and penetrates into the body of the virus removal membrane, and
• a portion where gold colloids having a diameter of 15 nm are captured is located at a place corresponding to 60% or more and 100% or less of the membrane thickness from the primary surface in the cross section of the virus removal membrane in a wet state after 40 mL of a solution containing the gold colloids having a diameter of 15 nm is applied to the filtration area of 0.001 m2 of the primary surface, filtered under a pressure of 196 kPa, and penetrates into the body of the virus removal membrane,
• wherein each of the solutions containing gold colloids are diluted with distilled water for injection, 1.59% by volume of polyoxyethylene-naphthyl ether, and 0.20% by volume of poly(sodium 4-styrenesulfonate) so that the absorbance at the maximum absorption wavelength of the gold colloids of the solution is 0.25 measured by an ultraviolet-visible spectrophotometer,
• and
• the virus removal membrane is formed of a hydrophilized synthetic polymer.