Hollow fiber membrane module for virus removal, and method of manufacturing the same

Abstract

To provide a hollow fiber membrane module for virus removal, which can exert high virus removal performance, even under high applied pressure conditions when bio-pharmaceuticals are produced on an industrial scale.SOLUTION: A hollow fiber membrane module for virus removal has a hollow fiber membrane. A membrane thickness part of an end surface of the hollow fiber membrane is coated with a potting material. A potting material coverage factor of the membrane thickness part of the end surface of the hollow fiber membrane on the side where a virus-containing solution is supplied or the side where a virus-removed solution is discharged is in the range of 0.96-1.00.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a hollow fiber membrane module for virus removal and a method for producing the same. [Background technology]

[0002] Antibodies and other biopharmaceuticals are highly effective and have few side effects, and are therefore used as treatments for a variety of diseases.

[0003] Biopharmaceuticals are manufactured using the protein synthesis ability of cells and are broadly divided into three processes: cell culture, separation and purification, and formulation. Virus removal is performed during the separation and purification process, where the target component is separated and purified from the culture supernatant containing impurities. Among virus removal methods, filtration using separation membranes is becoming increasingly useful because it has minimal impact on active ingredients and can remove energetically or chemically resistant viruses.

[0004] Hollow fiber membranes, which are used in industrial and medical applications, are widely used as virus removal membranes. For example, Patent Document 1 discloses a hollow fiber membrane module that can maintain protein permeability even after long-term use. Patent Document 2 also discloses a hollow fiber membrane module that can efficiently separate antibodies and viruses at low pressure.

[0005] When manufacturing biopharmaceuticals on an industrial scale, it is necessary to process large amounts of raw biopharmaceutical solution in a short period of time. Therefore, the hollow fiber membrane modules used for virus removal are required to achieve high virus removal performance under high applied pressure conditions.

[0006] One example of a hollow fiber membrane module is one in which a bundle of hollow fiber membranes is housed in a cylindrical case, and both ends of the bundle of hollow fiber membranes are fixed to both ends of the case with a potting material, etc. The role of the potting material is to fix the hollow fiber membranes to the case and to separate the raw solution supplied to the hollow fiber membrane module from the filtrate discharged from the hollow fiber membrane module.

[0007] Patent Document 3 discloses a hollow fiber membrane module in which the amount of membrane desiccant at the end of the hollow fiber membrane fiber bundle sealed with potting material during membrane production is reduced compared to other parts, thereby optimizing the balance between the penetration of the potting material into the porous parts of the hollow fiber membrane and the adhesion between the outer surface of the hollow fiber membrane and the potting material. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] International Publication No. 2021 / 100804 [Patent Document 2] International Publication No. 2019 / 225730 [Patent Document 3] Japanese Patent Application Laid-Open No. 2000-271451 Summary of the Invention [Problem to be solved by the invention]

[0009] However, as described in the Examples below, it has become clear that the hollow fiber membrane modules disclosed in Patent Documents 1 and 2 have poor virus removal performance under the high applied pressure conditions required for industrial-scale production of biopharmaceuticals.

[0010] Patent Document 3 describes a problem in which the adhesive peels off from the membrane when the adhesive strength between the outer periphery of the hollow fiber membrane and the potting material is low. To address the issue of leakage of the stock solution into the filtrate, optimizing the balance between the degree of penetration of the potting material into the membrane and its adhesiveness prevents a reduction in separation ability due to excessive penetration of the potting material and prevents mixing of the stock solution and filtrate due to poor adhesion between the membrane and the adhesive. However, the effects shown in the examples are limited to water permeability, and there is no mention of the separation ability of hollow fiber membrane modules for virus removal used in the industrial-scale production of biopharmaceuticals.

[0011] Therefore, an object of the present invention is to provide a hollow fiber membrane module for virus removal that exhibits high virus removal performance even under the high applied pressure conditions encountered in the industrial-scale production of biopharmaceuticals. [Means for solving the problem]

[0012] The present inventors have conducted extensive research to solve the above problems and have discovered the following inventions [1] to [6]. [1] A hollow fiber membrane module for virus removal, comprising a hollow fiber membrane, the membrane thickness portion of the end face of the hollow fiber membrane being covered with a potting material, and the coverage rate of the potting material in the membrane thickness portion of the end face of the hollow fiber membrane on the side to which a virus-containing solution is supplied or the side to which a virus-removed solution is discharged is 0.96 or more and 1.00 or less. [2] The hollow fiber membrane module for virus removal according to [1], wherein the hollow fiber membrane is mainly composed of a polysulfone polymer. [3] The hollow fiber membrane module for virus removal according to [1] or [2], wherein the hollow fiber membrane has an inner diameter of 160 μm or more and 450 μm or less and a membrane thickness of 30 μm or more and 100 μm or less. [4] The hollow fiber membrane module for virus removal according to [1] or [2], wherein the hollow fiber membrane is a hollow fiber membrane having a polymer containing a monocarboxylic acid vinyl ester unit and a vinylpyrrolidone unit supported on its surface. [5] A method for producing a hollow fiber membrane module for virus removal according to [1] or [2], comprising storing the hollow fiber membrane in a case, sealing both ends of the hollow fiber membrane with a potting material, cutting the ends to open them, and then coating the end faces of the hollow fiber membrane with the potting material. [6] A method for producing a hollow fiber membrane module for virus removal according to [1] or [2], comprising the steps of: housing a hollow fiber membrane in a case; sealing both ends of the hollow fiber membrane with a potting material; cutting the ends to open them; and then melting the end faces of the hollow fiber membrane. [7] A biopharmaceutical in which viruses have been removed using the hollow fiber membrane module for virus removal described in [1] or [2]. [8] A method for producing a biopharmaceutical, comprising a virus removal step of removing viruses contained in a biopharmaceutical raw material solution using the hollow fiber membrane module for virus removal described in [1] or [2]. [Effects of the Invention]

[0013] The virus removal hollow fiber membrane module of the present invention can exhibit high virus removal performance even under high applied pressure conditions such as those used in industrial-scale production of biopharmaceuticals. [Brief explanation of the drawings]

[0014] [Figure 1] 1 is a schematic diagram of a hollow fiber membrane module for virus removal according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0015] The hollow fiber membrane module for virus removal of the present invention is used to remove viruses from a solution containing viruses, and has hollow fiber membranes.

[0016] In the hollow fiber membrane module for virus removal of the present invention, the membrane thickness portion of the end face of the hollow fiber membrane is coated with a potting material, and the coverage rate of the potting material in the membrane thickness portion of the end face of the hollow fiber membrane on the side where a virus-containing solution is supplied or the side where the virus-removed solution is discharged is 0.96 or more and 1.00 or less.

[0017] The "coverage rate by the potting material in the membrane thickness portion of the end face of the hollow fiber membrane on the side where a virus-containing solution is supplied or the side where a virus-removed solution is discharged" (hereinafter, sometimes simply referred to as "coverage rate") refers to the ratio of the area of ​​the part obtained by subtracting the area of ​​the exposed part of the membrane thickness portion of the hollow fiber membrane that is not covered with the potting material from the area of ​​the membrane thickness portion of the hollow fiber membrane at the end face of the hollow fiber membrane in a hollow fiber membrane module for virus removal on the side where a virus-containing solution is supplied or the side where a virus-removed solution is discharged to the area of ​​the membrane thickness portion of the hollow fiber membrane.

[0018] Since it is desirable to minimize viral contamination of biopharmaceuticals, a higher coverage rate is preferable. Therefore, the coverage rate is 0.96 or higher, preferably 0.97 or higher, and more preferably 0.98 or higher. Since the maximum possible coverage rate is 1.00, the upper limit of the coverage rate is 1.00. When the coverage rate is 1.00, it is expected that no viruses will leak from the end face of the hollow fiber membrane. However, since the PDA Journal of GMP and Validation in Japan, Vol. 7, No. 1 (2005), pp. 44-54, states that the target virus log reduction value (LRV) to be achieved in process validation of the manufacturing process of biological pharmaceuticals is approximately 4, the upper limit of the coverage rate may be 0.99 or lower.

[0019] When a virus-containing solution is filtered using a virus removal hollow fiber membrane module, the coverage rate can be determined by observing and photographing with a scanning electron microscope the membrane thickness portion of the end face of the hollow fiber membrane on the side of the virus removal hollow fiber membrane module where the virus-containing solution is supplied or on the side where the virus-removed solution is discharged, and then analyzing the resulting image.

[0020] The hollow fiber membrane module for virus removal of the present invention is a module in which hollow fiber membranes for removing viruses from a virus-containing solution are housed in a case. In a preferred embodiment, as shown in FIG. 1, a bundle of hollow fiber membranes 2 cut to the required length is housed in a cylindrical case 1. In this case, both ends of the hollow fiber membranes are fixed to both ends of the cylindrical case 1 by potting material 6, and both ends of the hollow fiber membranes 2 are open. The hollow fiber membrane module for virus removal also has headers 3A and 3B at both ends of the case 1. The headers 3A and 3B have inlets 4A and 4B through which liquid can be introduced or discharged. Furthermore, the hollow fiber membrane module for virus removal also has nozzles 5A and 5B on the side of the case through which liquid can be introduced or discharged, as shown in FIG. 1.

[0021] A virus-containing solution can be introduced through injection ports 4A and / or 4B, permeate from the inner surface side to the outer surface side of the hollow fiber membrane, and then discharged from nozzles 5A and / or 5B. Alternatively, a virus-containing solution may be introduced through nozzles 5A and / or 5B, permeate from the outer surface side to the inner surface side of the hollow fiber membrane, and then discharged from injection ports 4A and / or 4B.

[0022] 1, when a virus-containing solution permeates from the inner surface side to the outer surface side of the hollow fiber membrane, i.e., when the virus-containing solution is introduced through injection ports 4A and / or 4B, the injection port 4A side and / or 4B side of potting material 6 corresponds to the end face of the hollow fiber membrane on the side where the virus-containing solution is supplied. Also, when a virus-containing solution permeates from the outer surface side to the inner surface side of the hollow fiber membrane, i.e., when the virus-containing solution is introduced through nozzles 5A and / or 5B, the injection port 4A side and / or 4B side of potting material 6 corresponds to the end face of the hollow fiber membrane on the side where the virus-removed solution is discharged.

[0023] The hollow fiber membrane of the present invention preferably contains a polysulfone polymer as a main component.

[0024] Polysulfone polymers are preferred as the main component of hollow fiber membranes because they are easy to form into separation membranes, the pore size is easy to adjust, and when made into membranes they have excellent substance permeability.

[0025] The polysulfone polymer in the present invention is a polymer having an aromatic ring, a sulfonyl group, and an ether group in the main chain, and specific examples thereof include polysulfone, polyethersulfone, polyallylethersulfone, etc. As the polysulfone polymer, a polymer having a repeating unit represented by the following formula (1) or (2) is preferred.

[0026] [ka]

[0027] The polysulfone-based polymer may contain other repeating units in addition to the repeating units represented by formula (1) or (2) above, as long as the effects of the present invention are not impaired. In this case, the content of the other repeating units is preferably 10 mass % or less of the polysulfone-based polymer. Furthermore, the hydrogen atoms of the hydrocarbon skeleton of the polysulfone-based polymer may be substituted with functional groups such as alkyl groups (e.g., methyl groups), carboxyl groups, amino groups, or hydroxyl groups, or with other atoms such as halogens. Furthermore, the polysulfone-based polymer may be a modified product.

[0028] The polysulfone polymer is preferably a polysulfone polymer represented by the following formula (3) or (4), which consists only of repeating units represented by the above formula (1) or (2), but is not limited thereto.

[0029] [ka]

[0030] In the formulas (3) and (4), n represents an integer of 50 or more, and preferably an integer of 50-200.

[0031] More preferred examples of polysulfone polymers include Udel (registered trademark) P-1700 (manufactured by Solvay), Udel (registered trademark) P-3500 (manufactured by Solvay), Ultrason (registered trademark) S3010 (manufactured by BASF), and Ultrason (registered trademark) S6010 (manufactured by BASF).

[0032] The above polysulfone polymers may be used alone or in combination of two or more.

[0033] The phrase "mainly composed of a polysulfone polymer" means that the polysulfone polymer accounts for 50% by mass or more of the total components constituting the hollow fiber membrane. The content of the polysulfone polymer is preferably 75% by mass or more, and more preferably 90% by mass or more, of the components constituting the hollow fiber membrane.

[0034] According to a preferred embodiment, the hollow fiber membrane of the present invention further contains a hydrophilic polymer. That is, the hollow fiber membrane of the present invention is preferably composed of a mixed resin of the aforementioned polysulfone-based polymer and a hydrophilic polymer. The hydrophilic polymer serves as a pore-forming agent, adjusts the viscosity of the membrane-forming solution, and imparts a protein adhesion inhibitory effect when forming a porous hollow fiber membrane with the polysulfone-based polymer. In particular, when the hollow fiber membrane module for virus removal of the present invention is used in the production process of biopharmaceuticals, solutions containing viruses generally contain proteins such as antibodies. Therefore, in order to inhibit a decrease in separation performance due to protein adhesion to the hollow fiber membrane, it is preferable that the hollow fiber membrane contain a hydrophilic polymer.

[0035] The hydrophilic polymer in the present invention means a polymer that is soluble in water or ethanol, and is a polymer that dissolves in these at a concentration of 0.1 g / mL or more.

[0036] The hydrophilic polymer is preferably a good solvent for polysulfone-based polymers and a hydrophilic polymer compatible with polysulfone-based polymers. Examples of such hydrophilic polymers include polyvinylpyrrolidone, polyethylene glycol, polyvinyl alcohol, and copolymers thereof. Examples of the copolymers include copolymers of two or more selected from the group consisting of vinylpyrrolidone, vinyl acetate, vinyl propionate, and vinyl butanoate, but are not particularly limited thereto. Among these, polyvinylpyrrolidone or its copolymers are preferred from the viewpoint of compatibility with polysulfone-based polymers.

[0037] The content of the hydrophilic polymer in the hollow fiber membrane is preferably 0.5% by mass or more, more preferably 1.0% by mass or more, from the viewpoints of its role as a pore-forming agent and its effect of inhibiting protein adhesion. On the other hand, if the content of the hydrophilic polymer is too high, membrane formation becomes difficult and there is a concern that the hydrophilic polymer may be eluted from the hollow fiber membrane. Therefore, the content of the hydrophilic polymer is preferably 10% by mass or less, more preferably 8% by mass or less.

[0038] Generally, hollow fiber membranes are classified into so-called symmetric membranes, which have a symmetric structure in which the pore size hardly changes across the membrane thickness, and so-called asymmetric membranes, which have an asymmetric structure in which the pore size changes across the membrane thickness. The hollow fiber membrane of the present invention is preferably an asymmetric membrane, which has an asymmetric structure in which one surface is dense and the other surface is coarse. Asymmetric membranes have the advantage of easily controlling the pore size of the dense layer, which is important for separating substances. Furthermore, asymmetric membranes have a small pore size region that contributes to the separation of target substances such as viruses, and a large pore size region with low water permeation resistance, which makes it easy to achieve both separation performance and water permeability.

[0039] If the membrane thickness of the hollow fiber membrane is too thick, the permeation rate may decrease, and the treatment efficiency may decrease. Therefore, the membrane thickness of the hollow fiber membrane is preferably 30 μm or more, more preferably 35 μm or more, and even more preferably 40 μm or more. If the membrane thickness of the hollow fiber membrane is too thin, it is difficult to maintain the strength of the membrane, so the membrane thickness of the hollow fiber membrane is preferably 100 μm or less, more preferably 95 μm or less, and even more preferably 90 μm or less.

[0040] The membrane thickness of the hollow fiber membrane can be measured by observing the cross section of the hollow fiber membrane under a microscope.

[0041] If the inner diameter of the hollow fiber membrane is too small, the potting material may seep out from the membrane thickness into the lumen, causing non-passing of the membrane and reducing the treatment efficiency. Therefore, the inner diameter of the hollow fiber membrane is preferably 160 μm or more, more preferably 170 μm or more, and even more preferably 175 μm or more. If the lumen is too large, the volume of the hollow fiber membrane lumen increases, leading to an increase in the size of the module. Therefore, the inner diameter of the hollow fiber membrane is preferably 450 μm or less, more preferably 440 μm or less, and even more preferably 430 μm or less.

[0042] The inner diameter of the hollow fiber membrane can be calculated from the membrane thickness and outer diameter of the hollow fiber membrane.

[0043] When a virus solution containing a large amount of protein is treated using a hollow fiber membrane module for virus removal, a large amount of protein may adhere to the membrane thickness of the hollow fiber membrane, resulting in a decrease in virus removal performance. Therefore, the hollow fiber membrane of the present invention preferably has a polymer supported on its surface that suppresses protein adhesion, and preferably has a polymer containing a monocarboxylic acid vinyl ester unit and a vinylpyrrolidone unit supported on its surface.

[0044] A monocarboxylic acid refers to a compound consisting of one carboxy group and a hydrocarbon group bonded to the carbon atom of the carboxy group, i.e., a compound represented by "R-COOH" (R is a hydrocarbon group). Examples of R include aliphatic hydrocarbon groups and aromatic hydrocarbon groups, but from the viewpoint of ease of synthesis, R is preferably an aliphatic hydrocarbon group, and more preferably a saturated aliphatic hydrocarbon group. From the viewpoint of the production cost of the carboxylic acid, the saturated aliphatic hydrocarbon group preferably has a linear or branched structure, and more preferably a linear structure. Examples of monocarboxylic acids in which R is an aromatic hydrocarbon group include benzoic acid and derivatives thereof. Examples of monocarboxylic acids in which R is a saturated aliphatic hydrocarbon group include acetic acid, propanoic acid, and butyric acid.

[0045] When R is an aliphatic hydrocarbon group or an aromatic hydrocarbon group, the carbon number is preferably 2 to 5. When R has a small number of carbon atoms, the hydrophobicity of the monocarboxylic acid decreases, thereby reducing the hydrophobic interaction with proteins and preventing protein adhesion. When R is a saturated aliphatic hydrocarbon group, a compound with 2 carbon atoms is propanoic acid.

[0046] In this specification, the term "unit" refers to a repeating unit in a homopolymer or copolymer obtained by polymerizing a monomer, and the term "carboxylic acid vinyl ester unit" refers to a repeating unit obtained by polymerizing a carboxylic acid vinyl ester monomer, i.e., a repeating unit represented by "-CH(OCO-R)-CH-" (R is a hydrocarbon group). R is the same as R in the monocarboxylic acid described above, and preferred examples are also the same.

[0047] Specific examples of monocarboxylic acid vinyl ester units in which R is saturated aliphatic include vinyl propanoate units, vinyl pivalate units, vinyl decanoate units, and vinyl methoxyacetate units. Since it is preferable that the monocarboxylic acid vinyl ester unit is not too hydrophobic, preferred examples include vinyl acetate units (R:CH), vinyl propanoate units (R:CHCH), vinyl butyrate units (R:CHCHCH), vinyl pentanoate units (R:CHCHCHCHCH), vinyl pivalate units (R:C(CH)), and vinyl hexanoate units (R:CHCHCHCHCHCH). Specific examples of monocarboxylic acid vinyl ester units in which R is aromatic include vinyl benzoate units and their substitution products.

[0048] The fact that a polymer containing a monocarboxylic acid vinyl ester unit is supported on the outer or inner surface of the hollow fiber membrane can be confirmed by combining composition analysis using a TOF-SIMS device with measurement using X-ray photoelectron spectroscopy (XPS). Specifically, first, a peak derived from the carboxylate ion of the monocarboxylic acid vinyl ester unit is detected by composition analysis using a TOF-SIMS device, and the structure of the monocarboxylic acid is revealed by analyzing its mass (m / z). Further, when XPS measurement is performed, the peak derived from the carbon of the ester group (COO) is detected as CH X These peaks appear at +4.0 to +4.2 eV from the main peak of CC (near 285 eV), indicating that the carboxylic acids form ester bonds. The results of these two measurements reveal the presence or absence of polymers containing monocarboxylic acid vinyl ester units on the surface of the hollow fiber membrane.

[0049] The polymer containing a monocarboxylic acid vinyl ester unit and a vinylpyrrolidone unit is preferably supported on the outer surface of the hollow fiber membrane, more preferably on the outer and inner surfaces, and even more preferably on the outer surface, inner surface, and membrane thickness portion. By supporting the polymer on the inner surface, outer surface, or membrane thickness portion, adhesion of proteins and the like can be effectively suppressed.

[0050] The polymer containing a vinyl monocarboxylate unit and a vinylpyrrolidone unit is preferably immobilized on the hollow fiber membrane by chemical bonding. The immobilization method by chemical bonding is not particularly limited, but examples thereof include a method in which the hollow fiber membrane is brought into contact with the polymer and then irradiated with radiation, and a method in which a reactive group such as an amino group or a carboxyl group is introduced into the surface of the polymer and the hollow fiber membrane to be immobilized, followed by condensation.

[0051] Methods for introducing reactive groups onto the surface of a hollow fiber membrane include a method in which a monomer having a reactive group is polymerized to obtain a substrate having a reactive group on the surface, and a method in which the reactive group is introduced by ozone treatment or plasma treatment after polymerization of the monomer.

[0052] The above-mentioned radiation irradiation method can use alpha rays, beta rays, gamma rays, X-rays, electron beams, or the like. Radiation is applied to a hollow fiber membrane in a virus removal hollow fiber membrane module after contacting it with a solution containing a polymer containing a monocarboxylic acid vinyl ester unit and a vinylpyrrolidone unit, after introducing the polymer onto the surface and then removing the solution from the virus removal hollow fiber membrane module, or after drying the hollow fiber membrane. This method is preferred because it can achieve sterilization of the virus removal hollow fiber membrane module while simultaneously immobilizing the polymer. The radiation dose is preferably 15 kGy or more, more preferably 25 kGy or more. On the other hand, a high radiation dose accelerates degradation or decomposition of the polymer, so the radiation dose is preferably 100 kGy or less.

[0053] When a hollow fiber membrane module for virus removal is used in the virus removal process of biopharmaceutical manufacturing, it is necessary for it to have a high initial permeation rate in addition to high virus removal performance, and to maintain a high permeation rate even when treating a large amount of virus solution containing protein. Therefore, the hollow fiber membrane module for virus removal must have an initial permeation rate of 20 L / m for virus solution containing protein. 2 / hr / kPa or more 100L / m 2 / hr / kPa or less, and the virus solution containing protein is applied with a pressure of 200 kPa and the cumulative protein amount is 500 g / m 2 The permeation rate after passing the solution is preferably 30% to 70% of the initial permeation rate. The lower limit of the initial permeation rate of the virus solution containing the protein is 24 L / m. 2 / hr / kPa is more preferable, 28 L / m 2 If the initial permeation rate of the virus solution containing a protein is too high, the shear stress when the protein contained in the virus solution comes into contact with the hollow fiber membrane increases, and there is a risk that the protein may be denatured. Therefore, the upper limit of the initial permeation rate of the virus solution containing a protein is 96 L / m 2 / hr / kPa is more preferable, 92 L / m 2 / hr / kPa is more preferred.

[0054] The initial permeation rate of a virus solution containing protein in a hollow fiber membrane module for virus removal, and the cumulative protein content of the virus solution at an applied pressure of 200 kPa and 500 g / m 2 The permeation rate after passing the liquid can be measured by the following method.

[0055] A virus solution containing protein is pumped from the outer or inner surface of the hollow fiber membrane to the inner or outer surface, and filtration is performed using the dead-end filtration method, and the filtrate is collected. When the cumulative protein amount in the filtrate (measurement method described later) reaches 500 g / m 2 Filtration was continued until the cumulative protein content in the filtrate reached 500 g / m. 25 mL of the filtrate is collected from each point, and the time required for collection is measured. The permeation rate is calculated using the following formula 1.

[0056] Permeation rate (L / hr / m 2 / kPa)=Qw / (P×T×A) Equation 1 (Qw: filtration volume (L), T: outflow time (hr), P: pressure (kPa), A: membrane area (m 2 ))

[0057] The initial permeation rate is the permeation rate of 5 mL of filtrate immediately after starting filtration, and the cumulative protein content is 500 g / m 2 The permeation rate for 5 mL of filtrate from the point where the cumulative protein content reaches 500 g / m 2 This is the permeation rate after the liquid has passed through.

[0058] The cumulative protein amount in the filtrate can be calculated using the virus solution containing the protein before filtration and the filtrate. Specifically, the absorbance at 280 nm of the virus solution containing the protein before filtration and the filtrate is measured, a calibration curve is created from the absorbance of the virus solution containing the protein before filtration, and the protein concentration of each solution is calculated. The protein amount in each solution is calculated by multiplying the protein concentration of each solution by the weight of each solution. The sum of the protein amounts in the filtrate collected up to a certain point in time is the cumulative protein amount at that point in time.

[0059] The virus removal performance can be expressed in terms of the virus logarithmic removal rate (LRV). In the present invention, the LRV determined from the filtrate immediately after the start of filtration is the initial LRV, and the LRV determined when the cumulative protein content in the filtrate is 500 g / m 2 The final LRV is the LRV calculated from the filtrate at the time when the 50% tissue culture infectious dose (TCID 50The virus amount can be measured by quantifying the amount of virus before and after filtration using the filtration method, plaque method, or the like. Specifically, it can be measured, for example, by the method described in the Examples below. PDA Journal of GMP and Validation in Japan, Vol. 7, No. 1 (2005), pp. 44-54, states that the target LRV to be achieved when performing process validation of the manufacturing process of biological pharmaceuticals is approximately 4. Therefore, it is preferable that the initial and final LRV of a virus removal hollow fiber membrane module are both 4 or more. Furthermore, it is more preferable that the initial LRV of a virus removal hollow fiber membrane module is 5 or more and the final LRV is 4 or more, and it is even more preferable that the initial and final LRV of both are 5 or more.

[0060] Common methods for manufacturing hollow fiber membrane modules include a method in which hollow fiber membranes are fixed in a case while being centrifuged, and a method in which hollow fiber membranes are formed into a U-shape and only the open side of the hollow fiber membranes is fixed in the case. Specifically, for example, hollow fiber membranes are cut to the required length, bundled together in the required number, and placed in a cylindrical case. Then, temporary caps are placed on both ends, and potting material is poured into both ends of the hollow fiber membranes. After the potting material is poured, the module is rotated in a centrifuge (by applying centrifugal force in both end directions), allowing the potting material to be evenly filled. After the potting material has solidified, both ends of the hollow fiber membranes are cut so that both ends are open, thereby producing a hollow fiber membrane module.

[0061] The virus removal hollow fiber membrane module of the present invention can be produced by housing hollow fiber membranes in a case, sealing both ends of the hollow fiber membranes with a potting material, cutting the ends to open them, and then coating the end faces of the hollow fiber membranes with the potting material. Alternatively, the module can be produced by housing hollow fiber membranes in a case, sealing both ends of the hollow fiber membranes with a potting material, cutting the ends to open them, and then melting the end faces of the hollow fiber membranes.

[0062] The potting material may be a polyurethane resin, an epoxy resin, a silicone resin, etc. Among these, a polyurethane resin is preferred because it is made of a low-viscosity raw material and therefore easily penetrates into the membrane thickness of the hollow fiber, and its usable time, such as curing, can be adjusted.

[0063] When cutting the ends of a hollow fiber membrane to open it, if the potting material is cut before it has reached sufficient hardness or if it is cut before it has cooled sufficiently after being heated to promote the curing reaction, shrinkage due to the progression of the crosslinking reaction or shrinkage due to cooling after cutting may occur, resulting in a decrease in the coverage of the potting material in the membrane thickness portion of the hollow fiber membrane end surface. Therefore, when cutting both ends of a hollow fiber membrane to open both ends, the preferred range of hardness of the solidified potting material, expressed in Type A durometer hardness or Type D durometer hardness, is 50 to 100. Type A durometer hardness can be measured using a Type A durometer, and Type D durometer hardness can be measured using a Type D durometer. Note that if the Type A durometer hardness is 90 or higher, measurement is performed using a Type D durometer.

[0064] The blade used to cut the end of the hollow fiber membrane is not particularly limited, but a single-edged razor, a microtome blade, a guillotine blade, a rotary blade, or the like is preferred.

[0065] A potting material is used to coat the end surface of the hollow fiber membrane. Methods for coating the end surface of the hollow fiber membrane include dipping, spraying, and coating. The solution used for coating is not particularly limited as long as it can cover the hollow fiber membrane thickness at the end surface of the hollow fiber membrane. However, a potting material, N,N-dimethylacetamide, or a solution of polysulfone dissolved in N,N-dimethylacetamide is preferred. N,N-dimethylacetamide is used as a solvent for polysulfone, and prolonged immersion in a hollow fiber membrane containing polysulfone may destroy the microstructure of the hollow fiber membrane, resulting in a decrease in virus removal performance. Therefore, a potting material is more preferred as the solution used for coating.

[0066] In immersion coating, if the end surface of the hollow fiber membrane is immersed in the coating solution for too long, the coating solution may penetrate beyond the potting portion and into the lumen side of the hollow fiber membrane, causing blockage of the hollow fiber membrane or blocking of the pores on the lumen side of the hollow fiber membrane, resulting in reduced virus removal performance. Conversely, if the immersion time is too short, the end surface of the hollow fiber membrane will not be completely coated, resulting in reduced virus removal performance. Therefore, the immersion time in the coating solution is preferably 10 seconds or more but less than 30 seconds.

[0067] In addition, examples of means for preventing the coating solution from excessively penetrating into the interior of the hollow fiber membrane include wiping off excess coating solution adhering to the end face of the hollow fiber membrane after immersion in the coating solution, and blowing compressed air from the end face opposite to the side immersed in the coating solution to expel excess coating solution from the inner cavity of the hollow fiber membrane.

[0068] Examples of methods for melting the end face of the hollow fiber membrane include contacting the end face of the hollow fiber membrane with a heat source heated to 300°C for 10 seconds, and bringing a heat source heated to 560°C close to the end face of the hollow fiber membrane so that the distance between the end face and the heat source is 3 mm and maintaining the heat source for 5 seconds. The heat source is not particularly limited as long as it is capable of heating to about 300°C to 600°C, but preferred are hot plates, and ceramic plates and heat-resistant steel plates heated by infrared rays, microwaves, light beams, heating elements, etc.

[0069] The coating of the end faces of the hollow fiber membranes with the potting material or the melting of the end faces of the hollow fiber membranes is preferably performed on both end faces. After the coating or melting of the potting material is performed, the end faces of the hollow fiber membranes are observed using a microscope or the like to confirm that the hollow fiber membranes are not clogged, and then headers are attached to both ends of the case and the nozzles of the headers and case are plugged, allowing the hollow fiber membrane module to be used for virus removal.

[0070] Biopharmaceuticals are pharmaceuticals manufactured by utilizing the ability of cells or microorganisms to produce proteins, etc., through the application of genetic recombination technology or cell culture technology. Examples of biopharmaceuticals include antibody drugs, hormone drugs, and enzyme preparations, and in a broad sense include gene therapy drugs, nucleic acid drugs, and peptide drugs. The proteins, etc. that are the active ingredients of biopharmaceuticals are generally produced by cultured cells.

[0071] The method for producing a biopharmaceutical includes a culture step in which cells that produce a desired protein, etc. are cultured; a separation step in which the cells and a solution containing the desired protein, etc. (hereinafter referred to as a "biopharmaceutical raw material solution") are separated from the cell culture solution obtained in the culture step; a purification step in which the desired protein, etc. contained in the biopharmaceutical raw material solution is purified; a virus inactivation step in which viruses contained in the biopharmaceutical raw material solution are inactivated; and a virus removal step in which viruses contained in the biopharmaceutical raw material solution are removed.

[0072] In the separation step, centrifugation or depth filtration is used. In the purification step, for example, when the desired protein is an antibody, a protein A column on which protein A, which specifically adsorbs the antibody, is immobilized is mainly used. In addition, in the purification step, a cation exchange column or anion exchange column is used to remove proteins derived from the cells used to produce the desired protein (host cell protein). In the virus inactivation step, a low pH treatment is generally performed to set the pH to 4 or less. In the virus removal step, a hollow fiber membrane module for virus removal is generally used.

[0073] As described above, the hollow fiber membrane module for virus removal of the present invention exhibits high virus removal performance even under conditions of high applied pressure, and therefore can be used in virus removal processes. [Example]

[0074] The present invention will be described in detail below with reference to examples and comparative examples, but the present invention is not limited to these.

[0075] (Evaluation method) A. Coverage Measurement After the virus fluid to be measured had been passed through, the virus removal hollow fiber membrane module was autoclaved at 121°C for 20 minutes for epidemic prevention purposes, and then the following procedure was performed. An ultrasonic cutter was used to remove the cap from the header of the virus removal hollow fiber membrane module, exposing the end face of the hollow fiber membrane. A microtome blade was used to cut the end face of the hollow fiber membrane to a thickness of approximately 2 mm, and the cut was observed at 1500x magnification using a scanning electron microscope (S-3000 Type H, Hitachi High-Technologies Corporation), and 10 hollow fiber membranes were randomly selected.

[0076] For each hollow fiber membrane, if exposed areas not covered with potting material were observed in the membrane thickness area of ​​the end surface, one field of view was selected from the area where the degree of exposure was most pronounced, and the image was imported into a computer. If no exposed areas were observed in the membrane thickness area, one field of view was selected from the area with the least color unevenness in the membrane thickness area, and the image was imported into a computer. The size of the imported image was 1280 pixels x 960 pixels.

[0077] Image processing software (ImageJ, developed by the National Institutes of Health, USA) was used for image analysis. After excluding from each image all areas other than the membrane thickness of the hollow fiber membrane, a threshold was set so that the exposed membrane thickness area was the dark area and the unexposed membrane thickness area (the membrane thickness area covered with potting material) was the bright area, resulting in a binarized image. The number of pixels in the bright and dark areas was counted, and the ratio of the bright area to the total number of pixels in the bright and dark areas was calculated. The lowest value of these ratios for the selected 10 hollow fiber membranes was taken as the coverage rate for the target hollow fiber membrane module for virus removal.

[0078] B. Measurement of membrane thickness and inner diameter of hollow fiber membrane The membrane thickness of the hollow fiber membrane was measured by cutting the hollow fiber membrane parallel to the end face with a single-edged razor and observing the cross section with a 1000x lens of a microwatcher (VH-Z100, manufactured by KEYENCE Corporation).

[0079] The inner diameter of the hollow fiber membrane was calculated using the following formula 2. The outer diameter of the hollow fiber membrane was determined by cutting the hollow fiber membrane parallel to the end face with a single-edged razor and measuring the cross section with a laser displacement meter (LS5040T, manufactured by KEYENCE Corporation). Inner diameter of hollow fiber membrane = outer diameter of hollow fiber membrane - (thickness of hollow fiber membrane x 2) Formula 2

[0080] C. Measurement of the log reduction rate (LRV) Approximately 1.0 × 10 bacteriophage MS-2 (ATCC 15597-B1) with a size of approximately 27 nm was added to PBS(-) containing 2 g / L of antibody. 6 The virus was dissolved to a concentration of 100 PFU / mL, and this was used as a virus solution containing protein. The PBS(-) used here had been sterilized by high-pressure steam at 121°C for 20 minutes. The virus solution containing protein was sent to a hollow fiber membrane module for virus removal at a temperature of approximately 25°C and an applied pressure of 200 kPa so that the virus solution flowed from the outer surface to the inner surface of the hollow fiber membrane, and filtration was carried out by dead-end filtration, and the filtrate was collected. The cumulative protein amount in the filtrate, determined by the method described below, was 500 g / m 2 Filtration was continued until the concentration reached 500 g / m. 2 In Example 8 described below, the virus solution containing the protein was pumped so that it flowed from the inner surface to the outer surface of the hollow fiber membrane.

[0081] Based on the Overlay Agar Assay, Standard Method 9211-D (APHA, 1998, Standard Methods for the Examination of Water and Wastewater, 18th ed.), 1 mL of the filtrate appropriately diluted with PBS(-) was inoculated into a test dish, and the concentration of bacteriophage MS-2 in the filtrate was determined by counting the plaques. Plaques are groups of bacteria that have been infected and killed by the virus, and can be counted as dot-like lytic spots.

[0082] In detail, the virus solution containing the protein before filtration was diluted with PBS(-) for 10 4 10x dilution 5 10x diluted solution or 10 6 The filtrate was diluted 10-fold with PBS(-). 2 10x diluted solution or 10 4 Two-fold dilutions were prepared. Pre-dilution or diluted virus solution containing pre-filtered protein or filtrate was dispensed in 1 mL aliquots onto agar plates. E. coli cultured until logarithmic growth phase was performed at 120°C for 20 minutes, autoclaved, and then added to agar medium for phage measurement that had been kept at 50°C, and then poured onto the agar plate. The plate was left to solidify for 30 minutes, and then the lid was removed and the plate was allowed to dry for 30 minutes. The plate was then placed in an incubator heated to 37°C, and after incubation for 17 hours or more, the number of colonies formed on the plate was counted.

[0083] The test was considered successful if the number of plaques in the diluted virus solution containing the protein decreased with increasing dilution. The logarithmic reduction rate (LRV) of the virus was calculated using the following formula 3. LRV=-log 10 (10%) of the virus solution containing protein before filtration 5 Number of plaques in 2-fold diluted solution x 10 5 ) / (number of plaques in diluted filtrate × dilution factor of the filtrate) Formula 3

[0084] For example, an LRV of 2 is -log 10 x=2, or x=0.01, which means that the virus concentration in the filtrate is 1 / 100 of the virus concentration in the virus solution containing protein before filtration (virus removal rate of 99%).

[0085] The smallest LRV of the filtrate obtained from each dilution immediately after the start of filtration was defined as the initial LRV, and the cumulative protein content in the filtrate was defined as 500 g / m 2The smallest LRV of the filtrate after reaching the LRV of each diluted solution was taken as the final LRV.

[0086] The cumulative protein amount in the filtrate was measured using the following method. The virus solution containing the protein before filtration and the filtrate were diluted 5-fold with PBS(-), and the absorbance at 280 nm was measured. The protein concentration in each solution was determined from a calibration curve created from the absorbance of the virus solution containing the protein before filtration, and the protein amount in each solution was calculated by multiplying this by the weight of each solution. The sum of the protein amounts in the solutions collected up to a certain point in time was taken as the cumulative protein amount at that point in time.

[0087] Example 1 A hollow fiber membrane was fabricated according to Patent Document 1. Specifically, 20 parts by weight of polysulfone (Udel® P-3500 manufactured by SOLVAY), 6 parts by weight of polyvinylpyrrolidone (povidone (PLASDONE®) K29 / K32 manufactured by ASHLAND LCC), and 3 parts by weight of polyvinylpyrrolidone (povidone (PLASDONE®) K90 manufactured by ASHLAND LCC) were added to a solution consisting of 70 parts by weight of N,N-dimethylacetamide and 1 part by weight of water, and the mixture was heated and dissolved at 90°C for 14 hours to obtain a membrane-forming solution. This membrane-forming solution was extruded through an orifice-type double cylindrical nozzle adjusted to 40°C, and simultaneously, a solution consisting of 72 parts by weight of N,N-dimethylacetamide and 28 parts by weight of water was extruded through the inner tube as a core liquid. The extruded solution was passed through a dry space with a length of 350 mm and then introduced into a coagulation bath containing water at 40°C to obtain a hollow fiber membrane.

[0088] Ten of the obtained hollow fiber membranes were packed into a case with a diameter of approximately 5 mm and a length of approximately 17 cm, and both ends were potted using QuickMender (registered trademark) (manufactured by Konishi Co., Ltd.), an epoxy resin-based chemical reaction adhesive, as a potting material.The end faces were then cut to open both ends of the hollow fiber membrane.

[0089] Next, both end faces of the hollow fiber membrane were melted by contacting them with a hot plate heated to 300°C for 10 seconds. Both end faces of the hollow fiber membrane were observed under a microscope to confirm that the hollow portion of the hollow fiber membrane was open. After that, headers were attached to both ends of the case and nozzles were attached to the sides to prepare a hollow fiber membrane module.

[0090] The interior of the hollow fiber membrane module was washed with pure water for 30 minutes, and then 10 mL of an aqueous solution containing a vinylpyrrolidone / vinyl propanoate random copolymer (molar fraction of vinyl propanoate units: 40%, number-average molecular weight: 68,000) dissolved at a concentration of 100 ppm and ethanol at a concentration of 1,000 ppm was passed through the hollow fiber membrane from the outside to the inside at an applied pressure of 100 kPa. The hollow fiber membrane was then irradiated with 25 kGy of gamma rays to support the vinylpyrrolidone / vinyl propanoate random copolymer on the surface. The interior of the hollow fiber membrane module was washed with pure water for 30 minutes, yielding the hollow fiber membrane module for virus removal of Example 1.

[0091] Example 2 A hollow fiber membrane was produced in accordance with Patent Document 2. Specifically, a hollow fiber membrane was obtained in the same manner as in Example 1, except that the weight parts of polysulfone (Udel (registered trademark) P-3500 manufactured by SOLVAY) in the membrane-forming solution were 18 weight parts, the weight parts of N,N-dimethylacetamide were 72 weight parts, and the temperature of the coagulation bath was 50°C.

[0092] A hollow fiber membrane module was produced in the same manner as in Example 1, except that the number of hollow fiber membranes was changed to 20.

[0093] The inside of the hollow fiber membrane module was washed with pure water for 30 minutes, and then 20 mL of an aqueous solution containing a vinylpyrrolidone / vinyl propanoate random copolymer (molar fraction of vinyl propanoate units: 40%, number-average molecular weight: 16,500) at a concentration of 50 ppm and ethanol at a concentration of 200 ppm was passed through the hollow fiber membrane from the inside to the outside at an applied pressure of 100 kPa. The hollow fiber membrane was then irradiated with 25 kGy of gamma rays to support the vinylpyrrolidone / vinyl propanoate random copolymer on the surface of the hollow fiber membrane. The inside of the hollow fiber membrane module was washed with pure water for 30 minutes, yielding a hollow fiber membrane module for virus removal of Example 2.

[0094] Example 3 A hollow fiber membrane was produced in the same manner as in Example 1.

[0095] Ten of the obtained hollow fiber membranes were packed into a case with a diameter of approximately 5 mm and a length of approximately 12 cm. Temporary caps were placed on both ends of the case, which was then placed in a centrifugal potting machine. While rotating the case in the centrifuge, urethane resin (manufactured by Tosoh Corporation) was poured into the case. After centrifugation, the potting material was cured at 40°C for one day. After removing the temporary caps, the end faces of the hollow fiber membranes were cut with a microtome blade to open both ends of the hollow fiber membranes.

[0096] Next, both end faces of the hollow fiber membrane were melted in the same manner as in Example 1. Both end faces of the hollow fiber membrane were observed under a microscope to confirm that the hollow portions of the hollow fiber membranes were open. Thereafter, headers were attached to both ends of the case and nozzles were attached to the sides, to prepare a hollow fiber membrane module.

[0097] The inside of the hollow fiber membrane module was washed with pure water for 30 minutes, and then the vinylpyrrolidone / vinyl propanoate random copolymer was supported on the surface of the hollow fiber membrane by the same procedure as in Example 1. The inside of the hollow fiber membrane module was washed with pure water for 30 minutes to obtain a hollow fiber membrane module for virus removal of Example 3.

[0098] Example 4 A hollow fiber membrane was obtained in the same manner as in Example 1, except that the weight parts of polysulfone (Udel (registered trademark) P-3500 manufactured by SOLVAY) in the membrane forming solution were 18 weight parts, the weight parts of N,N-dimethylacetamide were 72 weight parts, and the temperature of the coagulation bath was 50°C.

[0099] Twenty of the obtained hollow fiber membranes were packed into a case with a diameter of approximately 5 mm and a length of approximately 12 cm. Temporary caps were placed on both ends of the case, which was then placed in a centrifugal potting machine. While rotating the case in the centrifuge, urethane resin (manufactured by Tosoh Corporation) was poured into the case. The potting material was then cured at 40°C for one day. After removing the temporary caps, the end faces of the hollow fiber membranes were cut with a microtome blade to open both ends of the hollow fiber membranes.

[0100] Next, both end faces of the hollow fiber membrane were melted in the same manner as in Example 1. Both end faces of the hollow fiber membrane were observed under a microscope to confirm that the hollow portions of the hollow fiber membranes were open. Thereafter, headers were attached to both ends of the case and nozzles were attached to the sides, respectively, to prepare a hollow fiber membrane module.

[0101] The interior of the obtained hollow fiber membrane module was washed with pure water for 30 minutes, and then 20 mL of an aqueous solution containing a vinylpyrrolidone / vinyl propanoate random copolymer (molar fraction of vinyl propanoate units: 40%, number-average molecular weight: 16,500) at a concentration of 50 ppm and ethanol at a concentration of 200 ppm was passed through the hollow fiber membrane from the inside to the outside at an applied pressure of 100 kPa. The hollow fiber membrane was then irradiated with 25 kGy of gamma rays to support the vinylpyrrolidone / vinyl propanoate random copolymer on the surface of the hollow fiber membrane. The interior of the hollow fiber membrane module was washed with pure water for 30 minutes to obtain the hollow fiber membrane module for virus removal of Example 4.

[0102] Example 5 A hollow fiber membrane was obtained in the same manner as in Example 1, except that the weight parts of the membrane-forming solution were changed to 8 parts by weight of polyvinylpyrrolidone (manufactured by ASHLAND LCC, povidone (PLASDONE®) K29 / K32), 4 parts by weight of polyvinylpyrrolidone (manufactured by ASHLAND LCC, povidone (PLASDONE®) K90), and 67 parts by weight of N,N-dimethylacetamide, and the die temperature was changed to 50°C.

[0103] Ten of the obtained hollow fiber membranes were packed into a case with a diameter of approximately 5 mm and a length of approximately 12 cm. Temporary caps were placed on both ends of the case, which was then placed in a centrifugal potting machine. While rotating the case in the centrifuge, urethane resin (manufactured by Tosoh Corporation) was poured into the case. After centrifugation, the potting material was cured at 40°C for one day. After removing the temporary caps, the end faces of the hollow fiber membranes were cut with a microtome blade to open both ends of the hollow fiber membranes.

[0104] Next, one end of the hollow fiber membrane was immersed in the same urethane resin used for potting for 10 seconds, and excess urethane resin was removed with a paper towel. After leaving it to stand for 1 minute to allow the urethane resin to harden, compressed air was passed through the end opposite the end immersed in the urethane resin at an applied pressure of 100 kPa for 30 seconds. After curing at room temperature for 1 day, the opposite end was similarly coated and allowed to harden at room temperature for 1 day. Both end faces of the hollow fiber membrane were observed under a microscope to confirm that the hollow portion of the hollow fiber membrane was open. Headers were then attached to both ends of the case and nozzles were attached to the sides, completing the hollow fiber membrane module.

[0105] The interior of the obtained hollow fiber membrane module was washed with pure water for 30 minutes, and then 10 mL of an aqueous solution containing a vinylpyrrolidone / vinyl propanoate random copolymer (molar fraction of vinyl propanoate units: 40%, number-average molecular weight: 67,000) dissolved at a concentration of 100 ppm and ethanol dissolved at a concentration of 10,000 ppm was passed through the hollow fiber membrane from the outside to the inside at an applied pressure of 50 kPa. Subsequently, 6.5 mL of an aqueous solution containing ethanol dissolved at a concentration of 5,000 ppm was passed through the hollow fiber membrane from the outside to the inside at an applied pressure of 100 kPa. The hollow fiber membrane was then irradiated with 25 kGy of gamma rays to support the vinylpyrrolidone / vinyl propanoate random copolymer on the surface of the hollow fiber membrane. The interior of the hollow fiber membrane module was washed with pure water for 30 minutes to obtain the hollow fiber membrane module for virus removal of Example 5.

[0106] Example 6 A hollow fiber membrane was obtained in the same manner as in Example 1, except that the same membrane-forming solution as in Example 1 was used and the coagulation bath temperature was set to 50°C.

[0107] Ten of the obtained hollow fiber membranes were packed into a case with a diameter of approximately 5 mm and a length of approximately 12 cm. Temporary caps were placed on both ends of the case, which was then set in a centrifugal potting machine. While rotating the case in the centrifuge, urethane resin (manufactured by Tosoh Corporation) was poured into the case. After centrifugation, the potting material was cured at 40°C for one day. After removing the temporary caps, the end faces of the hollow fiber membranes were cut with a microtome blade to open both ends of the hollow fiber membranes.

[0108] Next, both end faces of the hollow fiber membrane were melted in the same manner as in Example 1. Both end faces of the hollow fiber membrane were observed using a microscope, and it was confirmed that the hollow portions of the hollow fiber membranes were open. Thereafter, headers were attached to both ends of the case and nozzles were attached to the sides, to prepare a hollow fiber membrane module.

[0109] After the interior of the hollow fiber membrane module was washed with pure water for 30 minutes, 10 mL of an aqueous solution containing a vinylpyrrolidone / vinyl propanoate random copolymer (molar fraction of vinyl propanoate units: 40%, number-average molecular weight: 67,000) dissolved at a concentration of 100 ppm and ethanol dissolved at a concentration of 10,000 ppm was passed through the hollow fiber membrane from the outside to the inside at an applied pressure of 50 kPa. Subsequently, 6.5 mL of an aqueous solution containing ethanol dissolved at a concentration of 5,000 ppm was passed through the hollow fiber membrane from the outside to the inside at an applied pressure of 100 kPa. The hollow fiber membrane was then irradiated with 25 kGy of gamma rays to support the vinylpyrrolidone / vinyl propanoate random copolymer on the surface of the hollow fiber membrane. The interior of the hollow fiber membrane module was washed with pure water for 30 minutes to obtain the hollow fiber membrane module for virus removal of Example 6.

[0110] Example 7 A hollow fiber membrane was obtained in the same manner as in Example 1, except that the membrane-forming solution contained 21 parts by weight of polysulfone (Udel (registered trademark) P-3500 manufactured by SOLVAY), 7 parts by weight of polyvinylpyrrolidone (PLASDONE K29 / K32 manufactured by ASHLAND LCC), 3.5 parts by weight of polyvinylpyrrolidone (PLASDONE K90 manufactured by ASHLAND LCC), and 67.5 parts by weight of N,N-dimethylacetamide as a solvent.

[0111] Ten of the obtained hollow fiber membranes were packed into a case with a diameter of approximately 5 mm and a length of approximately 12 cm. Temporary caps were placed on both ends of the case, which was then placed in a centrifugal potting machine. While rotating the case in the centrifuge, urethane resin (manufactured by Tosoh Corporation) was poured into the case. After centrifugation, the potting material was cured at 40°C for one day. After removing the temporary caps, the end faces of the hollow fiber membranes were cut with a microtome blade to open both ends of the hollow fiber membranes.

[0112] Next, both end faces of the hollow fiber membrane were coated with urethane resin in the same manner as in Example 5. Both end faces of the hollow fiber membrane were observed under a microscope to confirm that the hollow portions of the hollow fiber membranes were open. Thereafter, headers were attached to both ends of the case and nozzles were attached to the sides, to prepare a hollow fiber membrane module.

[0113] The interior of the obtained hollow fiber membrane module was washed with pure water for 30 minutes, and then 10 mL of an aqueous solution containing a vinylpyrrolidone / vinyl propanoate random copolymer (molar fraction of vinyl propanoate units: 40%, number-average molecular weight: 67,000) dissolved at a concentration of 100 ppm and ethanol dissolved at a concentration of 50,000 ppm was passed through the hollow fiber membrane from the outside to the inside at an applied pressure of 50 kPa. Subsequently, 6.5 mL of an aqueous solution containing ethanol dissolved at a concentration of 5,000 ppm was passed through the hollow fiber membrane from the outside to the inside at an applied pressure of 100 kPa. The hollow fiber membrane was then irradiated with 25 kGy of gamma rays to support the vinylpyrrolidone / vinyl propanoate random copolymer on the surface of the hollow fiber membrane. The interior of the hollow fiber membrane module was washed with pure water for 30 minutes to obtain the hollow fiber membrane module for virus removal of Example 7.

[0114] Example 8 A hollow fiber membrane was obtained in the same manner as in Example 1, except that the weight parts of polysulfone (Udel (registered trademark) P-3500 manufactured by SOLVAY) in the membrane forming solution were changed to 22 weight parts, the weight parts of N,N-dimethylacetamide as the solvent were changed to 65 weight parts, and the die temperature was changed to 70°C.

[0115] Ten of the obtained hollow fiber membranes were packed into a case with a diameter of approximately 5 mm and a length of approximately 12 cm. Temporary caps were placed on both ends of the case, which was then placed in a centrifugal potting machine. While rotating the case in the centrifuge, urethane resin (manufactured by Tosoh Corporation) was poured into the case. After centrifugation, the potting material was cured at 40°C for one day. After removing the temporary caps, the end faces of the hollow fiber membranes were cut with a microtome blade to open both ends of the hollow fiber membranes.

[0116] Next, both end faces of the hollow fiber membrane were coated with urethane resin in the same manner as in Example 5. Both end faces of the hollow fiber membrane were observed under a microscope to confirm that the hollow portions of the hollow fiber membranes were open. Thereafter, headers were attached to both ends of the case and nozzles were attached to the sides, to prepare a hollow fiber membrane module.

[0117] The interior of the obtained hollow fiber membrane module was washed with pure water for 30 minutes, and then 10 mL of an aqueous solution containing a vinylpyrrolidone / vinyl propanoate random copolymer (molar fraction of vinyl propanoate units: 40%, number-average molecular weight: 67,000) dissolved at a concentration of 100 ppm and ethanol dissolved at a concentration of 10,000 ppm was passed through the hollow fiber membrane from the outside to the inside at an applied pressure of 50 kPa. Subsequently, 6.5 mL of an aqueous solution containing ethanol dissolved at a concentration of 5,000 ppm was passed through the hollow fiber membrane from the outside to the inside at an applied pressure of 100 kPa. The hollow fiber membrane was then irradiated with 25 kGy of gamma rays to support the vinylpyrrolidone / vinyl propanoate random copolymer on the surface of the hollow fiber membrane. The interior of the hollow fiber membrane module was washed with pure water for 30 minutes to obtain the hollow fiber membrane module for virus removal of Example 8.

[0118] Example 9 A hollow fiber membrane was obtained in the same manner as in Example 1, except that the membrane-forming solution contained 21 parts by weight of polysulfone (Udel (registered trademark) P-3500 manufactured by SOLVAY), 7 parts by weight of polyvinylpyrrolidone (PLASDONE K29 / K32 manufactured by ASHLAND LCC), 3.5 parts by weight of polyvinylpyrrolidone (PLASDONE K90 manufactured by ASHLAND LCC), and 67.5 parts by weight of N,N-dimethylacetamide solvent, and that the coagulation bath temperature during spinning of the polysulfone hollow fiber membrane was 50°C.

[0119] Ten of the obtained hollow fiber membranes were packed into a case with a diameter of approximately 5 mm and a length of approximately 12 cm. Temporary caps were placed on both ends of the case, which was then placed in a centrifugal potting machine. While rotating the case in the centrifuge, urethane resin (manufactured by Tosoh Corporation) was poured into the case. After centrifugation, the potting material was cured at 40°C for one day. After removing the temporary caps, the end faces of the hollow fiber membranes were cut with a microtome blade to open both ends of the hollow fiber membranes.

[0120] Next, both end faces of the hollow fiber membrane were coated with urethane resin in the same manner as in Example 5. Both end faces of the hollow fiber membrane were observed under a microscope to confirm that the hollow portions of the hollow fiber membranes were open. Thereafter, headers were attached to both ends of the case and nozzles were attached to the sides, to prepare a hollow fiber membrane module.

[0121] The inside of the obtained hollow fiber membrane module was washed with pure water for 30 minutes, and then the hollow fiber membrane module was irradiated with gamma rays without passing the aqueous vinylpyrrolidone / vinyl propanoate random copolymer solution and the aqueous ethanol solution to be supported on the hollow fiber membrane, i.e., without passing the aqueous vinylpyrrolidone / vinyl propanoate random copolymer solution and the aqueous ethanol solution through the hollow fiber membrane, in a state where the module was filled with pure water, to obtain a hollow fiber membrane module for virus removal of Example 9.

[0122] Example 10 A hollow fiber membrane was obtained in the same manner as in the Examples, except that the weight parts of the membrane-forming solution were changed to 8 parts by weight of polyvinylpyrrolidone (manufactured by ASHLAND LCC, povidone (PLASDONE) K29 / K32), 4 parts by weight of polyvinylpyrrolidone (manufactured by ASHLAND LCC, povidone (PLASDONE) K90), and 67 parts by weight of N,N-dimethylacetamide, and the die temperature was changed to 50°C.

[0123] Ten of the obtained hollow fiber membranes were packed into a case with a diameter of approximately 5 mm and a length of approximately 12 cm. Temporary caps were placed on both ends of the case, which was then placed in a centrifugal potting machine. While rotating the case in the centrifuge, urethane resin (manufactured by Tosoh Corporation) was poured into the case. After centrifugation, the potting material was cured at 40°C for one day. After removing the temporary caps, the end faces of the hollow fiber membranes were cut with a microtome blade to open both ends of the hollow fiber membranes.

[0124] Next, both end faces of the hollow fiber membrane were coated with urethane resin in the same manner as in Example 5. Both end faces of the hollow fiber membrane were observed under a microscope to confirm that the hollow portions of the hollow fiber membranes were open. Thereafter, headers were attached to both ends of the case and nozzles were attached to the sides, to prepare a hollow fiber membrane module.

[0125] The interior of the obtained hollow fiber membrane module was washed with pure water for 30 minutes, and then 10 mL of an aqueous solution containing polyvinylpyrrolidone ((Ashland LLC, Povidone (PLASDONE) K90)) dissolved at a concentration of 100 ppm and ethanol dissolved at a concentration of 1,000 ppm was passed through the hollow fiber membrane from the outside to the inside at an applied pressure of 50 kPa. Next, 6.5 mL of an aqueous solution containing ethanol dissolved at a concentration of 5,000 ppm was passed through the hollow fiber membrane from the outside to the inside at an applied pressure of 100 kPa. Thereafter, the hollow fiber membrane was irradiated with 25 kGy of gamma rays to support polyvinylpyrrolidone on the surface of the hollow fiber membrane. The interior of the hollow fiber membrane module was washed with pure water for 30 minutes to obtain the hollow fiber membrane module for virus removal of Example 10.

[0126] (Comparative Example 1) A hollow fiber membrane module for virus removal of Comparative Example 1 was obtained in the same manner as in Example 1, except that both end faces of the hollow fiber membrane were not brought into contact with the hot plate heated to 300°C for 10 seconds.

[0127] (Comparative Example 2) A hollow fiber membrane was obtained in the same manner as in Example 2.

[0128] A hollow fiber membrane module was produced in the same manner as in Example 2, except that both end faces of the hollow fiber membrane were not brought into contact with the hot plate heated to 300° C. for 10 seconds.

[0129] A vinylpyrrolidone / vinyl propanoate random copolymer was supported on the surface of the hollow fiber membrane by the same procedure as in Example 2. The inside of the hollow fiber membrane module was washed with pure water for 30 minutes to obtain a hollow fiber membrane module for virus removal of Comparative Example 2.

[0130] (Comparative Example 3) A hollow fiber membrane was produced in the same manner as in Example 1.

[0131] Ten of the obtained hollow fiber membranes were packed into a case with a diameter of approximately 5 mm and a length of approximately 12 cm. Temporary caps were placed on both ends of the case, which was then set in a centrifugal potting machine. While the hollow fiber membrane module was being rotated in the centrifuge, urethane resin (manufactured by Tosoh Corporation) was poured into the case. After centrifugation, the potting material was cured at 40°C for one day. After removing the temporary caps, the end faces of the hollow fiber membranes were cut with a microtome blade to open both ends of the hollow fiber membranes.

[0132] Next, headers were attached to both ends of the case and a nozzle was attached to the side, to prepare a hollow fiber membrane module.

[0133] The inside of the obtained hollow fiber membrane module was washed with pure water for 30 minutes, and then a vinylpyrrolidone / vinyl propanoate random copolymer was supported on the surface of the hollow fiber membrane in the same manner as in Example 1, thereby obtaining a hollow fiber membrane module for virus removal of Comparative Example 3.

[0134] Comparative Example 4 A hollow fiber membrane was obtained in the same manner as in Example 1, except that the weight parts of polysulfone (Udel (registered trademark) P-3500 manufactured by SOLVAY) in the membrane forming solution were 18 weight parts, the weight parts of N,N-dimethylacetamide were 72 weight parts, and the temperature of the coagulation bath was 50°C.

[0135] Twenty of the obtained hollow fiber membranes were packed into a case with a diameter of approximately 5 mm and a length of approximately 12 cm. Temporary caps were placed on both ends of the case, which was then set in a centrifugal potting machine. Urethane resin (manufactured by Tosoh Corporation) was poured into the case while the hollow fiber membrane module was being rotated in the centrifuge. After centrifugation, the potting material was cured at 40°C for one day. After removing the temporary caps, the end faces of the hollow fiber membranes were cut with a microtome blade to open both ends of the hollow fiber membranes.

[0136] Next, headers were attached to both ends of the case and a nozzle was attached to the side, to prepare a hollow fiber membrane module.

[0137] The interior of the obtained hollow fiber membrane module was washed with pure water for 30 minutes, and then 20 mL of an aqueous solution containing a vinylpyrrolidone / vinyl propanoate random copolymer (molar fraction of vinyl propanoate units: 40%, number-average molecular weight: 16,500) dissolved at a concentration of 50 ppm and ethanol at a concentration of 200 ppm was passed through the hollow fiber membrane from the inside to the outside at an applied pressure of 100 kPa. The hollow fiber membrane was then irradiated with 25 kGy of gamma rays to support the vinylpyrrolidone / vinyl propanoate random copolymer on the surface of the hollow fiber membrane. The interior of the hollow fiber membrane module was washed with pure water for 30 minutes to obtain a hollow fiber membrane module for virus removal of Comparative Example 4.

[0138] (Comparative Example 5) A hollow fiber membrane was obtained in the same manner as in Example 1, except that the weight parts of the membrane-forming solution were changed to 8 parts by weight of polyvinylpyrrolidone (manufactured by ASHLAND LCC, povidone (PLASDONE) K29 / K32), 4 parts by weight of polyvinylpyrrolidone (manufactured by ASHLAND LCC, povidone (PLASDONE) K90), and 67 parts by weight of N,N-dimethylacetamide, and the die temperature was changed to 50°C.

[0139] Ten of the obtained hollow fiber membranes were packed into a case with a diameter of approximately 5 mm and a length of approximately 12 cm. Temporary caps were placed on both ends of the case, and the case was set in a centrifugal potting machine. While the hollow fiber membrane module was rotating in the centrifuge, urethane resin (manufactured by Tosoh Corporation) was poured into it. After centrifugation, the potting material was cured at 40°C for one day. After removing the temporary caps, the end faces of the hollow fiber membranes were cut with a microtome blade to open both ends of the hollow fiber membranes. Headers were attached to both ends of the case, and nozzles were attached to the sides, to produce a hollow fiber membrane module.

[0140] The interior of the obtained hollow fiber membrane module was washed with pure water for 30 minutes, and then 10 mL of an aqueous solution containing a vinylpyrrolidone / vinyl propanoate random copolymer (molar fraction of vinyl propanoate units: 40%, number-average molecular weight: 67,000) dissolved at a concentration of 100 ppm and ethanol dissolved at a concentration of 10,000 ppm was passed through the hollow fiber membrane from the outside to the inside at an applied pressure of 50 kPa. Subsequently, 6.5 mL of an aqueous solution containing ethanol dissolved at a concentration of 5,000 ppm was passed through the hollow fiber membrane from the outside to the inside at an applied pressure of 100 kPa. The hollow fiber membrane was then irradiated with 25 kGy of gamma rays to support the vinylpyrrolidone / vinyl propanoate random copolymer on the surface of the hollow fiber membrane. The interior of the hollow fiber membrane module was washed with pure water for 30 minutes to obtain a hollow fiber membrane module for virus removal of Comparative Example 5.

[0141] Table 1 shows the configuration and evaluation results of the virus removal hollow fiber membrane modules of each Example and Comparative Example.

[0142] [Table 1]

[0143] The virus removal hollow fiber membrane module of Comparative Example 1, which was produced in accordance with Patent Document 1; the virus removal hollow fiber membrane module of Comparative Example 2, which was produced in accordance with Patent Document 2; the virus removal hollow fiber membrane module of Comparative Example 3, in which the potting material of the virus removal hollow fiber membrane module of Comparative Example 1 was changed from epoxy resin to urethane resin; and the virus removal hollow fiber membrane module of Comparative Example 4, in which the potting material of the virus removal hollow fiber membrane module of Comparative Example 2 was changed from epoxy resin to urethane resin, all had low coverage rates and low initial LRV and final LRV, which are indicators of virus removal performance.

[0144] In contrast, the hollow fiber membrane modules for virus removal in Examples 1 to 4, which correspond to the hollow fiber membrane modules for virus removal in Comparative Examples 1 to 4 in which the end faces of the hollow fiber membranes after potting were melt-treated, had a coverage of 0.96 or more, and both the initial LRV and the final LRV were 4 or more.

[0145] These results demonstrate that the hollow fiber membrane module for virus removal, in which the end faces of the hollow fiber membranes after potting were melt-treated, has a high coverage rate and demonstrates high virus removal performance even under the high applied pressure conditions encountered in industrial-scale production of biopharmaceuticals.

[0146] The virus removal hollow fiber membrane module of Comparative Example 5, which was produced using a hollow fiber membrane produced under different spinning conditions than the hollow fiber membranes of Examples 1 and 2, i.e., a hollow fiber membrane having different virus removal performance than the hollow fiber membranes of Examples 1 and 2, and which was produced using a urethane resin as the potting material, different from that of Examples 1 and 2, had a low coverage rate and low initial and final LRVs. In contrast, the virus removal hollow fiber membrane module of Example 5, which corresponds to the virus removal hollow fiber membrane module of Comparative Example 5 in which the end faces of the hollow fiber membranes after potting were coated with the same urethane resin as that used for potting, had a coverage rate of 0.96 or higher, and both the initial and final LRVs were 4 or higher. Furthermore, the hollow fiber membrane module for virus removal in Example 7, which used hollow fiber membranes produced under spinning conditions different from those of the hollow fiber membranes in Examples 1, 2, or 5, and in which the end faces of the hollow fiber membranes after potting were coated with urethane resin in the same manner as in Example 5, had a coverage of 0.96 or more and an initial LRV and a final LRV of 4 or more.

[0147] These results demonstrate that a hollow fiber membrane module for virus removal, in which the end faces of the hollow fiber membranes after potting are coated with potting material, has a high coverage rate and demonstrates high virus removal performance even under the high applied pressure conditions encountered in industrial-scale production of biopharmaceuticals.

[0148] The virus removal hollow fiber membrane module of Example 6, which was produced using hollow fiber membranes produced under spinning conditions different from those of the hollow fiber membranes of Examples 1, 2, 5, or 7, using a urethane resin as the potting material as in Example 3 or 4, and further by melt-treating the end faces of the hollow fiber membranes after potting, had a coverage of 0.96 or more, and both the initial LRV and the final LRV were 4 or more. These results demonstrate that even when hollow fiber membranes other than those produced according to Patent Documents 1 or 2 are used, virus removal hollow fiber membrane modules in which the end faces of the hollow fiber membranes after potting are melt-treated have a high coverage and exhibit high virus removal performance under the high applied pressure conditions used in industrial-scale production of biopharmaceuticals.

[0149] On the other hand, the virus removal hollow fiber membrane modules of Examples 8 to 10 were produced using hollow fiber membranes produced under spinning conditions different from those of Examples 1, 2, or 3 to 7, and by coating the end faces of the hollow fiber membranes after potting with a urethane resin. When measuring the virus logarithmic removal rate in the virus removal hollow fiber membrane module of Example 8, unlike the measurements in the virus removal hollow fiber membrane modules of the other Examples, the protein-containing virus solution was delivered so that it flowed from the inner surface to the outer surface of the hollow fiber membrane. In the virus removal hollow fiber membrane module of Example 9, a vinylpyrrolidone / vinyl propanoate random copolymer was not supported on the surface of the hollow fiber membrane. In the virus removal hollow fiber membrane module of Example 10, vinylpyrrolidone, a polymer having no monocarboxylic acid vinyl ester units, was supported on the surface of the hollow fiber membrane. The virus removal hollow fiber membrane modules of Examples 8 to 10 had a coverage of 0.96 or more, and both the initial LRV and final LRV were 4 or more. These results demonstrate that, regardless of the flow direction of the virus-containing solution or the strength of the protein adhesion inhibitory effect on the hollow fiber membrane surface, hollow fiber membrane modules for virus removal, in which the end faces of the hollow fiber membranes after potting are coated with potting material, have a high coverage rate and demonstrate high virus removal performance under the high applied pressure conditions encountered in industrial-scale production of biopharmaceuticals. [Industrial Applicability]

[0150] The hollow fiber membrane module for virus removal of the present invention exhibits high virus removal performance even under the high applied pressure conditions encountered in the industrial-scale production of biopharmaceuticals, and can therefore be used in the virus removal step in the production of biopharmaceuticals. [Explanation of symbols]

[0151] 1 case 2. Hollow fiber membrane 3A Header 3B Header 4A inlet 4B Inlet 5A nozzle 5B nozzle 6 Potting material

Claims

1. It has a hollow fiber membrane, the membrane thickness portion of the end surface of the hollow fiber membrane is covered with a potting material, A hollow fiber membrane module for virus removal, wherein a coverage rate by the potting material in a membrane thickness portion of an end face of the hollow fiber membrane on a side to which a virus-containing solution is supplied or on a side to which a virus-removed solution is discharged is 0.96 or more and 1.00 or less.

2. 2. The virus removal hollow fiber membrane module according to claim 1, wherein the hollow fiber membranes are mainly composed of a polysulfone-based polymer.

3. 3. The virus removal hollow fiber membrane module according to claim 1, wherein the hollow fiber membrane has an inner diameter of 160 μm or more and 450 μm or less and a membrane thickness of 30 μm or more and 100 μm or less.

4. 3. The virus removal hollow fiber membrane module according to claim 1, wherein the hollow fiber membrane is a hollow fiber membrane having a polymer containing a monocarboxylic acid vinyl ester unit and a vinylpyrrolidone unit supported on the surface thereof.

5. 3. The method for producing a hollow fiber membrane module for virus removal according to claim 1 or 2, wherein the hollow fiber membranes are housed in a case, both end portions of the hollow fiber membranes are sealed with a potting material, the end portions are cut to form openings, and then the end faces of the hollow fiber membranes are coated with the potting material.

6. 3. The method for producing a hollow fiber membrane module for virus removal according to claim 1 or 2, wherein the hollow fiber membranes are housed in a case, both end portions of the hollow fiber membranes are sealed with a potting material, the end portions are cut to form openings, and then the end faces of the hollow fiber membranes are melted.

7. A biopharmaceutical product in which viruses have been removed using the hollow fiber membrane module for virus removal according to claim 1 or 2.

8. A method for producing a biopharmaceutical, comprising a virus removal step of removing viruses contained in a biopharmaceutical raw material solution using the virus removal hollow fiber membrane module according to claim 1 or 2.

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