Tangential flow virus filter

Abstract

A virus filter comprises a filter member characterized by a first surface and a second surface and having a thickness extending in a first direction from the first surface to the second surface, and a plurality of channels formed in the filter member, each having a channel axis; when in use, a solution having a virus load flows in a direction parallel to the first surface, wherein at least a portion of the virus load passes through the first surface and enters the membrane and propagates widely in the first direction, and at least 50% of the channels of the filter member have channel axes oriented at an angle of 5 to 85 degrees with respect to the first direction.

Description

Technology Field

[0001] Cross-reference of related applications

[0002] The present invention claims priority to U.S. provisional patent application No. 62 / 816,786 filed on March 11, 2019, the entire contents of which are incorporated herein by reference.

[0003] The present disclosure relates to biotechnology and biomanufacturing. Background Technology

[0004] Mammalian cells containing nucleic acids encoding recombinant proteins are often used to produce proteins of therapeutic or commercial importance. Given the diverse distribution channels available, biotechnology companies are increasingly devoting efforts to developing innovative solutions for manufacturing therapeutic protein raw materials in a highly flexible and cost-effective manner.

[0005] To perform biomanufacturing at production scale, many unit operations are implemented as continuous processes. Among these processes, removing viruses from product streams remains a challenging task. The present disclosure features a system and method for implementing tangential flow virus filtration (TFVF). In some embodiments, TFVF may be performed continuously or semi-continuously to enable online purification of various therapeutic protein raw materials, including therapeutic recombinant protein materials. In a TFVF system, a fluid (e.g., a process fluid containing one or more products to be purified) may be circulated through a fluid circuit comprising filter elements that capture or retain virus particles. A portion of the fluid and its contents may be recirculated without passing through the filter and pass back through the system.

[0006] According to one embodiment, the present disclosure features a virus filter comprising a filter member and a plurality of channels formed in the filter member. The filter member is characterized by a first surface and a second surface and has a thickness extending in a first direction from the first surface to the second surface. Each channel has a channel axis. When in use, a solution having a virus load flows in a direction parallel to the first surface, at least a portion of the virus load passes through the first surface into a membrane and propagates widely in the first direction, and at least 50% of the channels of the filter member have channel axes oriented at an angle of 5 to 85 degrees with respect to the first direction.

[0007] Examples of the filter may include one or more of the features described below.

[0008] The channel axis is oriented at an angle of 5 to 75 degrees (e.g., 10 to 60 degrees) with respect to the first direction. More than 70% (e.g., more than 90% of the channels) of the filter member may have the channel axis oriented at an angle of 5 to 85 degrees with respect to the first direction.

[0009] The thickness of the filter member may be 150 micrometers or more (e.g., 300 micrometers or more, or 500 micrometers or more). Each constituent channel forming the plurality of channels may include an opening on a first surface, and the ratio of the total opening area to the total area of ​​the first surface may be 0.10 or more (e.g., 0.20 or more, or 0.30 or more). Each constituent channel forming the plurality of channels may have any volume, and the ratio of the total volume of the channels to the total volume of the filter member may be 0.05 or more (e.g., 0.10 or more, or 0.20 or more).

[0010] Each of at least some member channels among the plurality of channels comprises an opening on a first surface, wherein the opening has a first cross-sectional area on the first surface, and the first cross-sectional area may be smaller than the second cross-sectional area of ​​the member channel at a location between the first surface and the second surface. The ratio of the first cross-sectional area to the second cross-sectional area may be 0.95 or less (e.g., 0.85 or less, or 0.75 or less). The at least some member channels may account for 40% or more (e.g., 60%, or all) of the member channels forming the plurality of channels.

[0011] The channel axes of the plurality of channels may exhibit an orientation distribution with respect to a first direction. The average orientation distribution with respect to the first direction may be 10 to 30 degrees (e.g., 30 to 50 degrees, or 50 to 80 degrees). The full width at half maximum (FWHM) value of the orientation distribution may be 60 degrees or less (e.g., 40 degrees or less, or 15 degrees or less).

[0012] Each of at least some member channels among the plurality of channels may include one or more secondary channels that extend from the channel axis. The one or more secondary channels may extend along the secondary axis from the channel axis at an angle of 10 to 80 degrees with respect to the channel axis. The one or more secondary channels may extend along the secondary axis from the channel axis at an angle of 50 to 90 degrees with respect to the channel axis.

[0013] One or more of the member channels may include three or more (e.g., five or more) secondary channels. These member channels may include, on average, five or more (e.g., seven or more) secondary channels.

[0014] Each of at least some member channels among the plurality of channels may include an opening on a first surface, wherein the opening has a first cross-sectional area on the first surface and a maximum cross-sectional area different from the first cross-sectional area at a location between the first surface and the second surface. The ratio of the first cross-sectional area to the maximum cross-sectional area may be 0.50 or less (e.g., 0.30 or less, or 0.10 or less).

[0015] Among the above multiple channels, at least some member channels may account for 50% or more (e.g., 80% or more) of the multiple channels. Each of the above multiple channels may have a maximum cross-sectional area and a minimum cross-sectional area at different locations along the channel axis, and the ratio of the minimum cross-sectional area to the maximum cross-sectional area may be 0.75 or less (e.g., 0.50 or less, or 0.30 or less).

[0016] The first surface may be flat and may have a maximum dimension measured on this flat surface, and the ratio of the maximum dimension to the thickness may be 10 or more (e.g., 20 or more). The porosity of this filter member may be 0.3 to 0.9.

[0017] The filter member may be formed from a first material, and each of at least some member channels among the plurality of channels may include a second material on its inner surface. The first material may be selected from the group consisting of polyvinylidene difluoride (PVDF), hydrophilized PVDF, and regenerated cellulose. The second material may be selected from the group consisting of cellulose, polyethersulfone, and polyethylene glycol.

[0018] The ratio of the average thickness of the second material on the inner surface of the member channel to the maximum cross-sectional dimension of the member channel may be 0.2 or less (e.g., 0.1 or less, 0.05 or less, or 0.02 or less).

[0019] The above-mentioned plurality of channels may be first plurality of channels, and the filter member may consist of a first layer characterized by the first plurality of channels and a second layer characterized by second plurality of channels. The second layer may be in contact with the first layer. At least some member channels among the first plurality of channels may be fluidly connected with at least some member channels among the second plurality of channels at the interface between the first layer and the second layer.

[0020] Each channel of the second plurality of channels may include a channel axis, and more than 50% of the second plurality of channels in the second layer may have their channel axes oriented at an angle of 5 to 90 degrees with respect to the first direction. The average orientation of the first plurality of channels with respect to the first direction may differ from the average orientation of the second plurality of channels with respect to the first direction.

[0021] In the case of a second plurality of channels, the average angle between the channel axis and the first direction may be greater than the average angle between the channel axis and the first direction in the case of a first plurality of channels. In the case of a second plurality of channels, the average angle between the channel axis and the first direction may be smaller than the average angle between the channel axis and the first direction in the case of a first plurality of channels.

[0022] The first layer may be formed from a first material selected from the group consisting of polyvinylidene difluoride (PVDF), hydrophilized PVDF, and regenerated cellulose, and the second layer may be formed from a second material selected from the group consisting of cellulose and regenerated cellulose, polyethersulfone, polyethylene glycol, polyethylene, polypropylene, polyvinylbenzene, polypropylene glycol, polyurethane, polymethyl methacrylate, and polyacrylic acid. The first material and the second material may be different.

[0023] At least some of the first plurality of channels may include a coating material on their inner surface. The coating material may be selected from the group consisting of cellulose, polyethersulfone, and polyethylene glycol. At least some of the second plurality of channels may include a coating material on their inner surface. The coating material may be selected from the group consisting of cellulose, polyethersulfone, and polyethylene glycol. At least some of the first plurality of channels may include a first coating material on their inner surface, and at least some of the second plurality of channels may include a second coating material on their inner surface.

[0024] Each member channel forming the first plurality of channels may include an opening on the first surface, and each member channel forming the second plurality of channels may include an opening on the interface between the first layer and the second layer, and the average opening cross-sectional area of ​​the first plurality of channels is different from the average opening cross-sectional area of ​​the second plurality of channels. The average opening cross-sectional area of ​​the first plurality of channels may be greater than the average opening cross-sectional area of ​​the second plurality of channels. The ratio of the total opening area of ​​the first plurality of channels on the first surface to the area of ​​the first surface may be greater than the ratio of the total opening area of ​​the second plurality of channels on the interface to the area of ​​the interface.

[0025] Each member channel forming the first plurality of channels may have a volume in the first layer, and each member channel forming the second plurality of channels may have a volume in the second layer, and the ratio of the total volume occupied by the first plurality of channels in the first layer to the volume of the first layer may be greater than the ratio of the total volume occupied by the second plurality of channels in the second layer to the volume of the second layer.

[0026] Each of at least some member channels among the second plurality of channels may include an opening having a first cross-sectional area at the interface between the first layer and the second layer and a second cross-sectional area at a location away from the interface along the member channel axis, wherein the first cross-sectional area may be smaller than the second cross-sectional area. The ratio of the first cross-sectional area to the second cross-sectional area may be 0.85 or less (e.g., 0.50 or less). Each member channel forming the second plurality of channels may be oriented with respect to a first direction defined by the axis of the said member channel, and the full width at half maximum (FWHM) of the orientation distribution of the second plurality of channels may be 20 degrees or less (e.g., 10 degrees or less).

[0027] Embodiments of the filter may also include all other features described herein, including any combination of features individually described in relation to other embodiments, except where otherwise explicitly stated.

[0028] As used herein, the term "approximately" means "about" (e.g., ±10% of the indicated value).

[0029] References to "one embodiment," "an example," etc., as used herein indicate that the described embodiment may include a specific aspect, feature, structure, or characteristic, and that not all embodiments necessarily include such aspect, feature, structure, or characteristic. Furthermore, such phrases may refer to the same embodiment mentioned in other parts of this invention, but are not necessarily so. Additionally, when a specific aspect, feature, structure, or characteristic is described in relation to one embodiment, those skilled in the art will, to the best of their knowledge, associate or link such aspect, feature, structure, or characteristic with other embodiments, regardless of whether it has been explicitly described.

[0030] As used herein, the word "one" preceding a noun encompasses one or more of the corresponding specific nouns. For example, the phrase "one recombinant mammalian cell" encompasses "one or more recombinant mammalian cells."

[0031] "Tangential flow filtration unit" or "TFF unit" is a term known in the art and refers to a device comprising at least one housing (e.g., a cylinder) and at least one cross-flow (tangential flow) virus filter located within the housing, wherein a significant portion of the surface of the cross-flow filter is positioned parallel to the flow of a fluid (e.g., a cell culture) passing through the unit. TFF units are well known in the art and are commercially available. The housing is provided with a first inlet / outlet and a second inlet / outlet. Thus, the fluid may flow, for example, through the first inlet / outlet, pass through the at least one cross-flow virus filter, and then pass through the second inlet / outlet. In some examples, a plurality of TFF units may be included in a circuit system, for example, connected in series and / or in parallel. For example, a circuit system comprising two or more TFF units may include fluid conduits that fluidly connect pairs of adjacent TFF units within the system. As another example, the circuit system may include two or more sets composed of two or more TFF units connected fluidly by a fluid conduit. All TFF units described herein or known in the art may receive fluid in a first flow direction and a second flow direction.

[0032] "Tangential flow virus filtration unit" or "TFVF unit" is a term known in the art and means a device comprising at least one housing (e.g., a cylinder) and at least one cross-flow (tangential flow) filter located within the housing, wherein a substantial portion of the surface of the cross-flow filter is positioned parallel to the flow of a fluid (e.g., a cell culture) passing through the unit. The housing is provided with a first inlet / outlet and a second inlet / outlet. Thus, the fluid may flow, for example, through the first inlet / outlet, through the at least one cross-flow filter, and then through the second inlet / outlet. According to some examples, a plurality of TFVF units may be included in a circuit system, for example, connected in series and / or in parallel. For example, a circuit system comprising two or more TFVF units may include fluid conduits that fluidly connect pairs of adjacent TFVF units within the system. As another example, the circuit system may include two or more sets composed of two or more TFVF units connected fluidly by a fluid conduit. All TFVF units described herein or known in the art can receive fluid in a first flow direction and a second flow direction.

[0033] "Cross-flow filter" or "tangential flow filter" is a term known in the art and refers to a filter designed to be placed within a TFF or TFVF unit such that a significant portion of its surface is parallel to the flow of a fluid (e.g., a fluid containing therapeutic recombinant proteins) (e.g., first and second flow directions). For example, a cross-flow filter may have any shape that enables tangential flow filtration, such as tubular or rectangular. A cross-flow filter of particular use is designed so that when the fluid flows across the surface of the cross-flow filter (e.g., from unidirectional to bidirectional), a small amount of fluid turbulence or shear stress is generated in the fluid (e.g., cell culture). Cross-flow filters are available for purchase, for example, from Sartorius, MembraPure, Millipore, and Pall Corporation.

[0034] "Low turbulence pump" or "LTP" is a term known in the art and refers to a device capable of moving a fluid (e.g., a fluid containing a therapeutic recombinant protein) in one direction (e.g., a first or second flow direction) or reversibly moving a fluid (e.g., a fluid containing a therapeutic recombinant protein) in two directions (first and second flow directions) within a system or circuit without causing a significant amount of shear stress or fluid turbulence in the fluid (e.g., a fluid containing a therapeutic recombinant protein). If the fluid (e.g., a fluid containing a therapeutic recombinant protein) is flowed alternately in the first and second flow directions using an LTP, the second flow direction is approximately opposite to the first flow direction. An example of an LTP is a peristaltic pump. Other examples of LTPs are known in the art.

[0035] The term “mammalian cell” means any cell obtained from or derived from any mammal (e.g., human, hamster, mouse, green monkey, rat, pig, cow, or rabbit). For example, a mammalian cell may be an indeterminate cell. In some embodiments, a mammalian cell is a differentiated cell. In some embodiments, a mammalian cell is an undifferentiated cell. Non-limiting examples of mammalian cells are described herein. Additional examples of mammalian cells are known in the art.

[0036] The expression “substantially absent” means that the content of a specific substance (e.g., mammalian cells) in a composition (e.g., liquid culture medium) is about 10% or less (e.g., about 5% or less, about 4% or less, about 3% or less, about 2% or less, about 1% or less, or about 0%).

[0037] The expression "0.5x volume" means approximately 50% of the volume. "0.6x volume" means approximately 60% of the volume. Likewise, 0.7x, 0.8x, 0.9x, and 1.0x mean approximately 70%, 80%, 90%, or 100% of the volume, respectively.

[0038] The terms "culture" or "cell culture" refer to maintaining or proliferating mammalian cells under a series of controlled physical conditions.

[0039] The term "mammalian cell culture" refers to a liquid culture medium containing multiple mammalian cells that are maintained or proliferated under a series of controlled physical conditions.

[0040] The term “liquid culture medium” means a fluid containing sufficient nutrients to grow or proliferate cells (e.g., mammalian cells) in a test tube. For example, the liquid culture medium may contain one or more of amino acids (e.g., 20 amino acids), purines (e.g., hypoxanthine), pyrimidines (e.g., thymidine), choline, inositol, thiamine, folic acid, biotin, calcium, niacinamide, pyridoxine, riboflavin, thymidine, cyanocobalamin, pyruvate, lipoic acid, magnesium, glucose, sodium, potassium, iron, copper, zinc, and sodium bicarbonate. In some embodiments, the liquid culture medium may contain serum from mammals. In some embodiments, the liquid culture medium does not contain serum or other extracts from mammals (prescribed liquid culture medium). In some embodiments, the liquid culture medium may contain trace amounts of metals, mammalian growth hormones, and / or mammalian growth factors. Another example of a liquid culture medium is a minimal medium (e.g., a medium containing only inorganic salts, a carbon source, and water). Non-limiting examples of liquid culture media are described herein. Additional examples of liquid culture media are known in the art and are commercially available. Liquid culture media may contain mammalian cells of any density. For example, as used herein, any volume of liquid culture medium isolated from a bioreactor may be substantially free of mammalian cells.

[0041] The term "liquid culture medium free of animal-derived components" refers to a liquid culture medium that does not contain components derived from mammals (e.g., proteins or serum).

[0042] The term "serum-free liquid culture medium" refers to a liquid culture medium that does not contain mammalian serum.

[0043] The term "serum-containing liquid culture medium" refers to a liquid culture medium containing mammalian serum.

[0044] The term "chemically identified liquid culture medium" is a term used in the art and refers to a liquid culture medium in which all chemical components are known. For example, a chemically identified liquid culture medium does not contain bovine fetal serum, bovine serum albumin, or human serum albumin, because these preparations typically contain a complex mixture of albumin and lipids.

[0045] The term "protein-free liquid culture medium" refers to a liquid culture medium that does not contain protein (e.g., detectable protein).

[0046] The term "stirring" means stirring or shaking a portion of the liquid culture medium inside a bioreactor. This is performed, for example, to increase the dissolved O2 concentration in the liquid culture medium inside the bioreactor. Stirring may be performed using any method known in the art, such as a device or a propeller. Exemplary devices and methods that can be used to stir a certain amount of liquid culture medium inside a bioreactor are known in the art.

[0047] The term “therapeutic protein raw material” means contaminated proteins, lipids, and nucleic acids (contaminated proteins, lipids, and nucleic acids present in liquid culture media or derived from host cells (e.g., mammalian, yeast, or bacterial host cells)) and recombinant proteins (e.g., immunoglobulins, protein fragments, engineered proteins, or enzymes) that have been sufficiently purified or isolated from biological contaminants (e.g., viral and bacterial contaminants) and may be formulated into pharmaceutical preparations without further substantial purification and / or decontamination steps.

[0048] The term "integrated process" refers to a process performed using structural elements that work together to achieve a specific result (e.g., production of therapeutic protein raw materials from liquid culture media).

[0049] The term “continuous process” means a process of continuously supplying a fluid through at least a part of a system. For example, in any exemplary continuous biological manufacturing system described herein, a liquid culture medium containing a therapeutic recombinant protein is continuously supplied to the operating system, and as a result, the system produces and discharges a therapeutic protein raw material drug. In another example, the continuous process is a process of continuously supplying a liquid culture medium containing a therapeutic recombinant protein from a bioreactor through a first MCCS. Another example of a continuous process is a process of continuously supplying a liquid culture medium containing a therapeutic recombinant protein from a bioreactor through a first and second MCCS. Additional examples include a process of continuously supplying a liquid culture medium containing a therapeutic recombinant protein through a first MCCS, a process of continuously supplying a liquid culture medium containing a therapeutic recombinant protein through a first and second MCCS, or a process of continuously supplying a fluid containing a therapeutic recombinant protein through a second MCCS.

[0050] The term “immunoglobulin” means a polypeptide containing an amino acid sequence (e.g., variable domain sequence, framework sequence, or constant domain sequence) consisting of 15 or more amino acids of an immunoglobulin protein (e.g., 20, 30, 40, 50, 60, 70, 80, 90, or 100 or more amino acids). The immunoglobulin may include, for example, 15 or more amino acids of a light chain immunoglobulin and, for example, 15 or more amino acids of a heavy chain immunoglobulin. The immunoglobulin may be an isolated antibody (e.g., IgG, IgE, IgD, IgA, or IgM). The immunoglobulin may be a subclass of IgG (e.g., IgG1, IgG2, IgG3, or IgG4). The immunoglobulin may be an antibody fragment, such as a Fab fragment, an F(ab')2 fragment, or a scFv fragment. Immunoglobulins are also bispecific or trispecific antibodies; dimeric, trimer, or polymeric antibodies; or diabody, Affibody®, or nanobody ® It may be. The immunoglobulin may also be a modified protein (e.g., a fusion protein) containing at least one immunoglobulin domain. Non-limiting examples of immunoglobulins have been described herein, and additional examples of immunoglobulins are known in the art.

[0051] The terms “protein fragment” or “polypeptide fragment” mean a part of a polypeptide sequence having a length of about 4 or more, about 5 or more, about 6 or more, about 7 or more, about 8 or more, about 9 or more, about 10 or more, about 11 or more, about 12 or more, about 13 or more, about 14 or more, about 15 or more, about 16 or more, about 17 or more, about 18 or more, about 19 or more, about 20 or more, or more than 20. Recombinant protein fragments may be produced using any one of the methods described herein.

[0052] The term “manipulative protein” means a polypeptide that is not naturally encoded by endogenous nucleic acids present in an organism (e.g., mammals). Examples of manipulative proteins include enzymes (e.g., in which the stability and / or catalytic activity of the manipulative enzyme is increased as a result of one or more amino acid substitutions, deletions, insertions, or additions), fusion proteins, antibodies (e.g., bivalent antibodies, trivalent antibodies, or diobodies), and antigen-binding proteins comprising at least one recombinant scaffolding sequence.

[0053] The terms “multi-column chromatography system” or “MCCS” refer to a system having a total of two or more interconnected or switching chromatography columns and / or chromatography membranes. A non-limiting example of a multi-column chromatography system is a periodic backflow chromatography system (PCC) comprising a total of two or more interconnected or switching chromatography columns and / or chromatography membranes. Additional examples of multi-column chromatography systems are described herein and are known in the art.

[0054] The term “capture” refers to a step performed to partially purify or isolate (e.g., about 5% or more by weight, e.g., about 10%, 15%, 20%, 25%, 30%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95% or more purity) a therapeutic recombinant protein from one or more other components present in a liquid culture medium or a diluted liquid culture medium (e.g., culture medium proteins, or one or more other components present in or secreted by mammalian cells (e.g., DNA, RNA, or other proteins)), concentrate, and stabilize the therapeutic recombinant protein. Typically, capture is performed using a resin that binds to the therapeutic recombinant protein (e.g., using affinity chromatography). Non-limiting methods for capturing therapeutic recombinant proteins from liquid culture media or diluted liquid culture media have been described herein, and other methods are known in the art. Therapeutic recombinant proteins can be captured from liquid culture media using at least one chromatography column and / or chromatography membrane (e.g., any one of the chromatography column and / or chromatography membrane described herein).

[0055] The term “purification” means a step performed to isolate the therapeutic recombinant protein from one or more other impurities (e.g., bulk impurities) or components (e.g., liquid culture medium proteins, or one or more other components present in or secreted from mammalian cells (e.g., DNA, RNA, other proteins, endotoxins, viruses, etc.)) present in the therapeutic recombinant protein-containing fluid. For example, purification may be performed during or after the initial capture step. Purification may be performed by using any method known in the art (e.g., by using a resin, membrane, or any other solid carrier that binds to the therapeutic recombinant protein or contaminants) using, for example, a resin, membrane, or any other solid carrier that binds to the therapeutic recombinant protein or contaminants. Therapeutic recombinant proteins can be purified from a therapeutic recombinant protein-containing fluid using at least one chromatography column and / or chromatography membrane (e.g., any chromatography column or chromatography membrane described herein).

[0056] The term "polishing" is a term used in the art and refers to a step performed to remove trace or small amounts of contaminants or impurities remaining in a therapeutic recombinant protein-containing fluid to a desired final purity. For example, polishing may be performed by passing the therapeutic recombinant protein-containing fluid through a chromatography column(s) or membrane absorber(s) that selectively binds to either the targeted therapeutic recombinant protein or small amounts of contaminants or impurities present in the therapeutic recombinant protein-containing fluid. In such examples, the eluent / filtrate from the chromatography column(s) or membrane absorber(s) contains the therapeutic recombinant protein.

[0057] The term "eluent / filter" is a term used in the relevant technical field and refers to a fluid separated from a chromatography column or chromatography membrane containing a detectable amount of therapeutic recombinant protein (e.g., therapeutic recombinant protein).

[0058] The term “filtration” means separating at least a portion (e.g., at least 80%, 90%, 95%, 96%, 97%, 98%, or 99%) of unwanted biological contaminants (e.g., mammalian cells, bacteria, yeast cells, viruses, or mycobacteria) and / or particulate matter (e.g., precipitated proteins) from a liquid (e.g., a liquid culture medium or fluid included in any one of the systems or processes described herein).

[0059] The terms "secretory protein" or "secretory recombinant protein" refer to a protein (e.g., recombinant protein) that originally contained at least one secretory signal sequence when translated within a mammalian cell, and at least a portion thereof is secreted into the extracellular space (e.g., liquid culture medium) through enzymatic cleavage of the secretory signal sequence within the mammalian cell. Those skilled in the art will understand that there is no need to completely distinguish a "secretory" protein from the cell in which it is considered a secretory protein.

[0060] The term “perfusion bioreactor” means a bioreactor containing a number of cells (e.g., mammalian cells) in a first liquid culture medium, and the operation of culturing the cells in the bioreactor involves adding a second liquid culture medium of substantially the same volume to the bioreactor simultaneously with or immediately thereafter removing the first liquid culture medium periodically or sequentially. In some examples, the volume of the first liquid culture medium removed and added during the culture period is subjected to a gradual change (e.g., increase or decrease) in the volume (e.g., daily standard culture medium replenishment rate) over an incremental period (e.g., about 24 hours, about 1 minute to about 24 hours, or a period longer than 24 hours). The fraction of medium removed and replaced daily may vary depending on the specific cells being cultured, the initial seeding density, and the cell density at a specific time. “RV” or “reactor volume” means the volume of culture medium present at the start of the culture process (e.g., the total volume of culture medium after seeding).

[0061] The term "batch-fed bioreactor" is a term in the art and refers to a bioreactor containing a number of cells (e.g., mammalian cells) in a first liquid culture medium, wherein the operation of culturing the cells in the bioreactor comprises adding a second liquid culture medium to the first liquid culture medium periodically or continuously without substantially or substantially removing the first liquid culture medium or the second liquid culture medium from the cell culture. The second liquid culture medium may be identical to the first liquid culture medium. In some examples of batch culture, the second liquid culture medium is a concentrated form of the first liquid culture medium. In some examples of batch culture, the second liquid culture medium is added in the form of a dry powder.

[0062] The expression “purified liquid culture medium” means a liquid culture medium obtained from a bacterial or yeast cell culture that is substantially free of bacterial or yeast cells (e.g., containing less than 20%, less than 15%, less than 10%, less than 8%, less than 6%, less than 4%, less than 2%, or less than 1%).

[0063] The term "unit operation" is a term used in the art and refers to a functional step that may be performed in the process of manufacturing a therapeutic protein active ingredient from a liquid culture medium. For example, a unit operation may be filtration of a fluid containing a therapeutic recombinant protein (e.g., removal of contaminating bacteria, yeast viruses, or mycobacteria, and / or specific substances in a fluid containing a therapeutic recombinant protein), capture, removal of epitope tags, purification, retention or storage, final purification, virus inactivation, adjustment of ion concentration and / or pH, and removal of unwanted salts.

[0064] "Specific productivity rate" or "SPR" is a term in the art and, as used herein, represents the mass or enzymatic activity of a therapeutic recombinant protein produced per mammalian cell per day. The SPR for therapeutic recombinant antibodies is typically measured in mass / cell / day. The SPR for therapeutic recombinant enzymes is typically measured in units / cell / day or titer / cell / day.

[0065] "Volume Production Rate" or "VPR" is a term in the art and, as used herein, represents the mass of therapeutic recombinant protein or enzymatic activity produced per day per volume of culture (e.g., per 1 liter of bioreactor, vessel, or tube volume). VPR for therapeutic recombinant antibodies is typically measured in mass / liter / day. VPR for recombinant therapeutic enzymes is typically measured in units / liter / day or mass / liter / day.

[0066] Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which the present invention pertains. Although methods and materials similar or equivalent to those described herein may be used to practice the methods and systems of this disclosure, suitable methods and systems will be described in the following description. All publications, patent applications, patents, and other references mentioned herein are incorporated by reference in their entirety. In the event of a conflict, this specification, including definitions, shall prevail. Furthermore, these methods and examples are merely illustrative and are not intended to be limiting. Brief explanation of the drawing

[0067] Figure 1 is a schematic diagram showing an example of a pressure-driven virus filtration subsystem. Figure 2 is a schematic diagram showing an example of a tangential flow virus filtration subsystem. Figure 3 is a schematic diagram showing an example of a tangential flow virus filtration subsystem driven by both pressure and a pump. Figure 4 is a schematic diagram showing an example of a constant pressure constant velocity tangential flow virus filtration subsystem. Figure 5 is a schematic diagram showing an example of a filter unit. Figure 6 is a schematic cross-sectional view of a filter member. FIGS. 7a to 7e are schematic diagrams showing examples of filter members having a variable thickness between a first surface and a second surface. FIG. 8a is a schematic cross-sectional view showing an example of a filter member. FIG. 8b is a schematic cross-sectional view showing another example of a filter member. FIG. 8c is a schematic diagram showing a portion of the surface of a filter member. FIG. 9a is a schematic cross-sectional view showing an example of a filter member having an inclined channel. FIG. 9b is a schematic cross-sectional view showing another example of a filter member having an inclined channel. FIG. 10 is a schematic cross-sectional view showing another example of a filter member. FIG. 11 is a schematic cross-sectional view showing an example of a filter member having a channel including side protrusions. FIG. 12 is a schematic cross-sectional view showing an example of a filter member comprising a channel having coating layers. FIG. 13 is a schematic cross-sectional view showing an example of a filter member including a plurality of channel layers. FIG. 14 is a schematic diagram showing an example of a laminar tangential flow virus filtration unit. Similar reference numbers indicate similar components. Specific details for implementing the invention

[0068] introduction

[0069] Biomanufacturing systems hold tremendous potential for the large-scale production of various biological products, including therapeutic drug species such as recombinant protein materials. In most of these systems, a suitable cell culture is combined with growth medium, buffer, and other input reagent streams in a bioreactor (e.g., a perfusion reactor) to produce a product material. The desired product is isolated from the process fluid by extracting the process fluid from the bioreactor and purifying it, usually through one or more multi-column chromatography purification devices. Various embodiments of biomanufacturing systems and their components are described, for example, in PCT patent application publication number WO2018 / 035116, the entire contents of which are incorporated herein by reference.

[0070] Typically, a biomanufacturing system also includes a virus filtration stage or subsystem for removing virus particles from a process fluid. A virus filtration subsystem can generally be implemented in various configurations. For example, some biomanufacturing systems include a pressure-driven virus filtration subsystem. FIG. 1 is a schematic diagram of a pressure-driven virus filtration subsystem (100). The subsystem (100) includes a feed vessel (102), a transfer conduit (106), and a filter unit (108) equipped with an internal filter membrane (110). When the subsystem (100) is operated, a fluid (104) (e.g., a process fluid extracted from a bioreactor, or a process fluid extracted from another component of the biomanufacturing system downstream of the bioreactor) is introduced into the feed vessel (102) continuously or in batches. As pressure is applied to the supply container (102), the gas pressure inside the supply container (102) becomes significantly higher than atmospheric pressure, and as a pressure gradient is formed at the outlet of the subsystem, the fluid (104) flow exits the supply container (102) and moves through the conduit (106) into the filter unit (108). Upon entering the filter unit (108), the fluid (104) passes through a filter member (110) that filters virus particles.

[0071] The fluid (104) flow in the subsystem (100) is entirely pressure-driven. That is, the flow rate passing through the filter unit (108) is determined by only one parameter (supply vessel gas pressure). Since the gas pressure downstream of the filter element (110) containing the product stream (112) is virtually atmospheric pressure, a pressure drop occurs before and after the filter element (110). The product stream (112) corresponds to the fluid (104) from which virus particles have been removed.

[0072] It should be noted that in this subsystem (100), virus particles or other process impurities (e.g., host cell proteins, particles invisible to the naked eye, or the protein product itself) accumulate in the filter element (110). Therefore, the effective life of the filter element (110) is limited by the elapsed time until virus breakthrough or filter clogging occurs, and virus particles in the fluid (104) upstream of the filter element (110) are not completely captured by the filter element (110) (i.e., a certain number of particles pass through the filter element (110) and appear in the product stream (112). Thus, although the subsystem (100) can be implemented with a fairly simple configuration and effectively filters virus particles, there are limitations to the efficiency of this type of virus filtration and it may be more expensive as the filter element (110) becomes easily contaminated and clogged during operation. Because the operating time until the filter element (110) changes is relatively short, the subsystem (100) may be more suitable for batch virus filtration rather than continuous virus filtration as part of a continuous bio-manufacturing process.

[0073] FIG. 2 is a schematic diagram of a tangential flow virus filtration subsystem (200). The subsystem (200) includes a supply vessel (202) in which a fluid (220) (e.g., a process fluid containing one or more products from a bioreactor) is stored. The subsystem (200) is a pump-driven system and includes a pump (206). During operation, the pump (206) draws the fluid (220) out of the supply vessel (202) and sends it through conduits (204, 208) to a filter unit (210) equipped with a filter element (212). The filter element (212) is typically, for example, a flat membrane and is oriented within the filter unit (210) generally parallel to the direction of flow of the fluid (220). Specifically, within the filter unit (210), the fluid (220) flows from the inlet (224) toward the outlet (226), generally along the length of the filter unit (210), as indicated by the arrow (228). As the fluid dynamically flows in the direction of the arrow (228), a portion of the fluid moves tangentially through the filter member (212) toward the outlet (230). As the fluid moving tangentially is filtered by the filter member (212) and virus particles are removed, the product stream (222) coming out through the outlet (230) is free of virus particles. The fluid (220) that does not move through the filter member (212) exits the filter unit (210) through the outlet (226) as residual liquid and is recirculated back into the supply vessel (202) via the conduits (214, 218). A flow control device (216) may be used to adjust the pressure of the residual liquid.

[0074] In fact, the rate at which the filtered product stream is generated in the subsystem (200) is controlled by two process variables: the flow rate of the fluid (220) controlled by the pump (206) and the residual liquid pressure controlled by the flow control device (216). Differential pressure occurs at several points in the subsystem (200) (i.e., between the inlet (224) and the outlets (230 and 226), and between the outlet (226) and the supply vessel (202).

[0075] Compared to a conventional "dead-end" filtration system as shown in FIG. 1, the tangential flow virus filtration (TFVF) subsystem has many advantages. In the case of TFVF, the flow rate of the fluid (220) passing through the filter element (212) is maintained through the "sweeping" flow of the fluid (220), which can increase the throughput per unit area of ​​the filter element. Therefore, the TFVF subsystem is more suitable for implementation in a continuous biomanufacturing system because it can accommodate a continuous inflow of process fluid from a bioreactor and continuously discharge a product stream for further purification and / or analysis. The TFVF subsystem can also be implemented in a batch biomanufacturing system, and thus the life of the virus filter membrane is extended because the amount of filter fouling under the tangential operation mode is relatively lower. The limitations of the TFVF subsystem are that the set of available filter membranes is generally small and that the recirculation pump used may impose some operational constraints on the subsystem.

[0076] It is possible to implement a TFVF subsystem driven by both pressure and a pump. FIG. 3 is a schematic diagram of such a subsystem (300), which includes a supply vessel (302), a filter unit (304), and a recirculation pump (306). These components function in a manner similar to the corresponding components of FIG. 2 described above. During operation, pressure is applied to the supply vessel (302) as air or other gas is delivered through the inlet (312). A fluid (308) flows from the supply vessel (302) to the filter unit (304), which is equipped with a filter element (314) tangentially oriented. As the fluid (308) flows through the filter element (314), a portion of the fluid passes through the filter element (314), and as the filter element removes virus particles from the fluid, the product stream (310) exiting the filter unit (304) is free of virus particles. The fluid that passes through the filter member (212) and is not diffused exits the filter unit (304) as residual liquid and is recirculated back into the supply container (302) by the pump (306). Thus, in this subsystem (300), the pressurized supply container (302) and the pump (306) perform the task of circulating the fluid (308) throughout the entire subsystem.

[0077] As described above, the circulation of the fluid (308) throughout the subsystem (300) can be controlled by adjusting two process variables, such as the recirculation flow rate (controlled by the pump (306)) and the system fluid pressure (through pressurization of the supply vessel (302)). One advantage of the subsystem (300) is that the fluid pressure in the recirculation portion of the subsystem is effectively kept constant. That is, the fluid pressure in the supply vessel (302), the fluid pressure at the inlet of the filter element (314), and the fluid pressure of the residual liquid coming out of the filter element (314) are nearly identical. In such a subsystem (300), the only significant differential pressure occurs before and after the filter element (314). As a result, it is relatively easy to control the velocity of the product stream as it comes out of the filter element (314).

[0078] The subsystem (300) is a type of constant pressure system. By appropriately adjusting the pump (306), the subsystem (300) can be operated at a constant tangential flow rate, ensuring that the product stream (310) continuously exits the filter unit (304) at a constant speed. The constant pressure constant speed tangential flow filtration subsystem can also be implemented in various ways. FIG. 4 is a schematic diagram showing another example of a filtration subsystem (400), said subsystem comprising a supply vessel (402), a conduit (404) connected between the supply vessel (402) and the filter unit (406), a conduit (408) connected between the filter unit (406) and the pump (410), and a conduit (412) connected between the pump (410) and the inlet (414) of the supply vessel (402).

[0079] When the subsystem (400) is operated, air or other gas is delivered to the supply vessel (402) through the inlet (424) and pressure is applied to the inside of the supply vessel. Due to the fluid pressure inside the supply vessel (402), the fluid (426) contained in the supply vessel (e.g., process fluid obtained from a bioreactor or an intermediate purification stage of a biomanufacturing system) exits the supply vessel and moves through the conduit (404) to the filter unit (406). The filter unit (406) includes a filter element (not shown in FIG. 4). The filter element is oriented so that the fluid (426) inside the filter unit (406) flows in a direction parallel (or approximately parallel) to one surface of the filter element. After passing through the filter element, a portion of the fluid (426) exits the filter unit (406) through the outlet (430) as a product stream (428) that is almost or entirely free of viruses. The residual fluid (426) exits the filter unit (406) as residual liquid through the outlet (432) and is circulated through the conduit (408, 412) and the pump (410). The pump (410) moves the residual liquid flow back to the supply vessel (402) through the inlet (414). In this way, the subsystem (400) can continuously filter the fluid (426), and a portion of the fluid (426) is separated from the subsystem as a filtered product stream (428), and the residual fluid (426) is recirculated to pass through the filter unit (406) again. Additional fluid (426) can be introduced into the subsystem (400) through the conduit (416) and the one-way valve (418) before or during operation; this additional fluid (426) is introduced into the supply vessel (402) through the inlet (420).

[0080] The structure of the filter unit (406) having a filter member therein is different from the corresponding filter unit of FIG. 3. In FIG. 4, the filter unit (406) has a hollow fiber-based filter member. FIG. 5 is a schematic cross-sectional view showing an example of the filter unit (406). The filter unit (406) includes a filter body (502), a filter member (504), and outlets (430). Conduits (404, 408) are connected to an internal channel (passage) of the filter body (502). As can be clearly seen in FIG. 5, the filter body (502) is formed of a hollow fiber with holes in its sidewalls. The filter member (504) contacts the sidewalls of this hollow fiber and effectively has a tubular structure. A fluid (426) is introduced into the filter body (520) and flows in the direction indicated by the arrow in FIG. 5. A portion of the fluid (426) passes through the filter member (504) and exits through the outlet (430) as a product stream. The remaining fluid (426) is recirculated as a residual liquid through the conduit (408) by a pump (e.g., pump (410)).

[0081] In the case of a full filter unit (e.g., as shown in Fig. 1), the fluid flow moves through the filter due to the fluid pressure inside the filter unit, and solid material is also compressed against the front surface of the filter, which reduces the open volume within the filter element and leads to a decrease in throughput. If the fluid contains a significant amount of solid suspended material, contamination of the filter element can occur relatively quickly.

[0082] Compared to such a total filter unit, this filter unit (406) has many advantages. Because the fluid (426) flows in a direction parallel to the side walls of the filter body (502) and the filter member (504), the cross flow of the fluid (426) helps to "sweep away" solid particles from the surface of the filter member (504), which also helps to slow down the rate of contamination on the surface of the filter member.

[0083] Additionally, by controlling the pump (410) and the internal pressure of the supply container (402), the flow rate (also referred to as "cross-flow flow rate") of the fluid (426) passing through the surface of the filter member (504) and the fluid pressure inside the filter member (504) can be adjusted, respectively. As the fluid (426) flows through the filter member (504) and the filter body (502), a transmembrane pressure (TMP) is applied toward the thickness of the filter member (504). TMP adjustment is possible by changing the flow rate of the cross-flow (e.g., through the pump (410)) and / or by changing the fluid pressure inside the container (402). As a portion of the fluid (426) moves through the filter member (504) due to the TMP, virus particles are filtered from the fluid, and a product stream (428) is generated. Thanks to the cross-flow sweeping action of the fluid (426) and the controllability of the cross-flow flow rate and TMP, this filter unit (406) can generally be operated for a significantly longer period until it becomes contaminated and requires replacement compared to a similar total volume filter unit.

[0084] Typically, virus filter elements are not used in tangential flow filtration systems but instead in total filtration systems such as those exemplified in FIG. 1. In the case of virus filtration in a total filtration system, virus filter elements are generally made relatively thin to ensure that the filter element allows fluid to pass through at a high flow rate (e.g., high velocity). As described above, such virus filter elements tend to become contaminated relatively quickly and are therefore not suitable for continuous filtration operations lasting several days or weeks.

[0085] Continuous virus filtration

[0086] To perform continuous virus filtration on process fluids directly extracted from a bioreactor or an intermediate purification stage of a biomanufacturing system, the inventors have implemented a tangential flow virus filtration subsystem as illustrated in FIGS. 4 and 5. Furthermore, the inventors have discovered that by configuring this subsystem (specifically, a virus filter element) in various ways to slow down the fouling rate of the filter element, long-term continuous operation can be enabled.

[0087] In some embodiments, the tangential flow virus filtration subsystem is provided with a filter element at 0 psi to 50 psi (e.g., 0 psi to 45 psi, 0 psi to 40 psi, 0 psi to 35 psi, 0 psi to 30 psi, 0 psi to 25 psi, 0 psi to 20 psi, 0 psi to 15 psi, 0 psi to 10 psi, 5 psi to 50 psi, 5 psi to 40 psi, 5 psi to 30 psi, 5 psi to 20 psi, 10 psi to 50 psi, 10 psi to 40 psi, 10 psi to 30 psi, 10 psi to 20 psi, 15 psi to 50 psi, 15 psi to 40 psi, 15 psi to 30 psi, It is configured to apply a lateral fluid pressure (i.e., transmembrane pressure) of 20 psi to 50 psi, 20 psi to 40 psi, 25 psi to 50 psi, or any pressure range from 0 psi to 50 psi. According to a specific embodiment, a lateral fluid pressure of 50 psi or less (e.g., 45 psi or less, 40 psi or less, 35 psi or less, 30 psi or less, 25 psi or less, 20 psi or less, 15 psi or less, 10 psi or less, 5 psi or less, 4 psi or less, 3 psi or less, 2 psi or less, 1 psi or less, 0.5 psi or less, 0.25 psi or less, or much less) is applied to the filter member.

[0088] Generally, by selecting a lower lateral fluid pressure, the flow rate applied to the filter element is reduced, and consequently, the generation rate of the product stream is reduced. However, the inventors observed that the lower the lateral fluid pressure, the longer the elapsed time until virus breakthrough occurs on the outer surface of the filter element, thereby extending the effective lifespan of the virus filter element.

[0089] FIG. 6 is a schematic cross-sectional view of a virus filter member (602). The filter member (602) has a first surface (604) and a second surface (606). A plurality of channels (612) are connected through the filter member from the first surface (604) to the second surface (606). A fluid (608) containing virus particles (610) meets the first surface (604) of the filter member and then flows from the first surface (604) to the second surface (606) through the channels (612). As the fluid (608) flows through the channels (612), the virus particles (610) are adsorbed to and remain on the channel walls, so there are substantially no virus particles in the product stream coming out of the second surface (606) before the filter member becomes contaminated and clogged.

[0090] Although not strictly bound by theory, it is believed that once virus particles are inside the channels (612), the virus particles are transported toward the second surface (606) by fluid transfer. Additionally, even adsorbed virus particles can be detached and spread toward the second surface (606) by Brownian motion or fluid transfer. By reducing the lateral fluid pressure applied to the filter member, the fluid flow rate through the membrane is reduced, thereby lowering the speed at which virus particles are transported toward the second surface (606) and extending the life of the filter member until a virus breakthrough occurs at the second surface.

[0091] In some embodiments, the thickness of the filter member (indicated as "d" in FIG. 6, which is the distance between the first surface and the second surface of the filter member) is significantly thicker than the thickness of a standard tangential filter membrane. For example, a conventional filter membrane used for tangential filtration has a thickness of about 20 microns to 140 microns. The thickness d of the filter member (602) used in the tangential flow virus filtration subsystem described herein may be 150 microns or more (e.g., 160 microns or more, 170 microns or more, 180 microns or more, 190 microns or more, 200 microns or more, 220 microns or more, 240 microns or more, 260 microns or more, 280 microns or more, 300 microns or more, 320 microns or more, 340 microns or more, 350 microns or more, 370 microns or more, 400 microns or more, 450 microns or more, or much more).

[0092] In certain embodiments, the thickness of the filter member, which is the distance between the first surface and the second surface, is variable. For example, the minimum thickness of the filter member between these surfaces may be 50 microns or more (e.g., 60 microns or more, 70 microns or more, 80 microns or more, 90 microns or more, 100 microns or more, 110 microns or more, 120 microns or more, 130 microns or more, 140 microns or more, 150 microns or more, 160 microns or more, 170 microns or more, 180 microns or more, 190 microns or more, 200 microns or more); The maximum thickness of the filter member between these surfaces may be 1,000 microns or less (e.g., 900 microns or less, 800 microns or less, 700 microns or less, 600 microns or less, 500 microns or less, 475 microns or less, 450 microns or less, 425 microns or less, 400 microns or less, 375 microns or less, 350 microns or less, 325 microns or less, 300 microns or less, or much less).

[0093] The thickness of the filter member between the first surface and the second surface may vary in an arbitrary manner or in a regular form. FIGS. 7a through 7e are schematic diagrams illustrating examples of a filter member (602) having a variable thickness between the first surface (604) and the second surface (606). In FIG. 7a, the thickness of the filter member varies irregularly along the length of the filter member. In FIG. 7b, the thickness of the filter member varies regularly, but the second surface (606) is sawtooth-shaped and has a crest-trough waveform, oscillatory, or sinusoidal pattern. In FIG. 7c, the thickness of the filter member varies regularly, but the second surface is sawtooth-shaped forming a crest-trough pattern, and the thickness of the filter member varies linearly between the crests and troughs. In FIG. 7d, the thickness of the filter member varies monotonically along the length of the filter member. The thickness may vary linearly or non-linearly along the length of the filter member. In FIG. 7e, the thickness of the filter member varies in a stepped form.

[0094] Generally, during tangential virus filtration, the flow rate of the fluid passing through the filter element is selected to ensure that the product stream velocity is sufficiently high to maintain continuous manufacturing operations, while simultaneously ensuring that it is sufficiently low so that virus particles do not penetrate the filter element and escape into the product stream. For example, the flow rate per unit area of ​​the filter element is 0.5 L / m² 2 / hr or more (e.g., 1.0 L / m²) 2 / hr or more, 2.0 L / m 2 / hr or more, 5.0 L / m 2 / hr or more, 10.0 L / m 2 / hr or more, 15.0 L / m 2 / hr or more, 20.0 L / m 2 / hr or more, 30.0 L / m 2 / hr or more, 40.0 L / m 2 It can be (more than / hr). Alternatively, the flow rate is 100 L / m³ 2 / hr or less (e.g., 90 L / m²)2 / hr or less, 80 L / m 2 / hr or less, 70 L / m 2 / hr or less, 60 L / m 2 It may be / hr or less)

[0095] Generally, the bulk porosity of the filter member is selected to strike a trade-off between the flow rate of the fluid passing through the filter member, the virus particle capture capacity of the filter member, and the mechanical strength of the filter member. In some embodiments, the porosity of the filter member (i.e., the volume fraction of the pores of the filter member) is 0.05 or greater (e.g., 0.10 or greater, 0.15 or greater, 0.20 or greater, 0.25 or greater, 0.30 or greater, 0.35 or greater, 0.40 or greater, 0.45 or greater, 0.50 or greater, 0.55 or greater, 0.60 or greater, or much greater). In certain embodiments, the porosity of the filter member is 0.90 or less (e.g., 0.88 or less, 0.86 or less, 0.84 or less, 0.82 or less, 0.80 or less, 0.78 or less, 0.76 or less, 0.74 or less, 0.72 or less, 0.70 or less, or much less). The porosity of the filter member may be, for example, 0.30 to 0.90 or any smaller range within this range.

[0096] In some embodiments, the thickness of the filter member may be smaller than the lateral dimension of the filter member. For example, the filter member has a maximum lateral dimension when unfolded into a flat plane, and the ratio of the maximum lateral dimension of the filter member to the thickness of the filter member may be 5 or more (e.g., 10 or more, 15 or more, 20 or more, 30 or more, 40 or more, 50 or more, 75 or more, 100 or more).

[0097] In general, filter members can be formed from a wide variety of materials. Examples of suitable materials include, but are not limited to, polyvinylidene difluoride (PVDF), hydrophilized PVDF, regenerated cellulose, and other materials used to form chemically synthesized membranes. Filter members described herein may also be manufactured using and / or modified filter manufacturing methods generally known in the art.

[0098] Channel Architecture

[0099] The filter element has pores or channels extending from a first surface to a second surface, allowing a fluid to pass through the filter element. At the same time, as virus particles are trapped within the pores (e.g., by adsorption), they are not contained in the product stream. In the following description, "channels" of the filter element will be referred to, but it should be understood that the term "pores" may also be used to describe the same feature.

[0100] FIG. 8a is a schematic cross-sectional view of a filter member (602) including channels (802). The density of the number of channels per unit on the first surface (604) of the filter member (602) is, for example, 100 / cm² 2 Up to 10,000 / cm 2 It can be. That is, the channel number density is 100 / cm³ 2 Above (e.g., 200 / cm²) 2 Above, 300 / cm 2 Above, 400 / cm 2 Above, 500 / cm 2 Above, 600 / cm 2 Above, 700 / cm 2 Above, 800 / cm 2 Above, 900 / cm 2 Above, 1000 / cm 2 Above, 1500 / cm 2 Above, 2000 / cm 2 Above, 2500 / cm 2 Above, 3000 / cm 2Above, 3500 / cm 2 Above, 4000 / cm 2 Above, 4500 / cm 2 It can be more than, or much more than that. The channel number density is 10,000 / cm³. 2 Less than (e.g., 9500 / cm²) 2 Below, 9000 / cm 2 Below, 8500 / cm 2 Below, 8000 / cm 2 Below, 7500 / cm 2 Below, 7000 / cm 2 Below, 6500 / cm 2 Below, 6000 / cm 2 Below, 5500 / cm 2 It can be less than, or much less than that.

[0101] In some embodiments, the opening sizes of one or more channels formed on the first and second surfaces (604, 606) of the filter member (602) are approximately the same (i.e., the difference between the cross-sectional areas of the openings on the surfaces is within 10%). However, according to certain embodiments, the opening sizes are different. In particular, for individual channels, it is possible to manufacture the filter member (602) such that the cross-sectional area of ​​the channel opening on the first surface (604) is larger than the cross-sectional area of ​​the channel opening on the second surface, so that the effective diameter of the channel passing through the body of the filter member becomes progressively narrower. It has been found that using these tapered channels prevents virus particle breakthrough on the second surface (606). Although not bound by theory, this is believed to be because the channel opening size is smaller and the flow rate of the fluid passing through the channel is also reduced.

[0102] FIG. 8b is a schematic diagram of a filter member (602) having a plurality of tapered channels (808) (only one channel is illustrated in FIG. 8b for clear visibility). The opening (806) of the channel (804) on the first surface (604) of the filter member has a cross-sectional area larger than the opening of the channel (804) on the second surface (606) of the filter member. Generally, the cross-sectional area (A1) of the opening (806) is 0.1 μm 2 to 10 μm 2 It can be. For example, the cross-sectional area is 0.1 μm 2 Above (e.g., 0.2 μm 2 Above, 0.3 μm 2 Above, 0.4 μm 2 Above, 0.5 μm 2 Above, 0.6 μm 2 Above, 0.7μm 2 Above, 0.8 μm 2 Above, 0.9 μm 2 Above, 1.0 μm 2 Above, 2.0 μm 2 Above, 3.0 μm 2 Above, 4.0 μm 2 Above, 5.0 μm 2 It may be greater than, or much more than that. Alternatively or additionally, the cross-sectional area is 10 μm 2 Less than (e.g., 9.5 μm 2 Below, 9.0 μm 2 Below, 8.5 μm 2 Below, 8.0 μm 2 Below, 7.5μm 2 Below, 7.0μm 2 Less than 6.5 μm 2 Less than 6.0 μm 2 It can be less than, or much less than that.

[0103] The cross-sectional area of ​​the opening (808) of the channel (804) is A2. Generally, the A2 / A1 ratio may be 1.0 or less (e.g., 0.95 or less, 0.90 or less, 0.85 or less, 0.80 or less, 0.75 or less, 0.70 or less, 0.65 or less, 0.60 or less, 0.55 or less, 0.50 or less, 0.45 or less, 0.40 or less, 0.35 or less, 0.30 or less, or much less). Any of the multiple channels of the filter member (602) may have cross-sectional areas A1 and A2 as described above. Additionally, within a single filter member, the cross-sectional areas A1 and / or A2 of these multiple channels may be the same or different.

[0104] In the case of a filter member (602) having a plurality of channels (804), the channels may have a cross-sectional area (A1) distribution. The average value of this cross-sectional area (A1) distribution is 0.1 μm 2 to 10 μm 2 It can be. For example, the mean value of the cross-sectional area distribution is 0.1 μm 2 Above (e.g., 0.2 μm 2 Above, 0.3 μm 2 Above, 0.4 μm 2 Above, 0.5 μm 2 Above, 0.6 μm 2 Above, 0.7 μm 2 Above, 0.8 μm 2 Above, 0.9 μm 2 Above, 1.0 μm 2 Above, 2.0 μm 2 Above, 3.0 μm 2 Above, 4.0 μm 2 Above, 5.0 μm 2 It may be greater than or much greater than that. Alternatively or additionally, the mean value of the cross-sectional area distribution is 10 μm 2 Less than (e.g., 9.5 μm 2 Below, 9.0 μm 2 Below, 8.5 μm 2 Below, 8.0 μm2 Below, 7.5 μm 2 Below, 7.0 μm 2 Less than 6.5 μm 2 Less than 6.0 μm 2 It can be less than, or much less than that.

[0105] The full width at half maximum (FWHM) value of the cross-sectional area (A1) distribution is 0.05 μm 2 to 5.0 μm 2 It can be. For example, the FWHM value of this cross-sectional area distribution is 0.05 μm 2 Above (e.g., 0.1 μm 2 Above, 0.2 μm 2 Above, 0.3 μm 2 Above, 0.5 μm 2 Above, 1.0 μm 2 Above, 2.0 μm 2 (or much higher) and / or 5.0 μm 2 Less than (e.g., 4.5 μm 2 Less than 4.0 μm 2 Less than 3.5 μm 2 Less than 3.0 μm 2 It can be less than, or much less than that.

[0106] The minimum aperture dimension of the opening (806) of each channel (804) on the first surface (604) corresponds to the shortest distance passing through the center of mass of the opening over the aperture range. For each opening (806), the minimum aperture dimension may be 20 nm or more (e.g., 25 nm or more, 30 nm or more, 35 nm or more, 40 nm or more, 45 nm or more, 50 nm or more, 60 nm or more, 70 nm or more, 80 nm or more, 90 nm or more, 100 nm or more, 120 nm or more, 140 nm or more, 160 nm or more, 180 nm or more, 200 nm or more, 250 nm or more, or much more). For each opening (806), the minimum opening dimension may be 1 micron or less (e.g., 900 nm or less, 850 nm or less, 800 nm or less, 750 nm or less, 700 nm or less, 650 nm or less, 600 nm or less, 550 nm or less, 500 nm or less, 450 nm or less, 400 nm or less, or much less).

[0107] The full width at half maximum (FWHM) value of the minimum aperture dimension distribution among the apertures (806) may be 500 nm or less (e.g., 450 nm or less, 400 nm or less, 350 nm or less, 300 nm or less, 250 nm or less, 200 nm or less, 150 nm or less, 100 nm or less, 75 nm or less, 50 nm or less, 40 nm or less, 30 nm or less, 20 nm or less, 15 nm or less, 10 nm or less, or much less).

[0108] Generally, the minimum opening dimension of the opening (808) of each channel (804) on the second surface (606) corresponds to the shortest distance passing through the center of mass of the opening over the opening range. For each opening (808), the minimum opening dimension may fall within any one of the limit values ​​and ranges described above in relation to the opening (806). Likewise, the full width at half maximum (FWHM) value of the minimum opening dimension distribution in the openings (808) may also fall within any one of the limit values ​​and ranges described above in relation to the opening (806).

[0109] In some embodiments, the openings (806) of the various channels (804) in the filter member (602) are irregularly distributed on the first surface (604) of the filter member (602). In certain embodiments, the openings (806) are distributed in a more regular pattern. For example, the openings (806) may be distributed according to a regular pattern and may form a rectangular array, a hexagonal array, or any other array pattern on the first surface (604). In some embodiments, the average spacing between the centers of mass of the openings (806) on the first surface (604) is 20 nm to 5 microns (e.g., 30 nm to 5 microns, 40 nm to 5 microns, 50 nm to 5 microns, 75 nm to 5 microns, 100 nm to 5 microns, 50 nm to 4 microns, 50 nm to 3 microns, 50 nm to 2 microns, 100 nm to 4 microns, 100 nm to 3 microns, 100 nm to 2 microns, 250 nm to 4 microns, 250 nm to 3 microns, 250 nm to 2 microns, 250 nm to 1 micron, 500 nm to 4 microns, 500 nm to 3 microns, 500 nm to 5 microns, 500 nm to 2 microns, 1 micron to 4 microns, 1 micron to 3 microns, or any other range within the aforementioned ranges.

[0110] FIG. 8c is a schematic diagram showing a portion of a first surface (604) containing openings (806) for a plurality of channels (804) formed in a filter member. The openings (806) exist in groups (820), and each group is indicated by surrounding the members belonging to the same group with a dotted line. In the case of the first surface (604) having a plurality of openings (806), the minimum opening dimension of each opening corresponds to the shortest distance passing through the center of mass of the opening over the opening range. For the plurality of openings (806) in the first surface (604), there exists an average value of the minimum opening dimensions.

[0111] Generally, a specific opening (806) is said to be part of a specific group when the distance between the center of mass of said opening and the center of mass of another opening within said group is less than twice the average value of the minimum opening dimensions of the first surface (604). In several groups (820) of openings (806) on the first surface (604), the center of each group may be defined as the point where the sum of the distances to the center of mass of each opening within said group is minimized. In the groups (820), the average distance between the centers of the nearest neighbor groups may be at least 2.5 times (e.g., at least 3.0 times, at least 3.5 times, at least 4.0 times, at least 4.5 times, at least 5.0 times, at least 5.5 times, at least 6.0 times, at least 7.0 times, at least 8.0 times, at least 8.5 times, at least 9.0 times, at least 10.0 times, at least 12.0 times, at least 15.0 times, or much more than that) than the average value of the minimum opening dimensions of the first surface (604).

[0112] According to some embodiments, for example as shown in FIG. 8b, one or more channels (804) are oriented such that their axes are approximately parallel to the direction of fluid flow passing through the filter member (602). However, if at least some of the axes of the channels (804) are oriented at an angle to the direction of the bulk flow of the fluid passing through the filter member (602), the rate of contamination of the filter member may be significantly slowed, and consequently, the elapsed time until the time to replace the filter member may be significantly increased. Although not bound by theory, it is believed that oriented the channel axes at the direction of the bulk fluid flow results in better capture of virus particles due to increased interaction of virus particles along the length of these channels.

[0113] FIG. 9a is a schematic diagram of a filter member (602) having inclined channels. In FIG. 9a, the arrow (902) indicates the direction of cross-flow (i.e., within the filter unit), and the arrow (904) indicates the direction of bulk fluid flow within the filter member (602) (tangential direction of the cross-flow direction (902)). The direction of bulk fluid flow is nominally orthogonal to the first surface (604) and the second surface (606) of the filter member (602).

[0114] A channel (906) is formed in a filter member (602), and openings (910 and 912) are formed on the surfaces (604 and 606) of the channel, respectively. The centers of mass of these openings (910 and 912) are connected to form a channel axis (908). The channel axis (908) is inclined at an angle α with respect to the direction of bulk fluid flow (904).

[0115] In some embodiments, the proportion of the channel inclined with respect to the direction of the bulk fluid flow within the filter member (602) is 20% or more (e.g., 30% or more, 40% or more, 50% or more, 60% or more, 70% or more, 75% or more, 80% or more, 85% or more, 90% or more, 95% or more, 97% or more, 98% or more, 99% or more, or even 100%). For any one particular channel (906), the α angle may be 5 degrees or more (e.g., 10 degrees or more, 15 degrees or more, 20 degrees or more, 25 degrees or more, 30 degrees or more, 35 degrees or more, 40 degrees or more, 45 degrees or more, 50 degrees or more, or much more). Alternatively or additionally, the angle α may be 90 degrees or less (e.g., 89 degrees or less, 88 degrees or less, 87 degrees or less, 86 degrees or less, 85 degrees or less, 80 degrees or less, 75 degrees or less, 70 degrees or less, 65 degrees or less, 60 degrees or less, or much less). The angle α may be from 1 degree to 90 degrees (or any smaller range within this range).

[0116] In a specific embodiment, in the channels (906) within the filter element, the average value of the angle of inclination (α) of the channels with respect to the direction of bulk fluid flow (904) is 5 degrees or more (e.g., 10 degrees or more, 15 degrees or more, 20 degrees or more, 25 degrees or more, 30 degrees or more, 35 degrees or more, 40 degrees or more, 45 degrees or more, 50 degrees or more, or much more). Alternatively or additionally, the angle α may be 90 degrees or less (e.g., 89 degrees or less, 88 degrees or less, 87 degrees or less, 86 degrees or less, 85 degrees or less, 80 degrees or less, 75 degrees or less, 70 degrees or less, 65 degrees or less, 60 degrees or less, or much less). The angle α may be from 1 degree to 90 degrees (or any smaller range within this range).

[0117] In some embodiments, for channels (906) inclined with respect to the direction (904) of the bulk fluid flow, the full width at half maximum (FWHM) of the α angle distribution may be 0 to 60 degrees. For example, the FWHM of the α angle distribution may be 60 degrees or less (e.g., 50 degrees or less, 40 degrees or less, 30 degrees or less, 20 degrees or less, 15 degrees or less, 10 degrees or less, or 5 degrees or less).

[0118] In FIG. 9a, the channel (906) is inclined toward the cross-flow direction (902). However, according to a specific embodiment, one or more of the channels formed in the filter member (602) may be inclined toward the direction of the bulk fluid flow (904) away from the cross-flow direction (902) (i.e., counterclockwise in FIG. 9a). FIG. 9b is a schematic diagram showing a filter member (602) having a channel (906) inclined toward the direction of the cross-flow (902). The angle of indentation between the direction of the bulk fluid flow (904) and the channel axis (908) is α. Various features described in relation to FIG. 9a are applied in a similar manner to the channel (906) of FIG. 9b.

[0119] In some embodiments, the proportion of channels inclined away from the cross-flow direction within the filter member (602) is 20% or more (e.g., 25% or more, 30% or more, 35% or more, 40% or more, 45% or more, 50% or more, 55% or more, 60% or more, 65% or more, 70% or more, 75% or more, 80% or more, 85% or more, 90% or more, 95% or more, 97% or more, 98% or more, 99% or more, or much more). In some embodiments, it has been found that if the filter member (602) is oriented such that some or all of the channels are inclined away from the cross-flow direction, the rate at which virus particles detach from internal binding sites within the channels and penetrate the second surface (606) of the filter member is reduced, thereby further extending the effective life of the filter member.

[0120] In FIG. 9a, the channel (906) does not oscillate back and forth across the entire filter member (602). Meanwhile, in some embodiments, the channels of the filter member may be extended in multiple directions relative to the direction of the bulk fluid flow (e.g., oscillating back and forth). However, the foregoing matters apply to these channels as well, along with the channel axis and inclination angle defined in the same manner as above.

[0121] In some embodiments, for a specific channel having an axis inclined or parallel to the direction of the bulk fluid flow, the opening or near the opening of the channel may be partially shielded or blocked. FIG. 10 is a schematic diagram of a filter member (602) having a channel (1006). As shown in the drawing, the maximum cross-sectional dimension of the channel (1006) is w. However, the maximum cross-sectional dimension at the opening (1010) is w0, which is smaller than w. Generally, it is desirable to select the w0 / w ratio so that a partially shielded channel (1006) is formed. For example, according to some embodiments, the w0 / w ratio is 0.98 or less (e.g., 0.97 or less, 0.96 or less, 0.95 or less, 0.94 or less, 0.93 or less, 0.92 or less, 0.91 or less, 0.90 or less, 0.85 or less, 0.80 or less, 0.75 or less, 0.70 or less, 0.65 or less, 0.60 or less, 0.55 or less, 0.50 or less, 0.45 or less, 0.40 or less, 0.35 or less, 0.30 or less, 0.25 or less, 0.20 or less, or much less).

[0122] In a specific embodiment, the shielding of the channel opening on the first surface (604) is measured relative to a location immediately below the first surface (604). For example, referring again to FIG. 10, w n is the maximum cross-sectional dimension of the channel (1006) at a position corresponding to 10% of the distance between the first surface (604) and the second surface (606). In a partially shielded channel (1006), w ncan be greater than w0. For example, according to some embodiments, w0 / w n The ratio is 0.99 or less (e.g., 0.97 or less, 0.96 or less, 0.95 or less, 0.94 or less, 0.93 or less, 0.92 or less, 0.91 or less, 0.90 or less, 0.85 or less, 0.80 or less, 0.75 or less, 0.70 or less, 0.65 or less, 0.60 or less, 0.55 or less, 0.50 or less, 0.45 or less, 0.40 or less, 0.35 or less, 0.30 or less, 0.25 or less, 0.20 or less, or much less).

[0123] To improve the retention of virus particles, the inner surface of the channel is structured to increase the surface area providing adsorption sites for virus particles. It has been found that the ratio of the average cross-sectional area of ​​the openings to the average surface area of ​​the inner surface of the channels can be an important factor in extending the lifespan of the filter member (602) by lowering the possibility of virus breakthrough on the second surface (606). For example, according to some embodiments, the ratio of the average cross-sectional area of ​​the channel openings of the first surface (604) to the average surface area of ​​the inner surface of the channels may be 0.05 or less (e.g., 0.04 or less, 0.03 or less, 0.02 or less, 0.01 or less, 0.005 or less, 0.003 or less, 0.001 or less, 0.0005 or less, 0.0001 or less, 0.00001 or less, 0.000001 or less, 0.0000001 or less, or much less).

[0124] In some embodiments, to further increase the surface area of ​​the inner surfaces of the channels, some or all of the channels may include side protrusions. FIG. 11 is a schematic diagram of a filter member (602) comprising a channel (1102) having openings (1104 and 1106) on each of the first and second surfaces (604 and 606) and five side protrusions (1108). The channel (1102) has a channel axis (1110) formed by connecting the centers of mass of the openings (1104 and 1106). The length L of this channel axis (1110) is obtained by measuring the distance between the centers of mass of the openings (1104 and 1106).

[0125] For the purposes of the present disclosure, an extension or protrusion of the channel (1102) is defined as a “side projection” when the extension or protrusion does not reach the second surface (606), and the vertical distance (w) between the axis (1110) and the point of the extension or protrusion furthest from the axis (1110) p This is the case where ) is 0.05L or more. In FIG. 11, the vertical distance (w) for each side projection is shown. p ) is displayed.

[0126] Generally, at a specific protrusion, w p It may be 0.05L or more (e.g., 0.10L or more, 0.20L or more, 0.30L or more, 0.40L or more, 0.50L or more, 0.75L or more, 1.0L or more, 1.25L or more, 1.5L or more, 2.0L or more, 2.5L or more, 3.0L or more, 3.5L or more, 4.0L or more, 5.0L or more, or much more).

[0127] Any particular channel (1102) may include any number of lateral projections (e.g., zero, one or more, two or more, three or more, four or more, five or more, six or more, seven or more, eight or more, or much more). Due to primary projections extending from the channel axis (1110) and secondary projections extending from these primary projections, each channel may have a branched "tree-like" structure. The average number of side protrusions per internal channel (1102) of the filter member (602) may be 0 or 0.25 or more (e.g., 0.50 or more, 1.0 or more, 1.5 or more, 2.0 or more, 2.5 or more, 3.0 or more, 3.5 or more, 4.0 or more, 4.5 or more, 5.0 or more, 5.5 or more, 6.0 or more, 6.5 or more, 7.0 or more, 7.5 or more, 8.0 or more, or much more).

[0128] In some embodiments, the channels of the filter member may include one or more coating materials. The coating material may be used, for example, to enhance the adsorption of virus particles and to facilitate fluid flow through the filter member. The coating may also be used to control the hydrophobic or hydrophilic properties of the filter member and / or to control the ionic properties of the filter member. Generally, each channel of the filter member may include zero, only one, or multiple (e.g., two or more, three or more, four or more, five or more, or much more) coating layers. FIG. 12 is a schematic diagram showing a filter member (602) including a channel (1202) having two coating layers (1204, 1206). Each coating layer follows the shape of the inner channel surface of FIG. 12. Various different coating materials may be used. Examples of such coating materials include, but are not limited to, cellulose and regenerated cellulose, hydrophilic polymers (e.g., polyethersulfone, polyethylene glycol), hydrophobic polymers (i.e., polyethylene, polypropylene, polyvinylbenzene), polypropylene glycol, other polyols, polyurethanes, polymethyl methacrylate, and polyacrylic acid.

[0129] Typically, the coating layer applied to the channel walls of the filter member is relatively thin. For example, in the case of a filter member having multiple channels, the maximum cross-sectional dimension of each channel is measured in a plane orthogonal to the direction of fluid flow within the filter member, and the filter member has an average maximum cross-sectional dimension among all such channels. In some embodiments, the ratio of the average thickness of the coating material applied to the inner surface of the channels to the average maximum cross-sectional dimension of the channels is 0.2 or less (e.g., 0.15 or less, 0.10 or less, 0.05 or less, 0.04 or less, 0.03 or less, 0.02 or less, 0.01 or less, 0.005 or less, 0.004 or less, 0.003 or less, 0.002 or less, or 0.001 or less).

[0130] Multilayer filter

[0131] According to some embodiments, the filter member (602) may be multilayered and may be effectively formed by two or more filter members in contact with each other. FIG. 13 is a schematic diagram showing a filter member (602) formed of three layers (602a to 602c). Although FIG. 13 shows three layers, more commonly the filter member (602) may be formed of two or more layers (e.g., three or more, four or more, five or more, six or more, seven or more, eight or more, nine or more, ten or more, or much more).

[0132] Each layer (602a to 602c) may have all of the aforementioned characteristics. That is, thickness, the geometry of the layer and the channel, and all other properties described herein may be present in any one or more of the layers (602a to 602c). Among any two layers (602a to 602c), one or more of the channels formed in the upstream layer may be in direct fluid communication with one or more of the channels formed in the downstream layer. In this regard, "direct fluid communication" means as follows.

[0133] Multilayer filter elements can provide several advantages in many different operating environments. For example, according to some embodiments, the first layer (602a) may have a relatively small number of openings per unit area and a relatively smooth surface texture. This structure allows fluid moving laterally across the surface of the first layer (602a) to effectively "sweep" the surface clean, preventing solid material from accumulating on the surface and hindering effective filtration. In certain embodiments, the second layer (602b) may be relatively porous and has a relatively large number of channels formed to capture virus particles, resulting in a relatively rough texture. In some embodiments, the third layer (602c) may have relatively small openings (e.g., openings with a maximum cross-sectional dimension of about 20 nm to 30 nm) on the second surface, thereby effectively serving as a size cutoff filter for particles in the fluid.

[0134] Geometric structure of fibers

[0135] As described above, the filter member (602) is typically implemented as a layer in contact with hollow fibers, through which the process fluid flows. Generally, the outer diameter of the assembly of hollow fibers and filter member (602) may be selected to ensure that cross and tangential flows pass through the filter unit properly. For example, according to some embodiments, the outer diameter may be 0.3 mm or more (e.g., 0.4 mm or more, 0.5 mm or more, 0.6 mm or more, 0.7 mm or more, 0.8 mm or more, 0.9 mm or more, 1.0 mm or more, 1.1 mm or more, 1.2 mm or more, 1.3 mm or more, 1.4 mm or more, 1.5 mm or more).

[0136] The inner diameter of the hollow fiber can also be preferably selected. For example, according to some embodiments, the inner diameter of the hollow fiber is 0.1 mm or more (e.g., 0.2 mm or more, 0.3 mm or more, 0.4 mm or more, 0.5 mm or more, 0.6 mm or more, 0.7 mm or more, 0.8 mm or more, 0.9 mm or more, 1.0 mm or more, or much more). The inner diameter of the hollow fiber is 0.001 mm or more (e.g., 0.005 mm or more, 0.01 mm or more, 0.012 mm or more, 0.014 mm or more, 0.016 mm or more, 0.018 mm or more, 0.020 mm or more, 0.022 mm or more, 0.024 mm or more, 0.026 mm or more, 0.028 mm or more, 0.030 mm or more, 0.032 mm or more, 0.034 or more, 0.036 mm or more, 0.038 mm or more, 0.040 mm or more, 0.042 mm or more, 0.044 mm or more, 0.046 mm or more, 0.048 mm or more, 0.05 mm or more, 0.055 mm or more, 0.060 mm or more) greater than the outer diameter of the assembly of the hollow fiber and filter member (602). It may be smaller than 0.065 mm, 0.070 mm, 0.075 mm, 0.080 mm, 0.085 mm, 0.090 mm, 0.10 mm, or much smaller.

[0137] Laminar flow tangential virus filtration

[0138] As described above, tangential flow virus filtration is performed using hollow fiber-based filter elements. Commercially available virus filters are implemented in this manner and are used in non-circulating filtration assemblies. However, the filter elements described herein can also be used in laminar tangential filtration subsystems to perform tangential flow virus filtration. Such subsystems have many advantages over fiber-based filtration. First, laminar filter elements are generally easier to manufacture than tubular filter elements. Second, laminar filter elements can handle higher process fluid velocities than fiber-based filter elements because they are manufactured to have relatively large surface areas. Third, laminar filter units may include a turbulence promoter (e.g., a screen mesh) that generates turbulent fluid flow across the filter element, which aids in "sweeping" the surface of the filter element through the cross-flow process fluid.

[0139] FIG. 14 is a schematic diagram showing an example of a laminar flow tangential virus filtration unit (1402). The unit (1402) includes an inlet (1404), an outlet (1406), a filter element (1410), a product stream outlet (1412), and a screen mesh (1414) that functions as a turbulence promoter. During operation, after the process fluid enters the inlet (1404), it flows toward the outlet (1406) along the direction indicated by the arrow (1408). When the process fluid flowing laterally interacts with the screen mesh (1414), turbulence is formed in the process fluid in flow, which helps to remove solid material from the surface of the filter element (1410).

[0140] As a portion of the process fluid moves through the filter member (1410) due to the transmembrane pressure difference inside the unit, a product stream is generated and then exits the filter member through the product stream outlet (1412). Since the virus particles remain trapped inside the filter member (1410), the product stream usually does not contain virus particles.

[0141] Generally, the filter member (1410) may have all the features described above in relation to the filter member (602). That is, thickness, the geometric structure of the layer and channel, and all other properties described herein may be present in the layer (1410).

[0142] Other Examples

[0143] The foregoing description is intended to illustrate the scope of the present disclosure, not to limit it, and it should be understood that embodiments other than those explicitly described also fall within the scope of the present disclosure.

Claims

Claim 1 A virus filter comprising: a filter member having a thickness extending in a first direction between the first outer surface and the second outer surface, and a plurality of channels formed in the filter member and extending from the first outer surface to the second outer surface, each channel including a channel axis extending between the first outer surface and the second outer surface and forming a tangential flow direction along the channel axis from the first outer surface to the second outer surface, wherein for at least 50% of the channels in the filter member, the channel axis is oriented at an angle of 5 to 85 degrees with respect to the first direction. Claim 2 A filter according to claim 1, wherein the thickness of the filter member is 150 micrometers or more. Claim 3 A filter according to claim 1, wherein each member of a plurality of channels includes an opening on a first outer surface, and the ratio of the total area of ​​the opening to the total area of ​​the first outer surface is 0.10 or greater. Claim 4 A filter according to claim 1, wherein each member of a plurality of channels has a volume, and the ratio of the total volume of the channels to the total volume of the filter member is 0.05 or greater. Claim 5 A filter according to claim 1, wherein for each of at least some members among a plurality of channels, the member channel includes an opening at a first outer surface having a first cross-sectional area at a first outer surface, and the first cross-sectional area is smaller than the second cross-sectional area of ​​the member channel at a position between the first outer surface and the second outer surface. Claim 6 A filter according to paragraph 5, wherein the ratio of the first cross-sectional area to the second cross-sectional area is 0.95 or less. Claim 7 A filter according to paragraph 5, wherein at least some of the above members account for 40% or more of the members of a plurality of channels. Claim 8 A filter according to claim 1, wherein the channel axes of a plurality of channels include a distribution of orientations with respect to a first direction, and the average orientation of the distribution is 10 to 30 degrees with respect to the first direction. Claim 9 A filter according to claim 1, wherein the channel axes of a plurality of channels include a distribution of orientations with respect to a first direction, and the average orientation of the distribution is 30 to 50 degrees with respect to the first direction. Claim 10 A filter according to claim 1, wherein for each of at least some members among a plurality of channels, the member channel includes one or more secondary channels extending from the channel axis, and said one or more secondary channels extend along the secondary axis from the channel axis at an angle of 10 to 80 degrees with respect to the channel axis. Claim 11 In paragraph 10, a filter in which the member channels include, on average, five or more secondary channels. Claim 12 A filter according to claim 1, wherein for each of at least some members among a plurality of channels, the member channel comprises an opening at a first outer surface having a first cross-sectional area at a first outer surface and a maximum cross-sectional area different from the first cross-sectional area at a position between the first outer surface and a second outer surface. Claim 13 A filter according to Clause 12, wherein the ratio of the first cross-sectional area to the maximum cross-sectional area is 0.50 or less. Claim 14 A filter according to claim 1, wherein for each of at least some members among a plurality of channels, the member channel includes a maximum cross-sectional area and a minimum cross-sectional area at different locations along the channel axis, and the ratio of the minimum cross-sectional area to the maximum cross-sectional area is 0.75 or less. Claim 15 A filter according to claim 1, wherein the first outer surface is flat, has a maximum dimension measured on the flat surface, and the ratio of the maximum dimension to the thickness is 10 or more. Claim 16 A filter according to claim 1, wherein the filter member is formed from a first material and comprises a second material such that each of at least some members among a plurality of channels is located on the inner surface of a member channel. Claim 17 A filter according to claim 16, wherein the first material is selected from the group consisting of polyvinylidene difluoride (PVDF), hydrophilized PVDF, and regenerated cellulose, and the second material is selected from the group consisting of cellulose, polyethersulfone, and polyethylene glycol. Claim 18 A filter according to claim 16, wherein the ratio of the average thickness of the second material on the inner surface of the member channel to the maximum cross-sectional dimension of the member channel is 0.2 or less. Claim 19 A filter according to claim 1, wherein a plurality of channels are first plurality of channels, and a filter member comprises a first layer including said first plurality of channels; and a second layer including said second plurality of channels. Claim 20 A filter according to claim 19, wherein at least some members of the first plurality of channels are in fluid communication with at least some members of the second plurality of channels at the interface between the first layer and the second layer. Claim 21 A filter according to claim 19, wherein each of the channels of the second plurality of channels includes a channel axis, and for at least 50% of the second plurality of channels in the second layer, the channel axis is oriented at an angle of 5 to 90 degrees with respect to the first direction. Claim 22 A filter according to claim 21, wherein the average orientation of a first plurality of channels with respect to a first direction is different from the average orientation of a second plurality of channels with respect to a first direction. Claim 23 A filter according to claim 19, wherein each member of the first plurality of channels includes an opening on the first outer surface, and each member of the second plurality of channels includes an opening at the interface between the first layer and the second layer, and the average cross-sectional area of ​​the openings of the first plurality of channels is different from the average cross-sectional area of ​​the openings of the second plurality of channels. Claim 24 A filter according to paragraph 23, wherein the ratio of the total area of ​​the openings of the first plurality of channels on the first outer surface to the area of ​​the first outer surface is greater than the ratio of the total area of ​​the number of the second plurality of channels on the boundary surface to the area of ​​the boundary surface. Claim 25 A filter according to claim 19, wherein each member of the first plurality of channels has a volume in the first layer, and each member of the second plurality of channels has a volume in the second layer, and the ratio of the total volume of the first plurality of channels in the first layer to the volume of the first layer is greater than the ratio of the total volume of the second plurality of channels in the second layer to the volume of the second layer. Claim 26 (a) a step of transporting a solution containing virus particles through a filter unit comprising a filter member; (b) a step of capturing a portion of the solution passing through the filter member and guiding the captured portion of the solution to flow through one or more of a plurality of channels of the filter member, wherein each of the channels comprises a channel axis forming a tangential flow direction along the channel axis extending from a first outer surface of the filter member to a second outer surface of the filter member, which is different from the flow direction of the solution transported through the filter unit; (c) a step of transporting the remainder of the solution that does not pass through the filter member to a container; (d) a step of recirculating a portion of the solution from the container through the filter unit; (e) a step of repeating steps (b) to (d) to capture a plurality of portions of the solution, wherein each captured portion of the solution passes through the filter member, wherein the filter member has a thickness measured in a direction perpendicular to the flow direction of the solution transported through the filter unit, and for each of the channels in the filter member, the channel axis is a filter A method oriented at an angle of 5 to 85 degrees with respect to the thickness direction of the member. Claim 27 A method according to claim 26, wherein the step of recirculating a portion of the solution from a container through a filter unit comprises applying fluid pressure to transfer a portion of the solution from the container to the filter unit. Claim 28 A method according to claim 27, further comprising maintaining a constant fluid pressure applied while a portion of the solution is transferred from a container to a filter unit. Claim 29 A method according to claim 26, wherein the filter unit has a cylinder shape and the filter member has a tube shape. Claim 30 A method according to claim 29, wherein a captured portion of the solution passes through a filter member in one or more radial directions of the filter unit. Claim 31 A method according to claim 26, wherein the filter member is tubular and includes a first outer surface which is the inner surface of the tubular filter member, and each member of a plurality of channels includes an opening on the first outer surface of the filter member, and the ratio of the total area of ​​the opening to the total area of ​​the first outer surface is 0.1 or greater. Claim 32 A method according to claim 26, wherein for each of at least some members of a plurality of channels, the member channel comprises an opening at a first outer surface having a first cross-sectional area at a first outer surface of a filter member, wherein the first cross-sectional area is smaller than the second cross-sectional area of ​​the member channel at a position between the first outer surface and the second outer surface of the filter member. Claim 33 A method according to paragraph 32, wherein the filter member is tubular and the first outer surface of the filter member is the inner surface of the tubular filter member. Claim 34 In paragraph 32, the method wherein at least some of the members account for 40% or more of the members of multiple channels. Claim 35 A method according to claim 26, wherein the channel axes of a plurality of channels form an orientation distribution with respect to the thickness direction of a filter member, and the average orientation of the distribution is selected from the group consisting of 10 to 30 degrees with respect to the thickness direction; 30 to 50 degrees with respect to the thickness direction; and 50 to 80 degrees with respect to the thickness direction. Claim 36 A method according to claim 26, wherein for each of at least some members among a plurality of channels, the member channel comprises one or more secondary channels extending from the channel axis. Claim 37 A method according to claim 26, wherein the filter member is formed from a first material and comprises a second material such that each of at least some members of a plurality of channels is located on the inner surface of the member channel. Claim 38 A method according to claim 37, wherein the ratio of the average thickness of the second material on the inner surface of the member channel to the maximum cross-sectional dimension of the member channel is 0.2 or less. Claim 39 A method according to claim 26, wherein a plurality of channels are first plurality of channels, and a filter member comprises a first layer including said first plurality of channels; and a second layer including said second plurality of channels. Claim 40 A method according to claim 39, wherein the average orientation of a first plurality of channels with respect to the thickness direction of a filter member is different from the average orientation of a second plurality of channels with respect to the thickness direction of a filter member. Claim 41 delete Claim 42 delete Claim 43 delete Claim 44 delete Claim 45 delete Claim 46 delete Claim 47 delete Claim 48 delete Claim 49 delete Claim 50 delete Claim 51 delete Claim 52 delete Claim 53 delete Claim 54 delete Claim 55 delete Claim 56 delete Claim 57 delete Claim 58 delete Claim 59 delete Claim 60 delete Claim 61 delete Claim 62 delete Claim 63 delete Claim 64 delete Claim 65 delete Claim 66 delete Claim 67 delete Claim 68 delete Claim 69 delete Claim 70 delete Claim 71 delete Claim 72 delete Claim 73 delete Claim 74 delete Claim 75 delete Claim 76 delete Claim 77 delete

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