Vaccine adjuvant agent containing polyacrylic acid polymer and use of same

Abstract

The present disclosure provides a vaccine adjuvant agent which contains a high molecular weight polymer that comprises an acrylic acid as a constituent unit, while having a carboxyl group content of 60.0% by mass to 62.5% by mass.

Description

Vaccine adjuvant containing polyacrylic acid polymer and use thereof

[0001] The present invention relates to vaccine adjuvants and uses thereof.

[0002] Vaccine adjuvants, which enhance the immunogenicity of vaccines when used in combination with antigens, are widely used in vaccination. Vaccine adjuvants such as aluminum salt adjuvants and oil emulsion adjuvants have been put into practical use. However, some vaccine adjuvants have limited administration routes, and some have been abandoned for practical use due to toxicity or allergic reactions. Although research and development of vaccine adjuvants is actively underway (Non-Patent Document 1, Patent Document 1), the emergence of unknown viruses such as SARS-CoV-2 (COVID-19) remains a pressing need for rapid development of vaccine antigens and the establishment of technologies that enable the development of vaccine adjuvants to complement them. In vaccine development, there is a strong need for an increased selection of vaccine adjuvants, particularly versatile vaccine adjuvants that can be used with a wide range of antigens, so that appropriate vaccine adjuvants can be selected depending on the administration route, formulation, etc.

[0003] Various high molecular weight polymers are used in pharmaceutical compositions, and are used as thickeners, adhesives, suspending agents, binders, emulsifiers, etc. Known high molecular weight polymers include, for example, acidic polymers such as sodium chondroitin sulfate, hyaluronic acid, and acrylic acid polymers, neutral polymers such as hypromellose and polyvinyl alcohol, and basic polymers such as chitin and chitosan.

[0004] WO2009 / 004900

[0005] "Medical Progress", 2018, Vol. 264, No. 5, pp. 368-373 Vaccine, 1990, Vol. 8, No. 6, pp. 573-576

[0006] An object of the present invention is to provide a highly versatile vaccine adjuvant agent that can be used with a wide range of antigens.

[0007] In view of the above problems, the present inventors conducted extensive research and surprisingly found that, among many high molecular weight polymers, an acidic polymer having acrylic acid as a structural unit and a carboxyl group content of 60.0 to 62.5% by mass enhances the immunogenicity of a wide range of antigens, including influenza virus, SARS-CoV-2, and ovalbumin, leading to the completion of the present invention. In addition, the present inventors discovered that polymers within a certain molecular size range (mass average molecular weight for non-crosslinked polymers, polymer particle size for crosslinked polymers) have superior vaccine adjuvant effects, leading to the present invention. Specifically, the present disclosure provides the following aspects of the invention.

[0008] (Item 1) A vaccine adjuvant comprising a high molecular weight polymer having acrylic acid as a constituent unit and having a carboxyl group content of 60.0 to 62.5% by mass. (Item 2) The vaccine adjuvant according to Item 1, wherein the high molecular weight polymer is polyacrylic acid and / or a salt thereof. (Item 3) The vaccine adjuvant according to Item 1 or 2, wherein the high molecular weight polymer is crosslinked polyacrylic acid and / or a salt thereof, the carboxyl group content of the polyacrylic acid is 60.0 to 62.0% by mass, and the number-based mode diameter of the high molecular weight polymer particles is 0.05 to 10 μm. (Item 4) The vaccine adjuvant according to any one of Items 1 to 3, wherein the high molecular weight polymer is crosslinked polyacrylic acid and / or a salt thereof, the carboxyl group content of the polyacrylic acid is 60.0 to 62.0% by mass, and the number-based mode diameter of the high molecular weight polymer particles is adjusted to 0.05 to 10 μm by applying a mechanical shearing force. (Item 5) The vaccine adjuvant according to Item 4, wherein the carboxyl group content of the polyacrylic acid is 60.0 to 61.0% by mass. (Item 6) The vaccine adjuvant according to Item 5, wherein the number-based mode diameter of the high molecular weight polymer particles is adjusted to 0.1 to 2.0 μm by applying a mechanical shearing force. (Item 7) The vaccine adjuvant according to Item 4, wherein the carboxyl group content of the polyacrylic acid is more than 61.0% by mass but not more than 62.0% by mass. (Item 8) The vaccine adjuvant according to Item 7, wherein the number-based mode diameter of the high molecular weight polymer particles is adjusted to 0.05 to 0.1 μm by applying a mechanical shearing force. (Item 9) The vaccine adjuvant according to Item 1 or 2, wherein the high molecular weight polymer is crosslinked polyacrylic acid and / or a salt thereof, the carboxyl group content of the polyacrylic acid is 60.0 to 62.0 mass%, and the number-based mode diameter of the high molecular weight polymer particles is 0.1 to 50 μm. (Item 10) The vaccine adjuvant according to Item 9, wherein no mechanical shearing force is applied to the high molecular weight polymer.(Item 11) The vaccine adjuvant according to Item 1 or 2, wherein the high molecular weight polymer is non-crosslinked polyacrylic acid and / or a salt thereof, and the high molecular weight polymer has a mass average molecular weight in the range of 50,000 to 300,000. (Item 12) The vaccine adjuvant according to Item 11, wherein the carboxyl group content of the polyacrylic acid is 62.0 to 62.5 mass%. (Item 13) The vaccine adjuvant according to any one of Items 1 to 12, further comprising water. (Item 14) The vaccine adjuvant according to any one of Items 3 to 9 and 13, wherein the vaccine adjuvant contains the high molecular weight polymer and water, and optionally contains at least one additive selected from the group consisting of sodium chloride, sodium hydroxide, and L-arginine, and the number-based mode diameter of the high molecular weight polymer particles is adjusted by applying a mechanical shearing force to a composition consisting of the high molecular weight polymer and water (provided that when the vaccine adjuvant contains the at least one additive, the composition may also contain the at least one additive). (Item 15) The vaccine adjuvant according to any one of Items 1 to 14, wherein sodium chloride is contained in an amount of 0.1 to 1.5% by mass relative to the total mass of the vaccine adjuvant. (Item 16) The vaccine adjuvant according to any one of Items 1 to 15, further containing sodium hydroxide and / or L-arginine. (Item 17) The vaccine adjuvant of any one of Items 1 to 16, further comprising L-arginine. (Item 18) The vaccine adjuvant of any one of Items 1 to 17, which has a pH of 6 to 8. (Item 19) The vaccine adjuvant of any one of Items 1 to 18, wherein the high molecular weight polymer accounts for 0.01 to 50% by mass of the total mass of the vaccine adjuvant. (Item 20) The vaccine adjuvant of any one of Items 1 to 19, further comprising at least one nonionic surfactant selected from the group consisting of ether-type nonionic surfactants and ester-ether-type nonionic surfactants. (Item 21) The vaccine composition of Item 20, wherein the nonionic surfactant is polysorbate 80.(Item 22) The vaccine adjuvant of any one of Items 1 to 21, further comprising at least one polyhydric alcohol selected from the group consisting of polyethylene glycol, glycerin, propylene glycol, and 1,3-butylene glycol. (Item 23) The vaccine adjuvant of Item 22, wherein the polyhydric alcohol is polyethylene glycol. (Item 24) The vaccine adjuvant of any one of Items 1 to 23, for enhancing an immune response to an antigen derived from a pathogen. (Item 25) The vaccine adjuvant of Item 24, wherein the disease caused by the pathogen is a respiratory disease. (Item 26) The vaccine adjuvant of any one of Items 1 to 25, for enhancing an immune response to an antigen derived from an enveloped virus. (Item 27) The vaccine adjuvant of any one of Items 1 to 26, for enhancing an immune response to at least one virus-derived antigen selected from the group consisting of coronaviruses and influenza viruses. (Item 28) The vaccine adjuvant of any one of Items 1 to 27, for administration selected from injection and mucosal administration. (Item 29) The vaccine adjuvant of any one of Items 1 to 28, wherein the amount of the high molecular weight polymer administered per administration is 1 μg to 100 mg. (Item 30) A method for enhancing an immune response to an antigen, comprising administering to a subject in need thereof an effective amount as a vaccine adjuvant of the vaccine adjuvant of any one of Items 1 to 29. (Item 31) Use of the vaccine adjuvant of any one of Items 1 to 29 for enhancing an immune response to an antigen. (Item 32) A method for inducing an immune response to an antigen, comprising administering to a subject in need thereof an effective amount as a vaccine adjuvant of the vaccine adjuvant of any one of Items 1 to 29 in combination with the antigen. (Item 33) Use of the vaccine adjuvant of any one of Items 1 to 29 in inducing an immune response to an antigen.(Item 34) A method for preventing a disease caused by a pathogen, comprising administering to a subject in need thereof an effective amount as a vaccine adjuvant of the vaccine adjuvant of any one of Items 1 to 29 in combination with a pathogen antigen. (Item 35) Use of the vaccine adjuvant of any one of Items 1 to 29 in preventing a disease caused by a pathogen. (Item 36) Use of the vaccine adjuvant of any one of Items 1 to 29 in the manufacture of a medicament for enhancing an immune response to an antigen, inducing an immune response to an antigen, or preventing a disease caused by a pathogen. (Item 37) A vaccine composition comprising (i) the vaccine adjuvant of any one of Items 1 to 29, and (ii) an antigen. (Item 38) A vaccine composition comprising (i) a high molecular weight polymer in an amount effective as a vaccine adjuvant, and (ii) an antigen, wherein the high molecular weight polymer has acrylic acid as a structural unit and has a carboxyl group content of 60.0 to 62.5% by mass. (Item 39) The vaccine composition of Item 37 or 38, wherein the antigen is an antigen derived from a pathogen. (Item 40) The vaccine composition of Item 39, wherein the disease caused by the pathogen is a respiratory disease. (Item 41) The vaccine composition of any one of Item 37 to 40, wherein the antigen is an antigen derived from an enveloped virus (e.g., coronavirus or influenza virus). (Item 42) The vaccine composition of any one of Item 37 to 41, for administration selected from injection and mucosal administration. (Item 43) The vaccine composition of any one of Item 37 to 42, wherein the high molecular weight polymer is contained in a mass ratio of antigen:high molecular weight polymer of 1:0.1 to 1:1000. (Item 44) A method for inducing an immune response against the antigen, comprising administering to a subject in need thereof an effective amount of the vaccine composition of any one of Items 37 to 43. (Item 45) Use of the vaccine composition of any one of Items 37 to 43 for inducing an immune response against the antigen. (Item 46) A method for preventing a disease caused by a pathogen, comprising administering to a subject in need thereof an effective amount of the vaccine composition of any one of Items 37 to 43.(Item 47) Use of the vaccine composition of any one of Items 37 to 43 for preventing a disease caused by a pathogen. (Item 48) The vaccine adjuvant of any one of Items 1 to 25 or the vaccine composition of any one of Items 37 to 43, further containing polyethylene glycol (e.g., macrogol 400 and / or macrogol 4000). (Item 49) The vaccine adjuvant of any one of Items 1 to 25 or the vaccine composition of any one of Items 37 to 43, further containing a polyhydric alcohol such as glycerin, propylene glycol, 1,3-butylene glycol, etc. (Item 50) The vaccine adjuvant of any one of Items 1 to 25 or the vaccine composition of any one of Items 37 to 43 and 48, further containing an ether-type or ester-ether-type nonionic surfactant. (Item 51) The vaccine composition according to Item 50, wherein the ether or ester-ether nonionic surfactant is polysorbate 80 (polyoxyethylene sorbitan oleate).

[0009] Any two or more of the configurations in [Item 1] to [Item 51] above can be selected and combined.

[0010] According to the present invention, the immune response to an antigen is improved, and an effective immune response can be induced with a smaller amount of antigen.

[0011] In the present disclosure, when a numerical range is expressed as X to Y, it means "at least X and at most Y."

[0012] In one aspect, the present invention provides a high molecular weight homopolymer (hereinafter, sometimes referred to as the "polymer of the present invention") that is useful as a vaccine adjuvant and has acrylic acid as a constituent unit and a carboxyl group content of 60.0 to 62.5 mass%.

[0013] In this disclosure, a vaccine adjuvant refers to a substance that can enhance the immune response to an antigen when used in combination with the antigen.

[0014] In one embodiment, the polymer of the present invention is polyacrylic acid, which is a homopolymer whose only main structural unit is acrylic acid. Polyacrylic acid may be in the form of a salt, such as a salt with sodium, potassium, or ammonium ion, or L-arginine, and all or part of the carboxyl groups in acrylic acid may form a salt. Unless otherwise specified in this disclosure, the term "polyacrylic acid" includes salt forms.

[0015] In the present application, the carboxyl group content means the proportion (mass %) of carboxyl groups contained in the polymer relative to the total amount of the polymer.

[0016] The carboxyl group content of the polymer of the present invention in the form of a salt means the carboxyl group content determined by regarding the polymer of the present invention as a free form. Although it is sometimes referred to as "the carboxyl group content as polyacrylic acid," this also means the carboxyl group content determined by regarding polyacrylic acid in the form of a salt as a free form.

[0017] In the present application, the method for quantifying the carboxyl group content is not particularly limited, but for example, the method for quantifying carboxyvinyl polymers listed in the Pharmaceutical Excipients Standards (2018) may be used.

[0018] The polymer of the present invention may be a crosslinked polymer made higher in molecular weight by a crosslinking agent, or a non-crosslinked polymer without a crosslinked structure. In the present disclosure, when no distinction is made between crosslinked and non-crosslinked, the polymer includes both crosslinked and non-crosslinked types unless the context indicates otherwise.

[0019] In one embodiment, the polymer of the present invention is a non-crosslinked polyacrylic acid having no crosslinked structure. In a linear non-crosslinked polyacrylic acid, the carboxyl group content is a maximum of 62.5% by mass. As the branched structure portion increases, the carboxyl group content decreases. In one embodiment, the carboxyl group content of the non-crosslinked polyacrylic acid is 62.0 to 62.5% by mass. In one embodiment, the carboxyl group content of the non-crosslinked polyacrylic acid is 62.5% by mass.

[0020] In one embodiment, the polymer of the present invention is a crosslinked polyacrylic acid. Examples of crosslinking agents for forming crosslinked polymers include, but are not limited to, polyalkenyl ethers such as allylpentaerythritol, allylsucrose, and allylpropylene, and divinyl compounds such as divinyl glycol. In one embodiment, the crosslinking agent for forming crosslinked polymers is at least one selected from the group consisting of allylpentaerythritol and allylsucrose. In one embodiment, the crosslinking agent for forming crosslinked polymers is allylpentaerythritol.

[0021] In crosslinked polyacrylic acid, the carboxyl group content decreases as a three-dimensional structure is formed, for example, by the addition of a crosslinking agent. In one embodiment, the carboxyl group content of the crosslinked polyacrylic acid is 60.0 to 62.0% by mass. In one embodiment, the polymer of the present invention is a crosslinked polyacrylic acid having a carboxyl group content of 60.0 to 61.0% by mass. In the present disclosure, a crosslinked polyacrylic acid having a carboxyl group content of 60.0 to 61.0% by mass may be referred to as a highly crosslinked polyacrylic acid. In one embodiment, the polymer of the present invention is a crosslinked polyacrylic acid having a carboxyl group content of more than 61.0% by mass and not more than 62.0% by mass. In the present disclosure, a crosslinked polyacrylic acid having a carboxyl group content of more than 61.0% by mass and not more than 62.0% by mass may be referred to as a low-crosslinked polyacrylic acid.

[0022] In one embodiment, the polymer of the present invention is a polyacrylic acid having a range of molecular sizes.

[0023] In one embodiment, the molecular size of non-crosslinked polyacrylic acid is defined by its weight average molecular weight (Mw). The weight average molecular weight of a non-crosslinked polymer can be measured by a commonly used method. For example, it can be determined by appropriate physical measurements of a very dilute solution. Commonly used methods include gel permeation chromatography (GPC) and intrinsic viscosity. Light scattering, ultracentrifugation, and osmometry can also be used. When the value of the weight average molecular weight differs depending on the measurement method, it is preferable to use the value measured by gel permeation chromatography (GPC).

[0024] In one embodiment, when the polymer of the present invention is a non-crosslinked polyacrylic acid and / or a salt thereof, the mass-average molecular weight is preferably 50,000 to 300,000, more preferably 100,000 to 200,000, from the viewpoint of a more excellent ability to improve immune induction.

[0025] In one embodiment, when the polymer of the present invention is a non-crosslinked polyacrylic acid and / or a salt thereof, from the viewpoint of a more excellent ability to improve immune induction, the carboxyl group content is 62.5% by mass and the mass average molecular weight is 100,000 to 200,000.

[0026] The above-mentioned methods for measuring the mass average molecular weight usually require solubility of the polymer, and therefore cannot usually be used to determine the molecular weight of insoluble crosslinked polyacrylic acid. In one embodiment, the molecular size of the crosslinked polyacrylic acid is defined by its polymer particle diameter. In one embodiment, the measurement result of the polymer particle diameter is defined by the mode diameter based on the number standard measured with a laser diffraction particle size distribution analyzer. Unless otherwise specified, the term "mode diameter" in this disclosure means the mode diameter based on the number standard measured with a laser diffraction particle size distribution analyzer.

[0027] In one embodiment, the polymer particle size (particle size distribution) is measured as a number-based particle size distribution that can be measured using a laser diffraction particle size distribution analyzer, but it is preferable that this is not significantly different from the volume-based particle size distribution result. If the mode diameter of the polymer particles is within a predetermined range using at least one analyzer, the mode diameter of the polymer particles can be considered to be within the predetermined range. Furthermore, if it is confirmed that a value equivalent to the number-based mode diameter measured using a laser diffraction particle size distribution analyzer is measured, the measurement value using a dynamic light scattering particle size distribution analyzer may be used as the number-based mode diameter measured using a laser diffraction particle size distribution analyzer. Furthermore, if it is confirmed that a value equivalent to the number-based mode diameter measured using a laser diffraction particle size distribution analyzer is measured, the mode diameter may be determined by observing the state of the polymer particles using a phase-contrast microscope, Opt-SEM (Optical Shadow Effect Mode Microscope), or the like. The polymer particle size may be measured using a laser diffraction particle size distribution analyzer (for example, Shimazu SALD-2300 or Shimazu SALD-7000, or an equivalent analyzer) according to the method described in the Test Examples of the present application.

[0028] The particle size (mode diameter) of the polymer particles may be adjusted by applying an external mechanical shear force to the polymer of the present invention (or an agent / composition containing the same). For example, the mode diameter of the polymer particles can be appropriately adjusted by applying an external shear force (mechanical shear force) to a commercially available acrylic acid-based polymer. The shear force is applied by a method known to those skilled in the art. For example, devices that can apply mechanical shear force include a high-speed rotary emulsifier, a colloid mill emulsifier, a high-pressure emulsifier, a roll mill emulsifier, an ultrasonic emulsifier, and a membrane emulsifier. High-speed rotary emulsifiers of the homomixer type, comb type, and intermittent jet flow generating type are particularly preferred. A high-speed rotary emulsifier of the intermittent jet flow generating type is particularly preferred.

[0029] In one embodiment, the phrase "the number-based mode diameter of the polymer particles is adjusted to a predetermined range (e.g., 0.05 to 10 μm) by applying a mechanical shearing force" means that the number-based mode diameter of the polymer particles is adjusted to be within a predetermined range by applying a mechanical shearing force to an agent / composition containing the polymer. The particle size of the polymer particles is preferably measured by mixing the polymer with other components (e.g., neutralizing agent, water) contained in the adjuvant of the present invention described below. These other components preferably do not contain substances that may significantly affect the measured particle size (e.g., surfactants, polyhydric alcohols, insoluble / slightly soluble substances), and these other components preferably form a uniform solution upon mixing. For example, the measurement may be performed by the following method. When the measured particle size may vary depending on the polymer concentration, it is desirable that the polymer concentration in the sample used for particle size measurement be close to the polymer concentration in the adjuvant of the present invention. When the adjuvant of the present invention described below contains water, it is preferable to add at least the water (e.g., the total amount) to measure the particle size (mode diameter) of the polymer particles. When the adjuvant of the present invention described below contains a pH adjuster (e.g., sodium hydroxide, L-arginine), it is preferable to add the pH adjuster (e.g., to achieve a predetermined pH) to measure the particle size (mode diameter) of the polymer particles. When the adjuvant of the present invention described below contains sodium chloride, it is preferable to add sodium chloride (e.g., the total amount) to measure the particle size (mode diameter) of the polymer particles.

[0030] In one embodiment, the cross-linked polyacrylic acid particles have a modal diameter of 0.05 to 50 μm.

[0031] In one embodiment, the polymer of the present invention is a crosslinked polyacrylic acid that is not subjected to mechanical shear.

[0032] In one embodiment, the polymer of the present invention is a cross-linked polyacrylic acid that has not been subjected to mechanical shear, and the mode diameter of the polymer particles is 0.1 to 50 μm.

[0033] In one embodiment, the polymer of the present invention is a cross-linked polyacrylic acid that has not been subjected to mechanical shear and has a polymer particle mode diameter of 1 to 15 μm.

[0034] In one embodiment, the polymer of the present invention is a crosslinked polyacrylic acid that has been subjected to mechanical shear.

[0035] In one embodiment, from the viewpoint of a more excellent immune induction improving ability, the polymer of the present invention is a crosslinked polyacrylic acid to which a mechanical shear force is applied, and the mode diameter of the polymer particles is 0.05 to 10 μm (e.g., 0.1 to 2.0 μm, 0.2 to 2.0 μm, 0.2 to 1.0 μm, 0.5 to 1.0 μm, 0.7 to 1.0 μm).

[0036] In one embodiment, the polymer of the present invention is a crosslinked polymer, and is treated by applying an external shear force (mechanical shear force) to the polymer in an agent / composition containing other components (e.g., water) so that the mode diameter of the polymer particles in the agent / composition falls within the range of 0.05 to 10 μm (e.g., 0.1 to 2 μm, 0.2 to 2.0 μm, 0.2 to 1.0 μm, 0.5 to 1.0 μm, 0.7 to 1.0 μm).

[0037] In one embodiment, the polymer of the present invention is a highly crosslinked polyacrylic acid having a carboxyl group content of 60.0 to 61.0% by mass, which is treated by applying mechanical shear force in an agent / composition containing other components (preferably water or an aqueous NaCl solution) so that the mode diameter of the polymer particles in the agent / composition falls within the range of 0.05 to 10 μm (e.g., 0.1 to 2.0 μm, 0.2 to 2.0 μm, 0.2 to 1.0 μm, 0.5 to 1.0 μm, 0.7 to 1.0 μm).

[0038] In one embodiment, the polymer of the present invention is a low-crosslinked polyacrylic acid having a carboxyl group content of more than 61.0% by mass and not more than 62.0% by mass, and is treated by applying an external shear force (mechanical shear force) to the polymer in an agent / composition containing other components (e.g., water) so that the mode diameter of the polymer particles in the agent / composition falls within the range of 0.05 to 10 μm (e.g., 0.05 to 1 μm, 0.05 to 0.1 μm).

[0039] The dose of the polymer of the present invention is not particularly limited as long as it is an amount that improves the immune response to the antigen, and may vary depending on the antigen, the formulation of the composition containing the polymer of the present invention, the administration route, the recipient, etc. For example, the dose of the polymer of the present invention per administration is 1 μg to 1000 mg, preferably 10 μg to 100 mg per administration, and more preferably 100 μg to 10 mg per administration. Furthermore, for example, the mass ratio of the dose of the polymer of the present invention to the dose of the antigen, antigen:polymer of the present invention, is in the range of 1:0.1 to 1:1000, more preferably 1:10 to 1:500.

[0040] In one embodiment, the dosage of the polymer per administration is 1 μg to 100 mg.

[0041] In one embodiment, the polymer of the present invention is administered by injection (eg, intradermally, subcutaneously, or intraperitoneally), with the dosage per administration being 1 μg to 10 mg, preferably 1 μg to 1 mg.

[0042] In one embodiment, the polymers of the present invention are administered mucosally (eg, intranasally) and the dosage per administration is 10 μg to 100 mg, preferably 100 μg to 10 mg.

[0043] In one aspect, the present invention provides a vaccine adjuvant containing the polymer of the present invention (hereinafter, may be referred to as the "adjuvant of the present invention"). The above description of the polymer of the present invention can be used to describe the polymer of the present invention contained in the adjuvant of the present invention.

[0044] The adjuvant of the present invention may be the polymer of the present invention itself, or may further contain other components such as water.

[0045] In one embodiment, the adjuvant of the present invention is used as an additive to a pharmaceutical composition containing other components (e.g., an antigen, etc.).

[0046] In one embodiment, the adjuvant of the present invention is a vaccine adjuvant formulation that does not contain an antigen. The administration route of the vaccine adjuvant formulation is not particularly limited as long as it is effective in enhancing the immune response to an antigen. Examples include oral administration and parenteral administration (injection, transmucosal administration, etc.). The adjuvant of the present invention can be administered separately from the antigen, for example, without being mixed with it. The administration route of the adjuvant of the present invention may be the same as or different from that of the antigen. For example, the adjuvant of the present invention can be mixed with the antigen at the time of use and then administered. Preferably, the adjuvant of the present invention is administered mixed with the antigen. The adjuvant of the present invention is usually administered simultaneously with the antigen, but may also be administered before or after antigen administration. Furthermore, when the adjuvant of the present invention is administered simultaneously with the antigen, it may be administered substantially simultaneously with the antigen. For example, the adjuvant of the present invention and the antigen may be administered to a subject completely simultaneously, or may be administered consecutively within a certain time period (preferably within a few minutes).

[0047] The amount of the polymer of the present invention contained in the adjuvant of the present invention may vary depending on the formulation, method of use, administration route, concomitant antigen, administration target, etc., but is, for example, 0.01 to 100% by mass, preferably 0.01 to 50% by mass, more preferably 0.01 to 10% by mass, and even more preferably 0.1 to 5% by mass, relative to the total mass of the adjuvant of the present invention. The adjuvant of the present invention may contain one or more types of polymer of the present invention. When the above-mentioned adjuvant of the present invention contains two or more types of polymer of the present invention, the amount of the polymer of the present invention contained in the adjuvant of the present invention means the total content of the two or more types of polymer of the present invention.

[0048] The adjuvant of the present invention can be produced by mixing the polymer of the present invention and other appropriate components, and by a method commonly used for producing pharmaceutical compositions or additives for pharmaceutical compositions. Using the polymer of the present invention having a large mode diameter, the mode diameter of the polymer particles may be appropriately adjusted to a preferred range by applying external shear force (mechanical shear force) during the production process of the adjuvant of the present invention.

[0049] In one embodiment of the adjuvant of the present invention, the mode diameter of the polymer particles is measured at a concentration equivalent to that when the polymer is mixed with the total amount of water that can be contained in the adjuvant of the present invention.

[0050] In one embodiment of the adjuvant of the present invention, the mode diameter of polymer particles is measured under conditions in which the polymer concentration corresponds to that when mixed with the total amount of water contained in the adjuvant of the present invention and the pH is adjusted to that of the adjuvant of the present invention (with a pH adjuster as necessary).

[0051] The pH of the adjuvant of the present invention is not particularly limited and can be adjusted appropriately depending on, for example, the formulation, method of use, administration route, concomitant antigen, etc. To adjust the pH, an appropriate acidic substance (phosphoric acid, citric acid, hydrochloric acid, etc.) or basic substance (sodium hydroxide, potassium hydroxide, basic amino acids such as lysine and arginine, etc.) can be used. Various buffer solutions adjusted to an acidic or basic state may also be used.

[0052] In one embodiment, the adjuvant of the present invention has a pH of 6 to 8 (preferably 6.5 to 7.5).

[0053] In one embodiment, the adjuvant of the present invention comprises water. In one embodiment, the adjuvant of the present invention comprises at least 50% by mass (e.g., at least 70% by mass, at least 80% by mass, or at least 90% by mass) of water relative to the total mass of the adjuvant of the present invention.

[0054] In one embodiment, the adjuvant of the present invention contains sodium hydroxide and / or L-arginine. In one embodiment, the adjuvant of the present invention is adjusted to a pH of 6 to 8 (preferably 6.5 to 7.5) with sodium hydroxide and / or L-arginine. In one embodiment, the adjuvant of the present invention is neutralized with sodium hydroxide and / or L-arginine. The order of adjusting the pH and applying mechanical shearing force is not particularly limited. In one embodiment, the mechanical shearing force is applied after adjusting the pH to 6 to 8 (preferably 6.5 to 7.5). In one embodiment, the mechanical shearing force is applied before adjusting the pH to 6 to 8 (preferably 6.5 to 7.5).

[0055] In one embodiment, the adjuvant of the present invention contains sodium chloride in an amount of 0.1 to 1.5% by mass (e.g., 0.2 to 1.0% by mass) relative to the total mass of the adjuvant of the present invention.

[0056] In one embodiment, the adjuvant of the present invention contains a high molecular weight polymer which is a crosslinked polyacrylic acid and / or a salt thereof having a carboxyl group content as polyacrylic acid of 60.0 to 62.0% by mass (preferably 60.0 to 61.0% by mass), and water, and optionally contains at least one additive selected from the group consisting of sodium chloride, sodium hydroxide, and L-arginine, and the number-based mode diameter of the high molecular weight polymer particles is adjusted to 0.05 to 50 μm (preferably 0.05 to 10 μm, 0.1 to 2 μm, 0.2 to 2.0 μm, 0.2 to 1.0 μm, 0.5 to 1.0 μm, or 0.7 to 1.0 μm) by applying a mechanical shearing force to a composition consisting of the high molecular weight polymer and water (however, when the vaccine adjuvant contains the at least one additive, the composition may contain the at least one additive). When the carboxyl group content of polyacrylic acid is 60.0 to 61.0% by mass, the number-based mode diameter of the high molecular weight polymer particles is preferably adjusted to 0.05 to 10 μm (e.g., 0.1 to 2.0 μm, 0.2 to 2.0 μm, 0.2 to 1.0 μm, 0.5 to 1.0 μm, 0.7 to 1.0 μm). When the carboxyl group content of polyacrylic acid is greater than 61.0% by mass and not greater than 62.0% by mass, the number-based mode diameter of the high molecular weight polymer particles is preferably adjusted to 0.05 to 10 μm (e.g., 0.05 to 1 μm, 0.05 to 0.1 μm). Here, "the number-based mode diameter of the high molecular weight polymer particles" refers to the number-based mode diameter of the high molecular weight polymer particles when the composition is measured as a specimen. Sodium hydroxide and L-arginine may be added as pH adjusters to adjust the pH of the composition to 6 to 8 (preferably 6.5 to 7.5). The composition contains the entire amount of the high molecular weight polymer. Preferably, the composition contains the entire amount of water. However, when water is used as a solvent for other components such as surfactants, the amount of water contained in the composition does not have to be the entire amount of water in the adjuvant of the present invention.The adjuvant of the present invention contains at least 50% by mass (e.g., at least 70%, at least 80%, or at least 90% by mass) of water relative to the total mass of the adjuvant of the present invention, and may contain at least one additive selected from the group consisting of nonionic surfactants and polyhydric alcohols.

[0057] In one embodiment, the adjuvant of the present invention comprises the polymer of the present invention and water, and optionally contains at least one additive selected from the group consisting of sodium chloride, sodium hydroxide, and L-arginine, and optionally contains at least one additive selected from the group consisting of a nonionic surfactant and a polyhydric alcohol.

[0058] The viscosity of the adjuvant of the present invention is not particularly limited and can be adjusted appropriately depending on, for example, the formulation, method of use, route of administration, etc. The method for adjusting the viscosity is not particularly limited and can be carried out by a commonly used method such as adding a viscosity regulator or applying external shear. The viscosity of the adjuvant of the present invention is, for example, 5 to 5,000 mPa s, preferably 5 to 1,000 mPa s, and more preferably 5 to 500 mPa s.

[0059] In one aspect, the present invention provides a vaccine composition (hereinafter, sometimes referred to as "the vaccine composition of the present invention") comprising (i) the adjuvant of the present invention and (ii) an antigen.

[0060] In one aspect, the present invention provides a vaccine composition (hereinafter, sometimes referred to as "the vaccine composition of the present invention") comprising (i) a polymer of the present invention and (ii) an antigen.

[0061] The amount of the polymer of the present invention contained in the vaccine composition of the present invention is not particularly limited, as long as it is an amount effective as a vaccine adjuvant, and can be appropriately selected depending on the formulation, administration route, antigen, administration subject, etc.

[0062] In the present disclosure, the term "effective amount as a vaccine adjuvant" refers to an amount that enhances the immune response to an antigen, for example, an amount of the polymer of the present invention that shows an improvement in the immune response to an antigen compared to a vaccine composition that does not contain the polymer of the present invention.

[0063] The amount of the polymer of the present invention contained in the vaccine composition of the present invention is, for example, 0.001 to 10% by mass, preferably 0.01 to 2.5% by mass, relative to the total mass of the vaccine composition of the present invention. The amount of the polymer of the present invention contained in the vaccine composition of the present invention may be 0.05 to 5% by mass, more preferably 0.1% to 2.5% by mass, relative to the total mass of the vaccine composition of the present invention.

[0064] The amount of the polymer of the present invention contained in the vaccine composition of the present invention is, for example, in the mass ratio to the antigen, antigen:polymer of the present invention = 1:0.1 to 1:1000, more preferably 1:10 to 1:500.

[0065] The amount of antigen contained in the vaccine composition of the present invention is not particularly limited and can be appropriately selected depending on the formulation, administration route, method of use, type of antigen, administration target, etc. For example, it is 0.0001 to 10.0% by mass, 0.01 to 10.0% by mass, and more preferably 0.05 to 5.0% by mass relative to the total mass of the vaccine composition of the present invention.

[0066] In the present invention, the amount of antigen to be administered is not particularly limited as long as it is an amount sufficient to produce antigen-specific antibodies [IgA, IgG, etc.] in combination with the polymer of the present invention, and may vary depending on the type of antigen, target disease, administration route, recipient, etc. For example, the amount of antigen administered per administration is 0.1 μg to 10 mg, preferably 1 μg to 5 mg per administration, and more preferably 1 μg to 1 mg per administration.

[0067] The vaccine composition of the present invention may contain one or more types of the polymer of the present invention. When the vaccine composition of the present invention contains two or more types of the polymer of the present invention, the amount of the polymer of the present invention contained in the vaccine composition of the present invention means the total content of the two or more types of the polymer of the present invention.

[0068] The vaccine composition of the present invention may contain one or more antigens. When the vaccine composition of the present invention contains two or more antigens, the amount of antigens contained in the vaccine composition of the present invention means the total content of the two or more antigens.

[0069] The method for producing the vaccine composition of the present invention is not particularly limited, and the composition can be produced by a method commonly used for producing vaccine compositions. For example, the vaccine composition of the present invention can be prepared by dissolving or suspending an antigen in an appropriate buffer such as physiological saline or phosphate-buffered saline, and gently mixing the resulting mixture with the polymer of the present invention / the adjuvant of the present invention until homogeneous.

[0070] The pH of the vaccine composition of the present invention is not particularly limited and can be adjusted appropriately depending on, for example, the formulation, method of use, administration route, antigen, etc. To adjust the pH, an appropriate acidic substance (phosphoric acid, citric acid, hydrochloric acid, etc.) or a basic substance (sodium hydroxide, potassium hydroxide, basic amino acids such as lysine and arginine, etc.) can be used. Various buffer solutions adjusted to be acidic or basic may also be used.

[0071] In one embodiment, the pH of the vaccine composition of the present invention is 6 to 8 (preferably 6.5 to 7.5).

[0072] In one embodiment, the vaccine composition of the invention comprises sodium hydroxide and / or L-arginine. In one embodiment, the vaccine composition of the invention is neutralized with sodium hydroxide and / or L-arginine.

[0073] In one embodiment, the vaccine composition of the present invention comprises sodium chloride, ie, 0.05 to 1.5% by mass (e.g., 0.1 to 1.0% by mass) of sodium chloride relative to the total mass of the vaccine composition of the present invention.

[0074] The viscosity of the vaccine composition of the present invention is not particularly limited and can be adjusted appropriately depending on, for example, the formulation, method of use, route of administration, etc. The method for adjusting the viscosity is not particularly limited and can be carried out by a commonly used method such as adding a viscosity regulator or applying external shear. The viscosity of the vaccine composition of the present invention is, for example, 5 to 5000 mPa·s, preferably 5 to 1000 mPa·s, and more preferably 5 to 500 mPa·s.

[0075] In the present invention, the viscosity can be measured by a commonly used method, preferably by using a rotational viscometer.

[0076] The route of administration of the vaccine composition of the present invention is not particularly limited, and may be oral or parenteral (e.g., injection or mucosal administration). Examples of mucous membranes to which it can be applied include the mucous membranes of the nasal cavity, oral cavity, pharynx, trachea, lungs, and intestinal tract. The vaccine composition of the present invention can be administered, for example, by intradermal, subcutaneous, intramuscular, or intraperitoneal injection; oral application, dripping, or spray spray; nasal dripping or spray spray; or lung aerosol or dry powder inhalation. The vaccine composition of the present invention is, for example, a nasal administration formulation, and the target site is, for example, the nasal mucosa or nasopharynx.

[0077] The vaccine composition of the present invention may be a formulation that is administered without dilution, or may be a formulation that is diluted appropriately before use.

[0078] The adjuvant agent of the present invention / vaccine composition of the present invention may contain active agents, diluents, bactericides, preservatives, surfactants, stabilizers, etc. that can be used in combination.

[0079] The adjuvant of the present invention / vaccine composition of the present invention may contain polyethylene glycol (e.g., macrogol 400, macrogol 4000, macrogol 20000) (e.g., 0.05 to 15% by mass, 0.1 to 10% by mass, or 0.1 to 5% by mass, relative to the total mass of the adjuvant of the present invention / vaccine composition of the present invention).

[0080] In one embodiment, the adjuvant of the present invention / vaccine composition of the present invention may contain at least one additive selected from the group consisting of a nonionic surfactant and a polyhydric alcohol, from the viewpoint of achieving a more excellent ability to improve immune induction. In the adjuvant of the present invention, when the number-based mode diameter of the high molecular weight polymer particles is adjusted by applying mechanical shearing force, the additive may affect the mode diameter, and therefore is preferably added after the application of mechanical shearing force.

[0081] Examples of nonionic surfactants include ether-type nonionic surfactants and ester-ether-type nonionic surfactants, and more specific examples include polysorbates and polyoxyethylene hydrogenated castor oils, with a preferred example being polysorbate 80 (also known as polyoxyethylene sorbitan oleate). Examples of the content of the nonionic surfactant include 0.01 to 1% by mass and 0.1 to 0.7% by mass relative to the total mass of the adjuvant of the present invention / vaccine composition of the present invention.

[0082] Examples of polyhydric alcohols include polyethylene glycol (e.g., Macrogol 400, Macrogol 4000, Macrogol 20000), glycerin, propylene glycol, and 1,3-butylene glycol. Examples of the content of polyhydric alcohols include 0.1 to 10% by mass, or 0.1 to 5% by mass, relative to the total mass of the adjuvant of the present invention / vaccine composition of the present invention.

[0083] In one embodiment, the adjuvant of the present invention comprises a high molecular weight polymer that is a crosslinked polyacrylic acid and / or a salt thereof, the carboxyl group content of which is 60.0 to 61.0% by mass as polyacrylic acid, and the number-based mode diameter of the high molecular weight polymer particles is adjusted to 0.05 to 10 μm (e.g., 0.1 to 2.0 μm, 0.2 to 2.0 μm, 0.2 to 1.0 μm, 0.5 to 1.0 μm, 0.7 to 1.0 μm) by applying a mechanical shearing force. Subsequently, at least one additive selected from the group consisting of a nonionic surfactant and a polyhydric alcohol may be optionally added.

[0084] In one embodiment, the adjuvant of the present invention comprises a high molecular weight polymer that is a crosslinked polyacrylic acid and / or a salt thereof, the carboxyl group content of which is 60.0 to 61.0% by mass as polyacrylic acid; and water, wherein the number-based mode diameter of the high molecular weight polymer particles in the presence of the total amount of water is adjusted to 0.05 to 10 μm (e.g., 0.1 to 2.0 μm, 0.2 to 2.0 μm, 0.2 to 1.0 μm, 0.5 to 1.0 μm, 0.7 to 1.0 μm) by applying a mechanical shear force. Then, optionally, at least one additive selected from the group consisting of a nonionic surfactant and a polyhydric alcohol may be added.

[0085] In one embodiment, the adjuvant of the present invention comprises a high molecular weight polymer that is a crosslinked polyacrylic acid and / or a salt thereof, the carboxyl group content of which is 60.0 to 61.0% by mass as polyacrylic acid; water; and a pH adjuster (e.g., sodium hydroxide, L-arginine). The high molecular weight polymer and water are mixed, the pH is adjusted to 6 to 8 (preferably 6.5 to 7.5) with the pH adjuster, and then mechanical shearing force is applied to adjust the number-based mode diameter of the high molecular weight polymer particles to 0.05 to 10 μm (e.g., 0.1 to 2.0 μm, 0.2 to 2.0 μm, 0.2 to 1.0 μm, 0.5 to 1.0 μm, 0.7 to 1.0 μm). Optionally, at least one additive selected from the group consisting of a nonionic surfactant and a polyhydric alcohol may then be added.

[0086] In one aspect, the present invention provides a method for enhancing an immune response to an antigen, comprising administering to a subject in need thereof an effective amount of a polymer of the present invention / adjuvant agent of the present invention.

[0087] In one aspect, the present invention provides the use of a polymer of the present invention / adjuvant agent of the present invention to enhance an immune response to an antigen.

[0088] In one aspect, the present invention provides a method for inducing an immune response to an antigen, comprising administering to a subject in need thereof an effective amount of the polymer of the present invention / the adjuvant of the present invention in combination with the antigen.

[0089] In one aspect, the present invention provides the use of the polymer of the present invention / the adjuvant of the present invention in inducing an immune response to an antigen.

[0090] In one aspect, the present invention provides a method for preventing a disease caused by a pathogen, comprising administering to a subject in need thereof an effective amount of the polymer of the present invention / the adjuvant agent of the present invention in combination with a pathogen antigen.

[0091] In one aspect, the present invention provides the use of the polymer of the present invention / the adjuvant agent of the present invention in the prevention of diseases caused by pathogens.

[0092] In one aspect, the present invention provides the use of a polymer of the present invention in the manufacture of an adjuvant composition of the present invention / a vaccine composition of the present invention.

[0093] In one aspect, the present invention provides the use of an adjuvant agent of the present invention in the manufacture of a vaccine composition of the present invention.

[0094] In the present disclosure, inducing an immune response against an antigen means producing at least one type of antigen-specific antibody (IgA, IgG, etc.).

[0095] In the present disclosure, enhancing the immune response to an antigen means increasing the production of at least one type of antigen-specific antibody (IgA, IgG, etc.), which can be evaluated, for example, by comparison with a vaccine composition that does not contain the polymer of the present invention.

[0096] Because antigen-specific IgG2a is closely related to helper T cell type 1 (Th1) cellular immunity, the adjuvant of the present invention is preferably effective in enhancing the production of antigen-specific IgG2a. Because antigen-specific IgG and IgA have different functions, it is preferable to enhance the production of both. In one embodiment, the adjuvant of the present invention can be used to enhance the production of both antigen-specific IgG and IgA.

[0097] Preventing a disease caused by a pathogen may include not only preventing infection / onset of the disease, but also suppressing the onset of the disease, alleviating the symptoms of the disease, and preventing the recurrence of the disease.

[0098] In the present disclosure, an "effective amount" of a vaccine composition of the present invention may refer to the amount of the vaccine composition of the present invention required to provide a benefit to a subject in inducing an immune response to an antigen / preventing a disease caused by a pathogen.

[0099] In the present invention, the subject is not particularly limited, and examples include humans and non-human animals, such as poultry (e.g., chickens, ducks, etc.), livestock (e.g., cows, pigs, etc.), and pets (e.g., dogs, cats), etc. Preferably, the subject is a human.

[0100] In the present invention, a pathogen refers to bacteria, viruses, mycoplasma, etc. that can cause disease in a subject. Examples of pathogens include coronaviruses (e.g., pathogens of severe acute respiratory syndrome (SARS), such as SARS-CoV-2), influenza viruses, hepatitis B viruses, hepatitis C viruses, human immunodeficiency viruses (HIV), varicella viruses, measles viruses, mumps viruses, polioviruses, rotaviruses, adenoviruses, herpes viruses, human papillomaviruses, rubella viruses, Streptococcus pneumoniae, Mycobacterium tuberculosis, Bordetella pertussis, Neisseria meningitidis, Haemophilus influenzae type b, Vibrio cholerae, Corynebacterium diphtheriae, and mycoplasmas.

[0101] In the present invention, the antigen is not particularly limited, and examples thereof include pathogen-derived antigens and tumor-associated antigens. Examples of pathogen-derived antigens include antigens derived from the above-mentioned pathogens.

[0102] In one embodiment of the invention, the pathogen-derived antigen is an enveloped virus-derived antigen.

[0103] In one embodiment of the present invention, the pathogen-derived antigen is at least one pathogen-derived antigen selected from the group consisting of coronavirus and influenza virus.

[0104] In one embodiment of the invention, the pathogen-derived antigen is a SARS-CoV-2-derived antigen.

[0105] In the present invention, pathogen-derived antigens may be those used in conventional vaccine preparations. These include natural products purified from pathogens, and proteins, glycoproteins, peptides, polysaccharides, lipopolysaccharides, polynucleotides, or DNA encoding antigens artificially produced by techniques such as genetic recombination. Examples of pathogen-derived antigens include complete virus particles (virions), incomplete virus particles, virion-constituting particles, viral nonstructural proteins, proteins or glycoproteins derived from pathogens, protective antigens, and neutralization epitopes, including those that retain infectious potential (live antigens) and those that have lost infectious potential (inactivated antigens). Examples of pathogen-derived antigens also include component vaccines, subunit vaccines, vector vaccines, and gene vaccines.

[0106] The present invention will be described in more detail below with reference to examples, comparative examples, and test examples, but the present invention is not limited to these examples. In the examples, "polyacrylic acid" refers to polyacrylic acid in a free form. "Mode diameter" is a result based on the number of particles.

[0107] [Test Example 1] Antibody production induction test in mice (nasal mucosal inoculation, influenza split antigen, part 1)

[0108] 1. Preparation of vaccine formulations (1) Preparation of antigen stock solution Influenza split antigen [H1N1] was mixed with physiological saline until homogeneous to obtain an antigen stock solution (antigen concentration 0.0066 HA w / v%).

[0109] (2)-1 Preparation of polymer-containing compositions used in sample numbers A#03 to A#10. The polymer was added to purified water or sodium chloride aqueous solution, neutralized with sodium hydroxide or L-arginine, and mixed until homogeneous to obtain a composition. For the polymer-containing compositions with mechanical shearing treatment, the resulting composition was subjected to mechanical shearing force using an intermittent jet-generating high-speed mixer to adjust the particle size of the polymer contained in the polymer-containing composition. (2)-2 Preparation of polymer-containing compositions used in sample numbers A#11 to A#19. The polymer was mixed with purified water until homogeneous to obtain a composition. For A#12, 0.375% by mass of L-arginine was added to the polymer composition. (2)-3 Preparation of compositions containing known vaccine adjuvants used in sample numbers A#20 to A#23 A known vaccine adjuvant (Poly I:C, CpG K3, R848, or aluminum hydroxide gel) was mixed with physiological saline until homogeneous to obtain a composition.

[0110] (2)-4 Measurement of mode diameter of polymer particles The mode diameter of each polymer before mixing with the antigen was measured using a laser diffraction particle size analyzer (Shimazu SALD-2300, Shimazu SALD-7000). For polymer-containing compositions to which mechanical shear force had been applied, the mode diameter of the polymer particles was measured using the polymer-containing composition after the application of mechanical shear force as a sample with the laser diffraction particle size analyzer.

[0111] The table below shows details of the high molecular weight polymer used in the preparation of the vaccine formulation and the measurement results of the mode diameter of the polymer particles; as well as the neutralizing agent used in the preparation of the high molecular weight polymer-containing composition, the sodium chloride concentration relative to the total amount of the high molecular weight polymer-containing composition, and whether or not mechanical shearing treatment was performed.

[0112]

[0113]

[0114] (3)-1 High molecular weight polymer-free vaccine preparation (sample number A#01) The antigen stock solution and physiological saline were mixed at a 1:1 (volume ratio) to obtain a high molecular weight polymer-free vaccine preparation with an antigen concentration of 0.0033 HA w / v%. (3)-2 High molecular weight polymer-containing vaccine preparation (sample numbers A#03 to A#19) The antigen stock solution and a high molecular weight polymer-containing composition were mixed at a 1:1 (volume ratio) to obtain a high molecular weight polymer-containing vaccine preparation with an antigen concentration of 0.0033 w / v%. (3)-3 Vaccine preparation containing a known vaccine adjuvant (sample numbers A#20 to A#23) The antigen stock solution and a known vaccine adjuvant-containing composition were mixed at a 1:1 (volume ratio) to obtain a high molecular weight polymer-containing vaccine preparation with an antigen concentration of 0.0033 HA w / v%.

[0115] 2. Antibody production induction test in mice (nasal mucosal inoculation) (Method) BALB / c mice (female, 6 weeks old) were given a single inoculation of 15 μL each of the vaccine formulations (A#01, A#03-A#23) into both nostrils (total 30 μL: antigen dose 1 μg HA) (3 mice per group). Three weeks after inoculation, alveolar lavage fluid was collected and the antibody titer of influenza HA antigen-specific IgA in the alveolar lavage fluid was measured to analyze the antibody production induction ability. The doses of high molecular weight polymers / known adjuvants are shown in the table below.

[0116] (Results) The results (mean values ​​of n = 3) are shown in the table below. (Discussion) Vaccine formulations A#03 to A#10, which contain a polyacrylic acid homopolymer with a carboxyl group content of 60.5% by mass, induced antibody production. On the other hand, the vaccine formulation without a high-molecular-weight polymer (sample number A#01) (which did not contain any known vaccine adjuvants) and the vaccine formulations containing other high-molecular-weight polymers (A#11 to A#19) did not induce antibody production. High influenza HA antigen-specific IgA was observed in A#05, A#06, A#09, and A#10, which contain influenza split antigen and polyacrylic acid, an acidic polymer with a carboxyl group content of 60.5% by mass, and whose crosslinked, unsheared polymer particles have a mode diameter of 8.3 to 9.0 μm. In addition, high production of influenza HA antigen-specific IgA was observed in A#03, A#07, and A#08, which are polyacrylic acid, an acidic polymer with a carboxyl group content of 60.5% by mass, and in which the crosslinked, shear-stressed polymer particles have a mode diameter of 0.64 to 1.3 μm.

[0117]

[0118] [Test Example 2] Antibody production induction test in mice (nasal mucosal inoculation, SARS-CoV-2 S1 protein)

[0119] 1. Preparation of vaccine formulations (1) Preparation of antigen stock solution SARS-CoV-2 S1 protein was mixed with saline until homogeneous to obtain an antigen stock solution (antigen concentration 0.02 w / v%).

[0120] (2)-1 Preparation of polymer-containing compositions Each polymer was placed in purified water or an aqueous sodium chloride solution, and some compositions were neutralized with sodium hydroxide or L-arginine, and mixed until homogeneous to obtain a polymer-containing composition. For the polymer-containing composition "with mechanical shear treatment," the obtained polymer-containing composition was subjected to mechanical shear force using an intermittent jet flow generating high-speed mixer to adjust the particle size of the polymer contained in the polymer-containing composition.

[0121] (2)-2 Measurement of mode diameter of polymer particles The mode diameter of each polymer before mixing with the antigen was measured using a laser diffraction particle size analyzer. For polymer-containing compositions to which mechanical shear force had been applied, the mode diameter of the polymer particles was measured using a laser diffraction particle size analyzer (Shimazu SALD-2300, Shimazu-7000) using the polymer-containing composition after the mechanical shear force as a sample.

[0122] The table below shows the details of the high molecular weight polymer used in the preparation of the vaccine formulation and the measurement results of the mode diameter of the polymer particles; the neutralizing agent used in the preparation of the high molecular weight polymer-containing composition, the sodium chloride concentration relative to the total amount of the high molecular weight polymer-containing composition, and whether or not mechanical shearing treatment was performed.

[0123]

[0124]

[0125]

[0126] (3) Preparation of Vaccine Preparation The antigen stock solution and the polymer-containing composition were mixed at a volume ratio of 1:1 to obtain a vaccine preparation with an antigen concentration of 0.01 w / v %.

[0127] 2. Antibody production induction test in mice (nasal mucosal inoculation) (Method) A single dose of the vaccine formulation (15 μL each, 30 μL total: 3 μg antigen, 105 μg or 165 μg polymer) was administered to BALB / c mice (female, 6 weeks old) in both nostrils (3 mice per group). Three weeks after inoculation, serum, nasal washes, and alveolar lavage fluids were collected. Antibody production induction was analyzed by measuring SARS-CoV-2 S1 protein-specific IgA in nasal washes, SARS-CoV-2 S1 protein-specific IgA in alveolar lavage fluids, and SARS-CoV-2 S1 protein-specific IgG in serum. A polymer-free vaccine formulation with an antigen concentration of 0.01 w / v%, obtained by mixing the original antigen solution with saline at a 1:1 (volume ratio), was used as a control.

[0128] (Results) The results (average of n = 10) are shown in the table below. (Discussion) Vaccine formulations B#00 to B#14, which contain polyacrylic acid homopolymers with a carboxyl group content of 60.7 to 62.5% by mass, induced higher antibody production than vaccine formulations without high-molecular-weight polymers. B#02, which is non-crosslinked and has a mass-average molecular weight of 150,000; B#05 to B#11, which are crosslinked and have no mechanical shearing and have a mode diameter of polymer particles of 2.2 to 11.2 μm; and B#00, which is crosslinked and has mechanical shearing and has a mode diameter of 0.71 μm, and B#12, which has a mode diameter of 0.45 μm, showed particularly high antibody production induction compared to administration of antigen alone.

[0129]

[0130] (Discussion 2) The ratio of the antibody titer of the polyacrylic acid homopolymer-containing specimen to that of B#00 was calculated. As shown in the table below, it was suggested that B#00, B#02, B#12, and B#14 improve the production of both IgG and IgA at different sites. The results for B#14 suggest that the combined use of polyacrylic acid homopolymer and polyethylene glycol synergistically improves antibody production.

[0131]

[0132] The components and amounts of representative examples of the polymer-containing composition prepared in (2)-1 above are shown in the table below.

[0133]

[0134]

[0135]

[0136]

[0137]

[0138] The pH and viscosity of representative examples of the vaccine preparations prepared in (3) above are shown in the table below.

[0139] <Method of measuring viscosity> Measurement was carried out using a rotational viscometer (cone-plate rotational viscometer) as specified in the viscosity measurement method of the Japanese Pharmacopoeia General Test Methods.

[0140] [Test Example 3] Antibody production induction test in mice (nasal mucosal inoculation, ovalbumin (OVA))

[0141] 1. Preparation of vaccine formulations (1) Preparation of antigen stock solution Ovalbumin (OVA, Sigma Grade V) was mixed with phosphate-buffered saline (PBS) until homogeneous to obtain an antigen stock solution (antigen concentration 0.2 w / v%).

[0142] (2)-1 Preparation of polymer-containing compositions used in sample numbers C#01 to C#05. The polymer was placed in PBS (phosphate buffered saline), neutralized with sodium hydroxide or L-arginine, and mixed until homogeneous to obtain a composition. For the polymer-containing compositions "with mechanical shearing treatment," the resulting composition was subjected to mechanical shearing force using an intermittent jet-generating high-speed mixer to adjust the particle size of the polymer contained in the polymer-containing composition. (2)-2 Preparation of polymer-containing compositions used in sample numbers C#06 to C#22. The polymer was mixed with PBS (phosphate buffered saline) until homogeneous to obtain a composition.

[0143] (2)-3 Measurement of mode diameter of polymer particles The mode diameter of each polymer before mixing with the antigen was measured using a laser diffraction particle size analyzer (Shimazu SALD-2300, Shimazu SALD-7000). For polymer-containing compositions to which mechanical shear force had been applied, the mode diameter of the polymer particles was measured using the polymer-containing composition after the application of mechanical shear force as a sample with the laser diffraction particle size analyzer.

[0144] The table below shows details of the high molecular weight polymer used in the preparation of the vaccine formulation and the measurement results of the mode diameter of the polymer particles; as well as the neutralizing agent used in the preparation of the high molecular weight polymer-containing composition, the sodium chloride concentration relative to the total amount of the high molecular weight polymer-containing composition, and whether or not mechanical shearing treatment was performed.

[0145]

[0146]

[0147]

[0148] (3)-1 High molecular weight polymer-free vaccine preparation (sample number C#00) The antigen stock solution and PBS (phosphate buffered saline) were mixed at a 1:1 (volume ratio) to obtain a high molecular weight polymer-free vaccine preparation with an antigen concentration of 0.1 w / v%. (3)-2 Preparation of high molecular weight polymer-containing vaccine preparation The antigen stock solution and a high molecular weight polymer-containing composition were mixed at a 1:1 (volume ratio) to obtain a vaccine preparation with an antigen concentration of 0.1 w / v%.

[0149] 2. Antibody production induction test in mice (nasal mucosal inoculation) (Method) The vaccine formulation was administered twice, 2 weeks apart, to BALB / c mice (female, 7 weeks old) at 5 μL each into both nostrils (10 μL total: 10 μg antigen dose) (10 mice per group). Two weeks after the second inoculation, blood and nasal washes were collected and absorbance was measured using a microplate reader (450 nm) to determine the amounts of OVA-specific IgA in the nasal washes and OVA-specific IgG in the blood.

[0150] (Results) The results (mean values ​​of n = 10) are shown in the table below. (Discussion) C#01 to C#07, which contain cross-linked polyacrylic acid homopolymer (carboxyl group content 60.5-62.5% by mass), showed improved antibody production in blood OVA-specific IgG compared to C#00, which contains no polymer. C#01 to C#03, which contain cross-linked polyacrylic acid homopolymer with a carboxyl group content of 60.5% by mass, showed improved antibody production in nasal wash OVA-specific IgA and blood OVA-specific IgG compared to C#00, which contains no polymer. Compared to C#00, which contains no polymer, C#01, C#02, and C#03, which contain ovalbumin antigen and a cross-linked acrylic acid homopolymer with a carboxyl group content of 60.5% by mass, which is an acidic polymer, mechanically sheared, and has a polymer particle size of 1.3 μm, showed a strong antibody production enhancement effect.

[0151]

[0152]

[0153]

[0154] [Test Example 4] Antibody production induction test in mice (subcutaneous inoculation, SARS-CoV-2 S1 protein)

[0155] 1. Vaccine Preparation (1) Polymer-Free Vaccine Formulation (Sample No. IA#00): SARS-CoV-2 S1 protein and saline (NaCl concentration 0.9 w / v%) were mixed until homogeneous to obtain a vaccine formulation. Each 200 μL of vaccine formulation contained 3 μg of SARS-CoV-2 S1 protein. (2) Polymer-Containing Vaccine Formulation (Sample No. IA#01): SARS-CoV-2 S1 protein and cross-linked polyacrylic acid homopolymer (carboxyl group content 61.5% by mass, polymer particle mode diameter 2.2 μm) were added to saline (NaCl concentration 0.9 w / v%), neutralized with sodium hydroxide, and mixed until homogeneous to obtain a vaccine formulation. Each 200 μL of vaccine formulation contained 3 μg of SARS-CoV-2 S1 protein and 600 μg of cross-linked polyacrylic acid homopolymer.

[0156] 2. Antibody production induction test in mice (subcutaneous inoculation) The vaccine formulation (200 μL) was subcutaneously inoculated twice at two-week intervals into BALB / c mice (female, 6 weeks old) (four mice per group). Serum was collected two weeks after the final inoculation, and the antibody production induction ability was analyzed by measuring the SARS-CoV-2 S1 protein-specific IgG antibody titer in the serum.

[0157] (Results) The results (mean values ​​of n=4) are shown in the table below.

[0158]

[0159] (Discussion) When cross-linked polyacrylic acid homopolymer (carboxyl group content: 61.5% by mass) was subcutaneously inoculated together with the antigen SARS-CoV-2 S1 protein, it improved the antibody production-inducing ability of the antigen.

[0160] Test Example 5: Antibody production induction test in mice (subcutaneous inoculation, influenza split antigen)

[0161] 1. Preparation of Vaccine Formulations (1) Polymer-Free Vaccine Formulation (Sample No. IB#00): Influenza split antigen [H1N1] was mixed with saline (NaCl concentration 0.9 w / v%) until homogeneous to obtain a vaccine formulation. Each 200 μL of vaccine formulation contained 1 μg of influenza HA split antigen. (2) Polymer-Containing Vaccine Formulations (Sample Nos. IB#01 and IB#02): Cross-linked polyacrylic acid homopolymer (carboxyl group content 60.7% by mass) was added to saline (NaCl concentration 0.9 w / v%), neutralized with sodium hydroxide, and mixed until homogeneous. The resulting mixture was subjected to mechanical shear using an intermittent jet-generating high-speed mixer to adjust the particle size of the polymer contained in the polymer-containing composition. The mode diameter of the polymer particles contained in the polymer-containing composition after mechanical shearing was 0.71 μm. The resulting mechanically sheared polymer-containing composition and influenza split antigen were mixed until homogeneous to obtain a vaccine formulation. 200 μL of vaccine formulation IB#01 contained 1 μg of influenza split antigen (HA) and 60 μg of cross-linked polyacrylic acid homopolymer. 200 μL of vaccine formulation IB#02 contained 1 μg of influenza split antigen (HA) and 600 μg of cross-linked polyacrylic acid homopolymer.

[0162] 2. Antibody production induction test in mice (subcutaneous inoculation) The vaccine formulation (200 μL) was subcutaneously inoculated twice at 2-week intervals into BALB / c mice (female, 6 weeks old) (4 mice per group). Serum was collected 2 weeks after the final inoculation, and the amount of influenza split antigen-specific antibody in the serum was measured to analyze the antibody production induction ability.

[0163] (Results) The results (average of n = 4) are shown in the table below. (Discussion) When administered subcutaneously together with an influenza split vaccine antigen, a highly cross-linked polyacrylic acid homopolymer (carboxyl group content 60.7% by mass, polymer particle mode diameter adjusted to 0.71 μm (after shearing treatment)) improved the antibody production-inducing ability of the antigen.

[0164]

[0165] [Test Example 6] Antibody production induction test in mice (nasal mucosal inoculation, influenza split antigen, part 2)

[0166] 1. Preparation of Vaccine Formulations (1) Preparation of Antigen Stock Solution: Influenza split antigen [H1N1] was mixed with saline until homogeneous to obtain an antigen stock solution (antigen concentration: 0.02% HA w / v). (2)-1 Preparation of Polymer-Containing Compositions Used in Samples D#01 to D#08: Polymers were added to purified water, neutralized with sodium hydroxide or L-arginine if necessary, and mixed until homogeneous to obtain compositions. For polymer-containing compositions with mechanical shearing, the resulting compositions were subjected to mechanical shearing using an intermittent jet-generating high-speed mixer to adjust the particle size (mode diameter) of the polymer contained in the composition to approximately 0.7-0.9 μm. For polymer-containing compositions containing other additives, other additives (polysorbate 80, glycerin, macrogol 4000, macrogol 4000, and polysorbate 80) were added. (2)-2 Measurement of polymer particle mode diameter The mode diameter of each polymer before mixing with the antigen (and other additives) was measured using a laser diffraction particle size analyzer (Shimazu SALD-7000) and a dynamic light scattering particle size analyzer (UPT-UT 151). Since the non-crosslinked polyacrylic acid homopolymer could not be measured using the laser diffraction particle size analyzer, it was measured using the dynamic light scattering particle size analyzer (UPT-UT 151). For polymer-containing compositions subjected to mechanical shearing force, the mode diameter of the polymer particles was measured using the polymer-containing composition after the mechanical shearing force was applied (for polymer-containing compositions containing other additives, the mode diameter was measured before the addition of the other additives) as a sample using the laser diffraction particle size analyzer.

[0167] The table below shows details of the high molecular weight polymer used in the preparation of the vaccine formulation and the measurement results of the mode diameter of the polymer particles; as well as the neutralizing agent used in the preparation of the high molecular weight polymer-containing composition made using the high molecular weight polymer, the sodium chloride concentration relative to the total amount of the high molecular weight polymer-containing composition, the types and concentrations of other additives relative to the total amount of the high molecular weight polymer-containing composition, and whether or not mechanical shearing treatment was performed.

[0168] (3)-1 High molecular weight polymer-containing vaccine preparations (sample numbers D#01 to D#08) The antigen stock solution and the high molecular weight polymer-containing composition were mixed at a 1:1 (volume ratio) to obtain high molecular weight polymer-containing vaccine preparations with an antigen concentration of 0.01 HA w / v%.

[0169] 2. Antibody production induction test in mice (nasal mucosal inoculation) (Method) BALB / c mice (female, 6 weeks old) were given a single inoculation of 5 μL each of the vaccine formulations (D#01 to D#08) into both nostrils (total 10 μL: antigen dose 1 μg) (4 mice per group). Two weeks after inoculation, nasal washes and alveolar washes were collected, and the antibody titers of influenza HA antigen-specific IgA in the nasal washes and alveolar washes were measured to analyze the antibody production induction ability. The dosage of the high molecular weight polymer is shown in the table below. (Results) The results (mean value of n=4) are shown in the table below.

[0170] (Discussion) By limiting immunization to the nasal cavity with an inoculation volume of 5 μL each into both nostrils (10 μL total), we were able to more clearly verify the differences in the antibody production-inducing ability of each polymer. Compared to untreated mice, non-crosslinked polyacrylic acid homopolymer (D#04, D#05) and crosslinked polyacrylic acid homopolymer with a low crosslinking rate (carboxyl group content 61.7%) and a molecular weight of 1 to 2 million (D#06) showed increased antibody production-inducing ability. Crosslinked polyacrylic acid homopolymer with a high crosslinking rate (carboxyl group content 60.5%), a molecular weight of 5 million or more, and mechanical shearing (D#01) showed a significant increase in antibody production-inducing ability. Furthermore, when cross-linked polyacrylic acid homopolymer, highly cross-linked (carboxyl group content 60.5%), had a molecular weight of 5 million or more, and was subjected to mechanical shearing, the antibody production-inducing ability was further increased by adding the polyhydric alcohol glycerin and macrogol 4000 (D#03, D#07, D#08) or the nonionic surfactant polysorbate 80 (D#02, D#08). In particular, the production of influenza HA antigen-specific IgA was observed in both nasal washes and alveolar lavage fluids, demonstrating a dramatic increase in antibody production-inducing ability when a highly cross-linked polyacrylic acid homopolymer, highly cross-linked (carboxyl group content 60.5%), had a molecular weight of 5 million or more, was subjected to mechanical shearing, and the nonionic surfactant polysorbate 80 was added (D#02).

[0171] [Test Example 7] Antibody production induction test in mice (nasal mucosal inoculation, SARS-CoV-2 S1 protein, part 2)

[0172] 1. Preparation of Vaccine Formulations (1) Preparation of Antigen Stock Solution: SARS-CoV-2 S1 protein was mixed with saline until homogeneous to obtain an antigen stock solution (antigen concentration 0.02 w / v%). (2)-1 Preparation of Polymer-Containing Compositions Used in Samples E#01 to E#13: Polymers were added to purified water or sodium chloride solution, neutralized with sodium hydroxide or L-arginine, and mixed until homogeneous to obtain compositions. For polymer-containing compositions with mechanical shearing, the resulting compositions were subjected to mechanical shearing using an intermittent jet-generating high-speed mixer to adjust the particle size (mode diameter) of the polymer contained in the composition to approximately 0.7-0.9 μm. For polymer-containing compositions containing other additives, the other additives were then added. (2)-2 Measurement of mode diameter of polymer particles The mode diameter of each polymer before mixing with the antigen (and other additives) was measured using a laser diffraction particle size analyzer (Shimazu SALD-2300, Shimazu SALD-7000). For polymer-containing compositions to which mechanical shear force had been applied, the mode diameter of the polymer particles was measured using the polymer-containing composition after the application of mechanical shear force (for polymer-containing compositions containing other additives, the mode diameter was measured before the addition of the other additives) as a sample using the laser diffraction particle size analyzer.

[0173] The table below shows details of the high molecular weight polymer used in the preparation of the vaccine formulation and the measurement results of the mode diameter of the polymer particles; as well as the neutralizing agent used in the preparation of the high molecular weight polymer-containing composition made using the high molecular weight polymer, the sodium chloride concentration relative to the total amount of the high molecular weight polymer-containing composition, the types and concentrations of other additives relative to the total amount of the high molecular weight polymer-containing composition, and whether or not mechanical shearing treatment was performed.

[0174] (3)-1 High molecular weight polymer-containing vaccine preparations (sample numbers E#01 to E#13) The antigen stock solution and the high molecular weight polymer-containing composition were mixed at a 1:1 (volume ratio) to obtain high molecular weight polymer-containing vaccine preparations with an antigen concentration of 0.01 HA w / v%.

[0175] 2. Antibody production induction test in mice (nasal mucosal inoculation) (Method) BALB / c mice (female, 6 weeks old) were given a single inoculation of 15μL each of the vaccine formulations (E#01-E#13) into both nostrils (total 30μL: antigen dose 3μg) (4 mice per group). Three weeks after inoculation, nasal washes and alveolar washes were collected, and antibody titers of SARS-CoV-2 S1 protein-specific IgA in the nasal washes and alveolar washes were measured to analyze antibody production induction ability. The dosage of the polymer is shown in the table below. (Results) The results (mean value of n=4) are shown in the table below.

[0176] (Discussion) Adding polyethylene glycol to both low-crosslinked and high-crosslinked polyacrylic acid homopolymers significantly increased the antibody production induction ability, particularly in SARS-CoV-2-specific IgA antibody titers in bronchoalveolar lavage fluid (bAF). (Compared to those without polyethylene glycol [E#01, E#05]) For low-crosslinked polyacrylic acid homopolymers, the addition of polyethylene glycol was effective, but antibody production induction ability increased when the polymer particle size was controlled to 0.1 μm or less. For high-crosslinked polyacrylic acid homopolymers, the effect of adding polyethylene glycol was not dependent on polymer particle size; antibody production induction ability increased when the particle size was controlled to 0.7-0.9 μm. (Comparison between [E#05] and [E#06]) For highly cross-linked polyacrylic acid homopolymer, the effect of polyethylene glycol at the same concentration (1.0%) was observed. The antibody production-inducing ability of SARS-CoV-2-specific IgA antibody titers in bronchoalveolar lavage fluid increased with increasing molecular weight (Macrogol 400 [E#07] < Macrogol 4000 [E#06] < Macrogol 20000 [E#08]). For highly cross-linked polyacrylic acid homopolymer, the antibody production-inducing ability of SARS-CoV-2-specific IgA antibody titers in bronchoalveolar lavage fluid increased with increasing polyethylene glycol 4000 concentration (0.1% [E#09], 0.5% [E#10], 1.0% [E#06], and 5.0% [E#11]). In the case of highly cross-linked polyacrylic acid homopolymer, no increase in antibody production induction ability was observed even when the amount of polymer was increased [E#12] or when the neutralizing agent was changed [E#13].

[0177] The polymers of the present invention may be used as vaccine adjuvants.

Claims

1. A vaccine adjuvant comprising a polymer having acrylic acid as a constituent unit and having a carboxyl group content of 60.0 to 62.5% by mass.

2. The vaccine adjuvant according to claim 1, wherein the polymer is polyacrylic acid and / or a salt thereof.

3. 2. The vaccine adjuvant according to claim 1, wherein the high molecular weight polymer is crosslinked polyacrylic acid and / or a salt thereof, and the carboxyl group content of the polyacrylic acid is 60.0 to 62.0% by mass, and the number-based mode diameter of the high molecular weight polymer particles is 0.05 to 10 μm.

4. 2. The vaccine adjuvant according to claim 1, wherein the high molecular weight polymer is crosslinked polyacrylic acid and / or a salt thereof, the carboxyl group content of the polyacrylic acid is 60.0 to 62.0% by mass, and the number-based mode diameter of the high molecular weight polymer particles is adjusted to 0.05 to 10 μm by applying a mechanical shearing force.

5. The vaccine adjuvant according to claim 4, wherein the carboxyl group content as polyacrylic acid is 60.0 to 61.0% by mass.

6. 6. The vaccine adjuvant according to claim 5, wherein the number-based mode diameter of the high molecular weight polymer particles is adjusted to 0.1 to 2.0 μm by applying a mechanical shearing force.

7. The vaccine adjuvant according to claim 4, wherein the carboxyl group content as polyacrylic acid is greater than 61.0% by mass and not greater than 62.0% by mass.

8. 8. The vaccine adjuvant according to claim 7, wherein the number-based mode diameter of the high molecular weight polymer particles is adjusted to 0.05 to 0.1 μm by applying a mechanical shearing force.

9. 2. The vaccine adjuvant according to claim 1, wherein the high molecular weight polymer is crosslinked polyacrylic acid and / or a salt thereof, the carboxyl group content of the polyacrylic acid is 60.0 to 62.0% by mass, and the number-based mode diameter of the high molecular weight polymer particles is 0.1 to 50 μm.

10. The vaccine adjuvant according to claim 9, wherein the high molecular weight polymer is not subjected to mechanical shear force.

11. 2. The vaccine adjuvant according to claim 1, wherein the high molecular weight polymer is non-crosslinked polyacrylic acid and / or a salt thereof, and the high molecular weight polymer has a mass average molecular weight in the range of 50,000 to 300,000.

12. The vaccine adjuvant according to claim 11, wherein the carboxyl group content as polyacrylic acid is 62.0 to 62.5% by mass.

13. The vaccine adjuvant according to claim 1, further comprising water.

14. the vaccine adjuvant comprises the high molecular weight polymer and water, and optionally comprises at least one additive selected from the group consisting of sodium chloride, sodium hydroxide, and L-arginine; 4. The vaccine adjuvant according to claim 3, wherein the number-based mode diameter of the particles of the polymer is adjusted by applying a mechanical shear force to a composition consisting of the polymer and water (provided that, when the vaccine adjuvant contains the at least one additive, the composition may contain the at least one additive).

15. The vaccine adjuvant according to claim 14, wherein sodium chloride is contained in an amount of 0.1 to 1.5% by mass relative to the total mass of the vaccine adjuvant.

16. The vaccine adjuvant according to claim 1, further comprising sodium hydroxide and / or L-arginine.

17. The vaccine adjuvant according to claim 1, further comprising L-arginine.

18. The vaccine adjuvant according to claim 1, which has a pH of 6 to 8.

19. The vaccine adjuvant according to claim 1, wherein the high molecular weight polymer is contained in an amount of 0.01 to 50% by mass relative to the total mass of the vaccine adjuvant.

20. 2. The vaccine adjuvant according to claim 1, further comprising at least one nonionic surfactant selected from the group consisting of ether-type nonionic surfactants and ester-ether-type nonionic surfactants.

21. 21. The vaccine composition of claim 20, wherein the non-ionic surfactant is polysorbate 80.

22. 2. The vaccine adjuvant according to claim 1, further comprising at least one polyhydric alcohol selected from the group consisting of polyethylene glycol, glycerin, propylene glycol, and 1,3-butylene glycol.

23. 23. The vaccine adjuvant of claim 22, wherein the polyhydric alcohol is polyethylene glycol.

24. The vaccine adjuvant according to any one of claims 1 to 23, for enhancing immune responses to pathogen-derived antigens.

25. The vaccine adjuvant according to claim 24, wherein the disease caused by the pathogen is a respiratory disease.

26. The vaccine adjuvant according to any one of claims 1 to 23, for enhancing immune responses to antigens derived from enveloped viruses.

27. The vaccine adjuvant according to any one of claims 1 to 23, for enhancing an immune response to at least one virus-derived antigen selected from the group consisting of coronavirus and influenza virus.

28. The vaccine adjuvant according to any one of claims 1 to 23, for administration selected from injection administration and mucosal administration.

29. The vaccine adjuvant according to any one of claims 1 to 23, wherein the amount of the high molecular weight polymer administered per administration is 1 µg to 100 mg.

30. The vaccine adjuvant according to any one of claims 1 to 23, which is administered in combination with an antigen.

31. The vaccine adjuvant according to any one of claims 1 to 23, which is administered in combination with a pathogen antigen to prevent a disease caused by the pathogen.

32. Use of a vaccine adjuvant agent according to any one of claims 1 to 23 in the manufacture of a medicament for enhancing an immune response to an antigen, for inducing an immune response to an antigen, or for preventing a disease caused by a pathogen.

33. A vaccine composition comprising (i) a vaccine adjuvant according to any one of claims 1 to 23, and (ii) an antigen.

34. A vaccine composition comprising (i) a high molecular weight polymer in an amount effective as a vaccine adjuvant, and (ii) an antigen, wherein the high molecular weight polymer has acrylic acid as a constituent unit and has a carboxyl group content of 60.0 to 62.5% by mass.

35. 35. The vaccine composition of claim 34, wherein the antigen is a pathogen-derived antigen.

36. 36. The vaccine composition of claim 35, wherein the disease caused by the pathogen is a respiratory disease.

37. 34. The vaccine composition of claim 33, wherein the antigen is an antigen derived from an enveloped virus.

38. 34. The vaccine composition of claim 33, for administration selected from injection and mucosal administration.

39. The vaccine composition according to claim 33, wherein the high molecular weight polymer is contained in a mass ratio of antigen to high molecular weight polymer in the range of 1:0.1 to 1:1000.