JP7274780B2 - Methods and kits for detection of pathogenic microorganisms - Google Patents

Description

The present invention relates to methods and kits for pathogenic microorganism detection. More specifically, in a very small volume of a hydrophilic solvent coated with a hydrophobic solvent, pathogenic microorganisms are detected by optically detecting reaction products produced as a result of reactions by enzymes on the surface or inside of pathogenic microorganisms. It relates to a method of detection and the like.

In recent years, a simple influenza virus test kit using immunochromatography has been developed (see Patent Document 1). A method using immunochromatography can detect an influenza virus within several minutes to several tens of minutes, and is therefore used for diagnosis and treatment of infection.

Further, conventionally, there is known a technique for optically detecting an influenza virus based on the reaction between neuraminidase, an enzyme possessed by the influenza virus, and a chromogenic substrate (see Patent Documents 2 and 3). Examples of chromogenic substrates include 4-methylumbelliferyl-α-D-neuraminic acid (4-Methylumbelliferyl-N-acetyl-α-D-neuraminic acid: 4MU-NANA, see Patent Document 2) and 4-alkoxy. -N-acetylneuraminic acid or derivatives of 4,7-dialkoxy-N-acetylneuraminic acid (see Patent Document 3) are used. For example, in the method using 4MU-NANA as a chromogenic substrate, 4-methylumbelliferone, which is a fluorescent substance, is produced by decomposition of 4MU-NANA by neuraminidase. The enzymatic activity value of neuraminidase can be calculated based on the amount of 4-methylumbelliferone produced, and the number of influenza virus particles can be quantified based on the enzymatic activity value.

In relation to the present invention, Non-Patent Document 1 describes a single-molecule enzyme assay using an array of femtoliter-order droplets in which the droplets are covered with oil and are directly accessible from the outside. method is described.

Japanese Patent Application Laid-Open No. 2008-275511 JP 2011-139656 A Special Table No. 2002-541858

S. Sakakihara et al., Lab Chip, 2010, 10, 3355-3362

Although the above-described method for detecting influenza virus based on immunochromatography is simple, it requires about 10 ³ to 10 ⁴ pfu/ml of virus for detection, and has the problem of low detection sensitivity.

Therefore, the main object of the present invention is to provide a technology that can be used to detect viruses such as influenza virus with high sensitivity.

In order to solve the above problems, the present invention provides the following [1] to [25].
[1] A method for detecting a pathogenic microorganism in a biological sample isolated from a subject infected or suspected of being infected with the pathogenic microorganism, comprising:
A plurality of accommodating portions capable of accommodating pathogenic microorganisms are opposed to a lower layer portion formed separated from each other by side walls having a hydrophobic upper surface and a surface of the lower layer portion on which the accommodating portions are formed. an introduction step of introducing a hydrophilic solvent containing the biological sample and a substance that serves as a substrate for a reaction by an enzyme present on the surface or inside the pathogenic microorganism into a space between the upper layer and the upper layer;
an encapsulation step of introducing a hydrophobic solvent into said space to form droplets of hydrophilic solvent within said reservoir coated with said hydrophobic solvent and containing said pathogenic microorganism and said substance;
a detection step of optically detecting a reaction product produced by a reaction between the enzyme and the substance in the droplet;
The method, wherein the hydrophilic solvent has a pH value greater than the acid dissociation constant (pKa) of the reaction product.
[2] The method of [1], further comprising determining the number and/or subspecies of the pathogenic microorganism based on the detection intensity of the reaction product.
[3] The pathogenic microorganism is influenza virus, the enzyme is neuraminidase, and the substance is 4-Methylumbelliferyl-N-acetyl-α-D-neuraminic acid. acid) and the reaction product is 4-methylumbelliferone.
[4] the pathogenic microorganism is coronavirus, severe acute respiratory syndrome (SARS) coronavirus, Middle East respiratory syndrome (MERS) virus, mump virus, measles virus, Nipah virus, canine distemper virus, human immunodeficiency virus (HIV), from hepatitis B virus, human T-cell leukemia virus (HTLV), Ebola virus, hepatitis C virus, Lassa virus, hantavirus, rabies virus, Japanese encephalitis virus, yellow fever virus, dengue virus, rubella virus, rotavirus and norovirus The method of [1] or [2], wherein the enzyme is one or more selected from the group consisting of hemagglutinin esterase, neuraminidase, reverse transcriptase, and RNA-dependent RNA polymerase.
[5] the substance is selected from the group consisting of a derivative containing 4-methylumbelliferone, a derivative containing fluorescein, a derivative containing Resorufin and a derivative containing Rhodamine; The method of [1] or [2], wherein the method is one or more.

[6] A method for diagnosing the presence or absence of infection with pathogenic microorganisms, comprising:
a procedure for isolating a biological sample from a suspected infected subject;
A plurality of accommodating portions capable of accommodating pathogenic microorganisms are opposed to a lower layer portion formed separated from each other by side walls having a hydrophobic upper surface and a surface of the lower layer portion on which the accommodating portions are formed. an introduction step of introducing a hydrophilic solvent containing the biological sample and a substance that serves as a substrate for a reaction by an enzyme present on the surface or inside the pathogenic microorganism into a space between the upper layer and the upper layer;
an encapsulation step of introducing a hydrophobic solvent into said space to form droplets of hydrophilic solvent within said reservoir coated with said hydrophobic solvent and containing said pathogenic microorganism and said substance;
a detection step of optically detecting a reaction product produced by a reaction of said enzyme with said substance in said droplet, wherein detection of said reaction product indicates infection with said pathogenic microorganism; ,
A method, including
[7] The method of [6], wherein the hydrophilic solvent has a pH value greater than the acid dissociation constant (pKa) of the reaction product.
[8] The method of [6] or [7], further comprising determining the number and/or subspecies of pathogenic microorganisms based on the detection intensity of the reaction product.
[9] The pathogenic microorganism is influenza virus, the enzyme is neuraminidase, and the substance is 4-Methylumbelliferyl-N-acetyl-α-D-neuraminic acid. acid), and the reaction product is 4-methylumbelliferone.
[10] the pathogenic microorganism is coronavirus, severe acute respiratory syndrome (SARS) coronavirus, Middle East respiratory syndrome (MERS) virus, mump virus, measles virus, Nipah virus, canine distemper virus, human immunodeficiency virus (HIV), from hepatitis B virus, human T-cell leukemia virus (HTLV), Ebola virus, hepatitis C virus, Lassa virus, hantavirus, rabies virus, Japanese encephalitis virus, yellow fever virus, dengue virus, rubella virus, rotavirus and norovirus any one of [6] to [8], wherein the enzyme is one or more selected from the group consisting of hemagglutinin esterase, neuraminidase, reverse transcriptase, and RNA-dependent RNA polymerase Method.
[11] the substance is selected from the group consisting of a derivative containing 4-methylumbelliferone, a derivative containing fluorescein, a derivative containing Resorufin and a derivative containing Rhodamine; The method according to any one of [6] to [8].

[12] A method for detecting drug susceptibility of a pathogenic microorganism in a biological sample isolated from a subject infected or suspected of being infected with the pathogenic microorganism, comprising:
A plurality of accommodating portions capable of accommodating pathogenic microorganisms are opposed to a lower layer portion formed separated from each other by side walls having a hydrophobic upper surface and a surface of the lower layer portion on which the accommodating portions are formed. introducing the biological sample, a substance that serves as a substrate for reaction by an enzyme present on the surface or inside of the pathogenic microorganism, and a hydrophilic solvent containing an inhibitor of the enzyme into a space between the upper layer and the upper layer of the pathogenic microorganism. installation procedure and
An encapsulation step of introducing a hydrophobic solvent into the space to form droplets of hydrophilic solvent within the container, coated with the hydrophobic solvent and containing the pathogenic microorganism, the substance, and the inhibitor. and,
A detection procedure for optically detecting a reaction product produced by a reaction between the enzyme and the substance in the droplet, (wherein the detection intensity of the reaction product in the presence of the inhibitor is the inhibitory a decrease in the detectable intensity of the reaction product below that in the absence of the drug indicates that the pathogenic microorganism is susceptible to the inhibitor; and
A method, including
[13] The method of [12], wherein the hydrophilic solvent has a pH value greater than the acid dissociation constant (pKa) of the reaction product.
[14] The pathogenic microorganism is influenza virus, the enzyme is neuraminidase, and the substance is 4-Methylumbelliferyl-N-acetyl-α-D-neuraminic acid.
acid), the reaction product is 4-methylumbelliferone, and the inhibitor is a neuraminidase inhibitor.

[15] A method of screening for an anti-pathogenic microbial agent comprising:
A lower layer portion in which a plurality of storage portions capable of storing pathogenic microorganisms are separated from each other by sidewalls having a hydrophobic upper surface, and the surface of the lower layer portion on which the storage portions are formed faces each other. An introduction procedure for introducing a hydrophilic solvent containing the pathogenic microorganism, a substance that is a substrate for a reaction by an enzyme present on or inside the pathogenic microorganism, and a candidate compound into the space between the upper layer where the pathogenic microorganism is located. and,
An encapsulation step of introducing a hydrophobic solvent into said space to form a droplet of hydrophilic solvent within said reservoir coated with said hydrophobic solvent and containing said pathogenic microorganism, said substance and said candidate compound. and,
A detection procedure for optically detecting a reaction product produced by a reaction between the enzyme and the substance in the droplet (wherein the detection intensity of the reaction product in the presence of the candidate compound is the candidate compound a decrease in the detectable intensity of the reaction product below that in the absence of the compound indicates that the candidate compound has antipathogenic microbial activity);
A method, including
[16] The method of [15], wherein the hydrophilic solvent has a pH value greater than the acid dissociation constant (pKa) of the reaction product.
[17] The pathogenic microorganism is influenza virus, the enzyme is neuraminidase, and the substance is 4-Methylumbelliferyl-N-acetyl-α-D-neuraminic acid.
acid), the reaction product is 4-methylumbelliferone, and the candidate compound is screened for a neuraminidase inhibitor.

[18] A kit for detecting a pathogenic microorganism in a biological sample isolated from a subject infected or suspected of being infected with said pathogenic microorganism, comprising:
a lower layer portion in which a plurality of storage portions capable of storing the pathogenic microorganism are separated from each other by side walls having a hydrophobic upper surface; an array comprising: an upper layer facing across the
a substance that serves as a substrate for reaction by an enzyme present on the surface or inside the pathogenic microorganism;
a hydrophilic solvent having a pH value greater than the acid dissociation constant (pKa) of the reaction product produced by the reaction between the enzyme and the substance;
a hydrophobic solvent; and a kit.
[19] The pathogenic microorganism is influenza virus, the enzyme is neuraminidase, and the substance is 4-Methylumbelliferyl-N-acetyl-α-D-neuraminic acid.
acid) and the reaction product is 4-methylumbelliferone.
[20] the pathogenic microorganism is coronavirus, severe acute respiratory syndrome (SARS) coronavirus, Middle East respiratory syndrome (MERS) virus, mump virus, measles virus, Nipah virus, canine distemper virus, human immunodeficiency virus (HIV), from hepatitis B virus, human T-cell leukemia virus (HTLV), Ebola virus, hepatitis C virus, Lassa virus, hantavirus, rabies virus, Japanese encephalitis virus, yellow fever virus, dengue virus, rubella virus, rotavirus and norovirus The kit of [18], wherein the enzyme is one or more selected from the group consisting of hemagglutinin esterase, neuraminidase, reverse transcriptase, and RNA-dependent RNA polymerase.
[21] the substance is selected from the group consisting of a derivative containing 4-methylumbelliferone, a derivative containing fluorescein, a derivative containing Resorufin, and a derivative containing Rhodamine; The kit of [18], which is one or more of

[22] A method of reacting an enzyme with a substance that serves as a substrate for the reaction by the enzyme in a hydrophilic solvent that is in interfacial contact with a hydrophobic solvent, and detecting a reaction product,
The method, wherein the hydrophilic solvent has a pH value greater than the acid dissociation constant (pKa) of the reaction product.
[21] the hydrophilic solvent contains a pathogenic microorganism;
the enzyme is an enzyme having a substrate-cleaving activity present on the surface or inside the pathogenic microorganism;
the substance is a chromogenic substrate,
The method of [22], wherein a reaction product produced by cleavage of the chromogenic substrate by the enzyme is optically detected.
[22] The pathogenic microorganism is influenza virus, the enzyme is neuraminidase, and the chromogenic substrate is 4-methylumbelliferyl-α-D-neuraminic acid (4-Methylumbelliferyl-N-acetyl-α-D- and the reaction product is 4-methylumbelliferone.
[23] the pathogenic microorganism is coronavirus, severe acute respiratory syndrome (SARS) coronavirus, Middle East respiratory syndrome (MERS) virus, mump virus, measles virus, Nipah virus, canine distemper virus, human immunodeficiency virus (HIV), from hepatitis B virus, human T-cell leukemia virus (HTLV), Ebola virus, hepatitis C virus, Lassa virus, hantavirus, rabies virus, Japanese encephalitis virus, yellow fever virus, dengue virus, rubella virus, rotavirus and norovirus The method of [21], wherein the enzyme is one or more selected from the group consisting of hemagglutinin esterase, neuraminidase, reverse transcriptase, and RNA-dependent RNA polymerase.
[24] the chromogenic substrate is selected from the group consisting of a derivative containing 4-methylumbelliferone, a derivative containing fluorescein, a derivative containing Resorufin, and a derivative containing Rhodamine; The method of [21], wherein one or more of
[25] The method of any one of [21] to [24], wherein the hydrophilic solvent comprises a biological sample isolated from a subject infected or suspected of being infected with the pathogenic microorganism.

In the present invention, "pathogenic microorganisms" include bacteria and viruses. Examples of bacteria include, but are not limited to, coliforms, Vibrio parahaemolyticus, campylobacter, enterobacter, and bacteria belonging to the genus Bacillus. In addition, the virus is not particularly limited, but for example, coronavirus, SARS virus, MARS virus, influenza virus, mump virus, measles virus, Nipah virus, canine distemper virus, HIV, hepatitis B virus, HTLV, Ebola virus, type C Hepatitis virus, Lassa virus, hantavirus, rabies virus, yellow fever virus, dengue virus, rubella virus, rotavirus and norovirus.

The present invention provides techniques that can be used to detect pathogenic microorganisms such as influenza viruses with high sensitivity.

FIG. 2 is a diagram for explaining the introduction procedure and the encapsulation procedure of the pathogenic microorganism detection method according to the present invention; FIG. 2 is a diagram for explaining a reaction product resulting from the reaction between an enzyme present on the surface of virus particles and a chromogenic substrate. 1 is a graph showing the results of examining the effect of the pH of a hydrophilic solvent on detection sensitivity (Example 1). FIG. 10 is a graph showing the results of examining the influence of the concentration of a buffer substance in a hydrophilic solvent on detection sensitivity (Example 2). FIG.

Preferred embodiments for carrying out the present invention will be described below with reference to the drawings. It should be noted that the embodiments described below are examples of representative embodiments of the present invention, and the scope of the present invention should not be construed narrowly.

1. Pathogenic Microorganism Detection Method The pathogenic microorganism detection method according to the present invention is used to detect pathogenic microorganisms in a biological sample separated from a subject infected or suspected of being infected with a pathogenic microorganism. be. A pathogenic microorganism detection method according to the present invention includes the following procedures.
(1A) A lower layer portion in which a plurality of storage portions capable of storing pathogenic microorganisms are separated from each other by sidewalls having a hydrophobic upper surface, and a surface of the lower layer portion on which the storage portions are formed. An introducing procedure for introducing a hydrophilic solvent containing the biological sample and a substance that is a substrate for a reaction by an enzyme present on the surface or inside of the particles of the pathogenic microorganism into a space between the opposing upper layers. .
(2A) An encapsulation step of introducing a hydrophobic solvent into said space to form droplets of hydrophilic solvent within said reservoir coated with said hydrophobic solvent and containing said pathogenic microorganism and said substance.
(3A) A detection procedure for optically detecting a reaction product produced by the reaction between the enzyme and the substance in the droplet.

In the present invention, the biological sample is not particularly limited as long as it is a biological material that can contain pathogenic microorganisms to be detected. Examples of biological samples include nasal aspirates, nasal swabs, pharyngeal swabs, tracheal swabs, saliva, sputum, blood (including whole blood, serum and plasma), urine, cell and tissue extracts, and organ extracts. is mentioned.

The pathogenic microorganism is not particularly limited as long as it has an enzyme on its surface or inside and produces an optically detectable reaction product as a result of the reaction by the enzyme. More specifically, pathogenic microorganisms have an enzyme on their surface or inside that has a substrate-cleaving activity for a chromogenic substrate, and the cleavage of the chromogenic substrate by the enzyme liberates a reaction product as a chromophore. . In addition, pathogenic microorganisms have an enzyme on their surface or inside that has the activity of synthesizing a polymer by binding a monomer, which is a substrate, and a chromophore reaction is generated as a result of polymer synthesis by the enzyme. It can be something that produces things. Examples of combinations of pathogenic microorganisms and enzymes thereof include the following.

[Introduction procedure (A1)]
The introduction procedure (A1) will be described with reference to FIG. 1A. In the present embodiment, a lower layer portion in which a plurality of storage portions capable of storing pathogenic microorganisms (hereinafter, a virus will be described as an example) are separated from each other by sidewalls having a hydrophobic upper surface; A case will be described in which the method for detecting pathogenic microorganisms according to the present invention is carried out using an array including an upper layer facing the surface on which the storage section is formed in the above with a space therebetween.

In the array 1, the lower layer 10 is formed with a plurality of containing parts 13 capable of containing virus particles separated from each other by sidewalls 12 having hydrophobic upper surfaces. Further, the upper layer portion 20 faces the surface of the lower layer portion 10 on which the accommodating portion 13 is formed.

In this step, a hydrophilic solvent 42 is introduced into the space 30 between the lower layer 10 and the upper layer 20 . Hydrophilic solvent 42 may contain virus 2 derived from a biological sample. Hydrophilic solvent 42 also contains substance 3 (hereinafter referred to as “substrate 3”) that serves as a substrate for reaction by an enzyme present on the particle surface (or inside) of virus 2 . The hydrophilic solvent 42 can be introduced into the space 30 through, for example, through holes (not shown) formed in at least one of the upper layer portion 20 and the lower layer portion 10 . The hydrophilic solvent 42 introduced into the space 30 flows in a direction parallel to the surfaces where the lower layer 10 and the upper layer 20 face each other, as shown in the drawing.

Water is used as the hydrophilic solvent 42 . The hydrophilic solvent 42 has a pH value greater than the acid dissociation constant (pKa) of the reaction product generated from the substrate 3 (details will be described later).

The substrate 3 may be any substance that produces a reaction product having optical properties different from those before the reaction after the reaction with the enzyme. is used. Substrate 3 will be described in detail later.

Hydrophilic solvent 42 may contain buffer substances necessary for optimizing the reaction between enzyme and substrate 3 . Furthermore, by setting the buffer substance in the hydrophilic solvent 42 to a predetermined concentration or higher, the reaction product can be detected with higher sensitivity in the detection procedure (3) (details will be described later).

The buffer substance is not particularly limited, but MES (2-Morpholinoethanesulfonic acid), ADA (N-(2-Acetamido)iminodiacetic acid), PIPES (Piperazine-1,4-bis(2- ethanesulfonic acid)), ACES (N-(2-Acetamido)-2-aminoethanesulfonic acid), BES (N,N-Bis(2-hydroxyethyl)-2-aminoethanesulfonic acid)
acid), TES (N-Tris(hydroxymethyl)methyl-2-aminoethanesulfonic acid) HEP
So-called Good's Buffers such as ES (4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid), Tris (Tris(hydroxymethyl)aminomethane), DEA (Diethanolamine) and the like can be used.

Moreover, the hydrophilic solvent 42 may contain a surfactant. By including a surfactant, the enzyme present inside the virus 2 may be exposed to the surface. Moreover, the inclusion of the surfactant tends to facilitate the introduction of the hydrophilic solvent 42 into the space 30 and the accommodating portion 13 .

Examples of surfactants include, but are not limited to, TWEEN 20 (CAS number: 9005-64-5, polyoxyethylene sorbitan monolaurate) and Triton X-100.
(CAS number: 9002-93-1, common name polyethylene glycol mono-4-octylphenyl ether (n≈10)) and the like. The concentration of the surfactant added to the first solvent 20 is
Although not particularly limited, it is preferably 0.01 to 1%.

Furthermore, as the surfactant, an anionic surfactant, a cationic surfactant, a nonionic surfactant, an amphoteric surfactant, a naturally derived surfactant, and the like can be widely used.

Anionic surfactants are classified into, for example, carboxylic acid types, sulfate ester types, sulfonic acid types, and phosphate ester types. Among these, specific examples include sodium dodecyl sulfate, sodium laurate, α-sulfo fatty acid methyl ester sodium, sodium dodecylbenzene sulfonate, sodium dodecyl ethoxylate sulfate, etc. Among them, sodium dodecylbenzene sulfonate It is preferable to use

Cationic surfactants are classified into, for example, quaternary ammonium salt types, alkylamine types, and heterocyclic amine types. Specific examples include stearyltrimethylammonium chloride, distearyldimethylammonium chloride, didecyldimethylammonium chloride, cetyltripyridinium chloride, dodecyldimethylbenzylammonium chloride and the like.

Examples of nonionic surfactants include polyoxyethylene alkyl ethers, polyoxyethylene hydrogenated castor oils, polyoxyethylene mono fatty acid esters, polyoxyethylene sorbitan mono fatty acid esters, sucrose fatty acid esters, polyglycerin fatty acid esters, and alkyl polyglycosides. , N-methylalkylglucamide and the like. Among others, dodecyl alcohol ethoxylate, nonylphenol ethoxylate, lauroyl diethanolamide, as well as Triton X (Triton X-100, etc.), Pluronic (Pluronic F-123, F-68, etc.), Tween (Tween 20, 40 , 60, 65, 80, 85, etc.), Brij® (Brij 35, 58, 98, etc.), Span (Span 20, 40, 60, 80, 83, 85) preferable.

Amphoteric surfactants include, for example, lauryldimethylaminoacetic acid betaine, dodecylaminomethyldimethylsulfopropyl betaine, 3-(tetradecyldimethylamino)propane-1-sulfonate and the like, but 3-[(3-cholamide Propyl)dimethylammonio]-1-propanesulfonate (CHAPS), 3-[(3-cholamidopropyl)dimethylammonio]-2-hydroxy-1-propanesulfonate (CHAPSO) and the like are preferably used.

Examples of naturally derived surfactants include lecithin and saponin, and among compounds referred to as lecithin, specific examples include phosphatidylcholine, phosphatidylethanolamine, phosphatidylinositol, phosphatidylserine, phosphatidic acid, and phosphatidylglycerol. preferable. As the saponin, quillaja saponin is preferable.

By this procedure, the virus 2 and the substrate 3 enter the container 13 . When the virus 2 is diluted to a sufficiently low concentration in the hydrophilic solvent 42, the number of viruses 2 entering one container 13 can be zero or at most one. When the concentration of virus 2 is higher in hydrophilic solvent 42 , two or more viruses 2 can be introduced into one container 13 .

[Enclosure procedure (A2)]
Encapsulation procedure (2) will be described with reference to FIG. 1B. In this procedure, a hydrophobic solvent 43 is introduced into the space 30 between the lower layer 10 and the upper layer 20 .

The hydrophobic solvent 43 may be any solvent (immiscible solvent) that is difficult to mix with the hydrophilic solvent 42 used in the introduction procedure (1). As the hydrophobic solvent 43, for example, at least one selected from the group consisting of saturated hydrocarbons, unsaturated hydrocarbons, aromatic hydrocarbons, silicone oils, perfluorocarbons, halogen-based solvents, and hydrophobic ionic liquids. A mixture or the like can be preferably used. Examples of saturated hydrocarbons include alkanes and cycloalkanes. Examples of alkanes include decane and hexadecane. Examples of unsaturated hydrocarbons include squalene and the like. Examples of aromatic hydrocarbons include benzene and toluene. Examples of perfluorocarbons include Fluorinert (registered trademark) FC40 (manufactured by SIGMA). As a halogen-based solvent,
Examples include chloroform, methylene chloride, chlorobenzene and the like. Hydrophobic ionic liquids refer to ionic liquids that do not dissociate at least in water, and include, for example, 1-Butyl-3-methylimidazolium hexafluorophosphate. Ionic liquids refer to salts that exist as liquids at room temperature.

Similar to the hydrophilic solvent 42 , the hydrophobic solvent 43 may also be introduced into the space 30 through through holes (not shown) formed in at least one of the upper layer 20 and the lower layer 10 . As shown in the figure, the hydrophobic solvent 43 introduced into the space 30 flows in a direction parallel to the surfaces where the lower layer 10 and the upper layer 20 face each other, and the hydrophilic solvent 42 in the space 30 becomes the hydrophobic solvent. 43. As a result, droplets of hydrophilic solvent 42 coated with hydrophobic solvent 43 and containing virus 2 and substrate 3 are formed in container 13 .

Then, the reaction between the substrate 3 and the enzyme existing on the surface or inside the particle of the virus 2, which coexists in the extremely small volume of the droplet of the hydrophilic solvent 42, proceeds, and the reaction product 4 is produced. A detailed description will be given with reference to FIG. Enzyme 5 is present on the particle surface or inside of virus 2 (the figure shows the case where enzyme 5 is present on the virus surface). When substrate 3 contacts and reacts with enzyme 5, reaction product 4 is produced. The chromogenic product 4 exhibits optical properties different from those of the substrate 3, such as a shift in absorbance or optical rotation, or luminescence (fluorescence).

According to this procedure, the virus 2 and the substrate 3 are enclosed in droplets of a very small volume, so that the reaction between the enzyme 5 and the substrate 3 produces a reaction product 4 in the droplets in a very small volume. This allows optical detection of the reaction product 4 . The volume of the storage section 13 (that is, the volume of the droplet of the hydrophilic solvent 42) is not particularly limited, but is, for example, 10aL to 100nL, preferably 1fL to 1pL.

Virus 2 is an influenza virus (see Table 1), and substrate 3 is 4-methylumbelliferyl-α-D-neuraminic acid (4-Methylumbelliferyl-N-acetyl-α-D-neuraminic acid: 4MU-NANA). The case of use will be specifically described with an example.

Neuraminidase (enzyme 5) is present on the surface of influenza virus particles. When 4MU-NANA (substrate 3) contacts and reacts with neuraminidase, the fluorescent substance 4-methylumbelliferone (reaction product 4) is produced.

Hydrolysis of 4MU-NANA by neuraminidase produces 4-methylumbelliferone (4MU) as a fluorescent chromophore represented by the following formula. Substrate 3 is not limited to 4MU-NANA, and conventionally known substrates can be used as long as they release an optically detectable chromophore by hydrolysis of neuraminic acid with neuraminidase. 4MU of the reaction product 4 has a hydroxyl group as shown by the following formula.

In the detection method according to the present invention, the hydrogen is desorbed from the hydroxyl groups of 4MU to make 4MU have an electric charge. set large. By removing hydrogen from the hydroxyl group of 4MU, 4MU contained in droplets of hydrophilic solvent 42 coated with hydrophobic solvent 43 cannot migrate to hydrophobic solvent 43 due to its charge, resulting in A high concentration accumulates in the droplets of the hydrophilic solvent 42 .

If the pH value of the hydrophilic solvent 42 is smaller than the acid dissociation constant (pKa) of 4MU, 4MU will have a hydroxyl group. The electric charge becomes smaller in comparison. When the 4MU contained in the droplet of the hydrophilic solvent 42 does not have an electric charge or when the electric charge is small, the 4MU tends to migrate to the hydrophobic solvent 43 that is in interface contact with the hydrophilic solvent 42. Therefore, the 4MU is hydrophilic. 4MU is lost from the liquid droplets of the organic solvent 42, or the 4MU concentration in the liquid droplets decreases.

Conventionally, the reaction between neuraminidase and 4MU-NANA is carried out under pH conditions around 5, which is the optimum pH for the enzymatic reaction by neuraminidase, and the detection of released 4MU is performed with the fluorescence efficiency (quantum efficiency) of 4MU maximized. It was carried out under pH conditions of around 10, which is the pH that is used. In contrast, one of the technical features of the present invention is that the reaction between neuraminidase and 4MU-NANA and the detection of 4MU are both carried out under pH conditions with a pKa greater than 7.79 for 4MU. be.

The reaction between the substrate 3 and the enzyme 5 can proceed even before this procedure if the substrate 3 and the enzyme 5 come into contact with each other. The produced reaction products 4 do not accumulate in the very small volume before the droplets are formed. Therefore, in the optical detection of the reaction product 4, the effect of the reaction product 4 produced before the encapsulation procedure (2) is negligibly small.

In addition to 4-methylumbelliferyl-α-D-neuraminic acid containing 4MU, similarly, the reaction product 4 from the droplets of the hydrophilic solvent 42 to the hydrophobic solvent 43 covering the droplets. Chromogenic substrates that can cause migration problems include:

Derivatives containing 4-Methylumbelliferone, other than 4MU-NANA. Here, "derivative" means a compound having 4MU as a "chromophore" and a "substrate" that is cleaved by reaction with enzyme 5 in its structure.

A derivative containing fluorescein as a chromophore. When it contacts with the enzyme 5 and reacts with it, the substrate is cleaved by the enzyme 5 and the fluorescent substance fluorescein (pKa: 6.4) is liberated as the reaction product 4 . The structure of fluorescein is shown below.

Derivatives containing Resorufin as a chromophore. Upon contact and reaction with the enzyme 5 , the substrate is cleaved by the enzyme 5 to release the fluorescent substance resorufin (pKa: 6.0) as the reaction product 4 . The structure of resorufin is shown below.

A derivative containing Rhodamine as a chromophore. Upon contact and reaction with the enzyme 5 , the substrate is cleaved by the enzyme 5 to liberate rhodamine (pKa: 6.0), which is a fluorescent substance, as a reaction product 4 . The structure of rhodamine is shown below.

When these derivatives are used as the substrate 3, the pH value of the hydrophilic solvent 42 is set higher than the acid dissociation constant (pKa) of the reaction product 4 generated from the derivatives. As a result, each reaction product 4 is charged to prevent migration (leakage) to the hydrophobic solvent 43, and the reaction product 4 is accumulated in droplets of the hydrophilic solvent 42 at a high concentration. (see Example 1).

Furthermore, leakage of the reaction product 4 from droplets of the hydrophilic solvent 42 into the hydrophobic solvent 43 can be more effectively prevented by setting the buffer substance in the hydrophilic solvent 42 to a predetermined concentration or higher. Yes (see Example 2). The concentration of the buffer substance is, for example, 50 mM or higher, preferably 100 mM or higher, more preferably 500 mM or higher, further preferably 1 M or higher.

[Detection procedure (A3)]
In this procedure, optical detection of the reaction product 4 generated in droplets of the hydrophilic solvent 42 is performed.

Optical detection of the reaction product 4 can be performed using known means capable of detecting the difference in optical properties between the substrate 3 and the reaction product 4 . For example, by detecting a shift in specific absorbance or optical rotation using an image sensor, an absorbance meter, or a polarimeter, or by detecting a specific fluorescence wavelength using an image sensor, fluorescence microscope, or fluorometer, the reaction Product 4 can be optically detected.

When the virus 2 is an influenza virus and 4MU-NANA is used as the substrate 3, fluorescence detection of the generated 4MU (reaction product 4) is performed.

Based on the detection intensity (for example, fluorescence intensity) of the detected reaction product 4 (for example, 4MU), the virus particle number and/or subspecies (subtype) can be determined.

Specifically, in the case of influenza virus, first, the enzymatic activity value of neuraminidase is calculated using the detected fluorescence intensity and a previously prepared standard curve defining the relationship between fluorescence intensity and neuraminidase activity. Next, the number of influenza virus particles is quantified using the calculated enzyme activity value and a previously prepared standard curve defining the relationship between the enzyme activity value and the number of virus particles. As a result, in addition to determining whether the virus is contained in the biological sample isolated from the subject, the amount of virus can also be determined quantitatively (analog quantification), and the presence or absence of influenza virus infection in the subject and infection can diagnose the strength of A standard curve that directly defines the relationship between fluorescence intensity and the number of virus particles may be used.

Further, for example, among influenza viruses, type A virus is known to have higher neuraminidase activity than type B virus. The present inventors have also found that, using the detection method of the present invention, the difference in neuraminidase activity between type A virus and type B virus is approximately twofold, and that both can be effectively distinguished and detected based on the magnitude of the activity value. Heading. In such a case, first, the enzymatic activity value of neuraminidase is calculated using the detected fluorescence intensity and a previously prepared standard curve defining the relationship between fluorescence intensity and neuraminidase activity. Next, the subtype of the influenza virus can be determined using the calculated enzyme activity value and a previously created relational expression between the enzyme activity value and the subtype. For example, in the case of influenza virus, if the calculated enzymatic activity value is equal to or higher than the standard value, it can be determined as type A, and if it is less than the standard value, it can be determined as type B. Thus, in addition to determining whether a biological sample isolated from a subject contains virus, the virus subtype can also be determined, and the subtype of the infectious influenza virus in the subject can be diagnosed. A relational expression that directly defines the relationship between fluorescence intensity and subtype may be used.

Furthermore, as described above, when the virus 2 is diluted to a sufficiently low concentration in the hydrophilic solvent 42, the number of viruses 2 entering one container 13 can be zero or at most one. In this case, by using the ratio between the number of storage units 13 in which the reaction product 4 is detected and the number of storage units 13 in which the reaction product 4 is not detected, the previously created relationship between the ratio and the number of virus particles is calculated. Viral load can also be determined quantitatively (digital quantification) based on defined standard curves.
In the encapsulation procedure (2), the reaction product 4 can be accumulated in the droplet of the hydrophilic solvent 42 at a high concentration. , the reaction product 4 can be detected with high sensitivity. Therefore, according to the detection method of the present invention, even viruses contained in a biological sample in extremely small amounts can be detected with high sensitivity, and the amount of pathogenic microorganisms can be determined with high accuracy.

In addition, since the reaction product 4 can be accumulated in the droplet of the hydrophilic solvent 42 at a high concentration, a high fluorescence intensity can be obtained. For example, it is expected that optical detection will be possible with a camera mounted on a smartphone. Optical detection by a simple imaging device, such as a camera mounted on a smart phone, can facilitate implementation of the pathogenic microorganism detection method according to the present invention in relatively small hospitals, clinics, and individuals. Furthermore, by using the communication means provided by smartphones, detection information of pathogenic microorganisms can be sent to the server, and by analyzing the accumulated information (big data), it is possible to grasp the epidemic area, time period, subtype, etc. It is expected that it can be used for prediction.

In the above description, the virus 2 is an influenza virus and 4MU-NANA is used as the substrate 3 as an example. In the present invention, for example, when coronavirus, severe acute respiratory syndrome (SARS) coronavirus or Middle East respiratory syndrome (MERS) virus is targeted for detection, substrate 3 contains hemagglutinin esterase ( A substance that is hydrolyzed by the enzyme 5) to liberate the chromophore (reaction product 4) as described above may be used.

Further, for example, when human immunodeficiency virus (HIV), hepatitis B virus or human T-cell leukemia virus (HTLV) is to be detected, the substrate 3 contains a reverse transcriptase ( It may be a nucleic acid monomer that is polymerized by enzyme 5). By labeling the nucleic acid monomers with a fluorescent dye, fluorescence intensity increased compared to the nucleic acid monomers is detected in the nucleic acid chain, which is the reaction product of polymerization. Similarly, for example, when Ebola virus, hepatitis C virus, Lassa virus, hantavirus, rabies virus, Japanese encephalitis virus, yellow fever virus, dengue fever virus, rubella virus, rotavirus or norovirus is to be detected, substrate 3 can use fluorescent dye-labeled nucleic acid monomers that are polymerized by RNA-dependent RNA polymerase (enzyme 5) on the surface or inside of these viruses. In addition, it is not limited to the configuration in which the fluorescence intensity increases as the nucleic acid monomers are polymerized into the nucleic acid chain, and any configuration in which optical properties (absorbance, optical rotation, fluorescence, etc.) that are different from those before the reaction appear after the reaction can be widely adopted. It is possible.

Thus, in the detection method according to the present invention, the substrate can be appropriately selected according to the enzymes present on the surface or inside of the pathogenic microorganism to be detected. At this time, according to the pKa of the selected reaction product, the pH value of the hydrophilic solvent used in the introduction procedure (1) may be designed to be higher than the pKa.

In addition, the substrate can be designed differently according to the substrate specificity of the enzyme of each pathogenic microorganism, even for pathogenic microorganisms that have the same enzyme (neuraminidase), such as influenza virus and mump virus. For example, 4MU-NANA is used as a chromogenic substrate for detecting influenza virus, and 4MU-NANA is used as a chromogenic substrate for detecting mump virus. Use the one changed to Thus, by changing a part of the substrate, the affinity of each chromogenic substrate for neuraminidase can be changed between the influenza virus enzyme and the mump virus enzyme, even for the same type of enzyme. . Thus, the detection method according to the present invention can detect both of them separately.

2. Method for detecting drug susceptibility of pathogenic microorganisms A method for detecting drug susceptibility of pathogenic microorganisms in a biological sample isolated from a subject infected or suspected to be infected with a pathogenic microorganism according to the present invention comprises the following steps. including.
(B1) A lower layer portion in which a plurality of storage portions capable of storing pathogenic microorganisms are separated from each other by sidewalls having a hydrophobic upper surface, and a surface of the lower layer portion on which the storage portions are formed. In the space between the opposing upper layers, the biological sample, a substance that serves as a substrate for reaction by an enzyme present on or inside the pathogenic microorganism, and a hydrophilic solvent containing an inhibitor of the enzyme are placed. Deployment steps to implement.
(B2) introducing a hydrophobic solvent into the space to form droplets of a hydrophilic solvent coated with the hydrophobic solvent and containing the pathogenic microorganism, the substance, and the inhibitor in the container; encapsulation procedure.
(B3) a detection procedure for optically detecting a reaction product produced by the reaction between the enzyme and the substance in the droplet, (wherein the detection intensity of the reaction product in the presence of the inhibitor is , indicating that the pathogenic microorganism is susceptible to the inhibitor if the detectable intensity of the reaction product is reduced below that in the absence of the inhibitor).

[Introduction procedure (B1)]
The introduction procedure (B1) of the method for detecting drug susceptibility of pathogenic microorganisms according to the present invention is different from the method for detecting pathogenic microorganisms described above only in that the enzyme inhibitor to be evaluated for drug susceptibility is contained in the hydrophilic solvent. It differs from the introduction procedure (A1). In the introduction procedure (B1), in addition to pathogenic microorganisms and substrates, inhibitors of enzymes present on or in pathogenic microorganisms enter the container.

[Enclosure procedure (B2)]
The operation of the encapsulation procedure (B2) of the method for detecting drug susceptibility of pathogenic microorganisms according to the present invention is the same as the encapsulation procedure (A2) of the above-described method for detecting pathogenic microorganisms. The encapsulation step (B2) results in the formation of droplets of hydrophilic solvent coated with a hydrophobic solvent and containing the pathogenic microorganism, the substrate and the inhibitor in the reservoir.

[Detection procedure (B3)]
In the detection procedure (B3) of the method for detecting drug susceptibility of pathogenic microorganisms according to the present invention, in the same manner as in the detection procedure (A3) of the method for detecting pathogenic microorganisms described above, the reaction generated in the droplet of the hydrophilic solvent Optical detection of the product is performed.

Comparing the detection intensity of the reaction product in the presence of the inhibitor with the detection intensity of the reaction product in the absence of the inhibitor, if the former is reduced more than the latter, the inhibitor causes the hydrophilic solvent solution to It is shown that the formation of reaction products in the drops is suppressed. That is, since the enzyme possessed by the pathogenic microorganism is inhibited, it is shown that the pathogenic microorganism is sensitive to the inhibitor.
On the other hand, if the detection intensity of the reaction product in the absence of the inhibitor is equivalent to the detection intensity of the reaction product in the absence of the inhibitor, the reaction in the hydrophilic solvent droplet It is shown that product formation is not suppressed by the inhibitor. That is, since the enzyme possessed by the pathogenic microorganism is not inhibited, it is shown that the pathogenic microorganism is resistant to the inhibitor.

Specifically, when the pathogenic microorganism is an influenza virus, for example, using 4MU-NANA as a substrate and a neuraminidase inhibitor (osetamivir, zanamivir, etc.) as an inhibitor, Fluorescence detection of the generated 4MU is performed for two test groups that are identical except for the following conditions. The intensity of detection of 4MU in the presence of the neuraminidase inhibitor is compared with the intensity of detection of 4MU in the absence of the neuraminidase inhibitor, and if the former decreases more than the latter, the neuraminidase inhibitor increases It is shown that the generation of 4MU is suppressed. That is, since neuraminidase possessed by influenza virus is inhibited, it is shown that influenza virus is sensitive to neuraminidase inhibitors.
On the other hand, if the intensity of detection of 4MU in the absence of a neuraminidase inhibitor is equivalent compared to the intensity of detection of 4MU in the absence of a neuraminidase inhibitor, then the generation of 4MU in droplets of hydrophilic solvent will result in neuraminidase It is shown not to be suppressed by inhibitors. That is, since the neuraminidase possessed by the influenza virus is not inhibited, it is shown that the influenza virus is resistant to neuraminidase inhibitors.

Combinations of pathogenic microorganisms and enzyme inhibitors that can detect such drug susceptibility include, for example, coronavirus, severe acute respiratory syndrome (SARS) coronavirus, or Middle East respiratory syndrome (MERS) virus. Inhibitors of hemagglutinin esterase (HE) that these viruses have on the surface (HE antibody, 3,4-dichloroisocoumarin,
9-O-Acetylated Polysialoside, etc.).

In addition, for example, when human immunodeficiency virus (HIV), hepatitis B virus or human T-cell leukemia virus (HTLV) is targeted for detection, inhibitors of reverse transcriptase (retrovir ( GlaxoSmithKline Inc., Zidovudine/AZT), Videx (Bristol-Myers Squibb Inc., Didanosine/ddI), Hivid (Hoffman-La Roche) (Zalcitabine/ddC), Zerrit (Bristol-Myers Squibb) Stavudine/d4T), Epivir (GlaxoSmithKline, Lamivudine/3TC) and Combivir (GlaxoSmithKline, Zidovudine/Lamivudine) Viramune (Boehringer Ingelheim Pharmaceuticals Inc., Nevirapine), Rescriptor (Pharmacia/Upjohn, Delavirdine) and Sustiva (DuPont Pharma Co., Efavirenz), etc.).
Similarly, for example, when detecting Ebola virus, hepatitis C virus, Lassa virus, hantavirus, rabies virus, Japanese encephalitis virus, yellow fever virus, dengue fever virus, rubella virus, rotavirus or norovirus, these viruses inhibitors of RNA-dependent RNA polymerases (favipiravir, ribavirin, etc.) on or in the surface of .

Furthermore, for example, when coliforms, Vibrio parahaemolyticus, Campylobacter, Enterobacter, or Bacillus are to be detected, inhibitors of galactosidase (Castanospermine, Conduritol B Epoxide, Bromoconduritol, 2- Deoxy-D-Galactose, etc.), glucuronidase inhibitors (acetogratone, D-glucaro-1,4-lactone, lysophospholipids, etc.), chymotrypsin, trypsin inhibitors (trypsin inhibitors derived from soybeans, chicken eggs, etc., Arg ⁴ - Met ⁵ -marinostatin, phenylmethylsulfonyl fluoride, aminoethyl benzylsulfonyl fluoride, aprotinin, tosyl lysine chloromethyl ketone, tosyl phenylalanine chloromethyl ketone, etc.), xylosidase inhibitors (castanospermine, Xyl-amidine, etc.).

Thus, in the method for detecting drug susceptibility of pathogenic microorganisms according to the present invention, inhibitors can be appropriately selected depending on the enzymes present on the surface or inside of pathogenic microorganisms to be detected.

3. Screening Method for Antipathogenic Microbial Agents A method for screening antipathogenic microbial agents according to the present invention comprises the following steps.
(C1) A lower layer portion in which a plurality of storage portions capable of storing pathogenic microorganisms are separated from each other by sidewalls having a hydrophobic upper surface, and a surface of the lower layer portion on which the storage portions are formed. A hydrophilic solvent containing the pathogenic microorganism, a substance that serves as a substrate for reaction by an enzyme present on or inside the pathogenic microorganism, and a candidate compound is introduced into the space between the opposing upper layers. installation procedure.
(C2) introducing a hydrophobic solvent into the space to form droplets of a hydrophilic solvent coated with the hydrophobic solvent and containing the pathogenic microorganism, the substance, and the candidate compound in the container; encapsulation procedure.
(C3) a detection procedure for optically detecting a reaction product produced by the reaction between the enzyme and the substance in the droplet, (wherein the detection intensity of the reaction product in the presence of the candidate compound is , indicating that the candidate compound has antipathogenic microbial activity if it is less than the detectable intensity of the reaction product in the absence of the candidate compound).

[Introduction procedure (C1)]
The introduction procedure (C1) of the screening method for an antipathogenic microbial agent according to the present invention is performed only in that the candidate compound to be evaluated for antipathogenic microbial activity is contained in the hydrophilic solvent. It differs from the detection method introduction procedure (A1). In the introduction procedure (C1), the candidate compound enters the reservoir in addition to the pathogenic microorganism and substrate.

[Enclosure procedure (C2)]
The operation of the encapsulation procedure (C2) of the screening method for antipathogenic microbial agents according to the present invention is as follows:
It is the same as the encapsulation procedure (A2) of the pathogenic microorganism detection method described above. In the encapsulation procedure (C2), a droplet of hydrophilic solvent is formed within the reservoir, coated with a hydrophobic solvent and containing the pathogenic microorganism, the substrate and the candidate compound.

[Detection procedure (C3)]
In the detection procedure (C3) of the screening method for an anti-pathogenic microbial agent according to the present invention, in the same manner as in the detection procedure (A3) of the above-described pathogenic microorganism detection method, a reaction generated in a droplet of a hydrophilic solvent Optical detection of the product is performed.

The detection intensity of the reaction product in the presence of the candidate compound is compared with the detection intensity of the reaction product in the absence of the candidate compound, and if the former is less than the latter, the candidate compound causes the hydrophilic solvent solution to It is shown that the formation of reaction products in the drops is suppressed. In other words, inhibition of enzymes possessed by pathogenic microorganisms indicates that the candidate compound has antipathogenic microbial activity.
On the other hand, when the detection intensity of the reaction product in the absence of the candidate compound is equivalent to the detection intensity of the reaction product in the absence of the candidate compound, the reaction in the hydrophilic solvent droplet It is shown that product formation is not suppressed by the inhibitor. That is, the enzyme possessed by the pathogenic microorganism is not inhibited, indicating that the candidate compound does not have antipathogenic microbial activity.

4. Pathogenic Microorganism Detection Kit The kit according to the present invention is a kit for detecting a pathogenic microorganism in a biological sample separated from a subject infected or suspected of being infected with a pathogenic microorganism,
a lower layer portion in which a plurality of storage portions capable of storing the pathogenic microorganism are separated from each other by side walls having a hydrophobic upper surface; an array comprising: an upper layer facing across the
a substance that serves as a substrate for reaction by an enzyme present on the surface or inside the particles of the pathogenic microorganism;
a hydrophilic solvent having a pH value greater than the acid dissociation constant (pKa) of the reaction product produced by the reaction between the enzyme and the substance;
and a hydrophobic solvent.

The kit according to the present invention includes the above-described array 1, substrate 3, hydrophilic solvent 42 and hydrophobic solvent 43. Since the substrate 3, the hydrophilic solvent 42 and the hydrophobic solvent 43 have already been explained, the construction of the array 1 will be explained in more detail below.

A lower layer 10 of the array 1 comprises a plate member 11 and sidewalls 12 having a hydrophobic upper surface. A plurality of housing portions 13 are formed in the lower layer portion 10 so as to be separated from each other by side walls 12 .

The plate member 11 preferably has a hydrophilic surface. A "hydrophilic surface" refers to a surface that has a higher affinity for hydrophilic solvents than it has for hydrophobic solvents. The plate member 11 may be made of a solid material such as glass, silicon, polymer resin, or the like.

The side wall 12 is a structure that separates each of the plurality of storage portions 13 provided on the surface of the plate-like member 11, preferably on the hydrophilic surface. Sidewall 12 has a hydrophobic upper surface. "Hydrophobic" is used here in the same sense as "lipophilic" and refers to a higher affinity with hydrophobic solvents than with hydrophilic solvents.

The side wall 12 may have a hydrophobic upper surface, that is, the surface facing the upper layer portion 20, and the side surface, that is, the inner wall inside the housing portion 13 may be hydrophobic or hydrophilic.

For example, sidewall 12 may be composed of a hydrophilic structure and a hydrophobic layer formed on the upper surface thereof. For example, glass, silicon, polymer resin, or the like can be used for the hydrophilic structure. For the hydrophobic layer, for example, a water-repellent resin, a fluoropolymer resin, or the like can be used. Examples of fluoropolymer resins include amorphous fluororesins. Amorphous fluororesin is preferably used because it has high hydrophobicity and low toxicity to biological samples.

As the amorphous fluororesin, for example, at least one selected from CYTOP (registered trademark), TEFLON (registered trademark) AF2400, and TEFLON (registered trademark) AF1600 can be preferably used. Among them, CYTOP (registered trademark) is most preferable because it is easily microfabricated.

Further, for example, the sidewall 12 may be made of a hydrophobic material. As the side wall 12, for example, fluorine-based polymer resin, paraxylylene-based polymer resin, or the like can be used. Examples of fluoropolymer resins include amorphous fluororesins. As the amorphous fluororesin, the resins described above can be preferably used.

The side wall 12 may be configured such that a plurality of housing portions 13 are formed on the plate member 11. For example, the side wall 12 may be a plate-shaped structure having holes formed at positions where the housing portions 13 are formed. There may be.

A part of the surface of the plate member 11 is used as a bottom surface of the housing portion 13, and the bottom surface is hydrophilic. The shape of the area surrounded by the bottom and side surfaces of the housing portion 13 may be, for example, a cylindrical shape, a prismatic shape, or the like.

In this embodiment, the bottom surface of the housing portion 13 is hydrophilic, and the top surface of the side wall 12 is hydrophobic. As a result, the hydrophilic solvent 42 can be efficiently introduced into the container 13 in the introduction procedure (1), and the hydrophobic solvent 43 is prevented from entering the container 13 in the encapsulation procedure (2). be able to.

Glass, silicon, polymer resin, or the like, for example, can be used for the upper layer portion 20 . The upper layer portion 20 faces the surface of the lower layer portion 10 on which the housing portion 13 is formed, with a space 30 therebetween. That is, there is a space 30 between the sidewall 12 and the hydrophobic layer 22 . This space 30 constitutes a channel. With this configuration, the array 1 has a flow cell structure.

The space 30 can be used as a channel for flowing a fluid between the lower layer part 10 and the upper layer part 20 in a direction parallel to the surfaces where the lower layer part 10 and the upper layer part 20 face each other.

A through hole (not shown) for introducing a fluid into the space 30 may be formed in the lower layer portion 10 or the upper layer portion 20 . For example, the lower layer portion 10 may have a region in which the accommodating portion 13 is formed and a region in which the accommodating portion 13 is not formed. A through-hole may be formed in a region of the lower layer portion 10 where the accommodation portion 13 is not formed or in a portion of the upper layer portion 20 facing this region.

In the present embodiment, the surface of the upper layer portion 20 forming the upper surface of the space 30 is hydrophobic, and the lower surface of the space 30 is the hydrophobic upper surface of the sidewall 12 and the accommodating portion 13 . Therefore, all portions of the space 30 other than the bottom surface of the housing portion 13 are hydrophobic. Thereby, the hydrophilic solvent 42 can be efficiently introduced into each container 13 in the introduction procedure (1). In addition, the hydrophobic solvent 43 is not allowed to enter each container 13 in the encapsulation procedure (2). Therefore, by introducing the hydrophobic solvent 43 into the space 30 , droplets can be efficiently formed in each container 13 .

[Test Example 1: Examination of pH value of hydrophilic solvent]
The following procedure was used to study the effect of the pH value of the hydrophilic solvent on the detection sensitivity.
First, according to the report of Kim et al. device (DAD) was created. A cover glass (24 mm×32 mm) was washed and dried, then spin-coated with an amorphous fluororesin (CYTOP 816AP, Asahi Glass) and baked at 180° C. for 1 hour. A cover glass coated with an amorphous fluororesin was spin-coated with a positive photoresist (AZ-4903, AZ Electronic Materials), baked at 55° C. for 3 minutes, and then baked at 110° C. for 5 minutes. Photolithography was performed using a photomask with 3 μm diameter holes at 5 μm intervals. After dry etching with oxygen plasma, the cleaned cover glass was obtained as DAD. The DAD has a well (accommodating portion) with a diameter of 4 μm and a depth of 3 μm (approximately 1 million/10 mm ² ), and the cover glass is exposed on the bottom surface of the well. Using the obtained DAD, an array with a flow cell structure as shown in FIG. 1 was produced.

4-M in a buffer solution (33 mM DEA-HCl, 4 mM CaCl ₂ ) adjusted to pH 6.5-9.0
U was dissolved to 50 μM.
30 μL of a buffer solution in which 4-MU was dissolved was introduced into the array to fill each well with the buffer solution (see FIG. 1A). Subsequently, 200 μL of a hydrophobic solvent (FC40) was introduced into the array to form droplets of hydrophilic solvent coated with the hydrophobic solvent in each well.
A fluorescence image of each droplet was taken with a CMOS camera (Neo sCMOS, Andor) connected to a fluorescence microscope (IX8, OLYMPUS), and fluorescence intensity was measured. 12 areas of 10 mm ² in each well
Shooting was performed with 0 division. One image contains approximately 8,600 wells. Fluorescence images were analyzed with image analysis software (Meta-Morph, Molecular Devices) to calculate fluorescence intensity.

The results are shown in FIG. By setting the pH value of the buffer solution to be higher than the pKa (7.79) of 4MU, fluorescence of 4MU could be detected with higher sensitivity. At a pH value of 8 or more, 4MU was in a state of being charged, and the transfer (leakage) of 4MU to FC40 was suppressed.

[Test Example 2: Investigation of buffer substance concentration of hydrophilic solvent]
The following procedure was used to study the effect of the concentration of the buffer substance in the hydrophilic solvent on the detection sensitivity.

Buffer solution (4 mM CaCl ₂ , pH 6.5) with DEA concentration adjusted to 25 mM to 1 M
4-MU was dissolved in 50 μM.
30 μL of a buffer solution in which 4-MU was dissolved was introduced into the array to fill each well with the buffer solution (see FIG. 1A). Subsequently, 200 μL of a hydrophobic solvent (FC40) was introduced into the array to form droplets of hydrophilic solvent coated with the hydrophobic solvent in each well.
Time-lapse photography was performed under a fluorescence microscope to measure the fluorescence intensity of each droplet.

The results are shown in FIG. At a DEA concentration of 1M, no decrease in fluorescence intensity over time was observed when the effects of fading due to exposure were subtracted. Even at DEA concentrations of 500 mM and 100 mM, the decrease in fluorescence intensity was remarkably suppressed until 30 minutes after observation. At a DEA concentration of 50 mM, fluorescence intensity was maintained 10 minutes after observation, but at 25 mM, a decrease in fluorescence intensity was observed.

Considering that the time required for detection in the detection method according to the present invention is about several minutes, setting the concentration of the buffer substance in the buffer solution to 50 mM or higher enables the fluorescence of 4MU to be detected with higher sensitivity. shown. It is considered that the migration (leakage) of 4MU of FC40 could be suppressed by setting the buffer substance in the buffer solution to a predetermined concentration or higher.

1: Array, 2: Virus, 3: Substrate, 4: Reaction Product, 5: Enzyme, 10: Lower Layer, 11: Plate-like Member, 12: Side Wall, 13: Storage Section, 20: Upper Layer, 30: Space , 42: hydrophilic solvent, 43: hydrophobic solvent

Claims (3)

1. A method for the digital quantitative detection of a pathogenic microorganism in a biological sample isolated from a subject infected or suspected of being infected with said pathogenic microorganism, comprising:
a procedure of introducing a hydrophilic solvent containing the biological sample and a substance that serves as a substrate for a reaction by an enzyme present on or inside the pathogenic microorganism into a container;
forming droplets of a hydrophilic solvent within the container, coated with a hydrophobic solvent and containing the pathogenic microorganism and the substance;
optically detecting a reaction product produced by a reaction between the enzyme and the substance in the droplet;
the volume of the accommodating portion is 1 fL to 1 pL ,
the reaction proceeds in droplets of a hydrophilic solvent in interfacial contact with a hydrophobic solvent,
The method, wherein the hydrophilic solvent has a pH value greater than the acid dissociation constant (pKa) of the reaction product. The pathogenic microorganism is influenza virus, the enzyme is neuraminidase, the substance comprises a chromophore that becomes optically detectable upon hydrolysis of neuraminic acid by neuraminidase, and the reaction product is the chromophore. A method according to claim 1. 4. The claim wherein said substance is 4-Methylumbelliferyl-N-acetyl-α-D-neuraminicacid and said reaction product is 4-methylumbelliferone. 2. The method described in 2.

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