WO2015025863A1 - 固相プローブを用いた修飾核酸塩基の測定方法およびそのキット - Google Patents
固相プローブを用いた修飾核酸塩基の測定方法およびそのキット Download PDFInfo
- Publication number
- WO2015025863A1 WO2015025863A1 PCT/JP2014/071704 JP2014071704W WO2015025863A1 WO 2015025863 A1 WO2015025863 A1 WO 2015025863A1 JP 2014071704 W JP2014071704 W JP 2014071704W WO 2015025863 A1 WO2015025863 A1 WO 2015025863A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- nucleic acid
- probe
- solid phase
- target nucleic
- modified nucleobase
- Prior art date
Links
Images
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
- G01N33/48—Biological material, e.g. blood, urine; Haemocytometers
- G01N33/50—Chemical analysis of biological material, e.g. blood, urine; Testing involving biospecific ligand binding methods; Immunological testing
- G01N33/53—Immunoassay; Biospecific binding assay; Materials therefor
- G01N33/543—Immunoassay; Biospecific binding assay; Materials therefor with an insoluble carrier for immobilising immunochemicals
- G01N33/54306—Solid-phase reaction mechanisms
-
- C—CHEMISTRY; METALLURGY
- C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
- C12Q—MEASURING OR TESTING PROCESSES INVOLVING ENZYMES, NUCLEIC ACIDS OR MICROORGANISMS; COMPOSITIONS OR TEST PAPERS THEREFOR; PROCESSES OF PREPARING SUCH COMPOSITIONS; CONDITION-RESPONSIVE CONTROL IN MICROBIOLOGICAL OR ENZYMOLOGICAL PROCESSES
- C12Q1/00—Measuring or testing processes involving enzymes, nucleic acids or microorganisms; Compositions therefor; Processes of preparing such compositions
- C12Q1/68—Measuring or testing processes involving enzymes, nucleic acids or microorganisms; Compositions therefor; Processes of preparing such compositions involving nucleic acids
- C12Q1/6804—Nucleic acid analysis using immunogens
-
- C—CHEMISTRY; METALLURGY
- C12—BIOCHEMISTRY; BEER; SPIRITS; WINE; VINEGAR; MICROBIOLOGY; ENZYMOLOGY; MUTATION OR GENETIC ENGINEERING
- C12Q—MEASURING OR TESTING PROCESSES INVOLVING ENZYMES, NUCLEIC ACIDS OR MICROORGANISMS; COMPOSITIONS OR TEST PAPERS THEREFOR; PROCESSES OF PREPARING SUCH COMPOSITIONS; CONDITION-RESPONSIVE CONTROL IN MICROBIOLOGICAL OR ENZYMOLOGICAL PROCESSES
- C12Q1/00—Measuring or testing processes involving enzymes, nucleic acids or microorganisms; Compositions therefor; Processes of preparing such compositions
- C12Q1/68—Measuring or testing processes involving enzymes, nucleic acids or microorganisms; Compositions therefor; Processes of preparing such compositions involving nucleic acids
- C12Q1/6813—Hybridisation assays
- C12Q1/6834—Enzymatic or biochemical coupling of nucleic acids to a solid phase
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
- G01N33/48—Biological material, e.g. blood, urine; Haemocytometers
- G01N33/50—Chemical analysis of biological material, e.g. blood, urine; Testing involving biospecific ligand binding methods; Immunological testing
- G01N33/53—Immunoassay; Biospecific binding assay; Materials therefor
- G01N33/5308—Immunoassay; Biospecific binding assay; Materials therefor for analytes not provided for elsewhere, e.g. nucleic acids, uric acid, worms, mites
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
- G01N33/48—Biological material, e.g. blood, urine; Haemocytometers
- G01N33/50—Chemical analysis of biological material, e.g. blood, urine; Testing involving biospecific ligand binding methods; Immunological testing
- G01N33/53—Immunoassay; Biospecific binding assay; Materials therefor
- G01N33/543—Immunoassay; Biospecific binding assay; Materials therefor with an insoluble carrier for immobilising immunochemicals
- G01N33/54393—Improving reaction conditions or stability, e.g. by coating or irradiation of surface, by reduction of non-specific binding, by promotion of specific binding
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N33/00—Investigating or analysing materials by specific methods not covered by groups G01N1/00 - G01N31/00
- G01N33/48—Biological material, e.g. blood, urine; Haemocytometers
- G01N33/50—Chemical analysis of biological material, e.g. blood, urine; Testing involving biospecific ligand binding methods; Immunological testing
- G01N33/68—Chemical analysis of biological material, e.g. blood, urine; Testing involving biospecific ligand binding methods; Immunological testing involving proteins, peptides or amino acids
Definitions
- the present invention relates to a method and kit for measuring modified nucleobases.
- nucleic acids eg, DNA, RNA
- nucleic acids eg, DNA, RNA
- many techniques have been reported so far for detecting nucleobases into which a substance such as biotin has been artificially introduced by an immunoassay using an antibody.
- a technique for detecting a naturally occurring modified nucleobase (eg, methylcytosine, hydroxylmethylcytosine) by immunoassay has been reported (Patent Document 1, and Non-Patent Documents 1 and 2).
- an immunoassay system for detecting a modified nucleobase as described above, the present inventors have a problem that the background value of a detection signal increases due to non-specific binding of an antibody to a nucleic acid probe with respect to the modified nucleobase. Found that there exists. Therefore, in order to construct a highly sensitive immunoassay system, it was necessary to develop a technique for suppressing the background value.
- the present inventors have determined that a background value can be obtained by using two types of probes (capture probe and solid phase probe) together in measurement of a modified nucleobase in a target nucleic acid using an antibody against the modified nucleobase. As a result, the present invention has been completed.
- a method for measuring a modified nucleobase comprising: (1) incubating the nucleic acid sample, capture probe and solid phase probe in solution; and (2) measuring the modified nucleobase in the solution obtained in (1) using an antibody against the modified nucleobase.
- [2] The method of [1], wherein the nucleic acid sample contains a target nucleic acid containing a modified nucleobase, and steps (1) and (2) are performed by (1 ′) and (2 ′), respectively: (1 ′) A nucleic acid sample containing a target nucleic acid containing a modified nucleobase, a capture probe and a solid phase probe are reacted in a solution by incubation to form a hybrid composed of the target nucleic acid, the capture probe and the solid phase probe. And (2 ′) measuring the modified nucleobase in the solution containing the hybrid using an antibody against the modified nucleobase.
- [3] The method of [1] or [2], wherein the target nucleic acid is a target nucleic acid that may contain two or more modified nucleobases.
- the method further comprises adding a solution containing the nucleic acid sample and the capture probe to the solid phase to which the solid phase probe is immobilized, to prepare a solution containing the nucleic acid sample, the capture probe and the solid phase probe. Any one of [1] to [3].
- [5] The method according to any one of [1] to [4], wherein the nucleic acid sample is a sample containing a target DNA containing a modified nucleobase.
- [10] The method according to any one of [1] to [9], wherein the modified nucleobase is methylcytosine.
- the capture probe of [2] to [10] is designed such that an unpaired portion of the modified nucleobase is formed in a double-stranded structure composed of the target nucleic acid and the capture probe in the hybrid. Either way.
- [12] The method according to any one of [2] to [11], wherein the capture probe is designed so that the modified nucleobase is present in the single-stranded structure portion of the hybrid.
- the measurement of the modified nucleobase using an antibody against the modified nucleobase is performed by ELISA.
- a kit for measuring a modified nucleobase comprising: (I) a capture probe; (II) a solid phase probe; and (III) an antibody against the modified nucleobase.
- the modified nucleobase in the target nucleic acid can be measured with high sensitivity by reducing the background value of the detection signal.
- FIG. 1 is a diagram showing an example of an outline of measurement of a modified nucleobase in a target nucleic acid according to the method of the present invention.
- RN a nucleotide residue having a modified nucleobase
- N a nucleotide residue having a nucleobase
- R a substituent that the nucleobase has.
- FIG. 2 is a diagram showing signal values (background values) measured in the presence of antibodies against solid phase probes 1 to 10 and modified nucleobases.
- FIG. 1 is a diagram showing an example of an outline of measurement of a modified nucleobase in a target nucleic acid according to the method of the present invention.
- RN a nucleotide residue having a modified nucleobase
- N a nucleotide residue having a nucleobase
- R a substituent that the nucleobase has.
- FIG. 2 is a diagram showing signal values (background values) measured in the presence of antibodies against solid phase probe
- FIG. 3 shows a target nucleic acid (0 mol, 0.001 pmol, 0.001 pmol, 0.1 mol or 1 pmol) containing a modified nucleobase, a capture probe (+), a solid phase probe (+: Examples 2 to 4; ⁇ : Reference
- FIG. 2 is a graph showing signal values measured in the measurement under the conditions of Example 1) and an antibody (+) against a modified nucleobase (Examples 2 to 4 and Reference Example 1).
- FIG. 4 shows the conditions of a target nucleic acid (0 mol) containing a modified nucleobase, a capture probe (+), a solid phase probe (+: Examples 2 to 4; ⁇ : Reference Example 1) and an antibody (+) against the modified nucleobase.
- FIG. 5 is a graph showing signal-to-noise ratio (S / N) calculated in the measurement of modified nucleobases (Examples 2 to 4 and Reference Example 1).
- S / N S was measured in measurements under conditions of target nucleic acid containing modified nucleobase (1 pmol), capture probe (+), solid phase probe (+) and antibody to modified nucleobase (+).
- a signal value is shown, and N was measured in the measurement under conditions of a target nucleic acid (0 mol) containing a modified nucleobase, a capture probe (+), a solid phase probe (+) and an antibody (+) against the modified nucleobase. Indicates the signal value (background value).
- FIG. 6 shows the conditions of a target nucleic acid (0 mol) containing a modified nucleobase, a capture probe (+), a solid phase probe (+: Example 5; ⁇ : Reference Example 2) and an antibody against the modified nucleobase (+). It is a figure which shows the signal value (background value) measured in this measurement.
- FIG. 7 shows a target nucleic acid (0 mol, 0.01 pmol, 0.1 pmol, 1 mol or 10 pmol) containing a modified nucleobase, a capture probe (+), a solid phase probe (+: Example 5; ⁇ : Reference Example 2) and It is a figure which shows the signal value measured in the measurement under the conditions of the antibody (+) with respect to a modified nucleobase.
- FIG. 6 shows the conditions of a target nucleic acid (0 mol) containing a modified nucleobase, a capture probe (+), a solid phase probe (+: Example 5; ⁇ : Reference Example 2) and an antibody against the modified nucleobase (+). It is a
- FIG. 8 shows the conditions of a target nucleic acid containing a modified nucleobase (0 mol), a capture probe (+), a solid phase probe (+: Example 6; ⁇ : Reference Example 3) and an antibody against the modified nucleobase (+). It is a figure which shows the signal value (background value) measured in this measurement.
- FIG. 9 shows a target nucleic acid (0 mol, 0.01 pmol, 0.1 pmol, 1 mol or 10 pmol) containing a modified nucleobase, a capture probe (+), a solid phase probe (+: Example 6; ⁇ : Reference Example 3) and It is a figure which shows the signal value measured in the measurement under the conditions of the antibody (+) with respect to a modified nucleobase.
- FIG. 9 shows a target nucleic acid (0 mol, 0.01 pmol, 0.1 pmol, 1 mol or 10 pmol) containing a modified nucleobase, a capture probe (+), a solid phase probe (+: Example 6; ⁇ :
- FIG. 10 shows the conditions of a target nucleic acid containing a modified nucleobase (0 mol), a capture probe (+), a solid phase probe (+: Example 7; ⁇ : Reference Example 4) and an antibody against the modified nucleobase (+). It is a figure which shows the signal value (background value) measured in this measurement.
- FIG. 11 shows a target nucleic acid (0 mol, 0.01 pmol, 0.1 pmol, 1 mol or 10 pmol) containing a modified nucleobase, a capture probe (+), a solid phase probe (+: Example 7; ⁇ : Reference Example 4) and It is a figure which shows the signal value measured in the measurement under the conditions of the antibody (+) with respect to a modified nucleobase.
- the present invention provides a method for measuring modified nucleobases.
- the method of the present invention includes: (1) incubating the nucleic acid sample, capture probe and solid phase probe in solution; and (2) measuring the modified nucleobase in the solution obtained in (1) using an antibody against the modified nucleobase.
- the nucleic acid sample is a sample containing a target nucleic acid containing a modified nucleobase, or a sample suspected of containing the target nucleic acid.
- the nucleic acid sample may also be a biological sample from an organism, or an environmental sample or the like. Examples of organisms from which biological samples are derived include animals such as mammals (eg, humans, monkeys, mice, rats, rabbits, cows, pigs, horses, goats, sheep), birds (eg, chickens), insects, and the like. , Microorganisms, plants, fungi, and fish.
- a biological sample can also be a blood-related sample (eg, whole blood, serum, plasma), saliva, urine, milk, tissue or cell extract, or a mixture thereof, which is the blood itself or a sample derived from blood. Also good.
- the biological sample may further be derived from a mammal suffering from a disease (eg, cancer, leukemia) or a mammal potentially having a disease.
- the environmental sample include samples derived from soil, seawater, and fresh water that may contain nucleic acids. Such samples may be subjected to other processing before being used in the method of the present invention. Examples of such treatment include extraction of nucleic acid (eg, DNA such as genomic DNA, RNA) and fragmentation (eg, treatment with an enzyme such as a restriction enzyme).
- the methods of the invention may further comprise extracting nucleic acid from the nucleic acid sample and / or fragmenting the nucleic acid.
- the method of the present invention may further comprise processing the sample by centrifugation, extraction, filtration, precipitation, heating, freezing, refrigeration, stirring, and the like.
- the target nucleic acid is DNA or RNA, but DNA is preferred.
- the target nucleic acid is also a coding or non-coding region of DNA (eg, a transcriptional regulatory region).
- the number of nucleotide residues constituting the target nucleic acid is not particularly limited as long as it can hybridize with the capture probe. For example, it is 10 or more, preferably 15 or more, more preferably 20 It may be the above.
- the number of nucleotides constituting the target nucleic acid is not particularly limited, and may be any number that may be generated by fragmentation processing of genomic DNA, for example.
- the number of nucleotides constituting the target nucleic acid may be 10,000 or less, 5000 or less, 2000 or less, 1000 or less, 500 or less, 200 or 100 or less.
- the GC content of the target nucleic acid is not particularly limited, and may be, for example, 10% or more, 20% or more, 30% or more, 40% or more, 50% or more, or 60% or more.
- the GC content of the target nucleic acid may also be 90% or less, 80% or less, or 70% or less, for example.
- the number of modified nucleobases contained in the target nucleic acid is not particularly limited as long as it is 1 or more (eg, 1 to 100, 1 to 20, 1 to 10, or 1 to 5).
- the modified nucleobase is modified with respect to a normal nucleobase selected from the group consisting of adenine (A), guanine (G), cytosine (C), thymine (T) and uracil (U).
- a nucleobase having a structure includes, for example, adenine (A), guanine (G), cytosine (C) and thymine (T) when the target nucleic acid is DNA. It is done.
- the target nucleic acid when the target nucleic acid is RNA, examples thereof include adenine (A), guanine (G), cytosine (C), and uracil (U).
- the nucleobase is preferably cytosine (C).
- Modifications include, for example, introduction of substituents into normal nucleobases, elimination of groups (eg, amino group, oxo group, methyl group) possessed by ordinary nucleobases, substituents of groups possessed by ordinary nucleobases The exchange to is mentioned.
- the substituent is not particularly limited as long as it can be possessed by a naturally occurring nucleobase.
- the substituent is preferably methyl, hydroxymethyl, or carboxyl, and more preferably methyl or hydroxymethyl.
- the position of modification such as substitution is not particularly limited, but in the case of a nucleobase having a pyrimidine ring (C, T or U), for example, it is at the 2-position, 4- to 6-position, preferably at the 5-position, In the case of a nucleobase (A or G) having a purine ring, they are, for example, the 2nd, 6th and 8th positions.
- the modified nucleobase is not particularly limited as long as it can exist in nature.
- Administrative Instructions under the Patent Cooperation Treaty (enforced on January 1, 2009), Annex C, Appendix 2, Table 2: Examples thereof include modified nucleobases possessed by modified nucleotides described in Modified Nucleotides.
- the modified nucleotides described in this document may be the same as the modified nucleotides described in Appendix 2, Table 2: Modified Base Table of the above guidelines. Accordingly, reference can also be made to the above guidelines for modified nucleobases.
- the modified nucleobase is methylcytosine (eg, 5-methylcytosine), hydroxymethylcytosine (eg, 5-hydroxymethylcytosine), carboxyl cytosine (eg, 5-carboxyl cytosine). More preferably, the modified nucleobase is methylcytosine (eg, 5-methylcytosine), hydroxymethylcytosine (eg, 5-hydroxymethylcytosine).
- a modified nucleobase is known to cause a change in the function of the nucleic acid (eg, a change in the transcriptional regulatory ability of a given gene).
- the capture probe used in the present invention is a nucleic acid molecule that can hybridize with a target nucleic acid and a solid phase probe.
- the capture probe can, for example, hybridize with the target nucleic acid in the first region and hybridize with the solid phase probe in the second region.
- the capture probe can be composed of homologous and / or heterologous nucleic acids with respect to the target nucleic acid.
- the term “same species” means that the capture probe has the same main-chain structure as the main-chain structure of the target nucleic acid (structure composed of a sugar moiety and a phosphate moiety) as a whole of the main-chain structure. .
- the term “heterologous” means that the capture probe has a main chain structure that is different from the main chain structure of the target nucleic acid (structure composed of a sugar moiety and a phosphate moiety) as a part of or the whole main chain structure means. Therefore, the type of capture probe is determined according to the type of target nucleic acid. For example, when the target nucleic acid is DNA, a DNA probe can be used as a capture probe for homologous nucleic acids, and a nucleic acid probe other than a DNA probe can be used as a capture probe for heterologous nucleic acids.
- the target nucleic acid is a natural RNA
- a normal RNA probe composed of the same type of RNA as the natural RNA can be used as the same type of nucleic acid capture probe, and a normal RNA probe as a heterologous nucleic acid capture probe.
- Other nucleic acid probes can be used.
- the capture probe may contain a nucleic acid heterologous to the target nucleic acid.
- the capture probe examples include a DNA probe, an RNA probe, a peptide nucleic acid (PNA) probe, a lock nucleic acid (also referred to as LNA, bridged nucleic acid (BNA)) probe, a phosphorothioate (S) nucleic acid probe, and such 2 probes.
- PNA peptide nucleic acid
- BNA bridged nucleic acid
- S phosphorothioate
- a chimeric nucleic acid probe in which the above nucleic acid probes are linked and / or mixed the chimeric nucleic acid probe necessarily includes a nucleic acid heterologous to the target nucleic acid).
- RNA probe examples include a normal RNA probe composed of a natural ribonucleotide having a hydroxyl group at the 2 ′ position, and a modified RNA probe composed of a ribonucleotide modified with a hydroxyl group at the 2 ′ position.
- a ribonuclease resistant RNA probe may be used as the modified RNA probe.
- modified RNA probes include 2′-O-alkylated RNA probes. The 2′-O-alkylated RNA probe is preferably a 2′-O—C 1 -C 6 alkylated RNA probe.
- the C 1 -C 6 alkylated C 1 -C 6 alkyl group is a linear, branched or cyclic alkyl group having 1 to 6 carbon atoms, such as a methyl, ethyl, propyl group (eg, n -Propyl, iso-propyl), butyl group (eg, n-butyl, iso-butyl, sec-butyl, tert-butyl), pentyl group, hexyl group and the like.
- the 2′-O—C 1 -C 6 alkylated RNA probe is preferably a 2′-O-methylated RNA probe.
- the number of nucleotide residues constituting the capture probe (that is, the length of the capture probe) is not particularly limited as long as it is long enough to hybridize with the target nucleic acid and the solid phase probe. , Preferably 25 or more, more preferably 30 or more.
- the number of nucleotides constituting the capture probe may also be, for example, 100 or less, 80 or less, 60 or less, or 50 or less.
- the GC content in the first region that can hybridize with the target nucleic acid in the capture probe is not particularly limited, but for example, 10% or more, 20% or more, 30% or more, 40% or more, 50% or more, Or 60% or more may be sufficient.
- the GC content in the first region may also be, for example, 90% or less, 80% or less, or 70% or less.
- the second region that can hybridize with the solid phase probe in the capture probe may be composed of only the same type of nucleotide residues, or may be composed of two or more different types of nucleotide residues.
- the second region is composed only of nucleotide residues of the same type and the capture probe is a DNA probe
- the second region is preferably only one of adenine, guanine or thymine as a nucleobase A poly A, poly G or poly T region composed only of nucleotide residues containing, more preferably a poly A or poly T region composed only of nucleotide residues containing only one of adenine or thymine .
- the second region is composed only of nucleotide residues of the same type and the capture probe is an RNA probe
- the second region is preferably only one of adenine, guanine or uracil as a nucleobase.
- a poly A, poly G or poly U region composed only of nucleotide residues containing, more preferably a poly A or poly U region composed only of nucleotide residues containing only one of adenine or uracil .
- the second region is a poly A or poly T region.
- Such a capture probe can be prepared, for example, by a probe synthesis method known in the art. The capture probe is used in free form.
- a solid phase probe refers to a probe that can hybridize with a capture probe and can be immobilized on a solid phase.
- the solid phase probe is used in a free form or a form immobilized on a solid phase (described later).
- the solid phase probe may be labeled with a substance or group that allows immobilization to the solid phase. Labeling is performed, for example, at either the 5 'end or the 3' end. Examples of the group or substance that enables immobilization to a solid phase include a group or substance that enables covalent binding to a solid phase, and an affinity substance.
- Examples of the group or substance capable of covalently binding to a solid phase include, for example, a thiol group or a substance having a thiol group (such a thiol group introduced into a solid phase probe is a maleimide group on a solid phase). And an amino group or a substance having an amino group (such an amino group introduced into a solid phase probe can bind to maleic anhydride on a solid phase).
- Examples of the affinity substance include streptavidin, biotin, digoxigenin, dinitrophenol, fluorescein, and fluorescein isothiocyanate. In this case, as the solid phase, one coated with another affinity substance having affinity with the affinity substance possessed by the solid phase probe can be used.
- the solid phase probe can be composed of the same type or different type of nucleic acid with respect to the target nucleic acid.
- the term “same species” means that the solid phase probe has the same main chain structure as the main chain structure of the target nucleic acid (a structure composed of a sugar moiety and a phosphate moiety).
- the term “heterologous” means that the solid phase probe has a main chain structure different from the main chain structure of the target nucleic acid (structure composed of a sugar moiety and a phosphate moiety). Therefore, the type of solid phase probe is determined according to the type of target nucleic acid.
- a DNA probe can be used as the solid phase probe of the same nucleic acid, and a nucleic acid probe other than the DNA probe can be used as the solid phase probe of the heterologous nucleic acid.
- a normal RNA probe composed of the same type of RNA as the natural RNA can be used as a solid phase probe of the same type of nucleic acid, and a normal phase probe of heterogeneous nucleic acid can be used as a normal phase.
- Nucleic acid probes other than RNA probes can be used.
- the solid phase probe may be composed of a nucleic acid heterologous to the target nucleic acid.
- Examples of the solid phase probe include a DNA probe, an RNA probe, a peptide nucleic acid (PNA) probe, a lock nucleic acid (also referred to as LNA, bridged nucleic acid (BNA)) probe, a phosphorothioate (S) nucleic acid probe, and the like.
- Examples include chimeric nucleic acid probes in which two or more nucleic acid probes are linked and / or mixed.
- Examples of RNA probes include those described above for capture probes.
- the total number of nucleotide residues constituting the solid phase probe ensures the distance of the target nucleic acid from the solid phase that hybridizes with the capture probe and to which the solid phase probe is immobilized.
- the length is not particularly limited as long as the length is sufficient, but may be, for example, 10 or more, preferably 15 or more, more preferably 20 or more.
- the modified nucleobase can be detected with high sensitivity by securing the distance of the target nucleic acid from the solid phase (that is, the modified nucleobase detected in the present invention).
- the total number of nucleotides constituting the solid phase probe may also be, for example, 100 or less, 80 or less, 70 or less, or 60 or less.
- Such a solid phase probe can be prepared, for example, by a nucleotide polymerization method known in the art.
- the solid phase probe is a homopolynucleotide or a heteropolynucleotide.
- a homopolynucleotide refers to a polynucleotide composed of only homologous nucleotide residues.
- the homopolynucleotide is preferably a poly A, poly C or poly T composed only of nucleotide residues containing only one of adenine, cytosine or thymine as the nucleobase. More preferably, it is poly A or poly T composed of only nucleotide residues containing only one of adenine or thymine.
- the homopolynucleotide is preferably a poly A, poly C or poly U composed only of nucleotide residues containing only one of adenine, cytosine or uracil as a nucleobase. More preferably, it is poly A or poly U composed only of nucleotide residues containing only one of adenine or uracil.
- the homopolynucleotide is poly A or poly T.
- a heteropolynucleotide refers to a polynucleotide composed of two or more heterologous nucleotide residues.
- the heteropolynucleotide is preferably composed of nucleotide residues containing adenine, cytosine or thymine as a nucleobase, and more preferably composed of nucleotide residues containing adenine or thymine.
- the heteropolynucleotide is an RNA probe, the heteropolynucleotide is preferably composed of nucleotide residues containing adenine, cytosine or uracil as a nucleobase, more preferably composed of nucleotide residues containing adenine or uracil.
- the incubation is performed when the target nucleic acid is contained in the nucleic acid sample, and is hybridized with the capture probe (free), the solid phase probe (free or fixed on the solid phase described later) and the target nucleic acid in the nucleic acid sample. It is carried out in a suitable solution under conditions where the reaction is possible.
- a suitable solution for example, a buffer solution containing a salt (eg, sodium citrate) and other components (eg, a surfactant) can be used.
- the hybridization temperature is, for example, 15 to 95 ° C. (preferably 25 to 65 ° C.).
- the expression “incubating nucleic acid sample, capture probe and solid phase probe in solution” for step (1) means target nucleic acid (when nucleic acid sample contains target nucleic acid), capture probe and solid phase probe. It is contemplated that the nucleic acid sample, capture probe and solid phase probe are incubated simultaneously or in a time lag manner so that a hybrid composed of Accordingly, the above expression specifically encompasses the following aspects: (1-1) Incubating nucleic acid sample, capture probe and solid phase probe in solution simultaneously; (1-2) The nucleic acid sample and the capture probe are first incubated (if the nucleic acid sample contains the target nucleic acid, an intermediate hybrid composed of the target nucleic acid and the capture probe is formed), and then the solution obtained by the main incubation In combination with a solid phase probe (if the nucleic acid sample comprises a target nucleic acid, a hybrid composed of the target nucleic acid, the capture probe and the solid phase probe is formed); and (1-3) the capture probe and The solid phase probe is first incuba
- the nucleic acid sample does not contain the target nucleic acid, incubation of the nucleic acid sample, capture probe and solid phase probe in solution does not form the desired hybrid composed of the target nucleic acid, capture probe and solid phase probe.
- the modified nucleobase cannot be detected, but it can be determined that the modified nucleobase is not present in the nucleic acid sample. If the nucleic acid sample contains a target nucleic acid that does not contain a modified nucleobase (in other words, a target nucleic acid that contains only an unmodified nucleobase), the nucleic acid sample, capture probe and solid phase probe can be modified by incubating in solution.
- a target nucleic acid that does not contain a nucleobase, a capture probe, and a solid phase probe react to form a hybrid composed of the target nucleic acid, the capture probe, and the solid phase probe.
- the modified nucleobase cannot be detected, but the modified nucleobase is not present in the nucleic acid sample (although the target nucleic acid is present), in other words, the target It can be determined that a given nucleobase in the nucleic acid is not modified.
- the target nucleic acid containing the modified nucleobase, the capture probe and the solid phase probe react by incubating the nucleic acid sample, the capture probe and the solid phase probe in solution.
- a hybrid composed of the target nucleic acid, the capture probe and the solid phase probe is formed.
- the presence of the modified nucleobase can be determined, and the modified nucleobase can also be quantified.
- the hybrid is formed by the double-stranded structure of the target nucleic acid and the capture probe formed by hybridization between the target nucleic acid and the capture probe, and the hybridization between the capture probe and the solid phase probe.
- a hybridization complex composed of a target nucleic acid, a capture probe and a solid phase probe, having a double-stranded structure of the capture probe and the solid phase probe. Examples of hybrid structures are as described in Tables 1-1 to 1-5 below.
- the double-stranded structure of the target nucleic acid and the capture probe may be formed in the entire region or a partial region of the target nucleic acid.
- the hybrid may have a single-stranded structure of the target nucleic acid in either the 5 ′ terminal region or the 3 ′ terminal region [eg, (a-1) to (a-5), (b ⁇ 1) to (b-5)], or a double-stranded structure may be formed in the entire region of the target nucleic acid [eg, (c-1) to (c-5), (d-1) to ( d-5), (e-1) to (e-5), (f-1) to (f-5)].
- a single-stranded structure of the target nucleic acid in either the 5 ′ terminal region or the 3 ′ terminal region [eg, (a-1) to (a-5), (b ⁇ 1) to (b-5)]
- a double-stranded structure may be formed in the entire region of the target nucleic acid [eg, (c-1) to (c-5), (d-1) to ( d-5), (e-1) to (e-5), (f-1) to (f-5)].
- the solid phase probe may hybridize with a capture probe at the 5 ′ end region to form a double-stranded structure [eg, (a-1) to (a-2), (c-1) to ( c-2), (e-1) to (e-2), (b-3) to (b-5), (d-3) to (d-5), (f-3) to (f- 5)], or may be hybridized with a capture probe at the 3 ′ end region to form a double-stranded structure [eg, (a-3) to (a-5), (c-3) to ( c-5), (e-3) to (e-5), (b-1) to (b-2), (d-1) to (d-2), (f-1) to (f- 2)].
- a double-stranded structure eg, (a-1) to (a-2), (c-1) to ( c-2), (e-1) to (e-2), (b-3) to (b-5), (d-1) to (d-2), (f-1) to (f- 2)].
- a single-stranded structure is a non-hybridized region of one or more nucleotide residues at the 5 ′ and / or 3 ′ end of a hybridized target nucleic acid, capture probe or solid phase probe, or non-terminal of a complementary probe It is a structure formed by having. In (a-1) to (f-5), the 5 ′ terminal region and 3 ′ terminal region of the target nucleic acid, the 5 ′ terminal region and 3 ′ terminal region of the capture probe, and the 5 ′ terminal region of the solid phase probe And a structure in which at least three of the 3 ′ terminal regions are hybridized.
- these three terminal regions do not necessarily have to hybridize either, and single-stranded structural portions (ie, non-hybridized) in both the 3 ′ end region of the target nucleic acid and the 5 ′ end region of the capture probe.
- Soybean region may have a single-stranded structure in both the 5 ′ end region of the target nucleic acid and the 3 ′ end region of the capture nucleic acid.
- Both of the 5 ′ end regions of the phase probe may have a single-stranded structure portion, and both the 5 ′ end region of the capture probe and the 3 ′ end region of the solid phase probe have a single-stranded structure portion. It may be.
- the number of nucleotide residues of the target nucleic acid and the capture probe corresponding to the double-stranded structure part of the target nucleic acid and the capture probe, and the capture probe and the solid phase corresponding to the double-stranded structure part of the capture probe and the solid phase probe The number of nucleotide residues of the probe (ie, the length of the double-stranded structure) is not particularly limited as long as it is long enough to allow hybridization with the target nucleic acid. The number may be 15 or more, more preferably 20 or more. The number of such nucleotide residues may also be, for example, 100 or less, 80 or less, 60 or less, 50 or less, 40 or less, or 30 or less.
- the GC content in the double-stranded structure portion of the target nucleic acid and the capture probe is not particularly limited.
- the GC content is 10% or more, 20% or more, 30% or more, 40% or more, 50% or more, or 60% or more. There may be.
- the GC content in the double-stranded structure part of the target nucleic acid and the capture probe may also be 90% or less, 80% or less, or 70% or less, for example.
- the GC content in the double-stranded structure portion of the capture probe and the solid phase probe is preferably low.
- the number of nucleotide residues of the target nucleic acid, the capture probe, and the solid phase probe corresponding to the single-stranded structure portion is not particularly limited as long as it is 1 or more. Is, for example, 2 or more, 3 or more, 4 or more, 5 or more, 6 or more, 7 or more, 8 or more, 9 or more, 10 or more, 15 or more, 20 or more, or 50 It is more than one. Such a number is not particularly limited, and may be, for example, 10,000 or less, 5000 or less, 2000 or less, 1000 or less, 500 or less, 200 or less, or 100 or less. Capture probes and / or solid phase probes may be designed to form such single-stranded structural moieties in the hybrid at the 5 'end region or the 3' end region.
- the capture probe may be designed such that an unpaired portion of the modified nucleobase is formed in a double stranded structure composed of the target nucleic acid and the capture probe in the hybrid.
- the unpaired portion of the modified nucleobase can be introduced to facilitate detection of the modified nucleobase by the antibody.
- a capture probe having a nucleotide sequence that is not completely complementary to the target nucleic acid in the double-stranded structure portion may be used.
- An example of a capture probe in which an unpaired portion of a modified nucleobase is formed in a double-stranded structure composed of a target nucleic acid and a capture probe in a hybrid is complementary to a nucleotide residue having a modified nucleobase in the target nucleic acid
- Capture probe lacking a typical nucleotide residue [eg, (I) of Table 2].
- Such a capture probe may lack only one nucleotide residue complementary to a nucleotide residue having a modified nucleobase in the target nucleic acid (eg, (I-1) in Table 2), It may lack two or more (eg, 2-20, 2-10, or 2-5) contiguous nucleotide residues including nucleotide residues with modified nucleobases in nucleic acids [eg, (I-2) in Table 2].
- the number in the unpaired portion of the nucleotide residue having the modified nucleobase is not particularly limited as long as it is 1 or more as described above.
- Patent Document 1 and Non-Patent Document 2 See, for example, Patent Document 1 and Non-Patent Document 2. Such a design is possible if the position of the nucleotide residue having the modified nucleobase in the target nucleic acid to be measured is known.
- Another example of a capture probe in which an unpaired portion of a modified nucleobase is formed in a double stranded structure composed of a target nucleic acid and a capture probe in a hybrid is for nucleotide residues having modified nucleobases in the target nucleic acid.
- Capture probes having non-complementary nucleotide residues [eg, (I ′) in Table 2].
- Such a capture probe may have only one nucleotide residue that is non-complementary to a nucleotide residue having a modified nucleobase in the target nucleic acid [eg, (I′-1) in Table 2], Two or more (for example, 2 to 20, 2 to 10, or 2 to 5) adjacent nucleotide residues including a nucleotide residue having a modified nucleobase in the target nucleic acid may be non-complementary. [Example, (I′-2) in Table 2].
- Such a design is possible if the position of the nucleotide residue having the modified nucleobase in the target nucleic acid to be measured is known.
- the capture probe may be designed such that the modified nucleobase is present in the hybrid single stranded structure.
- the modified nucleobase may be present at the non-terminal portion of the single-stranded structure portion on the 5 ′ end side (eg, (II) in Table 4), It may be present at the end of the single-stranded structure portion on the 5 ′ end side (eg, (III) in Table 4), and may be present at the non-terminal portion of the single-stranded structure portion on the 3 ′ end side.
- the capture probe may be designed such that the hybrid single-stranded structural portion (target nucleic acid) contains the modified nucleobase in this manner.
- the number in the single-stranded structure portion of the nucleotide residue having a modified nucleobase is not particularly limited as long as it is 1 or more as described above.
- the capture probe is such that the modified nucleobase is present in the hybrid single-stranded structure and, as described above, an unpaired portion of the modified nucleobase is further formed in the hybrid double-stranded structure. May be designed. Such a design is possible if the position of the nucleotide residue having the modified nucleobase in the target nucleic acid to be measured is known.
- the method of the present invention further comprises preparing a solution containing the nucleic acid sample, the capture probe and the solid phase probe by adding a solution containing the nucleic acid sample and the capture probe to the solid phase to which the solid phase probe is immobilized. You may go out.
- the method of the present invention may further include preparing a solution containing both the nucleic acid sample and the capture probe by adding the capture probe to the solution containing the nucleic acid sample.
- the capture probe can be added to the nucleic acid sample in solid form or as a solution.
- a nucleic acid sample and a capture probe are added simultaneously or separately to a solid phase probe in a solution fixed to a solid phase, and a solution containing the nucleic acid sample, the capture probe and the solid phase probe is added. It may further comprise preparing.
- the concentration of the target nucleic acid in the solution is not particularly limited as long as it can be detected by the method of the present invention. It may be 0.01 nM or more, preferably 0.1 nM or more, more preferably 1 nM or more, 5 nM or more, or 10 nM or more.
- the concentration of the target nucleic acid in the solution may also be, for example, 1 M or less, 100 mM or less, 10 mM or less, 1 mM or less, 100 ⁇ M or less, 10 ⁇ M or less, or 1 ⁇ M or less.
- the target nucleic acid concentration in the nucleic acid sample is often unknown, so it may be difficult to set the exact target nucleic acid concentration.
- concentration of the target nucleic acid may be known (eg, the presence and absence of modified nucleobases in the target nucleic acid, although the size and / or concentration of the target nucleic acid is separately measured) And the content of the modified nucleobase in the target nucleic acid is unknown). In such a case, the concentration of the target nucleic acid may be set as described above.
- the concentration of the capture probe in the solution is not particularly limited as long as the target nucleic acid can be detected by the method of the present invention. For example, 0.01 nM or more, preferably 0.1 nM or more, more preferably 1 nM or more, and even more preferably It may be 5 nM or more, particularly preferably 10 nM or more.
- the concentration of the capture probe in the solution may also be, for example, 1 M or less, 100 mM or less, 10 mM or less, 1 mM or less, 100 ⁇ M or less, 10 ⁇ M or less, or 1 ⁇ M or less.
- capture probes may be added to the solution so that such concentrations are achieved.
- the concentration of the solid phase probe in the solution is not particularly limited as long as the target nucleic acid can be detected by the method of the present invention. For example, 0.01 nM or more, preferably 0.1 nM or more, more preferably 1 nM or more, 5 nM or more, Alternatively, it may be 10 nM or more.
- the concentration of the capture probe in the solution may also be, for example, 1 M or less, 100 mM or less, 10 mM or less, 1 mM or less, 100 ⁇ M or less, 10 ⁇ M or less, or 1 ⁇ M or less.
- a solid phase probe may be added to the solution so that such a concentration is achieved.
- the target nucleic acid may be a target nucleic acid that may contain two or more modified nucleobases.
- the number of modified nucleobases that may be contained in the target nucleic acid is not particularly limited as long as it is 2 or more. For example, 2 to 30, 2 to 20, 2 to 10, or 2 to 5 (Eg, 2, 3, 4 or 5).
- the methods of the invention can use heterologous nucleic acid probes designed to hybridize with target nucleic acids that may contain two or more modified nucleobases. Such a design is possible if the number of nucleobases that may be modified in the target nucleic acid to be measured is known.
- the modified nucleobase is measured using an antibody against the modified nucleobase in a solution containing the hybrid.
- the solution obtained in the step (1) may be used as it is.
- another solution is added and / or another solution is added.
- Exchange to a solution may be performed. Such exchange can be performed, for example, by adding the solution obtained in step (1) to the solid phase, immobilizing the hybrid that may be contained in the solution to the solid phase, and then removing the solution from the solid phase. Accordingly, after washing with a washing solution, another solution (eg, a solution containing an antibody against a modified nucleobase) can be added.
- the solution used for the measurement is not particularly limited as long as it is a solution suitable for the antigen / antibody reaction.
- Measurement can be performed by immunological techniques.
- immunological techniques include enzyme immunoassay (EIA) (eg, direct competition ELISA, indirect competition ELISA, sandwich ELISA), radioimmunoassay (RIA), fluorescence immunoassay (FIA), Examples include immunochromatography, luminescence immunoassay, spin immunoassay, western blot, and latex agglutination.
- EIA enzyme immunoassay
- RIA radioimmunoassay
- FFA fluorescence immunoassay
- Examples include immunochromatography, luminescence immunoassay, spin immunoassay, western blot, and latex agglutination.
- the antibody against the modified nucleobase may be a polyclonal antibody or a monoclonal antibody.
- the antibody against the modified nucleobase may be any isotype of immunoglobulin (eg, IgG, IgM, IgA, IgD, IgE, IgY).
- the antibody against the modified nucleobase may also be a full-length antibody.
- a full-length antibody refers to an antibody comprising a heavy chain and a light chain comprising a variable region and a constant region, respectively (eg, an antibody comprising two Fab portions and an Fc portion).
- the antibody against the modified nucleobase may also be an antibody fragment derived from such a full-length antibody.
- the antibody fragment is a part of a full-length antibody, and examples thereof include F (ab ′) 2 , Fab ′, Fab, and Fv.
- the antibody against the modified nucleobase may also be a modified antibody such as a single chain antibody.
- the antibody against the modified nucleobase may be further used as a primary antibody in an immunoassay such as ELISA, and in this case, a secondary antibody is used in combination.
- An antibody against a modified nucleobase is a modified nucleobase, a nucleoside having a modified nucleobase (a structural unit composed of a modified nucleobase and 2′-deoxyribose or ribose), or a nucleotide having a modified nucleobase (modified nucleobase, 2 '-Deoxyribose or structural unit composed of ribose and phosphate) or affinity to two or more nucleotides (eg, oligonucleotide composed of 2 to 5 nucleotides) including nucleotides with modified nucleobases If you do.
- the antibody against the modified nucleobase is 1) from the group consisting of 2′-deoxy modified adenosine, 2′-deoxy modified guanosine, 2′-deoxy modified cytidine and 2′-deoxy modified thymidine Selected antibodies against deoxyribonucleosides with modified nucleobases 2) 2'-deoxy modified adenosine 5'-phosphate, 2'-deoxy modified guanosine 5'-phosphate, 2'-deoxy modified cytidine 5'-phosphate and 2 ' -An antibody against deoxyribonucleotides having a modified nucleobase selected from the group consisting of deoxy-modified thymidine 5'-phosphate, and 3) against two or more deoxyribonucleotides comprising the above deoxyribonucleotides having a modified nucleobase Body, and the like.
- an antibody against a modified nucleobase when the target nucleic acid is RNA for example, 1 ′
- an antibody against a nucleoside having a modified nucleobase selected from the group consisting of modified adenosine, modified guanosine, modified cytidine and modified uridine e.g., 1 ′
- an antibody against a ribonucleotide having a modified nucleobase selected from the group consisting of modified adenosine 5'-phosphate, modified guanosine 5'-phosphate, modified cytidine 5'-phosphate and modified uridine 5'-phosphate e.g., 3'
- An antibody against two or more ribonucleotides including the ribonucleotide having a modified nucleobase can be mentioned.
- An antibody against a modified nucleobase includes, for example, a modified nucleobase, a nucleoside having a modified nucleobase, a nucleotide having a modified nucleobase, or two or more nucleotides including a nucleotide having a modified nucleobase, and a carrier protein (eg, BSA, KLH). ) And a complex prepared using an antigen as an antigen.
- a complex prepared using an antigen as an antigen may be used in the method of the present invention.
- an antibody against a modified nucleobase prepared as described below may be used.
- a polyclonal antibody against a modified nucleobase is used about 2 to 4 times every 2 to 3 weeks subcutaneously or intraperitoneally in an animal together with a commercially available adjuvant (eg, complete or incomplete Freund's adjuvant) using the above complex as an antigen. It is obtained by collecting whole blood about 3 to about 10 days after the final immunization and purifying the antiserum.
- adjuvant eg, complete or incomplete Freund's adjuvant
- animals to which the antigen is administered include mammals such as rats, mice, rabbits, goats, cows, guinea pigs, and hamsters.
- a monoclonal antibody against the modified nucleobase can be produced, for example, by a cell fusion method.
- the above complex is administered to a mouse subcutaneously or intraperitoneally 2-4 times together with a commercially available adjuvant, and the spleen or lymph node is collected about 3 days after the final administration, and white blood cells are collected.
- the leukocytes and myeloma cells eg, NS-1) are fused to obtain a hybridoma that produces a monoclonal antibody against the factor.
- Examples of cell fusion include a PEG method and a voltage pulse method.
- a hybridoma producing a desired monoclonal antibody can be selected by detecting an antibody that specifically binds to an antigen from the culture supernatant using a well-known EIA or RIA method.
- the hybridoma producing the monoclonal antibody can be cultured in vitro or in vivo, such as mouse or rat, preferably mouse ascites, and the antibody can be obtained from the culture supernatant of the hybridoma and the ascites of the animal, respectively.
- the monoclonal antibody may be any isotype such as IgG, IgM, IgA, and IgE.
- monoclonal antibody production methods include phage display (Ulman et al., Proc. Natl. Acad. Sci. USA, 90, 1184-89 (1993)), ADLib system (International Publication No. 2004 / Since in vitro methods such as No. 016444) are also known, such methods may be used for the production of antibodies against modified nucleobases.
- the antibody against the modified nucleobase may be used by being immobilized on a solid phase.
- the solid phase include particles (eg, magnetic particles), membranes (eg, nitrocellulose membrane), supports such as glass, plastic and metal, containers such as plates (eg, multiwell plates), and devices. It is done.
- the antibody may also be provided in a form impregnated in a medium such as filter paper.
- the antibody against the modified nucleobase may be labeled with a labeling substance.
- the labeling substance examples include enzymes (eg, peroxidase, alkaline phosphatase, luciferase, ⁇ -galactosidase), affinity substances (eg, streptavidin, biotin), fluorescent substances or proteins (eg, fluorescein, fluorescein isothiocyanate, rhodamine, green) Fluorescent proteins, red fluorescent proteins), luminescent substances (eg, luciferin, aequorin), radioactive substances (eg, 3 H, 14 C, 32 P, 35 S, 125 I).
- enzymes eg, peroxidase, alkaline phosphatase, luciferase, ⁇ -galactosidase
- affinity substances eg, streptavidin, biotin
- fluorescent substances or proteins eg, fluorescein, fluorescein isothiocyanate, rhodamine, green Fluorescent proteins, red fluorescent proteins), luminescent substances (eg, luci
- the measurement of the modified nucleobase by the antibody against the modified nucleobase is performed qualitatively or quantitatively, and the presence or amount of the modified nucleobase can be evaluated.
- the measurement of the modified nucleobase is intended not only to measure the modified nucleobase itself but also to measure the target nucleic acid containing the modified nucleobase.
- the determination of the presence or absence of a modified nucleobase may be performed as follows: (2-1) measuring the signal value by assaying with the antibody against the modified nucleobase in the solution obtained in the above step (1); (2-2) Measuring a background value by assaying with an antibody against the modified nucleobase in a solution that does not contain the target nucleic acid containing the modified nucleobase and contains the capture probe and the solid phase probe; And (2-3) comparing the signal value with the background value to evaluate the presence or absence of modified nucleobases.
- the signal value and the background value are values measured using a label bound to an antibody against the modified nucleobase or a secondary antibody (when a secondary antibody is used) (eg, absorbance, Fluorescence, color development, and radioactivity).
- the measurement of the amount of the modified nucleobase may be performed together with the measurement of the background value, for example. Specifically, it may be done by: (2-1 ′) measuring the signal value by assaying with an antibody against the modified nucleobase in the solution obtained in the above step (1); (2-2 ') Measuring a background value by assaying with an antibody against a modified nucleobase in a solution containing no target nucleic acid containing a modified nucleobase and containing a capture probe and a solid phase probe. ; (2-3 ′) correcting the signal value with the background value to obtain a corrected signal value; and (2-4 ′) evaluating the amount of modified nucleobase based on the corrected signal value.
- the amount of modified nucleobase may be measured using a standard. Specifically, it may be done by: (2-1 ′′) measuring the signal value by assaying with an antibody against the modified nucleobase in the solution obtained in the above step (1); (2-2 ′′) A target nucleic acid containing a modified nucleobase (standard) and a solution containing a capture probe and a solid phase probe are assayed using an antibody against the modified nucleobase, and a calibration value is measured. And (2-3 ′′) assessing the amount of modified nucleobases by comparing signal values to calibration values. The measurement using the standard may be used in combination with the measurement of the background value.
- the methods of the invention may be performed by ELISA.
- the method of the invention by ELISA may be performed as follows: (I) A nucleic acid sample containing a target nucleic acid containing a modified nucleobase, a capture probe and a solid phase probe labeled with a first affinity substance are incubated in a solution, and the target nucleic acid, the capture probe and the solid phase Forming a hybrid composed of probes; (Ii) immobilizing the hybrid to a solid phase treated with a second affinity substance; (Iii) reacting a primary antibody against the modified nucleobase with a hybrid immobilized on a solid phase to obtain a primary complex of the primary antibody and the hybrid; (Iv) reacting a secondary antibody labeled with a labeling substance with the primary complex to obtain a secondary complex of the secondary antibody and the primary antibody; and (v) 2 in the secondary
- the first affinity substance and the second affinity substance are Used in combination with affinity (eg, combination of biotin and streptavidin).
- affinity eg, combination of biotin and streptavidin.
- obtaining a solid phase probe immobilized on a solid phase eg, adding a solid phase probe labeled with a first affinity substance to a solid phase treated with a second affinity substance
- the method of the present invention may comprise washing the solid phase prior to step (iii).
- the secondary antibody may be an antibody that recognizes only the primary antibody (eg, an antibody that binds to the constant region of the primary antibody), but both the primary antibody and the primary complex in the secondary complex. May be recognized.
- the methods of the invention involving (i)-(v) can also be performed according to the methodology described in detail herein.
- the present invention also provides a kit for measuring a modified nucleobase.
- the kit of the present invention includes, for example: (I) a capture probe; (II) a solid phase probe; and (III) an antibody against the modified nucleobase.
- the antibodies for the capture probe, solid phase probe and modified nucleobase are as described above.
- the solid phase probe may be labeled with an affinity substance
- the antibody against the modified nucleobase may be labeled with a labeling substance.
- the kit of the present invention comprises an affinity substance, a labeling substance, a secondary antibody, a detection reagent for the secondary antibody (eg, a substrate for the enzyme when the secondary antibody is labeled with an enzyme), a solid phase, etc. It may further contain the components as described above.
- the solid phase may be treated with an affinity substance.
- the kit of the present invention may also contain a modified nucleobase preparation or a target nucleic acid preparation containing the modified nucleobase as a solution or as a
- the kit of the present invention includes each component in an isolated form or a mixed form.
- each component may be provided in a form accommodated in a different container (eg, tube, plate).
- the capture probe and the solid phase probe are mixed.
- the kit of the present invention may be provided in the form of a device. Specifically, all of the components may be provided in a form housed in the device. Alternatively, some of the components may be provided in a form housed in the device, and the rest may be provided in a form that is not housed in the device (eg, a form housed in a different container). In this case, components that are not contained in the device may be used by being injected into the device during measurement of the target substance.
- Example 1 Examination of solid phase probe The influence of the solid phase probe on the background value of the detection signal was examined.
- the nucleotide sequence of the solid phase probe (DNA) is as shown in Table 5, and those artificially synthesized by Hokkaido System Saens were used.
- a solid phase probe was dissolved in 100 ⁇ L of hybridization buffer (4 ⁇ SSC, 0.1% SDS), and then added to a streptavidin-coated plate (manufactured by Thermo Scientific) at 37 ° C. By reacting for 30 minutes, the solid phase probe was immobilized on the streptavidin plate. Washed twice with 300 ⁇ L of PBS-T, and 500 ng / mL anti-methylcytosine antibody (Millipore, Clone33D3.
- This antibody is not limited to 5-methylcytosine but also the main chain structure of DNA (eg, deoxyribose moiety and 50 ⁇ L of an antibody that recognizes at least a part of a structure composed of repeating units of a phosphate moiety) was added and reacted at 37 ° C. for 1 hour. After washing 3 times with 300 ⁇ L PBS-T, 50 ⁇ L of 500 ng / mL peroxidase-labeled anti-IgG antibody (Thermo Scientific) was added and reacted at 37 ° C. for 30 minutes.
- DNA eg, deoxyribose moiety and 50 ⁇ L of an antibody that recognizes at least a part of a structure composed of repeating units of a phosphate moiety
- Example 2 Use of solid phase and capture probes in the measurement of modified nucleobases (1)
- the nucleotide sequence of the target nucleic acid (DNA) is 5′-TTGCCGCGCGTC [C] GTCCTGTTGAACTTC-3 ′ (SEQ ID NO: 11, [C] is 5-methylcytosine)
- the nucleotide sequence of the capture probe (DNA) for capturing the target nucleic acid Is 5'-GAAGTCCAACAGGACGACGCCCGCGCAAAAAAAAAAAAAAAAAAAAAA-3 '(SEQ ID NO: 12)
- nucleotide sequence of solid phase probe (DNA) is 5'-TTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTT
- the capture probe When the capture probe is hybridized with the target nucleic acid and the solid phase probe, an unpaired portion is formed at the modified nucleobase [C] in the double-stranded structure portion composed of the target nucleic acid and the capture probe. Designed.
- the measurement of the modified nucleobase using the solid phase probe and the capture probe was performed as follows. First, 5 pmol of a solid phase probe was dissolved in 100 ⁇ L of PBS buffer, and then added to a streptavidin-coated plate (Thermo Scientific), and reacted at 37 ° C. for 30 minutes. A solid phase probe was immobilized on the surface.
- the immobilized solid phase probe nucleic acid was washed twice with 300 ⁇ L of PBS-T, and a target nucleic acid (1-pmol, 0.1-pmol) containing 5-methylcytosine in hybridization buffer (4 ⁇ SSC, 0.1% SDS) was obtained.
- the concentration of the target nucleic acid is 10 nM, 1 nM, 0.1 nM, or 0.01 nM, respectively
- the concentration of the solid phase probe is theoretically 50 nM or less (50 nM assuming that the total amount of the solid phase probe used is immobilized on the solid phase), and the reaction is performed at 60 ° C. for 2 hours. Subsequently, the reaction is carried out at 37 ° C. for 30 minutes to hybridize the target nucleic acid, the capture probe, and the solid phase probe. It was allowed to form.
- Example 3 Use of solid phase and capture probes in the measurement of modified nucleobases (2)
- the nucleotide sequence of the capture probe (DNA) is 5'-GAAGTCAACAGGACGACGCCCGCGCAATTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTT
- Example 4 Use of solid phase and capture probes in the measurement of modified nucleobases (3) 5'-GAAGTCAACAGGACGACGCCCGCCGCAACCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCCC-3 '(SEQ ID NO: 16) as the nucleotide sequence of the capture probe (DNA), and 5'-GGGGGGGGGGGGGG-3' (SEQ ID NO: 17, 5 'end is biotin-labeled as the nucleotide sequence of the solid phase probe (DNA) ) was used in the same manner as in Example 2, except that As a result, it was confirmed that the combined use of the solid phase probe and the capture probe suppressed the background value and improved the S / N value as compared with the single use of the capture probe (Reference Example 1) (Table 7). 3-5). In addition, the solid-phase probe and the capture probe used in this example had lower background value suppression efficiency than those in Examples 2 and 3. This indicates that a solid phase probe with a low content of guanine residues is more appropriate.
- Reference Example 1 Use of capture probe in measurement of modified nucleobases (1)
- the nucleotide sequence of the target nucleic acid (DNA) is 5′-TTGCCGCGCGTC [C] GTCCTGTTGAACTTC-3 ′ (SEQ ID NO: 11, [C] is 5-methylcytosine), and the nucleotide sequence of the capture probe (DNA) is 5′-GAAGTCACAGAGCGACGCCGCGCAA-3 '(SEQ ID NO: 18, 5' ends are labeled with biotin), and those artificially synthesized by Hokkaido System Science Co., Ltd. were used.
- the measurement of the modified nucleobase using the capture probe was performed as follows. First, a hybridization buffer (4 ⁇ SSC, 0.
- Example 5 Use of solid phase and capture probes in the measurement of modified nucleobases (4)
- the nucleotide sequence of the target nucleic acid (DNA) is 5′-AATCAG [C] GGGAGCTCTTTCTTTGCGCGGGCGTCCGTCCTGTTGACTTC-3 ′ (SEQ ID NO: 19, [C] is 5-methylcytosine)
- the nucleotide sequence of the capture probe (DNA) for capturing the target nucleic acid Is 5'-GAAGTCAACAGGACGGACGCCGCGCAAAAAAAAAAAAAA-3 '(SEQ ID NO: 12)
- the nucleotide sequence of the solid phase probe (DNA) is 5'-TTTTTTTTTTTTTTTTTTTTTTTTTTTTTT-3'
- the artificially synthesized products were used.
- the capture probe was designed such that the modified nucleobase [C] is present in the single-stranded structure portion of the hybrid when a hybrid with the target nucleic acid and the solid phase probe is formed.
- Measurement of modified nucleobases using capture probes and solid phase probes uses different target nucleic acids in different amounts (10 pmol, 1 pmol, 0.1 pmol or 0.01 pmol) and uses different capture probes and different solid phase probes.
- Reference Example 2 Use of capture probe in measurement of modified nucleobases
- the nucleotide sequence of the target nucleic acid (DNA) is 5′-AATCAG [C] GGGAGCTCTTTCTTTGCGCGGGCGTCCGTCCTGTTGACTTC-3 ′ (SEQ ID NO: 19, [C] is 5-methylcytosine), the nucleotide sequence of the capture probe (DNA) for capturing the target nucleic acid Is 5′-GAAGTCAACAGGACGGACGCCGCCAA-3 ′ (SEQ ID NO: 18, 5 ′ end is biotin-labeled), and those artificially synthesized by Hokkaido System Science Co., Ltd. were used.
- the measurement of the modified nucleobase using the capture probe was performed as follows.
- a target nucleic acid (10 pmol, 1 pmol, 0.1 pmol or 0.01 pmol) containing 5-methylcytosine and a capture probe (5 pmol) were dissolved in 100 ⁇ L of hybridization buffer (4 ⁇ SSC, 0.1% SDS). Thereafter, the reaction was performed at 60 ° C. for 2 hours to form a hybrid of the target nucleic acid and the capture probe. A solution not containing the target nucleic acid was also prepared and the same operation was performed. 100 ⁇ L of the solution after the hybridization reaction was added to a streptavidin-coated plate (Thermo Scientific) and reacted at 37 ° C. for 30 minutes to immobilize the nucleic acid hybrid on the streptavidin plate.
- streptavidin-coated plate Thermo Scientific
- Example 6 Use of solid phase and capture probes in the measurement of modified nucleobases (5)
- the nucleotide sequence of the target nucleic acid (DNA) is 5′-G [C] GGAGCTCTCCCT [C] GGGA [C] GGTGGCAGCCCTGAGGTGTCCTGCA-3 ′ (SEQ ID NO: 20, [C] is 5-methylcytosine), for capturing the target nucleic acid
- the nucleotide sequence of the capture probe (DNA) is 5′-AAAAAAAAAAAAAAAAAAAAAGCAGGACCACTCGGAGCTGCCAC-3 ′ (SEQ ID NO: 21)
- the nucleotide sequence of the solid phase probe (DNA) is 5′-TTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTT
- the capture probe was designed such that the modified nucleobase [C] is present in the single-stranded structure portion of the hybrid when a hybrid with the target nucleic acid and the solid phase probe is formed.
- the measurement of the modified nucleobase using the capture probe and the solid phase probe was performed as follows. First, 5 pmol of a solid phase probe was dissolved in 100 ⁇ L of PBS buffer, and then added to a streptavidin-coated plate (Thermo Scientific), and reacted at 37 ° C. for 30 minutes. A solid phase probe was immobilized on the surface.
- the detection sensitivity is amplified by the combined use of a capture probe and a solid phase probe in a low concentration range (eg, 0 to 0.01 pmol) of a target nucleic acid containing a plurality of modified nucleobases.
- Reference Example 3 Use of capture probe in measurement of modified nucleobases (3)
- the nucleotide sequence of the target nucleic acid (DNA) is 5′-G [C] GGAGCTCTCCCT [C] GGGA [C] GGTGGCAGCCCTGAGGTGTCCTGCA-3 ′ (SEQ ID NO: 20, [C] is 5-methylcytosine), for capturing the target nucleic acid
- the nucleotide sequence of the capture probe (DNA) was 5′-TGCAGGACCACTCGAGGCTGCCAC-3 ′ (SEQ ID NO: 22, 5 ′ end was labeled with biotin), and those artificially synthesized by Hokkaido System Science Co., Ltd. were used.
- target nucleic acid (1 pmol, 0.1 pmol, 0.01 pmol or 0.001 pmol) containing 5-methylcytosine and a capture probe (5 pmol) are dissolved in 100 ⁇ L of hybridization buffer (4 ⁇ SSC, 0.3% Tween 20). Then, the reaction was carried out at 60 ° C. for 2 hours to form a hybrid of the target nucleic acid and the capture probe. A solution not containing the target nucleic acid was also prepared and the same operation was performed. 100 ⁇ L of the solution after the hybridization reaction was added to a streptavidin-coated plate (Thermo Scientific) and reacted at 37 ° C.
- streptavidin-coated plate Thermo Scientific
- Example 7 Use of solid phase and capture probes in the measurement of modified nucleobases (6)
- the nucleotide sequence of the target nucleic acid (DNA) is 5′-G [C] GCAC [C] GTTTG [C] GACTTGGTGAGTGTCTGGGT [C] GCCT [C] GCCTCC-3 ′ (SEQ ID NO: 23, [C] is 5-methylcytosine)
- the nucleotide sequence of the capture probe (DNA) for capturing the target nucleic acid is 5′-AAAAAAAAAAAAAAAAACCCACAACTCACCCAAGTC-3 ′ (SEQ ID NO: 24)
- the nucleotide sequence of the solid phase probe (DNA) is 5′-TTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTT
- the capture probe was designed such that the modified nucleobase [C] is present in the single-stranded structure portion of the hybrid when a hybrid with the target nucleic acid and the solid phase probe is formed.
- the measurement of the modified nucleobase using the capture probe and the solid phase probe was performed in the same manner as in Example 6 except that a different target nucleic acid and a different capture probe were used.
- a target nucleic acid different from Example 2 Example 5 and Example 6 and a different capture probe were used, a decrease in the background value, And the improvement of S / N value was recognized (Table 10, FIG. 10, 11).
- the combined use of a capture probe and a solid phase probe is between the target nucleic acid concentration range (0.001 to 1 pmol) and the detection signal value.
- the use of only the capture probe showed almost no change in the detection signal value in the low concentration range (0 to 0.01 pmol) of the target nucleic acid ( FIG. 11).
- the detection sensitivity is amplified by the combined use of a capture probe and a solid phase probe in a low concentration range (eg, 0 to 0.01 pmol) of a target nucleic acid containing a plurality of modified nucleobases.
- Reference Example 4 Use of capture probe in measurement of modified nucleobases (4)
- the nucleotide sequence of the target nucleic acid (DNA) is 5′-G [C] GCAC [C] GTTTG [C] GACTTGGTGAGTGTCTGGGT [C] GCCT [C] GCCTCC-3 ′ (SEQ ID NO: 23, [C] is 5-methylcytosine)
- the nucleotide sequence of the capture probe (DNA) for capturing the target nucleic acid is 5′-ACCCAGACACTCACCCAAGTC-3 ′ (SEQ ID NO: 25, 5 ′ end is biotin-labeled), and is artificially synthesized by Hokkaido System Science Co., Ltd. Each was used.
- the measurement of the modified nucleobase using the capture probe was performed in the same manner as in Reference Example 3 except that a different target nucleic acid and a different capture probe were used. The results were as shown in Table 10 and FIGS.
- Example 8 Use of heterologous nucleic acid probe in the measurement system of the present invention
- the nucleotide sequence of the target nucleic acid (DNA) is 5'-TTGCCGGGCGTC [C] GTCCTGTTGAACTTC-3 '(SEQ ID NO: 11, [C] is 5-methylcytosine)
- the nucleotide sequence of the capture probe (heterologous nucleic acid probe: 2′-O-methylated RNA + DNA) for capturing the target nucleic acid is 5′-GAAGUCAACAGGACGGAGCCCCGCAAAAAAAAAAAAAAAAAAA-3 ′ (SEQ ID NO: 26, 1st to 26th on the 5 ′ end side)
- the main chain of nucleotide residues is 2′-O-methylated RNA, and the main chain of nucleotide residues 27 to 48 is DNA).
- the nucleotide sequence of the solid phase probe is 5′-TTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTT- '(SEQ ID NO: 1, 5' end biotin-labeled), and artificially synthesized ones were used respectively by Hokkaido System Science Co..
- an unpaired portion is formed at the modified nucleobase [C] in the double-stranded structure portion composed of the target nucleic acid and the capture probe.
- Measurement of the modified nucleobase using a heterologous nucleic acid probe (Experiment 1) was performed in the same manner as in Example 6 except that a different target nucleic acid and a different capture probe were used.
- Experiment 2 uses a homologous nucleic acid probe (5′-GAAGTCAACAGAGCGACGCCGCGCAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA) whose main chain is DNA (in contrast to the target nucleic acid) instead of the capture probe whose main chain is 2′-O-methylated RNA used in Experiment 1. -3 ′ (SEQ ID NO: 12)) was used in the same manner as in Experiment 1.
- Experiment 2 is similar to Example 2 from the viewpoint of the types of target nucleic acid (DNA), capture probe (DNA) and solid phase probe (DNA) used.
- the absorbance measured in Experiment 1 was divided by the absorbance measured in Experiment 2 (same species) to obtain an OD450 ratio (different species / same species).
- the ratio of background values was determined by measuring the absorbance (background value (heterogeneous)) measured in the absence of a target nucleic acid containing a modified nucleobase (ie, 0 pmol) in Experiment 1.
- 2 corresponds to the value obtained by dividing by the absorbance (background value (same type)) measured in the absence of the target nucleic acid containing the modified nucleobase (ie, 0 pmol).
- S / N (heterogeneous) and S / N (homogeneous) were calculated from the absorbance measured in Experiment 1 and Experiment 2, respectively, and then S / N (heterogeneous) was divided by S / N (similar). , S / N (different / same species) was determined.
- S represents the absorbance measured in the presence of a target nucleic acid (1 ppmol, 1 pmol, 0.1 pmol or 0.01 pmol) containing a modified nucleobase.
- N represents the absorbance (background value) measured in the absence of the target nucleic acid containing the modified nucleobase (ie, 0 pmol).
- the results are shown in Table 11.
- the heterologous nucleic acid probe suppressed the background value compared to the homologous nucleic acid probe (Table 11).
- the amount of the target nucleic acid is smaller (for example, 0.1 pmol or less, particularly 0.01 pmol or less), in other words, when the concentration of the target nucleic acid in the solution is lower (for example, 1 nM or less, particularly 0.1 nM or less).
- the heterologous nucleic acid probe suppressed the detection signal value more than the homologous nucleic acid probe.
- the heterologous nucleic acid probe In the range of the amount of the target nucleic acid used, the heterologous nucleic acid probe always showed an excellent effect on the suppression of the detection signal value as compared with the same type nucleic acid probe.
- the S / N value measured using the heterologous nucleic acid probe was equivalent to the S / N value measured using the same kind of nucleic acid probe.
- the heterologous nucleic acid probe improved the S / N value more than the homologous nucleic acid probe. That is, with respect to the S / N value, the heterologous nucleic acid probe always showed the same or better effect than the homologous nucleic acid probe. From the above, it was shown that the use of a heterologous nucleic acid probe in the method of the present invention is beneficial.
- the method and kit of the present invention are useful for measuring modified nucleobases.
Landscapes
- Health & Medical Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Immunology (AREA)
- Molecular Biology (AREA)
- Hematology (AREA)
- Biomedical Technology (AREA)
- Urology & Nephrology (AREA)
- Analytical Chemistry (AREA)
- Organic Chemistry (AREA)
- Biotechnology (AREA)
- Microbiology (AREA)
- General Health & Medical Sciences (AREA)
- Biochemistry (AREA)
- Physics & Mathematics (AREA)
- Proteomics, Peptides & Aminoacids (AREA)
- Pathology (AREA)
- Wood Science & Technology (AREA)
- Zoology (AREA)
- Food Science & Technology (AREA)
- General Physics & Mathematics (AREA)
- Cell Biology (AREA)
- Medicinal Chemistry (AREA)
- Bioinformatics & Cheminformatics (AREA)
- Biophysics (AREA)
- General Engineering & Computer Science (AREA)
- Genetics & Genomics (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Tropical Medicine & Parasitology (AREA)
- Measuring Or Testing Involving Enzymes Or Micro-Organisms (AREA)
Abstract
Description
〔1〕以下を含む、修飾核酸塩基の測定方法:
(1)核酸サンプル、捕捉プローブおよび固相プローブを溶液中でインキュベートすること;ならびに
(2)(1)で得られた溶液において、修飾核酸塩基に対する抗体を用いて修飾核酸塩基を測定すること。
〔2〕核酸サンプルが、修飾核酸塩基を含む標的核酸を含有し、かつ工程(1)および(2)がそれぞれ(1’)および(2’)により行われる、〔1〕の方法:
(1’)修飾核酸塩基を含む標的核酸を含有する核酸サンプル、捕捉プローブおよび固相プローブを溶液中でインキュベートにより反応させて、当該標的核酸、捕捉プローブおよび固相プローブから構成されるハイブリッドを形成すること;ならびに
(2’)当該ハイブリッドを含む溶液において、修飾核酸塩基に対する抗体を用いて修飾核酸塩基を測定すること。
〔3〕標的核酸が、2以上の修飾核酸塩基を含む可能性がある標的核酸である、〔1〕または〔2〕の方法。
〔4〕核酸サンプルおよび捕捉プローブを含有する溶液を固相プローブが固定された固相に添加して、核酸サンプル、捕捉プローブおよび該固相プローブを含有する溶液を調製することをさらに含む、〔1〕~〔3〕のいずれかの方法。
〔5〕前記核酸サンプルが、修飾核酸塩基を含む標的DNAを含有するサンプルである、〔1〕~〔4〕のいずれかの方法。
〔6〕捕捉プローブまたは固相プローブの一方または双方が、標的核酸に対して異種の核酸を含むプローブである、〔1〕~〔5〕のいずれかの方法。
〔7〕捕捉プローブが、標的核酸に対して異種の核酸を含むプローブである、〔6〕の方法。
〔8〕固相プローブがポリAまたはポリTである、〔1〕~〔7〕のいずれかの方法。
〔9〕修飾核酸塩基を構成する核酸塩基がシトシンである、〔1〕~〔8〕のいずれかの方法。
〔10〕修飾核酸塩基がメチルシトシンである、〔1〕~〔9〕のいずれかの方法。
〔11〕ハイブリッド中の標的核酸および捕捉プローブから構成される二本鎖構造部分において修飾核酸塩基の不対部分が形成されるように、捕捉プローブが設計される、〔2〕~〔10〕のいずれかの方法。
〔12〕ハイブリッドの一本鎖構造部分において修飾核酸塩基が存在するように、捕捉プローブが設計される、〔2〕~〔11〕のいずれかの方法。
〔13〕修飾核酸塩基に対する抗体を用いる修飾核酸塩基の測定が、ELISAにより行われる、〔1〕~〔12〕のいずれかの方法。
〔14〕以下を含む、修飾核酸塩基の測定用キット:
(I)捕捉プローブ;
(II)固相プローブ;および
(III)修飾核酸塩基に対する抗体。
(1)核酸サンプル、捕捉プローブおよび固相プローブを溶液中でインキュベートすること;ならびに
(2)(1)で得られた溶液において、修飾核酸塩基に対する抗体を用いて修飾核酸塩基を測定すること。
ホモポリヌクレオチドとは、同種のヌクレオチド残基のみから構成されるポリヌクレオチドをいう。ホモポリヌクレオチドがDNAプローブである場合、ホモポリヌクレオチドは、好ましくは、核酸塩基としてアデニン、シトシンまたはチミンのいずれか一つのみを含むヌクレオチド残基のみから構成されるポリA、ポリCまたはポリTであり、より好ましくは、アデニンまたはチミンの一方のみを含むヌクレオチド残基のみから構成されるポリAまたはポリTである。ホモポリヌクレオチドがRNAプローブである場合、ホモポリヌクレオチドは、好ましくは、核酸塩基としてアデニン、シトシンまたはウラシルのいずれか一つのみを含むヌクレオチド残基のみから構成されるポリA、ポリCまたはポリUであり、より好ましくは、アデニンまたはウラシルの一方のみを含むヌクレオチド残基のみから構成されるポリAまたはポリUである。好ましくは、ホモポリヌクレオチドは、ポリAまたはポリTである。
ヘテロポリヌクレオチドとは、2以上の異種のヌクレオチド残基から構成されるポリヌクレオチドをいう。ヘテロポリヌクレオチドがDNAプローブである場合、ヘテロポリヌクレオチドは、好ましくは、核酸塩基としてアデニン、シトシンまたはチミンを含むヌクレオチド残基から構成され、より好ましくは、アデニンまたはチミンを含むヌクレオチド残基から構成される。ヘテロポリヌクレオチドがRNAプローブである場合、ヘテロポリヌクレオチドは、好ましくは、核酸塩基としてアデニン、シトシンまたはウラシルを含むヌクレオチド残基から構成され、より好ましくは、アデニンまたはウラシルを含むヌクレオチド残基から構成される。
ここで、工程(1)についての表現「核酸サンプル、捕捉プローブおよび固相プローブを溶液中でインキュベートする」とは、標的核酸(核酸サンプルが標的核酸を含有する場合)、捕捉プローブおよび固相プローブから構成されるハイブリッドが最終的に形成されるように、核酸サンプル、捕捉プローブおよび固相プローブが同時または時間差の様式においてインキュベートされることが意図される。
したがって、上記表現は、具体的には、以下の態様を包含するものである:
(1-1)核酸サンプル、捕捉プローブおよび固相プローブを溶液中で同時にインキュベートすること;
(1-2)核酸サンプルおよび捕捉プローブを先ずインキュベートし(核酸サンプルが標的核酸を含む場合、標的核酸および捕捉プローブから構成される中間ハイブリッドが形成される)、次いで、本インキュベーションにより得られた溶液を固相プローブと組み合わせてさらにインキュベートすること(核酸サンプルが標的核酸を含む場合、標的核酸、捕捉プローブおよび固相プローブから構成されるハイブリッドが形成される);ならびに
(1-3)捕捉プローブおよび固相プローブを先ずインキュベートし(捕捉プローブおよび固相プローブから構成される中間ハイブリッドが形成される)、次いで、本インキュベーションにより得られた溶液を核酸サンプルと組み合わせてさらにインキュベートすること(核酸サンプルが標的核酸を含む場合、標的核酸、捕捉プローブおよび固相プローブから構成されるハイブリッドが形成される)。
核酸サンプルが標的核酸を含まない場合、核酸サンプル、捕捉プローブおよび固相プローブを溶液中でインキュベートしても、標的核酸、捕捉プローブおよび固相プローブから構成される目的のハイブリッドは形成されない。この場合、後述する工程(2)において、修飾核酸塩基を検出することはできないが、核酸サンプル中に修飾核酸塩基が存在しないことを判定できる。
核酸サンプルが修飾核酸塩基を含まない標的核酸(換言すれば、非修飾核酸塩基のみを含む標的核酸)を含有する場合、核酸サンプル、捕捉プローブおよび固相プローブを溶液中でインキュベートすることにより、修飾核酸塩基を含まない標的核酸、捕捉プローブおよび固相プローブが反応して、当該標的核酸、捕捉プローブおよび固相プローブから構成されるハイブリッドが形成される。この場合、後述する工程(2)において、修飾核酸塩基を検出することはできないが、核酸サンプル中に(標的核酸が存在するにもかかわらず)修飾核酸塩基が存在しないこと、換言すれば、標的核酸中の所定の核酸塩基が修飾されていないことを判定できる。
核酸サンプルが修飾核酸塩基を含む標的核酸を含有する場合、核酸サンプル、捕捉プローブおよび固相プローブを溶液中でインキュベートすることにより、修飾核酸塩基を含む標的核酸、捕捉プローブおよび固相プローブが反応して、当該標的核酸、捕捉プローブおよび固相プローブから構成されるハイブリッドが形成される。この場合、後述する工程(2)において、修飾核酸塩基が存在することを判定でき、また修飾核酸塩基を定量することもできる。
溶液中の捕捉プローブの濃度は、本発明の方法により標的核酸が検出可能である限り特に限定されないが、例えば0.01nM以上、好ましくは0.1nM以上、より好ましくは1nM以上、さらにより好ましくは5nM以上、特に好ましくは10nM以上であってもよい。溶液中の捕捉プローブの濃度はまた、例えば1M以下、100mM以下、10mM以下、1mM以下、100μM以下、10μM以下または1μM以下であってもよい。したがって、このような濃度が達成されるように、捕捉プローブを溶液に添加してもよい。
溶液中の固相プローブの濃度は、本発明の方法により標的核酸が検出可能である限り特に限定されないが、例えば0.01nM以上、好ましくは0.1nM以上、より好ましくは1nM以上、5nM以上、または10nM以上であってもよい。溶液中の捕捉プローブの濃度はまた、例えば1M以下、100mM以下、10mM以下、1mM以下、100μM以下、10μM以下または1μM以下であってもよい。したがって、このような濃度が達成されるように、固相プローブを溶液に添加してもよい。
例えば、修飾核酸塩基に対するポリクローナル抗体は、上記複合体を抗原として、市販のアジュバント(例、完全または不完全フロイントアジュバント)とともに、動物の皮下あるいは腹腔内に2~3週間おきに2~4回程度投与し、最終免疫から約3~約10日後に全血を採取して抗血清を精製することにより取得できる。抗原を投与する動物としては、例えば、ラット、マウス、ウサギ、ヤギ、ウシ、モルモット、ハムスターなどの哺乳動物が挙げられる。
修飾核酸塩基に対するモノクローナル抗体は、例えば、細胞融合法により作製できる。例えば、上記複合体を市販のアジュバントと共にマウスに2~4回皮下または腹腔内に投与し、最終投与の約3日後に脾臓あるいはリンパ節を採取し、白血球を採取する。この白血球と骨髄腫細胞(例、NS-1)を細胞融合して該因子に対するモノクローナル抗体を産生するハイブリドーマを得る。細胞融合としては、PEG法、電圧パルス法が挙げられる。所望のモノクローナル抗体を産生するハイブリドーマは、周知のEIAまたはRIA法等を用いて抗原と特異的に結合する抗体を、培養上清中から検出することにより選択できる。モノクローナル抗体を産生するハイブリドーマの培養は、インビトロ、またはマウスもしくはラット、好ましくはマウス腹水中等のインビボで行うことができ、抗体はそれぞれハイブリドーマの培養上清および動物の腹水から取得できる。モノクローナル抗体は、IgG、IgM、IgA、IgE等のいずれのアイソタイプであってもよい。あるいは、モノクローナル抗体の作製方法としては、ファージディスプレイ法(Ulmanら,Proc.Natl.Acad.Sci.U.S.A.,90,1184-89(1993))、ADLibシステム(国際公開第2004/011644号)等のin vitro法も知られているので、修飾核酸塩基に対する抗体の作製のため、このような方法を使用してもよい。
(2-1)上記工程(1)で得られた溶液において、修飾核酸塩基に対する抗体を用いてアッセイして、シグナル値を計測すること;
(2-2)修飾核酸塩基を含む標的核酸を含有せず、かつ捕捉プローブおよび固相プローブを含有する溶液において、修飾核酸塩基に対する抗体を用いてアッセイして、バックグランド値を計測すること;および
(2-3)シグナル値をバックグランド値と比較して、修飾核酸塩基の有無を評価すること。
修飾核酸塩基の測定において、シグナル値およびバックグランド値は、修飾核酸塩基に対する抗体または2次抗体(2次抗体が用いられる場合)に結合した標識を利用して計測される値(例、吸光度、蛍光度、発色度、および放射活性)である。
(2-1’)上記工程(1)で得られた溶液において、修飾核酸塩基に対する抗体を用いてアッセイして、シグナル値を計測すること;
(2-2’)修飾核酸塩基を含む標的核酸を含有せず、かつ捕捉プローブおよび固相プローブを含有する溶液において、修飾核酸塩基に対する抗体を用いてアッセイして、バックグランド値を計測すること;
(2-3’)バックグランド値でシグナル値を補正して、補正シグナル値を得ること;ならびに
(2-4’)補正シグナル値に基づき、修飾核酸塩基の量を評価すること。
(2-1’’)上記工程(1)で得られた溶液において、修飾核酸塩基に対する抗体を用いてアッセイして、シグナル値を計測すること;
(2-2’’)修飾核酸塩基を含む標的核酸(標品)、かつ捕捉プローブおよび固相プローブを含有する溶液において、修飾核酸塩基に対する抗体を用いてアッセイして、検量用値を計測すること;ならびに
(2-3’’)シグナル値を検量用値に照合して、修飾核酸塩基の量を評価すること。
標品を用いる上記測定は、バックグランド値の上記測定と併用されてもよい。
(i)修飾核酸塩基を含む標的核酸を含有する核酸サンプル、捕捉プローブおよび第1の親和性物質で標識された固相プローブを溶液中でインキュベートして、当該標的核酸、捕捉プローブおよび当該固相プローブから構成されるハイブリッドを形成すること;
(ii)ハイブリッドを、第2の親和性物質で処理された固相に固定すること;
(iii)修飾核酸塩基に対する1次抗体を、固相に固定されたハイブリッドと反応させて、1次抗体とハイブリッドとの1次複合体を得ること;
(iv)標識物質で標識された2次抗体を1次複合体と反応させて、2次抗体と1次抗体との2次複合体を得ること;ならびに
(v)2次複合体中の2次抗体が有する標識物質を利用して、形成されたハイブリッド(換言すれば、修飾核酸塩基)の存在および/または量を測定すること
第1の親和性物質および第2の親和性物質は、互いに親和性を有する組合せ(例、ビオチンとストレプトアビジンとの組合せ)で用いられる。なお、本発明の方法は、上記工程(i)および(ii)の代わりに、(i’)修飾核酸塩基を含む標的核酸を含有する核酸サンプル、捕捉プローブおよび固相に固定された固相プローブを溶液中でインキュベートして、当該標的核酸、捕捉プローブおよび当該固相プローブから構成されるハイブリッドを形成することを含んでいてもよい。この場合、固相に固定された固相プローブを得ること(例、第1の親和性物質で標識された固相プローブを、第2の親和性物質で処理された固相に加えること)をさらに含んでいてもよい。本発明の方法は、工程(iii)の前に、固相を洗浄することを含んでいてもよい。2次抗体は、1次抗体のみを認識する抗体(例、1次抗体の定常領域に結合する抗体)であってもよいが、2次複合体中の1次抗体および1次複合体の双方を認識するものであってもよい。(i)~(v)を含む本発明の方法はまた、本明細書中に詳細に記載された方法論にしたがって行うことができる。
(I)捕捉プローブ;
(II)固相プローブ;および
(III)修飾核酸塩基に対する抗体。
捕捉プローブ、固相プローブおよび修飾核酸塩基に対する抗体は、上述したとおりである。例えば、固相プローブは、親和性物質で標識されていてもよく、修飾核酸塩基に対する抗体は、標識物質で標識されていてもよい。本発明のキットは、親和性物質、標識物質、2次抗体、2次抗体の検出試薬(例、2次抗体が酵素で標識されている場合には、その酵素の基質)および固相等の上述したような構成成分をさらに含んでいてもよい。固相は、親和性物質で処理されていてもよい。本発明のキットはまた、修飾核酸塩基の標品、または修飾核酸塩基を含む標的核酸の標品を、溶液としてまたは粉末として含んでいてもよい。
固相プローブが検出シグナルのバックグランド値に与える影響を検討した。
固相プローブ(DNA)のヌクレオチド配列は表5に示したとおりであり、北海道システムサエンス社により人工合成されたものをそれぞれ使用した。
その結果、固相プローブ配列により検出シグナルのバックグラウンド値が大きく変化することが確認された(表6、図2)。表6の結果より、固相プローブとしては、Aおよび/またはT(もしくはU)を含むもの(換言すれば、CおよびGを含まないもの)が好ましいと考えられた。
標的核酸(DNA)のヌクレオチド配列は5’-TTGCGCGGCGTC[C]GTCCTGTTGACTTC-3’(配列番号11、[C]は5-メチルシトシン)、標的核酸を捕捉するための捕捉プローブ(DNA)のヌクレオチド配列は5’-GAAGTCAACAGGACGACGCCGCGCAAAAAAAAAAAAAAAAAAAAAA-3’(配列番号12)、固相プローブ(DNA)のヌクレオチド配列は5’-TTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTTT-3’(配列番号13、5’末端はビオチン標識)であり、北海道システムサイエンス社により人工合成されたものをそれぞれ使用した。捕捉プローブは、標的核酸および固相プローブとのハイブリッドが形成されたとき、標的核酸および捕捉プローブから構成される二本鎖構造部分中の修飾核酸塩基[C]で不対部分が形成されるように設計した。
固相プローブおよび捕捉プローブを用いた修飾核酸塩基の測定は、以下のとおり行った。まず、5pmolの固相プローブをPBS緩衝液100μL中に溶解させた後、ストレプトアビジンでコートされたプレート(Thermo Scientific社製)に全量加え、37℃で30分反応させることで、ストレプトアビジンプレート上に固相プローブを固定化した。固定化された固相プローブ核酸を300μLのPBS-Tで2回洗浄し、ハイブリダイゼーションBuffer(4×SSC、0.1%SDS)中に5-メチルシトシンを含む標的核酸(1pmol、0.1pmol、0.01pmolまたは0.001pmol)と捕捉プローブ(5pmol)を含む溶液を100μL加え(核酸サンプル溶液中、標的核酸の濃度はそれぞれ10nM、1nM、0.1nM、または0.01nMであり、捕捉プローブの濃度は50nMであり、固相プローブの濃度は理論上50nM以下(用いた全量の固相プローブが固相に固定されたと仮定した場合、50nM)である)、60℃で2時間反応させ、続いて37℃で30分反応させることで、標的核酸、捕捉プローブ、および固相プローブ3者のハイブリッドを形成させた。また、標的核酸を含まない溶液でも同様の操作を行った。300μLのPBS-Tで2回洗浄し、500ng/mLの抗メチルシトシン抗体(Millipore社製、Clone33D3)を50μLずつ加え、37℃で1時間反応させた。300μLのPBS-Tで3回洗浄し、500ng/mLのペルオキシダーゼ標識抗IgG抗体(Thermo Scientific社製)を50μLずつ加え、37℃で30分反応させた。300μLのPBS-Tで3回洗浄した後、3,3’,5,5’-Tetramethylbenzidineを100μLずつ加え、遮光室温で7分反応させた。その後、2N塩酸溶液を100μLずつ加え、マイクロプレートリーダー(PerkinElmer社製Arvo)により450nmの吸光度を測定した。
その結果、固相プローブおよび捕捉プローブの併用は、捕捉プローブの単独使用(参考例1)に比し、バックグラント値を抑制し、かつS/N値を向上させることが確認された(表7、図3~5)。
捕捉プローブ(DNA)のヌクレオチド配列として5’-GAAGTCAACAGGACGACGCCGCGCAATTTTTTTTTTTTTTTTTTTT-3’(配列番号14)、固相プローブ(DNA)のヌクレオチド配列として5’-AAAAAAAAAAAAAAAAAAAA-3’(配列番号15、5’末端はビオチン標識)を使用した以外は、実施例2と同様の方法で試験した。
その結果、固相プローブおよび捕捉プローブの併用は、捕捉プローブの単独使用(参考例1)に比し、バックグラント値を抑制し、かつS/N値を向上させることが確認された(表7、図3~5)。
捕捉プローブ(DNA)のヌクレオチド配列として5’-GAAGTCAACAGGACGACGCCGCGCAACCCCCCCCCCCCCCCCCCCC-3’(配列番号16)、固相プローブ(DNA)のヌクレオチド配列として5’-GGGGGGGGGGGGGGGGGGGG-3’(配列番号17、5’末端はビオチン標識)を使用した以外は、実施例2と同様の方法で試験した。
その結果、固相プローブおよび捕捉プローブの併用は、捕捉プローブの単独使用(参考例1)に比し、バックグラント値を抑制し、かつS/N値を向上させることが確認された(表7、図3~5)。また、本実施例で用いた固相プローブおよび捕捉プローブは、実施例2及び3のものに比し、バックグランド値の抑制効率が低かった。このことは、グアニン残基の含量が少ない固相プローブがより適切であることを示す。
標的核酸(DNA)のヌクレオチド配列は5’-TTGCGCGGCGTC[C]GTCCTGTTGACTTC-3’(配列番号11、[C]は5-メチルシトシン)、捕捉プローブ(DNA)のヌクレオチド配列は5’-GAAGTCAACAGGACGACGCCGCGCAA-3’(配列番号18、5’末端はビオチン標識)であり、北海道システムサイエンス社により人工合成されたものをそれぞれ使用した。
捕捉プローブを用いた修飾核酸塩基の測定は、以下のとおり行った。まず、5-メチルシトシンを含む標的核酸(1pmol、0.1pmol、0.01pmol、または0.001pmol)と標的核酸を捕捉するためのプローブ核酸(5pmol)をハイブリダイゼーションBuffer(4×SSC、0.1%SDS)100μL中に溶解させた後、60℃で2時間反応させることで、標的核酸と標的核酸を捕捉するためのプローブ核酸のハイブリッドを形成させた。また、標的核酸を含まない溶液も調製し、同様の操作を行った。ハイブリダイゼーション反応後の溶液を、ストレプトアビジンでコートされたプレート(Thermo Scientific社製)に100μL加え、37℃で30分反応させることで、ストレプトアビジンプレート上に核酸のハイブリッドを固定化した。300μLのPBS-Tで2回洗浄し、500ng/mLの抗メチルシトシン抗体(Millipore社製、Clone33D3)を50μLずつ加え、37℃で1時間反応させた。300μLのPBS-Tで3回洗浄し、500ng/mLのペルオキシダーゼ標識抗IgG抗体(Thermo Scientific社製)を50μLずつ加え、37℃で30分反応させた。300μLのPBS-Tで3回洗浄した後、3,3’,5,5’-Tetramethylbenzidineを100μLずつ加え、遮光室温で7分反応させた。その後、2N塩酸溶液を100μLずつ加え、マイクロプレートリーダー(PerkinElmer社製Arvo)により450nmの吸光度を測定した。
結果は、表7、図3~5に示すとおりであった。
標的核酸(DNA)のヌクレオチド配列は5’-AATCAG[C]GGGAGCTCTTTCTTTGCGCGGCGTCCGTCCTGTTGACTTC-3’(配列番号19、[C]は5-メチルシトシン)、標的核酸を捕捉するための捕捉プローブ(DNA)のヌクレオチド配列は5’-GAAGTCAACAGGACGACGCCGCGCAAAAAAAAAAAAAAAAAAAAAA-3’(配列番号12)、固相プローブ(DNA)のヌクレオチド配列は5’-TTTTTTTTTTTTTTTTTTTT-3’(配列番号1、5’末端はビオチン標識)であり、北海道システムサイエンス社により人工合成されたものをそれぞれ使用した。捕捉プローブは、標的核酸および固相プローブとのハイブリッドが形成されたとき、ハイブリッドの一本鎖構造部分において修飾核酸塩基[C]が存在するように設計した。
捕捉プローブおよび固相プローブを用いる修飾核酸塩基の測定は、異なる標的核酸を異なる量(10pmol、1pmol、0.1pmolまたは0.01pmol)で用いたこと、ならびに異なる捕捉プローブおよび異なる固相プローブを用いたこと以外は、実施例2と同様の方法で行った。
その結果、標的核酸、捕捉プローブおよび固相プローブのハイブリッドが形成されたとき、ハイブリッドの一本鎖構造部分において修飾核酸塩基[C]が存在するように、捕捉プローブを設計した場合にも、バックグラント値の低下、およびS/N値の向上が認められた(表8、図6、7)。
標的核酸(DNA)のヌクレオチド配列は5’-AATCAG[C]GGGAGCTCTTTCTTTGCGCGGCGTCCGTCCTGTTGACTTC-3’(配列番号19、[C]は5-メチルシトシン)、標的核酸を捕捉するための捕捉プローブ(DNA)のヌクレオチド配列は5’-GAAGTCAACAGGACGACGCCGCGCAA-3’(配列番号18、5’末端はビオチン標識)であり、北海道システムサイエンス社により人工合成されたものをそれぞれ使用した。
捕捉プローブを用いた修飾核酸塩基の測定は、以下のとおり行った。まず、5-メチルシトシンを含む標的核酸(10pmol、1pmol、0.1pmolまたは0.01pmol)と捕捉プローブ(5pmol)をハイブリダイゼーションBuffer(4×SSC、0.1%SDS)100μL中に溶解させた後、60℃で2時間反応させることで、標的核酸と捕捉プローブのハイブリッドを形成させた。また、標的核酸を含まない溶液も調製し、同様の操作を行った。ハイブリダイゼーション反応後の溶液を、ストレプトアビジンでコートされたプレート(Thermo Scientific社製)に100μL加え、37℃で30分反応させることで、ストレプトアビジンプレート上に核酸のハイブリッドを固定化した。300μLのPBS-Tで2回洗浄し、500ng/mLの抗メチルシトシン抗体(Millipore社製、Clone33D3)を50μLずつ加え、37℃で1時間反応させた。300μLのPBS-Tで3回洗浄し、500ng/mLのペルオキシダーゼ標識抗IgG抗体(Thermo Scientific社製)を50μLずつ加え、37℃で30分反応させた。300μLのPBS-Tで3回洗浄した後、3,3’,5,5’-Tetramethylbenzidineを100μLずつ加え、遮光室温で7分反応させた。その後、2N塩酸溶液を100μLずつ加え、マイクロプレートリーダー(PerkinElmer社製Arvo)により450nmの吸光度を測定した。
結果は、表8、図6、7に示すとおりであった。
標的核酸(DNA)のヌクレオチド配列は5’-G[C]GGAGCTCTCCCT[C]GGGA[C]GGTGGCAGCCTCGAGTGGTCCTGCA-3’(配列番号20、[C]は5-メチルシトシン)、標的核酸を捕捉するための捕捉プローブ(DNA)のヌクレオチド配列は5’-AAAAAAAAAAAAAAAAAAAATGCAGGACCACTCGAGGCTGCCAC-3’(配列番号21)、固相プローブ(DNA)のヌクレオチド配列は5’-TTTTTTTTTTTTTTTTTTTT-3’(配列番号1、5’末端はビオチン標識)であり、北海道システムサイエンス社により人工合成されたものをそれぞれ使用した。捕捉プローブは、標的核酸および固相プローブとのハイブリッドが形成されたとき、ハイブリッドの一本鎖構造部分において修飾核酸塩基[C]が存在するように設計した。
捕捉プローブおよび固相プローブを用いる修飾核酸塩基の測定は、以下のとおり行った。まず、5pmolの固相プローブをPBS緩衝液100μL中に溶解させた後、ストレプトアビジンでコートされたプレート(Thermo Scientific社製)に全量加え、37℃で30分反応させることで、ストレプトアビジンプレート上に固相プローブを固定化した。300μLのPBS-Tで2回洗浄し、ハイブリダイゼーションBuffer(4×SSC、0.3%Tween20)中に5-メチルシトシンを含む標的核酸(1pmol、0.1pmol、0.01pmolまたは0.001pmol)と捕捉プローブ(5pmol)を含む溶液を100μL加え、60℃で2時間反応させ、続いて37℃で30分反応させることで、標的核酸、捕捉プローブ、および固相プローブ3者のハイブリッドを形成させた。また、標的核酸を含まない溶液でも同様の操作を行った。300μLのPBS-Tで2回洗浄し、50ng/mLの抗メチルシトシン抗体(ニッポンジーン社製、Clone33D3)を100μLずつ加え、37℃で1時間反応させた。300μLのPBS-Tで3回洗浄し、250ng/mLのペルオキシダーゼ標識抗IgG抗体(Thermo Scientific社製)を100μLずつ加え、37℃で30分反応させた。300μLのPBS-Tで3回洗浄した後、3,3’,5,5’-Tetramethylbenzidineを100μLずつ加え、遮光室温で15分反応させた。その後、2N塩酸溶液を100μLずつ加え、マイクロプレートリーダー(PerkinElmer社製Arvo)により450nmの吸光度を測定した。
その結果、捕捉プローブおよび固相プローブを用いる修飾核酸塩基の測定において、実施例2および実施例5と異なる標的核酸および異なる捕捉プローブを使用した場合にも、バックグラント値の低下、およびS/N値の向上が認められた(表9、図8、9)。興味深いことに、複数の修飾核酸塩基を含む標的核酸を用いた本試験では、捕捉プローブおよび固相プローブの併用は、標的核酸の濃度範囲(0.001~1pmol)と検出シグナル値との間でより直線的な関係(傾きがほぼ一定)を示したが、捕捉プローブのみの使用は、標的核酸の低い濃度範囲(0~0.01pmol)において、検出シグナル値に殆ど変化は認められなかった(図9)。このことは、複数の修飾核酸塩基を含む標的核酸の低い濃度範囲(例、0~0.01pmol)では、捕捉プローブおよび固相プローブの併用により、検出感度が増幅されることを示唆する。
標的核酸(DNA)のヌクレオチド配列は5’-G[C]GGAGCTCTCCCT[C]GGGA[C]GGTGGCAGCCTCGAGTGGTCCTGCA-3’(配列番号20、[C]は5-メチルシトシン)、標的核酸を捕捉するための捕捉プローブ(DNA)のヌクレオチド配列は5’-TGCAGGACCACTCGAGGCTGCCAC-3’(配列番号22、5’末端はビオチン標識)であり、北海道システムサイエンス社により人工合成されたものをそれぞれ使用した。
捕捉プローブを用いた修飾核酸塩基の測定は、以下のとおり行った。まず、5-メチルシトシンを含む標的核酸(1pmol、0.1pmol、0.01pmolまたは0.001pmol)と捕捉プローブ(5pmol)をハイブリダイゼーションBuffer(4×SSC、0.3%Tween20)100μL中に溶解させた後、60℃で2時間反応させることで、標的核酸と捕捉プローブのハイブリッドを形成させた。また、標的核酸を含まない溶液も調製し、同様の操作を行った。ハイブリダイゼーション反応後の溶液を、ストレプトアビジンでコートされたプレート(Thermo Scientific社製)に100μL加え、37℃で30分反応させることで、ストレプトアビジンプレート上に核酸のハイブリッドを固定化した。300μLのPBS-Tで2回洗浄し、50ng/mLの抗メチルシトシン抗体(ニッポンジーン社製、Clone33D3)を100μLずつ加え、37℃で1時間反応させた。300μLのPBS-Tで3回洗浄し、250ng/mLのペルオキシダーゼ標識抗IgG抗体(Thermo Scientific社製)を100μLずつ加え、37℃で30分反応させた。300μLのPBS-Tで3回洗浄した後、3,3’,5,5’-Tetramethylbenzidineを100μLずつ加え、遮光室温で15分反応させた。その後、2N塩酸溶液を100μLずつ加え、マイクロプレートリーダー(PerkinElmer社製Arvo)により450nmの吸光度を測定した。
結果は、表9、図8、9に示すとおりであった。
標的核酸(DNA)のヌクレオチド配列は5’-G[C]GCAC[C]GTTTG[C]GACTTGGTGAGTGTCTGGGT[C]GCCT[C]GCTCC-3’(配列番号23、[C]は5-メチルシトシン)、標的核酸を捕捉するための捕捉プローブ(DNA)のヌクレオチド配列は5’-AAAAAAAAAAAAAAAAAAAAACCCAGACACTCACCAAGTC-3’(配列番号24)、固相プローブ(DNA)のヌクレオチド配列は5’-TTTTTTTTTTTTTTTTTTTT-3’(配列番号1、5’末端はビオチン標識)であり、北海道システムサイエンス社により人工合成されたものをそれぞれ使用した。捕捉プローブは、標的核酸および固相プローブとのハイブリッドが形成されたとき、ハイブリッドの一本鎖構造部分において修飾核酸塩基[C]が存在するように設計した。
捕捉プローブおよび固相プローブを用いる修飾核酸塩基の測定は、異なる標的核酸および異なる捕捉プローブを用いたこと以外は、実施例6と同様の方法で行った。
その結果、捕捉プローブおよび固相プローブを用いる修飾核酸塩基の測定において、実施例2、実施例5および実施例6と異なる標的核酸および異なる捕捉プローブを使用した場合にも、バックグラント値の低下、およびS/N値の向上が認められた(表10、図10、11)。興味深いことに、複数の修飾核酸塩基を含む標的核酸を用いた本試験では、捕捉プローブおよび固相プローブの併用は、標的核酸の濃度範囲(0.001~1pmol)と検出シグナル値との間でより直線的な関係(傾きがほぼ一定)を示したが、捕捉プローブのみの使用は、標的核酸の低い濃度範囲(0~0.01pmol)において、検出シグナル値に殆ど変化は認められなかった(図11)。このことは、複数の修飾核酸塩基を含む標的核酸の低い濃度範囲(例、0~0.01pmol)では、捕捉プローブおよび固相プローブの併用により、検出感度が増幅されることを示唆する。
標的核酸(DNA)のヌクレオチド配列は5’-G[C]GCAC[C]GTTTG[C]GACTTGGTGAGTGTCTGGGT[C]GCCT[C]GCTCC-3’(配列番号23、[C]は5-メチルシトシン)、標的核酸を捕捉するための捕捉プローブ(DNA)のヌクレオチド配列は5’-ACCCAGACACTCACCAAGTC-3’(配列番号25、5’末端はビオチン標識)であり、北海道システムサイエンス社により人工合成されたものをそれぞれ使用した。
捕捉プローブを用いた修飾核酸塩基の測定は、異なる標的核酸および異なる捕捉プローブを用いたこと以外は、参考例3と同様の方法で行った。
結果は、表10、図10、11に示すとおりであった。
標的核酸(DNA)のヌクレオチド配列は5’-TTGCGCGGCGTC[C]GTCCTGTTGACTTC-3’(配列番号11、[C]は5-メチルシトシン)、標的核酸を捕捉するための捕捉プローブ(異種核酸プローブ:2’-O-メチル化RNA+DNA)のヌクレオチド配列は5’-GAAGUCAACAGGACGACGCCGCGCAAAAAAAAAAAAAAAAAAAAAA-3’(配列番号26、5’末端側の1番目から26番目までのヌクレオチド残基の主鎖は2’-O-メチル化RNAであり、27番目から48番目までのヌクレオチド残基の主鎖はDNAである)、固相プローブのヌクレオチド配列は5’-TTTTTTTTTTTTTTTTTTTT-3’(配列番号1、5’末端はビオチン標識)であり、北海道システムサイエンス社により人工合成されたものをそれぞれ使用した。捕捉プローブは、標的核酸および固相プローブとのハイブリッドが形成されたとき、標的核酸および捕捉プローブから構成される二本鎖構造部分中の修飾核酸塩基[C]で不対部分が形成されるように設計した。
異種核酸プローブを用いる修飾核酸塩基の測定(実験1)は、異なる標的核酸および異なる捕捉プローブを用いたこと以外は、実施例6と同様の方法で行った。
次いで、同種核酸プローブを用いて修飾核酸塩基の測定(実験2)を同様に行った。実験2は、実験1で使用した一部の主鎖が2’-O-メチル化RNAである捕捉プローブの代わりに、主鎖がDNAである(標的核酸に対する)同種核酸プローブ(5’-GAAGTCAACAGGACGACGCCGCGCAAAAAAAAAAAAAAAAAAAAAA-3’(配列番号12))を用いた以外は、実験1と同様の方法で試験した。なお、実験2は、用いた標的核酸(DNA)、捕捉プローブ(DNA)および固相プローブ(DNA)の種類の観点から、実施例2に類する。
実験1で測定された吸光度(異種)を、実験2で測定された吸光度(同種)で除算して、OD450比(異種/同種)を求めた。ここで、バックグランド値の比(異種/同種)は、実験1において、修飾核酸塩基を含む標的核酸の不在下(即ち、0pmol)で測定された吸光度(バックグランド値(異種))を、実験2において、修飾核酸塩基を含む標的核酸の不在下(即ち、0pmol)で測定された吸光度(バックグランド値(同種))で除算して求めた値に対応する。
また、実験1および実験2で測定された吸光度からS/N(異種)およびS/N(同種)をそれぞれ算出し、次いで、S/N(異種)をS/N(同種)で除算して、S/N(異種/同種)を求めた。なお、S/N(異種)およびS/N(同種)について、Sは、修飾核酸塩基を含む標的核酸(1ppmol、1pmol、0.1pmolまたは0.01pmol)の存在下で測定された吸光度を表し、Nは、修飾核酸塩基を含む標的核酸の不在下(即ち、0pmol)で測定された吸光度(バックグランド値)を表す。結果を表11に示す。
その結果、バックグランド値の比(異種/同種)より明らかであるように、異種核酸プローブは、同種核酸プローブに比し、バックグランド値を抑制した(表11)。また、標的核酸の量がより少ないとき(例えば0.1pmol以下、特に0.01pmol以下)、換言すれば、溶液中の標的核酸の濃度がより低いとき(例えば1nM以下、特に0.1nM以下)、OD450比(異種/同種)の低下が認められた(表11)。さらに、標的核酸の量がより多いとき(例えば0.1pmol以上、特に1pmol以上)、換言すれば、溶液中の標的核酸の濃度が高いとき(例えば1nM以上、特に10nM以上)、S/N比(異種/同種)の向上が認められた(表11)。
1)標的核酸が存在しないか、または標的核酸の濃度が少ない場合、異種核酸プローブは、同種核酸プローブに比し、検出シグナルの値をより抑制した。使用した標的核酸の量の範囲では、検出シグナル値の抑制に関し、異種核酸プローブは、同種核酸プローブに比し、常に優れた効果を奏した。
2)使用した標的核酸の量が少ない場合、異種核酸プローブを用いて計測されたS/N値は、同種核酸プローブを用いて計測されたS/N値と同等であった。一方、使用した標的核酸の量が多い場合、異種核酸プローブは、同種核酸プローブに比し、S/N値をより向上させた。つまり、S/N値に関して、異種核酸プローブは、同種核酸プローブに比し、常に同等以上の効果を奏した。
以上より、本発明の方法における異種核酸プローブの使用は有益であることが示された。
Claims (14)
- 以下を含む、修飾核酸塩基の測定方法:
(1)核酸サンプル、捕捉プローブおよび固相プローブを溶液中でインキュベートすること;ならびに
(2)(1)で得られた溶液において、修飾核酸塩基に対する抗体を用いて修飾核酸塩基を測定すること。 - 核酸サンプルが、修飾核酸塩基を含む標的核酸を含有し、かつ工程(1)および(2)がそれぞれ(1’)および(2’)により行われる、請求項1記載の方法:
(1’)修飾核酸塩基を含む標的核酸を含有する核酸サンプル、捕捉プローブおよび固相プローブを溶液中でインキュベートにより反応させて、当該標的核酸、捕捉プローブおよび固相プローブから構成されるハイブリッドを形成すること;ならびに
(2’)当該ハイブリッドを含む溶液において、修飾核酸塩基に対する抗体を用いて修飾核酸塩基を測定すること。 - 標的核酸が、2以上の修飾核酸塩基を含む可能性がある標的核酸である、請求項1または2記載の方法。
- 核酸サンプルおよび捕捉プローブを含有する溶液を固相プローブが固定された固相に添加して、核酸サンプル、捕捉プローブおよび該固相プローブを含有する溶液を調製することをさらに含む、請求項1~3のいずれか一項記載の方法。
- 前記核酸サンプルが、修飾核酸塩基を含む標的DNAを含有するサンプルである、請求項1~4のいずれか一項記載の方法。
- 捕捉プローブまたは固相プローブの一方または双方が、標的核酸に対して異種の核酸を含むプローブである、請求項1~5のいずれか一項記載の方法。
- 捕捉プローブが、標的核酸に対して異種の核酸を含むプローブである、請求項6記載の方法。
- 固相プローブがポリAまたはポリTである、請求項1~7のいずれか一項記載の方法。
- 修飾核酸塩基を構成する核酸塩基がシトシンである、請求項1~8のいずれか一項記載の方法。
- 修飾核酸塩基がメチルシトシンである、請求項1~9のいずれか一項記載の方法。
- ハイブリッド中の標的核酸および捕捉プローブから構成される二本鎖構造部分において修飾核酸塩基の不対部分が形成されるように、捕捉プローブが設計される、請求項2~10のいずれか一項記載の方法。
- ハイブリッドの一本鎖構造部分において修飾核酸塩基が存在するように、捕捉プローブが設計される、請求項2~11のいずれか一項記載の方法。
- 修飾核酸塩基に対する抗体を用いる修飾核酸塩基の測定が、ELISAにより行われる、請求項1~12のいずれか一項記載の方法。
- 以下を含む、修飾核酸塩基の測定用キット:
(I)捕捉プローブ;
(II)固相プローブ;および
(III)修飾核酸塩基に対する抗体。
Priority Applications (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US14/913,195 US10107802B2 (en) | 2013-08-21 | 2014-08-20 | Method for measuring modified nucleobase using solid phase probe, and kit for same |
EP14837574.4A EP3037532A4 (en) | 2013-08-21 | 2014-08-20 | Method for measuring modified nucleobase using solid phase probe, and kit for same |
JP2015532869A JP6451633B2 (ja) | 2013-08-21 | 2014-08-20 | 固相プローブを用いた修飾核酸塩基の測定方法およびそのキット |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP2013-171659 | 2013-08-21 | ||
JP2013171659 | 2013-08-21 |
Publications (1)
Publication Number | Publication Date |
---|---|
WO2015025863A1 true WO2015025863A1 (ja) | 2015-02-26 |
Family
ID=52483636
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/JP2014/071704 WO2015025863A1 (ja) | 2013-08-21 | 2014-08-20 | 固相プローブを用いた修飾核酸塩基の測定方法およびそのキット |
Country Status (4)
Country | Link |
---|---|
US (1) | US10107802B2 (ja) |
EP (1) | EP3037532A4 (ja) |
JP (1) | JP6451633B2 (ja) |
WO (1) | WO2015025863A1 (ja) |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO2017217530A1 (ja) * | 2016-06-17 | 2017-12-21 | 富士レビオ株式会社 | 修飾核酸塩基を含む標的核酸の測定方法 |
WO2020054782A1 (ja) | 2018-09-13 | 2020-03-19 | 国立研究開発法人国立がん研究センター | 乳癌細胞存在率の推定方法 |
Families Citing this family (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
CN107075505A (zh) * | 2014-09-29 | 2017-08-18 | 富士瑞必欧株式会社 | 含有修饰核酸碱基的靶核酸的测定方法及试剂盒 |
Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO2004011644A1 (ja) | 2002-07-30 | 2004-02-05 | Riken | 体細胞相同組換えの促進方法及び特異的抗体の作製方法 |
JP2012230019A (ja) | 2011-04-27 | 2012-11-22 | National Institute Of Advanced Industrial & Technology | メチル化核酸検出法 |
Family Cites Families (8)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0481999B1 (en) * | 1989-03-10 | 1997-07-23 | VYSIS, Inc. | Preventing interference with affinity capture schemes |
AU2144000A (en) * | 1998-10-27 | 2000-05-15 | Affymetrix, Inc. | Complexity management and analysis of genomic dna |
US6989235B2 (en) * | 2002-02-13 | 2006-01-24 | Motorola, Inc. | Single molecule detection of bio-agents using the F1-ATPase biomolecular motor |
JP2005536998A (ja) | 2002-08-30 | 2005-12-08 | バイエル・ヘルスケア・エルエルシー | 高親和性および高特異性を組み合わせた固相ベースの核酸アッセイ |
US20080124735A1 (en) * | 2006-10-16 | 2008-05-29 | Matthias Schuster | Method for detection of one or more CpG positions |
US7794939B2 (en) * | 2007-02-26 | 2010-09-14 | University Of Idaho | Methods of DNA methylation detection |
JP2009247260A (ja) * | 2008-04-04 | 2009-10-29 | Sumitomo Chemical Co Ltd | Dnaメチル化測定方法 |
US20120107808A1 (en) * | 2010-10-27 | 2012-05-03 | Weiwei Li | High throughput detection of gene-specific hydroxymethylation |
-
2014
- 2014-08-20 US US14/913,195 patent/US10107802B2/en not_active Expired - Fee Related
- 2014-08-20 EP EP14837574.4A patent/EP3037532A4/en not_active Withdrawn
- 2014-08-20 WO PCT/JP2014/071704 patent/WO2015025863A1/ja active Application Filing
- 2014-08-20 JP JP2015532869A patent/JP6451633B2/ja not_active Expired - Fee Related
Patent Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO2004011644A1 (ja) | 2002-07-30 | 2004-02-05 | Riken | 体細胞相同組換えの促進方法及び特異的抗体の作製方法 |
JP2012230019A (ja) | 2011-04-27 | 2012-11-22 | National Institute Of Advanced Industrial & Technology | メチル化核酸検出法 |
Non-Patent Citations (7)
Title |
---|
GUIDELINES FOR PREPARATION OF SPECIFICATIONS CONTAINING NUCLEOTIDE SEQUENCES OR AMINO ACID SEQUENCES, July 2002 (2002-07-01) |
KURITA ET AL., ANAL. CHEM., vol. 84, 2012, pages 7533 - 7538 |
KURITA R. ET AL.: "DNA methylation analysis triggered by bulge specific immune-recognition.", ANAL. CHEM., vol. 84, no. 17, 2012, pages 7533 - 7538, XP055213627 * |
PROLL ET AL., DNA RESEARCH, vol. 13, 2006, pages 37 - 42 |
RYOJI KURITA: "DNA Methylation Analysis by Electrogenerated Chemiluminescence and Bulge- Specific Immuno-Recognition", KAGAKU TO MICRO NANO SYSTEM, vol. 12, no. 1, March 2013 (2013-03-01), pages 8 - 15, XP008182408 * |
See also references of EP3037532A4 |
ULMAN ET AL., PROC. NATL. ACAD. SCI. U.S.A., vol. 90, 1993, pages 1184 - 89 |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO2017217530A1 (ja) * | 2016-06-17 | 2017-12-21 | 富士レビオ株式会社 | 修飾核酸塩基を含む標的核酸の測定方法 |
WO2020054782A1 (ja) | 2018-09-13 | 2020-03-19 | 国立研究開発法人国立がん研究センター | 乳癌細胞存在率の推定方法 |
Also Published As
Publication number | Publication date |
---|---|
US10107802B2 (en) | 2018-10-23 |
EP3037532A4 (en) | 2017-05-03 |
EP3037532A1 (en) | 2016-06-29 |
JPWO2015025863A1 (ja) | 2017-03-02 |
US20160274096A1 (en) | 2016-09-22 |
JP6451633B2 (ja) | 2019-01-16 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
JP6497323B2 (ja) | ガイドプローブを用いた修飾核酸塩基の測定方法およびそのためのキット | |
WO2021222827A1 (en) | Methods and kits for virus detection | |
JP6451632B2 (ja) | 異種核酸プローブを用いた修飾核酸塩基の測定方法およびキット | |
WO2012057689A1 (en) | Proximity ligation technology for western blot applications | |
WO2011062933A2 (en) | Array-based proximity ligation association assays | |
CN104884634A (zh) | 利用链置换交换反应检测非核酸分析物 | |
CN110117595B (zh) | 一种特异性结合pdl1的核酸适配体及其应用 | |
KR20130102612A (ko) | 모체 혈액에서 태아 세포의 농화 및 확인 및 이러한 용도의 리간드 | |
JP6451633B2 (ja) | 固相プローブを用いた修飾核酸塩基の測定方法およびそのキット | |
JP6451634B2 (ja) | 吸収剤ポリヌクレオチドを用いた修飾核酸塩基の測定方法およびそのキット | |
US8927210B2 (en) | Conjugate complexes for analyte detection | |
CN112226485A (zh) | 核酸检测方法 | |
WO2016052368A1 (ja) | 修飾核酸塩基を含む標的核酸の測定方法およびキット | |
Hu et al. | Antibodies specific for nucleic acids and applications in genomic detection and clinical diagnostics | |
WO2007054515A1 (en) | Method for detecting microorganisms | |
US20100120033A1 (en) | Method for measuring dna methylation | |
WO2017217530A1 (ja) | 修飾核酸塩基を含む標的核酸の測定方法 | |
CA2272924A1 (en) | A whole blood/mitogen assay for the early detection of a subject with cancer and kit | |
CN111363749A (zh) | 一种用于检测中华鳖虹彩病毒的核酸适配体及其构建方法和应用 | |
CN110257384B (zh) | 一种核酸适配体及其构建方法和应用 | |
KR20170067217A (ko) | 골질환의 예방 또는 치료용 약학적 조성물 | |
KR20190012519A (ko) | 개 정원줄기세포의 미분화 정도 분석용 조성물 |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
121 | Ep: the epo has been informed by wipo that ep was designated in this application |
Ref document number: 14837574 Country of ref document: EP Kind code of ref document: A1 |
|
ENP | Entry into the national phase |
Ref document number: 2015532869 Country of ref document: JP Kind code of ref document: A |
|
WWE | Wipo information: entry into national phase |
Ref document number: 2014837574 Country of ref document: EP |
|
WWE | Wipo information: entry into national phase |
Ref document number: 14913195 Country of ref document: US |
|
NENP | Non-entry into the national phase |
Ref country code: DE |