SARS-CoV-2 derived polynucleotides and uses thereof

Abstract

Provided are: a polynucleotide that includes (i) a base sequence according to any of SEQ ID NOS: 1-3, (ii) a base sequence in which one to three bases have been deleted, substituted, inserted, or added in a base sequence according to any of SEQ ID NOS: 1-3, or (iii) a base sequence having 60% or greater sequence identity with a base sequence according to any of SEQ ID NOS: 1-3, the polynucleotide having activity to promote replication of the coronavirus when present in coronavirus-infected cells; a mimic thereof; an inhibitor thereof; and the use of these.

Description

[Technical Field]

[0001] The present invention relates to polynucleotides derived from Severe Acute Respiratory Syndrome Coronavirus (SARS-CoV)-2 and uses thereof. More specifically, the present invention relates to polynucleotides, polynucleotide mimetics, polynucleotide inhibitors, coronavirus replication promoters, compositions for promoting coronavirus replication, coronavirus replication inhibitors, compositions for inhibiting coronavirus replication, animal cells, methods for inhibiting coronavirus replication, methods for promoting coronavirus replication, and methods for producing coronavirus. This application claims priority based on Japanese Patent Application No. 2022-011911, filed on January 28, 2022, the contents of which are incorporated herein by reference. [Background technology]

[0002] MicroRNAs (miRNAs) are short, non-coding RNAs of approximately 22 bases that are responsible for post-transcriptional regulation of gene expression. miRNAs are molecules commonly found in eukaryotes such as mammals and plants. Some viruses also encode small viral RNAs (svRNAs) in their genomes and regulate gene expression in the host and the virus itself using a mechanism similar to miRNAs. For example, multiple svRNAs have been found in the genome of SARS-CoV-1, and one of these has been suggested to be associated with pulmonary inflammation (see Non-Patent Document 1). [Prior art documents] [Non-patent literature]

[0003] [Non-Patent Document 1] Morales et al., SARS-CoV-Encoded Small RNAs Contribute to Infection-Associated Lung Pathology, Cell Host & Microbe, 21, 344-355, 2017. Summary of the Invention [Problem to be solved by the invention]

[0004] Elucidating the molecular mechanisms of how viruses control their own gene expression and replication, and how they lead to disease after infection, is important for developing effective treatments.

[0005] However, the existence of svRNA produced by SARS-CoV-2 has not been reported to date. The present invention aims to identify svRNA produced by SARS-CoV-2 and provide a technology to control the coronavirus life cycle. [Means for solving the problem]

[0006] The present invention includes the following aspects. [1] A polynucleotide comprising: (i) a nucleotide sequence set forth in any one of SEQ ID NOs: 1 to 3; (ii) a nucleotide sequence in which 1 to 3 nucleotides are deleted, substituted, inserted or added in the nucleotide sequence set forth in any one of SEQ ID NOs: 1 to 3; or (iii) a nucleotide sequence having 60% or more sequence identity to the nucleotide sequence set forth in any one of SEQ ID NOs: 1 to 3; and having activity of promoting coronavirus replication when present in coronavirus-infected cells. [2] The polynucleotide according to [1], which comprises (i) a base sequence set forth in any one of SEQ ID NOs: 1 to 3, (ii) a base sequence in which 1 to 3 bases are deleted, substituted, inserted or added in the base sequence set forth in any one of SEQ ID NOs: 1 to 3, or (iii) a base sequence having 60% or more sequence identity to the base sequence set forth in any one of SEQ ID NOs: 1 to 3, and which has the activity of promoting coronavirus replication when present in coronavirus-infected cells. [3] A mimetic of the polynucleotide described in [1] or [2]. [4] An inhibitor of the polynucleotide according to [1] or [2]. [5] A coronavirus replication promoter having as an active ingredient the polynucleotide described in [1] or [2] or the mimetic substance described in claim [3]. [6] A composition for promoting coronavirus replication, comprising as an active ingredient a combination of two or more of the polynucleotides described in [1] or [2], a combination of two or more of the mimetic substances described in [3], or a combination thereof. [7] [4] A coronavirus replication inhibitor containing the inhibitor described in [4] as an active ingredient. [8] A composition for inhibiting coronavirus replication, comprising a combination of two or more of the inhibitors described in [4] as active ingredients. [9] A pharmaceutical composition for preventing and / or treating coronavirus infection, comprising the replication inhibitor described in [7] or the replication inhibitor composition described in [8].

[10] An animal cell comprising the polynucleotide according to [1] or [2] or a combination of two or more thereof.

[11] The animal cell according to

[10] , which has been modified to express the polynucleotide according to [1] or [2] or a combination of two or more thereof.

[12] A method for inhibiting coronavirus replication in animal cells, comprising a step of contacting the animal cells with the replication inhibitor described in [7] or the composition for inhibiting replication described in [8].

[13] A method for promoting coronavirus replication in animal cells, comprising the steps of contacting animal cells with the replication promoter described in [5] or the replication-promoting composition described in [6], and infecting the animal cells with coronavirus before or after the step.

[14] A method for producing a coronavirus, comprising the steps of infecting the animal cells according to

[10] or

[11] with a coronavirus, and culturing the animal cells infected with the coronavirus.

[15] A method for producing a coronavirus, comprising the steps of replicating the coronavirus by the method described in

[13] and isolating the replicated coronavirus from the animal cells. [Effects of the Invention]

[0007] The present invention provides a technology for controlling the life cycle of coronaviruses, and also provides a preventive and / or therapeutic agent or vaccine for coronavirus infections. [Brief explanation of the drawings]

[0008] [Figure 1] Figure 1 is a graph showing the percentage of reads mapped to the SARS-CoV-2 genome as a result of small RNA-seq performed in Experimental Example 1. [Figure 2] Figure 2 shows the results of small RNA-seq performed in Experimental Example 1, showing the reads mapped to the SARS-CoV-2 genome. [Figure 3] FIG. 3 is a diagram in which the prominent peak in FIG. 2 is focused on and the surrounding area is enlarged. [Figure 4] FIG. 4 is an enlarged view of the area surrounding a prominent peak in FIG. [Figure 5A] FIG. 5A is a graph showing the results of quantitative RT-PCR in Experimental Example 2. [Figure 5B] FIG. 5B is a graph showing the results of quantitative RT-PCR in Experimental Example 2. [Figure 5C] FIG. 5C is a graph showing the results of quantitative RT-PCR in Experimental Example 2. [Figure 5D] FIG. 5D is a graph showing the results of quantitative RT-PCR in Experimental Example 2. [Figure 6] FIG. 6 shows the results of predicting the secondary structure of svRNA ORF1ab and the regions 100 nt upstream and 100 nt downstream thereof in Experimental Example 3. [Figure 7] FIG. 7 shows the results of predicting the secondary structures of svRNA ORF7a-1, svRNA ORF7a-2, and the regions 100 nt upstream and 100 nt downstream thereof in Experimental Example 3. [Figure 8] FIG. 8 is a schematic diagram showing the structure of the svRNA inhibitor prepared in Experimental Example 4. [Figure 9]The left side of Figure 9 is a schematic diagram showing the structure of the svRNA mimetic prepared in Experimental Example 4. The right side of Figure 9 is a schematic diagram showing the state in which the svRNA mimetic is incorporated into the RISC complex. [Figure 10] FIG. 10 is a diagram illustrating the experimental schedule of Experimental Example 5. [Figure 11] FIG. 11 is a graph showing the results of quantifying the number of copies of the viral genome contained in the cell culture supernatant when svRNA inhibitors were introduced alone or in combination in Experimental Example 5. [Figure 12] FIG. 12 is a graph showing the results of quantifying the copy number of the viral genome contained in the cell culture supernatant when svRNA mimics were introduced alone or in combination in Experimental Example 5. [Figure 13] FIG. 13 is a diagram illustrating the experimental schedule of Experimental Example 6. [Figure 14] FIG. 14 is a graph showing the results of quantifying the copy number of the viral genome contained in the cell culture supernatant when svRNA inhibitors were introduced alone or in combination in Experimental Example 6. [Figure 15A] FIG. 15A is a graph showing the results of quantitative RT-PCR in Experimental Example 7. [Figure 15B] FIG. 15B is a graph showing the results of quantitative RT-PCR in Experimental Example 7. [Figure 15C] FIG. 15C is a graph showing the results of quantitative RT-PCR in Experimental Example 7. [Figure 16A] FIG. 16A is a graph showing the results of quantitative RT-PCR in Experimental Example 8. [Figure 16B] FIG. 16B is a graph showing the results of quantitative RT-PCR in Experimental Example 8. [Figure 16C] FIG. 16C is a graph showing the results of quantitative RT-PCR in Experimental Example 8. DETAILED DESCRIPTION OF THE INVENTION

[0009] As used herein, the term "active ingredient" means that the active ingredient (a polynucleotide, mimetic, or inhibitor, as described below) is contained in an amount sufficient to achieve the efficacy or activity of the active ingredient. Alternatively, the term means that the polynucleotide, mimetic, or inhibitor, as described below, is contained as the main active ingredient.

[0010] [Polynucleotide] In one embodiment, the present invention provides a polynucleotide comprising (i) a nucleotide sequence set forth in any one of SEQ ID NOs: 1 to 3, (ii) a nucleotide sequence in which 1 to 3 nucleotides are deleted, substituted, inserted, or added in the nucleotide sequence set forth in any one of SEQ ID NOs: 1 to 3, or (iii) a nucleotide sequence having 60% or more sequence identity to the nucleotide sequence set forth in any one of SEQ ID NOs: 1 to 3, and which has activity of promoting coronavirus replication when present in a coronavirus-infected cell.

[0011] As described later in the Examples, the inventors identified polynucleotides consisting of the nucleotide sequences set forth in SEQ ID NOs: 1 to 3 as svRNAs derived from SARS-CoV-2. The inventors further demonstrated that the presence of these polynucleotides in SARS-CoV-2-infected cells promotes SARS-CoV-2 replication. Furthermore, the nucleotide sequences of the polynucleotides consisting of the nucleotide sequences set forth in SEQ ID NOs: 1 to 3 are conserved in coronaviruses other than SARS-CoV-2.

[0012] Therefore, the polynucleotide of this embodiment can be used to control the life cycle of coronavirus. Specifically, for example, by allowing coronavirus and the polynucleotide of this embodiment to coexist in a cell, coronavirus replication can be promoted. In other words, the polynucleotide of this embodiment can be used for mass cultivation of coronavirus as a raw material for attenuated or inactivated coronavirus vaccines.

[0013] As used herein, coronaviruses include, but are not limited to, SARS-CoV-2, SARS-CoV, MERS-CoV, HCoV-229E, HCoV-OC43, HCoV-NL63, HCoV-HKU1, and the like.

[0014] The polynucleotide of this embodiment is thought to be incorporated into an RNA-induced silencing complex (RISC) and degrades or suppresses the expression of target mRNA via the RNAi pathway or miRNA pathway.

[0015] It is known that in the miRNA pathway, the guide strand, which is incorporated into the RISC complex and is involved in the recognition of the target mRNA, may have base mismatches with the target mRNA. Therefore, the polynucleotide of this embodiment may be a polynucleotide consisting of a base sequence in which one to three, for example, one to two, for example, one base, has been deleted, substituted, inserted, or added in the base sequence set forth in any of SEQ ID NOS: 1 to 3, as long as it has the activity of promoting coronavirus replication when present in coronavirus-infected cells. Hereinafter, a polynucleotide consisting of a base sequence in which approximately one to three bases have been deleted, substituted, inserted, or added in the base sequence set forth in any of SEQ ID NOS: 1 to 3 may also be referred to as a mutant.

[0016] Similarly, the polynucleotide of this embodiment may be a polynucleotide consisting of a base sequence having 60% or more, for example 70% or more, for example 80% or more, for example 90% or more, for example 95% or more sequence identity to the base sequence set forth in any of SEQ ID NOs: 1 to 3, as long as it has the activity of promoting coronavirus replication when present in coronavirus-infected cells.

[0017] Here, the sequence identity of a subject base sequence to a reference base sequence can be determined, for example, as follows: First, the reference base sequence and the subject base sequence are aligned. Here, gaps may be included in each base sequence to maximize sequence identity. Next, the number of matching bases in the reference base sequence and the subject base sequence is calculated, and the sequence identity can be determined according to the following formula (1). Sequence identity (%) = number of matched bases / total number of bases in the target sequence × 100 (1)

[0018] Hereinafter, a polynucleotide consisting of a base sequence having 60% or more, for example 70% or more, for example 80% or more, for example 90% or more, for example 95% or more sequence identity to the base sequence set forth in any of SEQ ID NOs: 1 to 3 may also be referred to as a mutant.

[0019] The mutant may be a contiguous partial sequence of any of the nucleotide sequences (i) to (iii) above, as long as it has the activity of promoting coronavirus replication when present in coronavirus-infected cells. For example, the mutant may be a polynucleotide consisting of a shorter contiguous nucleotide sequence contained in the 23-base nucleotide sequence set forth in SEQ ID NO: 1, the 28-base nucleotide sequence set forth in SEQ ID NO: 2, or the 24-base nucleotide sequence set forth in SEQ ID NO: 3, or any of these mutant nucleotide sequences. The length of the shorter nucleotide sequence can be, for example, 10 to 20 bases.

[0020] The polynucleotide of this embodiment may be a polynucleotide consisting of any of the nucleotide sequences (i) to (iii) above, or a polynucleotide comprising any of the nucleotide sequences (i) to (iii) above, i.e., a polynucleotide comprising any of the nucleotide sequences (i) to (iii) above, to which a polynucleotide consisting of any nucleotide sequence is further added at the 5' end, the 3' end, or both of the nucleotide sequences. Thus, even a polynucleotide comprising any of the nucleotide sequences (i) to (iii) above exhibits coronavirus replication-promoting activity after being processed and incorporated into the RISC complex. The length of a polynucleotide comprising any of the nucleotide sequences (i) to (iii) above is not particularly limited, and may be, for example, about 1,000 bases, about 500 bases, about 100 bases, about 50 bases, or about 20 bases. The most common length of human mature miRNAs is 22 bases. The shortest length is 16 bases, and the longest is 28 bases. The length of a miRNA precursor (pre-miRNA) is about 70 bases. The length of a polynucleotide containing any of the base sequences (i) to (iii) above may be approximately the same as that of these miRNAs.

[0021] The polynucleotide of this embodiment may be a single-stranded RNA, or may form a double-stranded RNA with a polynucleotide consisting of a complementary base sequence.

[0022] [Mimetic substances] In one embodiment, the present invention provides a mimetic of the aforementioned polynucleotide. That is, the mimetic of this embodiment may be a polynucleotide mimetic that includes (i) a nucleotide sequence set forth in any one of SEQ ID NOS: 1 to 3, (ii) a nucleotide sequence set forth in any one of SEQ ID NOS: 1 to 3 in which 1 to 3 bases are deleted, substituted, inserted, or added, or (iii) a nucleotide sequence having 60% or more, e.g., 70% or more, e.g., 80% or more, e.g., 90% or more, e.g., 95% or more, sequence identity to the nucleotide sequence set forth in any one of SEQ ID NOS: 1 to 3, and that has the activity of promoting coronavirus replication when present in coronavirus-infected cells. Alternatively, the mimetic of this embodiment may be a polynucleotide mimetic that consists of any one of the nucleotide sequences (i) to (iii) above and has the activity of promoting coronavirus replication when present in coronavirus-infected cells. In this embodiment, the terms "coronavirus" and "sequence identity" are as defined above.

[0023] As used herein, a mimetic substance refers to a substance that has the same activity as a polynucleotide that consists of any of the base sequences (i) to (iii) above and that has the activity of promoting coronavirus replication when present in coronavirus-infected cells.

[0024] As will be described later in the Examples, the mimetic substance of this embodiment can be used to control the life cycle of coronavirus. Specifically, for example, by allowing the coronavirus and the mimetic substance of this embodiment to coexist in cells, coronavirus replication can be promoted. In other words, the mimetic substance of this embodiment can be used for mass-culturing coronavirus as a raw material for attenuated or inactivated coronavirus vaccines.

[0025] The mimetic of this embodiment may be a double-stranded polynucleotide in which a polynucleotide consisting of any one of the base sequences (i) to (iii) above and having the activity of promoting coronavirus replication when present in coronavirus-infected cells is hybridized with a polynucleotide of its complementary strand. The mimetic of this embodiment may be a single-stranded polynucleotide or a circular polynucleotide. The polynucleotide may be DNA or RNA, with RNA being preferred. Furthermore, the mimetic of this embodiment may be natural RNA or chemically modified RNA.

[0026] Chemically modified RNA includes sugar-modified ribonucleotides, backbone-modified ribonucleotides, base-modified ribonucleotides, etc. Chemical modification can improve RNA function and nuclease resistance.

[0027] Examples of sugar-modified ribonucleotides include ribonucleotides in which the 2'-OH group of the sugar is replaced with a hydrogen atom, a halogen atom, or a group selected from the group consisting of OR, R, SH, SR, NH, NHR, NR, and CN. 10 Preferably, the halogen atom is a C1-C6 alkyl, alkoxy, alkenyl, or alkynyl group, and more preferably a methyl, ethyl, methoxyethyl, amino, aminopropyl, or isopropyl group. The halogen atom is preferably F, Cl, Br, or I, and more preferably F.

[0028] Among these, 2'-fluoro, 2'-O-methyl, or 2'-O-methoxyethyl modified ribonucleotides are particularly suitable for use. Among these, 2'-O-methylated RNA has properties such as high nuclease resistance, high thermal stability of the double strand, and the ability to avoid innate immune responses.

[0029] The mimetic of this embodiment may contain sulfonated nucleotides (phosphorothioates) to form a phosphorothioate bond between the sugar and phosphate. Phosphorothioation of DNA / RNA can confer high nuclease resistance without affecting the base pairing.

[0030] The mimetics of this embodiment may include ribonucleotides containing non-naturally occurring bases, such as uridine or cytidine modified at the 5-position (e.g., 5-(2-amino)propyluridine, 5-bromouridine), adenosine or guanosine modified at the 8-position (e.g., 8-bromo-guanosine), deazanucleotides (e.g., 7-deazaadenosine), O- or N-alkylated nucleotides (e.g., N6-methyladenosine, etc.).

[0031] Furthermore, there are 2',4'-BNA (bridge nucleic acid) / LNA (locked nucleic acid) in which the oxygen atom at the 2' position of the sugar is bridged to the carbon atom at the 4' position via a methylene bond (Koshkin AA et al., LNA (locked nucleic acid): An RNA mimic forming exceedingly stable LNA:LNA duplexes, J. Am. Chem. Soc., 120 (50), 13252-13253, 1998), ENA (2'-O,4'-C-ethylene-bridged nucleic acids) (International Publication No. 2000 / 047599), and 4'-thionucleotides in which the oxygen atom of the furanose ring is replaced with a sulfur atom (Dande P., et al., Improving RNA Interference in Mammalian Cells by 4'-Thio-Modified Small Interfering RNA (siRNA): Effect on siRNA Activity and Nuclease Activity). Nucleotide analogs such as "Stability When Used in Combination with 2'-O-Alkyl Modifications, J. Med. Chem., 49 (5), 1624-1634, 2006., International Publication No. 2004 / 18494) can also be suitably used.

[0032] The above-mentioned modified nucleotides are all known in the art and are widely used as a method for improving the in vivo stability of oligonucleic acids. In the mimetic of this embodiment, some or all of the nucleotides may be substituted with one or more modified nucleotides selected from the above-mentioned modified nucleotides.

[0033] Furthermore, for the purpose of tissue-specific delivery or improving cell membrane permeability, peptides, aptamers, hydrophobic molecules, etc. may be conjugated to the terminal (5'-end and / or 3'-end) nucleotides of the mimetic substance of this embodiment. Suitable hydrophobic molecules for this purpose include cholesterol, vitamin E (α-tocopherol), palmitic acid, etc.

[0034] The above modifications may be used in combination, for example, the above-mentioned peptide, aptamer, hydrophobic molecule, etc. may be conjugated to the above-mentioned S-modified RNA. Also, different types of the above-mentioned modified nucleotides may be contained at the terminus and at other sites.

[0035] The mimetic substance of this embodiment is preferably one that, when expressed in a cell or introduced into a cell, is incorporated into the RISC complex and mimics the post-transcriptional gene expression regulatory function of a natural miRNA.

[0036] [Inhibitor] In one embodiment, the present invention provides an inhibitor of the above-mentioned polynucleotide. That is, in one aspect, the inhibitor of this embodiment is an inhibitor of a polynucleotide consisting of the nucleotide sequence set forth in any one of SEQ ID NOs: 1 to 3. In another aspect, the inhibitor of this embodiment is an inhibitor of a polynucleotide consisting of the nucleotide sequence set forth in any one of SEQ ID NOs: 1 to 3, in which 1 to 3 nucleotides have been deleted, substituted, inserted, or added, and which has the activity of promoting coronavirus replication when present in coronavirus-infected cells. In another aspect, the inhibitor of this embodiment is an inhibitor of a polynucleotide consisting of a nucleotide sequence having 60% or more, for example, 70% or more, for example, 80% or more, for example, 90% or more, for example, 95% or more, sequence identity to the nucleotide sequence set forth in any one of SEQ ID NOs: 1 to 3, and which has the activity of promoting coronavirus replication when present in coronavirus-infected cells. In this embodiment, the terms "coronavirus" and "sequence identity" are as defined above.

[0037] In this embodiment, the inhibitor is a substance that suppresses the activity of the polynucleotide or mimetic. The inhibitor of this embodiment may be, for example, a polynucleotide that binds complementarily to the polynucleotide or mimetic and inhibits its function by binding to the polynucleotide or mimetic. Alternatively, the inhibitor of this embodiment may be, for example, an siRNA or shRNA that targets the polynucleotide.

[0038] As described later in the Examples, the life cycle of the coronavirus can be controlled using the inhibitor of this embodiment. For example, by allowing the coronavirus and the inhibitor of this embodiment to coexist in cells, coronavirus replication can be suppressed. The inhibitor of this embodiment's viral replication inhibitory effect was also effective against multiple SARS-CoV-2 mutant strains. Therefore, the inhibitor of this embodiment may be useful as a therapeutic agent for COVID-19.

[0039] The inhibitor of this embodiment may be a single-stranded or double-stranded polynucleotide having a base sequence complementary to the polynucleotide or mimetic described above, or may be a circular polynucleotide. Furthermore, the inhibitor of this embodiment may be a natural polynucleotide or a chemically modified polynucleotide. Examples of chemically modified polynucleotides include the chemically modified RNA described above and polynucleotides containing the nucleotide analogs described above.

[0040] The inhibitor of this embodiment may be one that, when expressed in a cell or introduced into a cell, traps the above-mentioned polynucleotide or mimetic substance and inhibits the above-mentioned polynucleotide or mimetic substance from being incorporated into the RISC complex.

[0041] A specific example of an inhibitor of a polynucleotide consisting of the nucleotide sequence of SEQ ID NO: 1 (svRNA ORF1ab) is a double-stranded polynucleotide obtained by hybridizing an RNA strand having the nucleotide sequence of SEQ ID NO: 13 with an RNA strand having the nucleotide sequence of SEQ ID NO: 14, as described below in the Examples.

[0042] A specific example of an inhibitor of a polynucleotide consisting of the nucleotide sequence of SEQ ID NO: 2 (svRNA ORF7a-1) is a double-stranded polynucleotide obtained by hybridizing an RNA strand having the nucleotide sequence of SEQ ID NO: 15 with an RNA strand having the nucleotide sequence of SEQ ID NO: 16, as described below in the Examples.

[0043] A specific example of an inhibitor of a polynucleotide consisting of the nucleotide sequence of SEQ ID NO: 3 (svRNA ORF7a-2) is a double-stranded polynucleotide obtained by hybridizing an RNA strand having the nucleotide sequence of SEQ ID NO: 17 with an RNA strand having the nucleotide sequence of SEQ ID NO: 18, as described below in the Examples.

[0044] [Coronavirus replication promoter] In one embodiment, the present invention provides a coronavirus replication promoter comprising the above-mentioned polynucleotide or mimetic as an active ingredient.

[0045] That is, in one aspect, the replication promoter of this embodiment has as an active ingredient a polynucleotide consisting of the base sequence set forth in any one of SEQ ID NOS: 1 to 3. In another aspect, the replication promoter of this embodiment has as an active ingredient a polynucleotide consisting of a base sequence in which one to three bases are deleted, substituted, inserted, or added in the base sequence set forth in any one of SEQ ID NOS: 1 to 3, and which has activity to promote coronavirus replication when present in coronavirus-infected cells. In another aspect, the replication promoter of this embodiment has as an active ingredient a polynucleotide consisting of a base sequence that has 60% or more, for example, 70% or more, for example, 80% or more, for example, 90% or more, or for example, 95% or more sequence identity to the base sequence set forth in any one of SEQ ID NOS: 1 to 3, and which has activity to promote coronavirus replication when present in coronavirus-infected cells.

[0046] In one aspect, the replication promoter of this embodiment has as its active ingredient a polynucleotide mimetic consisting of the base sequence set forth in any one of SEQ ID NOS: 1 to 3. In another aspect, the replication promoter of this embodiment has as its active ingredient a polynucleotide mimetic consisting of the base sequence set forth in any one of SEQ ID NOS: 1 to 3, in which one to three bases have been deleted, substituted, inserted, or added, and which has the activity of promoting coronavirus replication when present in coronavirus-infected cells. In another aspect, the replication promoter of this embodiment has as its active ingredient a polynucleotide mimetic consisting of a base sequence that has 60% or more, for example, 70% or more, for example, 80% or more, for example, 90% or more, or for example, 95% or more sequence identity to the base sequence set forth in any one of SEQ ID NOS: 1 to 3, and which has the activity of promoting coronavirus replication when present in coronavirus-infected cells. In this embodiment, the terms "coronavirus," "sequence identity," and "mimetic" are the same as those defined above.

[0047] As described later in the Examples, the inventors have demonstrated that the coexistence of a coronavirus and the replication promoter of this embodiment in cells can promote coronavirus replication. Therefore, the replication promoter of this embodiment can be used for mass-culturing coronaviruses as raw materials for attenuated or inactivated coronavirus vaccines.

[0048] [Composition for promoting coronavirus replication] In one embodiment, the present invention provides a composition for promoting coronavirus replication, comprising, as an active ingredient, a combination of two or more of the above-described polynucleotides, a combination of two or more of the above-described mimetics, or a combination thereof. The composition of this embodiment may contain three or more of the above-described polynucleotides. The composition of this embodiment may also contain three or more of the above-described mimetics. The composition of this embodiment may also contain a combination of the above-described polynucleotides and the above-described mimetics.

[0049] Combining the above-mentioned polynucleotides or the above-mentioned mimetics can significantly enhance coronavirus replication compared to using the above-mentioned polynucleotides or the above-mentioned mimetics alone.

[0050] As described later in the Examples, the inventors have demonstrated that coronavirus replication is significantly promoted when a combination of a svRNA ORF7a-1 mimetic and a svRNA 1ab mimetic, a combination of a svRNA ORF7a-2 mimetic and a svRNA 1ab mimetic, or a combination of a svRNA ORF7a-1 mimetic, a svRNA ORF7a-2 mimetic and a svRNA 1ab mimetic is introduced into cells, compared to when a polynucleotide mimetic (svRNA ORF7a-1) consisting of the nucleotide sequence of SEQ ID NO: 2, a polynucleotide mimetic (svRNA ORF7a-2) consisting of the nucleotide sequence of SEQ ID NO: 3, or a polynucleotide mimetic (svRNA ORF1ab) consisting of the nucleotide sequence of SEQ ID NO: 1 is introduced into cells alone.

[0051] Therefore, in the composition of this embodiment, the combination of polynucleotides or mimetics is preferably any one of the following: (i) a combination of a polynucleotide consisting of the base sequence of SEQ ID NO: 1 or a variant thereof or a mimetic thereof with a polynucleotide consisting of the base sequence of SEQ ID NO: 2 or a variant thereof or a mimetic thereof; (ii) a combination of a polynucleotide consisting of the base sequence of SEQ ID NO: 1 or a variant thereof or a mimetic thereof with a polynucleotide consisting of the base sequence of SEQ ID NO: 3 or a variant thereof or a mimetic thereof; or (iii) a combination of a polynucleotide consisting of the base sequence of SEQ ID NO: 1 or a variant thereof or a mimetic thereof with a polynucleotide consisting of the base sequence of SEQ ID NO: 2 or a variant thereof or a mimetic thereof with a polynucleotide consisting of the base sequence of SEQ ID NO: 3 or a variant thereof or a mimetic thereof.

[0052] [Coronavirus replication inhibitors] In one embodiment, the present invention provides an agent for suppressing coronavirus replication, which comprises the above-mentioned inhibitor as an active ingredient.

[0053] That is, in one aspect, the replication inhibitor of this embodiment contains, as an active ingredient, an inhibitor of a polynucleotide consisting of the base sequence set forth in any one of SEQ ID NOS: 1 to 3. In another aspect, the replication inhibitor of this embodiment contains, as an active ingredient, an inhibitor of a polynucleotide consisting of a base sequence in which one to three bases are deleted, substituted, inserted, or added in the base sequence set forth in any one of SEQ ID NOS: 1 to 3, and which has the activity of promoting coronavirus replication when present in coronavirus-infected cells. In another aspect, the replication inhibitor of this embodiment contains, as an active ingredient, an inhibitor of a polynucleotide consisting of a base sequence having 60% or more, e.g., 70% or more, e.g., 80% or more, e.g., 90% or more, e.g., 95% or more, sequence identity to the base sequence set forth in any one of SEQ ID NOS: 1 to 3, and which has the activity of promoting coronavirus replication when present in coronavirus-infected cells. In this embodiment, the terms "coronavirus," "sequence identity," and "inhibitor" are the same as those defined above.

[0054] As described later in the Examples, the inventors have demonstrated that SARS-CoV-2 replication can be suppressed by coexisting SARS-CoV-2 and the replication inhibitor of this embodiment in cells. Therefore, the replication inhibitor of this embodiment can be used to suppress the replication of SARS-CoV-2. Furthermore, the replication inhibitor of this embodiment may potentially be used as a therapeutic agent for COVID-19.

[0055] [Composition for inhibiting coronavirus replication] In one embodiment, the present invention provides a composition for inhibiting coronavirus replication, which comprises, as active ingredients, a combination of two or more of the above-mentioned inhibitors. The composition of this embodiment may also comprise three or more of the above-mentioned inhibitors.

[0056] That is, in one aspect, the composition of this embodiment contains, as an active ingredient, a combination of two or more inhibitors of a polynucleotide consisting of the nucleotide sequence set forth in any one of SEQ ID NOS: 1 to 3. In another aspect, the composition of this embodiment contains, as an active ingredient, a combination of two or more inhibitors of a polynucleotide consisting of a nucleotide sequence in which one to three nucleotides are deleted, substituted, inserted, or added in the nucleotide sequence set forth in any one of SEQ ID NOS: 1 to 3, and which has the activity of promoting coronavirus replication when present in coronavirus-infected cells. In another aspect, the composition for inhibiting replication of this embodiment contains, as an active ingredient, a combination of two or more inhibitors of a polynucleotide consisting of a nucleotide sequence having 60% or more, e.g., 70% or more, e.g., 80% or more, e.g., 90% or more, e.g., 95% or more, sequence identity to the nucleotide sequence set forth in any one of SEQ ID NOS: 1 to 3, and which has the activity of promoting coronavirus replication when present in coronavirus-infected cells. In this embodiment, the terms "coronavirus," "sequence identity," and "inhibitor" are the same as those defined above.

[0057] By combining the above inhibitors, coronavirus replication can be significantly suppressed.

[0058] As will be described later in the Examples, the inventors have revealed that the copy number of the viral genome is reduced when a combination of an inhibitor for a polynucleotide consisting of the nucleotide sequence of SEQ ID NO: 1 (svRNA ORF1ab) and an inhibitor for a polynucleotide consisting of the nucleotide sequence of SEQ ID NO: 2 (svRNA ORF7a-1); a combination of an inhibitor for a polynucleotide consisting of the nucleotide sequence of SEQ ID NO: 1 (svRNA ORF1ab) and an inhibitor for a polynucleotide consisting of the nucleotide sequence of SEQ ID NO: 3 (svRNA ORF7a-2); or a combination of an inhibitor for a polynucleotide consisting of the nucleotide sequence of SEQ ID NO: 1 (svRNA ORF1ab), an inhibitor for a polynucleotide consisting of the nucleotide sequence of SEQ ID NO: 2 (svRNA ORF7a-1) and an inhibitor for a polynucleotide consisting of the nucleotide sequence of SEQ ID NO: 3 (svRNA ORF7a-2).

[0059] Therefore, in the composition of this embodiment, the combination of inhibitors is preferably any one of (i) a combination of an inhibitor for a polynucleotide consisting of the base sequence of SEQ ID NO: 1 and an inhibitor for a polynucleotide consisting of the base sequence of SEQ ID NO: 2, (ii) a combination of an inhibitor for a polynucleotide consisting of the base sequence of SEQ ID NO: 1 and an inhibitor for a polynucleotide consisting of the base sequence of SEQ ID NO: 3, or (iii) a combination of an inhibitor for a polynucleotide consisting of the base sequence of SEQ ID NO: 1, an inhibitor for a polynucleotide consisting of the base sequence of SEQ ID NO: 2 and an inhibitor for a polynucleotide consisting of the base sequence of SEQ ID NO: 3.

[0060] [Animal cells] In one embodiment, the present invention provides an animal cell comprising the above-described polynucleotides or a combination of two or more thereof.

[0061] By infecting the animal cells of this embodiment with coronavirus and incubating them, coronavirus replication can be promoted and a larger amount of coronavirus can be obtained. In other words, the animal cells of this embodiment can be referred to as animal cells for promoting coronavirus replication, animal cells for producing coronavirus, etc.

[0062] In one aspect, the animal cell of this embodiment comprises a polynucleotide comprising a nucleotide sequence set forth in any one of SEQ ID NOS: 1 to 3, or a combination of two or more thereof. In another aspect, the animal cell of this embodiment comprises a polynucleotide comprising a nucleotide sequence in which one to three nucleotides are deleted, substituted, inserted, or added in the nucleotide sequence set forth in any one of SEQ ID NOS: 1 to 3, or a combination of two or more thereof, and which has activity to promote coronavirus replication when present in coronavirus-infected cells. In another aspect, the animal cell of this embodiment comprises a polynucleotide comprising a nucleotide sequence that has 60% or more, for example, 70% or more, for example, 80% or more, for example, 90% or more, for example, 95% or more sequence identity to the nucleotide sequence set forth in any one of SEQ ID NOS: 1 to 3, and which has activity to promote coronavirus replication when present in coronavirus-infected cells, or a combination of two or more thereof.

[0063] In one aspect, the animal cell of this embodiment comprises a polynucleotide consisting of the nucleotide sequence set forth in any one of SEQ ID NOs: 1 to 3, or a combination of two or more thereof. In another aspect, the animal cell of this embodiment comprises a polynucleotide consisting of the nucleotide sequence set forth in any one of SEQ ID NOs: 1 to 3, in which one to three bases are deleted, substituted, inserted, or added, and which has activity to promote coronavirus replication when present in coronavirus-infected cells, or a combination of two or more thereof. In another aspect, the animal cell of this embodiment comprises a polynucleotide consisting of a nucleotide sequence that has 60% or more, for example, 70% or more, for example, 80% or more, for example, 90% or more, for example, 95% or more, sequence identity to the nucleotide sequence set forth in any one of SEQ ID NOs: 1 to 3, and which has activity to promote coronavirus replication when present in coronavirus-infected cells, or a combination of two or more thereof.

[0064] In the animal cells of this embodiment, "comprising the above-mentioned polynucleotides or a combination of two or more thereof" means that the above-mentioned polynucleotides or a combination of two or more thereof are present in the animal cells.

[0065] In one aspect, the animal cell of this embodiment may be modified to express the above-described polynucleotides or a combination of two or more thereof. For example, a construct encoding the above-described polynucleotides or a combination of two or more thereof may be transiently or stably introduced into the animal cell and expressed in the animal cell. The construct may be introduced into the genome of the animal cell by genome editing, or may be introduced into the genome of the animal cell in the form of an expression vector or episomally.

[0066] In one aspect, the animal cells of this embodiment may be cells into which the above-mentioned polynucleotides or a combination of two or more thereof have been directly introduced.

[0067] The method for introducing the construct or polynucleotide into animal cells is not particularly limited, and can be carried out by, for example, transfection using a transfection reagent such as a cationic lipid, electroporation, or injection using a microcapillary.

[0068] More preferably, the animal cell of this embodiment is a cell that expresses any of the following combinations: (i) a combination of a polynucleotide consisting of the nucleotide sequence of SEQ ID NO: 1 or a mutant thereof and a polynucleotide consisting of the nucleotide sequence of SEQ ID NO: 2 or a mutant thereof, (ii) a combination of a polynucleotide consisting of the nucleotide sequence of SEQ ID NO: 1 or a mutant thereof and a polynucleotide consisting of the nucleotide sequence of SEQ ID NO: 3 or a mutant thereof, or (iii) a combination of a polynucleotide consisting of the nucleotide sequence of SEQ ID NO: 1 or a mutant thereof, a polynucleotide consisting of the nucleotide sequence of SEQ ID NO: 2 or a mutant thereof, and a polynucleotide consisting of the nucleotide sequence of SEQ ID NO: 3 or a mutant thereof. As described above, expression of these combinations further promotes coronavirus replication.

[0069] The animal cells of this embodiment are not particularly limited as long as they are cells that can be infected with coronavirus, and examples include epithelial cells. Examples of epithelial cells include bronchial organoid-derived epithelial cells and established epithelial cell lines. Examples of established epithelial cell lines include Vero cells derived from African green monkey kidney epithelial cells. Vero cells may be introduced with an expression vector for the transmembrane protease, serine 2 (TMPRSS2) gene. Alternatively, iPS cells may be used instead of epithelial cells. iPS cells may be introduced with an expression vector for the angiotensin-converting enzyme (ACE) 2 gene.

[0070] [Methods for inhibiting coronavirus replication] In one embodiment, the present invention provides a method for inhibiting coronavirus replication in animal cells, comprising the step of contacting the animal cells with the replication inhibitor or composition for inhibiting replication described above. In the method of this embodiment, the terms "coronavirus," "replication inhibitor," and "composition for inhibiting replication" are the same as those defined above.

[0071] When the replication inhibitor or composition for replication inhibition described above is brought into contact with animal cells, the replication inhibitor or composition for replication inhibition is introduced into the cytoplasm of the animal cells, thereby exerting its function of inhibiting coronavirus replication. In the replication inhibition method of this embodiment, "contacting with animal cells" may be rephrased as "introducing into animal cells."

[0072] The replication-inhibiting method of this embodiment may be performed in vivo in a human or non-human animal body, or in vitro. When the replication-inhibiting method of this embodiment is performed in vivo, it can also be said to be a method for preventing or treating COVID-19.

[0073] The replication inhibition method of this embodiment may include a step of contacting the above-described replication inhibitor or composition for replication inhibition with animal cells before coronavirus infection, or may include a step of contacting the above-described replication inhibitor or composition for replication inhibition with animal cells after coronavirus infection.

[0074] Contact of animal cells with a replication inhibitor or a composition for replication inhibition may be carried out, for example, in the presence of a transfection reagent such as a cationic lipid, or may be carried out in conjunction with electroporation.

[0075] [Pharmaceutical composition for preventing and / or treating coronavirus infection] In one embodiment, the present invention provides a pharmaceutical composition for preventing and / or treating coronavirus infection, comprising the above-described replication inhibitor or composition for inhibiting replication as an active ingredient. In this embodiment, the terms "coronavirus," "replication inhibitor," and "composition for inhibiting replication" are the same as those defined above.

[0076] By administering a replication inhibitor or a composition for inhibiting replication formulated as a pharmaceutical preparation to the living body of a human or non-human animal, coronavirus infections can be prevented and / or treated.

[0077] The formulation can be carried out by combining the active ingredient (the replication inhibitor or the replication-inhibiting composition) with a pharmaceutically acceptable carrier using a general formulation technique. The pharmaceutical formulation is preferably one that is administered parenterally in the form of an injection, an intravenous drip, an inhalant, or the like.

[0078] Pharmaceutically acceptable carriers that are commonly used in the formulation of nucleic acid drugs can be used without particular limitation. Specific examples of such carriers include cationic liposomes, non-cationic liposomes, polyethylene glycol (PEG)-modified liposomes, lipid nanoparticles, and block copolymers.

[0079] Examples of materials for liposomes or lipid nanoparticles include, but are not limited to, cholesterol, 1,2-distearoyl-sn-glycero-3-phosphocholine (DSPC), 1,2-dimyristoyl-rac-glycero-3-methylpolyoxyethylene (PEG2000-DMG), and the like.

[0080] The pharmaceutical preparation may contain an additive, which may be any additive typically used in pharmaceutical preparations, including, but not limited to, buffers such as trometamol and trometamol hydrochloride, pH adjusters such as glacial acetic acid and sodium acetate hydrate, and isotonic agents such as refined sucrose.

[0081] The dosage of a replication inhibitor or replication inhibitor composition formulated as a pharmaceutical preparation varies depending on the patient's symptoms, weight, age, sex, etc., and cannot be determined in general terms. However, for example, for a typical adult (body weight 60 kg), it is considered that approximately 0.1 to 30 mg of the active ingredient (replication inhibitor or replication inhibitor composition) would normally be administered per day by intravenous injection, subcutaneous injection, intravenous drip infusion, inhalation, etc.

[0082] [Methods for promoting coronavirus replication] In one embodiment, the present invention provides a method for promoting coronavirus replication in animal cells, the method comprising the steps of: contacting animal cells with the above-described replication-promoting agent or replication-promoting composition; and infecting the animal cells with a coronavirus before or after the above-described step. In this embodiment, the terms "coronavirus," "replication-promoting agent," and "replication-promoting composition" are the same as those defined above.

[0083] That is, in one aspect, the method of this embodiment may be a replication promotion method comprising the steps of contacting animal cells with the above-described replication promoter or replication-promoting composition and, after the above-described step, infecting the animal cells with a coronavirus. Alternatively, in one aspect, the method of this embodiment may be a replication promotion method comprising the steps of infecting animal cells with a coronavirus and contacting the animal cells after coronavirus infection with the above-described replication promoter or replication-promoting composition.

[0084] When the replication-promoting agent or the replication-promoting composition is brought into contact with animal cells, the replication-promoting agent or the replication-promoting composition is introduced into the cytoplasm of the animal cells, thereby promoting coronavirus replication. In the replication-promoting method of this embodiment, "contacting with animal cells" may be rephrased as "introducing into animal cells."

[0085] The method of this embodiment can promote coronavirus replication and produce larger amounts of coronavirus, for example, as a raw material for attenuated or inactivated coronavirus vaccines. Therefore, the method of this embodiment can also be called a method for producing coronavirus.

[0086] [How coronavirus is produced] In one embodiment, the present invention provides a method for producing a coronavirus, the method comprising the steps of infecting the above-described animal cells with a coronavirus and culturing the animal cells infected with the coronavirus.

[0087] In one aspect, the animal cell used in the production method of this embodiment comprises a polynucleotide comprising a nucleotide sequence set forth in any one of SEQ ID NOS: 1 to 3, or a combination of two or more thereof. Also, in another aspect, the animal cell used in the production method of this embodiment comprises a polynucleotide comprising a nucleotide sequence in which one to three nucleotides are deleted, substituted, inserted, or added in the nucleotide sequence set forth in any one of SEQ ID NOS: 1 to 3, and which has the activity of promoting coronavirus replication when present in coronavirus-infected cells, or a combination of two or more thereof. Also, in another aspect, the animal cell used in the production method of this embodiment comprises a polynucleotide comprising a nucleotide sequence having 60% or more, for example, 70% or more, for example, 80% or more, for example, 90% or more, or for example, 95% or more sequence identity to the nucleotide sequence set forth in any one of SEQ ID NOS: 1 to 3, and which has the activity of promoting coronavirus replication when present in coronavirus-infected cells, or a combination of two or more thereof.

[0088] In one aspect, the animal cell used in the production method of this embodiment comprises a polynucleotide consisting of the nucleotide sequence set forth in any one of SEQ ID NOS: 1 to 3, or a combination of two or more thereof. Also, in another aspect, the animal cell used in the production method of this embodiment comprises a polynucleotide consisting of the nucleotide sequence set forth in any one of SEQ ID NOS: 1 to 3, in which one to three bases have been deleted, substituted, inserted, or added, and which has an activity of promoting coronavirus replication when present in coronavirus-infected cells, or a combination of two or more thereof. Also, in another aspect, the animal cell used in the production method of this embodiment comprises a polynucleotide consisting of a nucleotide sequence that has 60% or more, for example, 70% or more, for example, 80% or more, for example, 90% or more, or for example, 95% or more sequence identity to the nucleotide sequence set forth in any one of SEQ ID NOS: 1 to 3, and which has an activity of promoting coronavirus replication when present in coronavirus-infected cells, or a combination of two or more thereof.

[0089] In one aspect, the animal cells in the production method of this embodiment include any of the following combinations: (i) a combination of a polynucleotide consisting of the base sequence of SEQ ID NO: 1 or a mutant thereof with a polynucleotide consisting of the base sequence of SEQ ID NO: 2 or a mutant thereof; (ii) a combination of a polynucleotide consisting of the base sequence of SEQ ID NO: 1 or a mutant thereof with a polynucleotide consisting of the base sequence of SEQ ID NO: 3 or a mutant thereof; or (iii) a combination of a polynucleotide consisting of the base sequence of SEQ ID NO: 1 or a mutant thereof with a polynucleotide consisting of the base sequence of SEQ ID NO: 2 or a mutant thereof with a polynucleotide consisting of the base sequence of SEQ ID NO: 3 or a mutant thereof.

[0090] As described above, these animal cells promote the replication of coronaviruses, and therefore the production method of this embodiment makes it possible to produce large amounts of coronaviruses.

[0091] In one aspect, the present invention provides a method for producing a coronavirus, comprising the steps of contacting animal cells with the replication-promoting agent or replication-promoting composition described above, infecting the animal cells with a coronavirus before or after the step, and culturing the animal cells so that the coronavirus replicates. The production method of this embodiment differs from the above-described methods for producing a coronavirus mainly in that it includes infecting the animal cells with a coronavirus before contacting the animal cells with the replication-promoting agent or replication-promoting composition.

[0092] That is, in the method for producing coronavirus, animal cells may be contacted with a replication-promoting agent or a replication-promoting composition and then infected with the coronavirus, or animal cells may be infected with the coronavirus and then contacted with a replication-promoting agent or a replication-promoting composition. In either case, large amounts of coronavirus can be produced.

[0093] The production method of this embodiment may further include a step of separating the coronavirus from the animal cells. The coronavirus can be separated, for example, by recovering the culture supernatant of the animal cells and subjecting it to ultracentrifugation. The coronavirus produced by the production method of this embodiment can be suitably used, for example, in the production of an attenuated vaccine or an inactivated vaccine.

[0094] [How to make a vaccine against coronavirus] In one embodiment, the present invention provides a method for producing an inactivated coronavirus vaccine, the method comprising the steps of producing a coronavirus by the above-described method and inactivating the produced coronavirus. Coronavirus inactivation can be performed by any commonly used method, such as peracetic acid treatment, heat treatment, organic solvent treatment, surfactant treatment, ultraviolet irradiation, or radiation exposure.

[0095] In one embodiment, the present invention provides a method for producing an attenuated coronavirus vaccine, the method comprising the steps of producing a coronavirus by the above-described method and attenuating the produced coronavirus. The attenuated coronavirus serves as the attenuated vaccine. Methods for attenuating coronaviruses include, for example, ultraviolet irradiation and radiation exposure. Alternatively, pathogenicity can be attenuated by repeatedly subculturing primary cultured cells or cultured cells for several tens of generations.

[0096] In one embodiment, the present invention provides a method for producing an attenuated coronavirus vaccine, the method comprising the step of producing an attenuated coronavirus by the method described above. Conventional methods can be used to attenuate coronaviruses, such as long-term culture (passage culture) of coronaviruses to accumulate genetic mutations and select coronavirus strains that maintain infectivity but have reduced pathogenicity. Alternatively, coronavirus strains that maintain infectivity but have reduced pathogenicity can be obtained by artificial genetic mutation.

[0097] [Other embodiments] In one embodiment, the present invention provides a method for preventing and / or treating a coronavirus infection, comprising administering an effective amount of the inhibitor described above to a subject in need thereof.

[0098] In one embodiment, the present invention provides an inhibitor as described above for the prevention and / or treatment of coronavirus infection.

[0099] In one embodiment, the present invention provides use of the inhibitor described above for the manufacture of a medicament for the prophylaxis and / or treatment of coronavirus infection.

[0100] In one embodiment, the present invention provides a pharmaceutical composition for the prevention and / or treatment of coronavirus infections, comprising the inhibitor described above.

[0101] In these embodiments, the coronavirus infection particularly includes COVID-19. Furthermore, in these embodiments, the inhibitor may be a polynucleotide that binds complementarily to a polynucleotide consisting of a nucleotide sequence set forth in any one of SEQ ID NOS: 1 to 3 or a mutant thereof, and inhibits the function of the polynucleotide by binding to it. Alternatively, the inhibitor may be an siRNA or shRNA that targets a polynucleotide consisting of a nucleotide sequence set forth in any one of SEQ ID NOS: 1 to 3. [Example]

[0102] The present invention will now be described in more detail with reference to examples, but the present invention is not limited to the following examples.

[0103] Materials and Methods This study was approved by the Research Ethics Committee of Kyoto University. All experiments, including viral infections, were performed in a biosafety level 3 facility at Kyoto University in strict accordance with regulations.

[0104] (Preparation of SARS-CoV-2) The SARS-CoV-2 B.1.1.214 strain (SARS-CoV-2 / CiRA / KP557) was isolated from a nasopharyngeal swab specimen of a COVID-19 patient. The virus was propagated in Vero / TMPRSS2 cells (JCRB1818, JCRB Cell Bank) and stored at -80°C. Vero / TMPRSS2 cells were cultured in Minimum Essential Media (MEM, Sigma-Aldrich) supplemented with 5% fetal bovine serum (FBS) and 1% penicillin / streptomycin.

[0105] (Bronchial organoids) Human bronchial organoids (BO) were generated using normal human bronchial epithelial cells (hereinafter sometimes referred to as "NHBE", #CC-2540, Lonza).

[0106] NHBEs were suspended in 10 mg / mL chilled Matrigel (growth factor reduced, GFR). Subsequently, 50 μL droplets of the cell suspension were placed on a 24-well plate (Nunc) preheated to 37°C and incubated for 10 minutes to solidify. Subsequently, 500 μL of expansion culture medium was added to each well. The composition of the expansion culture medium is shown in Table 1 below. In Table 1, "+" indicates the presence of the substance, and "-" indicates the absence of the substance. The medium was changed every two days.

[0107] BOs were passaged as follows: BOs were suspended in 1 mL of 0.5 mM EDTA / PBS (Nacalai Tesque) and mechanically sheared using a P1000 pipette tip. 2 mL of TrypLE Select (Thermo Fisher Scientific) was then added to the suspension. After 5 minutes of incubation at room temperature, the BOs were again mechanically sheared using a P1000 pipette tip. 7 mL of expansion medium was then added, the tube was transferred to, and centrifuged at 400 rpm. The organoid fragments were then resuspended in chilled expansion medium and seeded as described above. BOs were passaged every 10 days.

[0108] To mature the BOs, the expanded BOs were cultured for 5 days in a differentiation medium, the composition of which is shown in Table 1 below.

[0109] [Table 1]

[0110] (Inhibitor / mimetic transfection and SARS-CoV-2 infection) Human bronchial organoids (BOs) were dissociated with TrypLE Select (1×, phenol red-free, Thermo Fisher Scientific), and BO-derived bronchial epithelial cells were seeded into 96-well plates (Thermo Fisher Scientific) and cultured in differentiation medium for 24 h.

[0111] Next, BO-derived bronchial epithelial cells were transfected with svRNA mimics or svRNA inhibitors (final concentration 300 nM) using Lipofectamine RNAiMAX Transfection Reagent (Thermo Fisher Scientific) for 4 hours, and then infected with SARS-CoV-2 at a multiplicity of infection (MOI) of 0.01 for 2 hours.

[0112] (Quantification of viral RNA copy number) The cell culture supernatant was mixed with an equal volume of 2x RNA lysis buffer and incubated at room temperature for 10 minutes. The 2x RNA lysis buffer consisted of 0.4 U / μL SUPERase·In RNase Inhibitor (Thermo Fisher Scientific), 2% Triton X-100, 50 mM KCl, 100 mM Tris-HCl (pH 7.4), and 40% glycerol in distilled water. The mixture was then diluted 10-fold with distilled water.

[0113] Viral RNA was quantified using the One Step TB Green PrimeScript PLUS RT-PCR Kit (Perfect Real Time, Takara Bio) on a StepOnePlus real-time PCR system (Thermo Fisher Scientific). The primer sequences used were 5'-AGCCTCTTCTCGTTCCTCATCAC-3' (forward, SEQ ID NO: 4) and 5'-CCGCCATTGCCAGCCATTC-3' (reverse, SEQ ID NO: 5). A standard curve was prepared using SARS-CoV-2 RNA (10 5 copies / μL, Nihon Gene Research Institute).

[0114] (Viruses for small RNA-seq) The SARS-CoV-2 / UT-NCGM02 / Human / 2020 / Tokyo (NCGM02) strain was propagated in Vero / TMPRSS2 cells (JCRB1818, JCRB Cell Bank) and used for small RNA-seq.

[0115] (cell) Vero / TMPRSS2 cells were cultured in Dulbecco's Modified Eagle Medium (Thermo Fisher Scientific) supplemented with 10% FBS (Thermo Fisher Scientific) and 1% penicillin / streptomycin (Nacalai Tesque). Calu-3 cells were cultured in RPMI 1640 medium supplemented with 10% FBS and 1% penicillin / streptomycin. Cells were incubated at 37°C in a 5% CO environment.

[0116] (Virus inoculation for small RNA-seq) Calu-3 cells (HTB-55, ATCC) were infected with SARS-CoV-2 NCGM02 strain at an MOI of 0.001. After 1 h of exposure, the inoculum was washed, and the cells were incubated for 3 days in RPMI 1640 medium (Nacalai Tesque) supplemented with 2% FBS (Thermo Fisher Scientific).

[0117] (small RNA-seq) Total RNA was extracted using the mirVana miRNA Isolation Kit (Thermo Fisher Scientific) according to the manufacturer's instructions. Total RNA was then eluted with RNAse-free water. RNA concentration was then measured using a NanoDrop 2000 spectrophotometer (Thermo Fisher Scientific). Total RNA quality was assessed using an Agilent 2100 Bioanalyzer (Agilent).

[0118] Next, libraries for small RNA-seq were prepared using a slightly modified AQ-seq method (Kim H., et al., Bias-minimized quantification of microRNA reveals widespread alternative processing and 3' end modification, Nucleic Acids Research, 47 (5), 2630-2640, 2019). First, total RNA (5 μg) was separated on a 15% denaturing polyacrylamide gel, and small RNAs ranging from 17 to 29 nt were excised. The excised gel pieces were then fragmented by centrifugation at 20,400 × g for 10 minutes in Gel Breaker Tubes (Cosmo Bio). Subsequently, size-fractionated RNA was eluted from the gel pieces in 0.3 M NaCl (Nacalai Tesque) by shaking overnight at 1,500 rpm at 25°C. Subsequently, the RNA was ethanol precipitated with sodium acetate (Nippon Genetics) and GlycoBlue Coprecipitant (Thermo Fisher Scientific).

[0119] The size-fractionated RNA was then ligated to 3'-randomized adapters in a reaction mixture at 25°C for 16 hours. The reaction mixture contained 0.25 μM 3'-randomized adapter (5'-App / NNNNTGGAATTCTCGGGTGCCAAGG / ddC-3', SEQ ID NO: 6, IDT), 200 U of T4 RNA Ligase 2, truncated KQ (NEB), 1x T4 RNA ligase reaction buffer (NEB), 20% PEG 8000 (NEB), and 10 U of SUPERase·In RNase Inhibitor (Thermo Fisher Scientific). The adapter-ligated RNA was then fractionated by 15% denaturing polyacrylamide gel electrophoresis, and unligated adapters were removed. The size-fractionated RNA was then gel-purified as described above.

[0120] Next, the adapter-ligated RNA was reacted with 0.18 μM 5'-randomized adapter (5'-GUUCAGAGUUCUACAGUCCGACGAUCNNNN-3', sequence number 7, IDT), 14 U of T4 RNA Ligase 1, 1x T4 RNA ligase reaction buffer (NEB), 20% PEG8000 (NEB), 1 mM ATP, and 14 U of SUPERase·In RNase Inhibitor (Thermo Fisher Scientific) at 37°C for 1 hour, followed by 15 minutes at 65°C to inactivate the enzyme.

[0121] Subsequently, the adapter-ligated RNA was reacted with 200 U of SuperScript III reverse transcriptase (Thermo Fisher Scientific), 1× first-strand buffer (Thermo Fisher Scientific), 0.2 μM RT primer (RTP, 5′-GCCTTGGCACCCGAGAATTCCA-3′, SEQ ID NO: 8), 0.5 mM dNTPs (included in the TruSeq Small RNA kit (Illumina)), and 5 mM DTT (Thermo Fisher Scientific) at 37°C for 1 hour.

[0122] The reverse transcriptase was then heat-inactivated by incubation at 70°C for 15 minutes. The cDNA library was amplified using 1U of Phusion High-Fidelity DNA Polymerase (Thermo Fisher Scientific), 1X Phusion HF buffer (Thermo Fisher Scientific), 0.5 μM primers (RP1 forward primer and RPIX reverse primer, TruSeq Small RNA kit, Illumina), and 0.2 mM dNTPs (Takara Bio). The amplified cDNA library was then fractionated on a 6% non-denaturing polyacrylamide gel to remove adapter dimers. The size-fractionated cDNA library was then gel-purified and precipitated as described above. The size of the cDNA library was then assessed using an Agilent 2100 Bioanalyzer (Agilent), and the concentration was quantified using KAPA Library Quantification Kits (KAPA Biosystems).

[0123] The pooled cDNA library was then sequenced on the NextSeq 500 platform (Illumina) using the NextSeq 500 / 550 High Output Kit v2.5 (75 cycles, Illumina).

[0124] (Small RNA-seq data analysis) Adapter trimming, quality filtering, and quality control were performed using fastp ver. 0.20.1. 4-nt degenerate sequences at both the 5' and 3' ends were removed using cutadapt ver. 2.10.

[0125] The preprocessed reads were then mapped to the index of the SARS-CoV-2 genome (NCGM02; missing sequences were complemented with the SARS-CoV-2 genome reference sequence (NC_045512, NCBI)) using BWA version 0.7.17 with the following parameters: bwa aln -n 1 -k 1 -o 0.

[0126] (Quantification of svRNA by stem-loop real-time quantitative RT-PCR) Total RNA was extracted using the mirVana miRNA Isolation Kit using a method similar to that described above.

[0127] Custom TaqMan Small RNA assays (Cat# 4398987, Thermo Fisher Scientific) were ordered and used: svRNA ORF1ab (5'-GUGAAAUCAUAGGAUACAAGG-3', SEQ ID NO: 9), svRNA ORF7a-1 (5'-UUCUUGGCACUGAUAACACUCGCUA-3', SEQ ID NO: 10), svRNA ORF7a-2 (5'-GUGAGCUUUAUCACUACCAAGAGU-3', SEQ ID NO: 11), and neg (5'-GUGCUAUGAGGCCCAAUUUC-3', SEQ ID NO: 12).

[0128] TaqMan Small RNA Assay for RNU6B (Cat # 4427975, Assay ID 001093, Thermo Fisher Scientific) was used to detect human RNU6B and served as an internal control.

[0129] Total RNA (10 ng) was reverse transcribed using the TaqMan MicroRNA Reverse Transcription Kit (Thermo Fisher Scientific) according to the manufacturer's instructions.

[0130] Quantitative RT-PCR was performed using TaqMan Fast Advanced Master Mix (Thermo Fisher Scientific) with a QuantStudio 3 Real-Time PCR System (Thermo Fisher Scientific).

[0131] [Experimental Example 1] (Identification of SARS-CoV-2-derived small viral RNAs) We identified SARS-CoV-2-derived small viral RNAs (svRNAs). Calu-3 cells were infected with SARS-CoV-2 (NCGM02) at a multiplicity of infection (MOI) of 0.001. Total RNA was extracted 3 days postinfection. A small RNA-seq library was then constructed using the AQ-seq method.

[0132] Next, a comprehensive miRNA expression profile was obtained using a next-generation sequencer, and the resulting reads were mapped onto the viral genome to identify SARS-CoV-2-derived svRNA.

[0133] Figure 1 is a graph showing the percentage of analyzed reads that mapped to the SARS-CoV-2 genome (NCGM02). In Figure 1, "Mock" indicates the results for Calu-3 cells not infected with SARS-CoV-2, and "SARS-CoV-2-infected" indicates the results for Calu-3 cells infected with SARS-CoV-2. Additionally, "Replicate 1" and "Replicate 2" each indicate the results of two independent experiments.

[0134] Figure 2 shows the reads mapped to the SARS-CoV-2 genome in an analysis of Calu-3 cells infected with SARS-CoV-2. The results are from two independent experiments. In Figure 2, the vertical axis indicates the number of reads mapped to each base in the viral genome. The higher the value on the vertical axis, the higher the expression level.

[0135] The lower part of Figure 2 shows the full length of the viral genome and indicates the protein-coding regions (open reading frames: ORFs). "1ab" indicates ORF1ab, "S" indicates the spike protein, "3" indicates ORF3, "E" indicates the envelope protein, "M" indicates the membrane protein, "6" indicates ORF6, "7a" indicates ORF7a, "7b" indicates ORF7b, "8" indicates ORF8, "N" indicates the nucleocapsid protein, and "10" indicates ORF10.

[0136] Figures 3 and 4 are enlarged views of the surrounding area, focusing on a prominent peak in Figure 2. Figure 3 shows reads mapped to the ORF1ab region. The svRNA corresponding to the peak in Figure 3 is hereinafter referred to as svRNA ORF1ab. svRNA ORF1ab has the nucleotide sequence 5'-AAGUGAAAUCAUAGGAUACAAGG-3' (SEQ ID NO: 1), is 23 nt in length, and was derived from the (+) strand of the viral genome.

[0137] Figure 4 shows the reads mapped to the ORF7a region. The svRNAs corresponding to the two peaks in Figure 4 are hereinafter referred to as svRNA ORF7a-1 and ORF7a-2, respectively. svRNA ORF7a-1 had the nucleotide sequence 5'-CUUUUCUUGGCACUGAUAACACUCGCUA-3' (SEQ ID NO: 2), was 28 nt in length, and was derived from the positive (+) strand of the viral genome. svRNA ORF7a-2 had the nucleotide sequence 5'-GUGAGCUUUAUCACUACCAAGAGU-3' (SEQ ID NO: 3), was 24 nt in length, and was derived from the positive (+) strand of the viral genome.

[0138] [Experimental Example 2] (Confirmation of SARS-CoV-2 derived svRNA expression by quantitative RT-PCR 1) Using reverse transcription primers specific for mature svRNA and a TaqMan probe, we quantified the expression levels of svRNA in Calu-3 cells uninfected with SARS-CoV-2 and Calu-3 cells infected with SARS-CoV-2. The cells were infected with SARS-CoV-2 at an MOI of 0.001, and svRNA expression levels in each cell type were quantified 3 days post-infection.

[0139] Figures 5A to 5D are graphs showing the results of quantitative RT-PCR. Each graph shows the results of two independent experiments. Figure 5A shows the results of quantification of the expression of svRNA ORF1ab. Figure 5B shows the results of quantification of the expression of svRNA ORF7a-1. Figure 5C shows the results of quantification of the expression of svRNA ORF7a-2. Figure 5D shows the results of quantification of the expression of the svRNA negative control region (neg). Based on the miRNA-seq results, a 20-base sequence with the fewest mapped reads was selected from the viral genome and used as the negative control region. In Figures 5A to 5D, the black bars represent the average values ​​of two experiments. RNU6B was used as an internal standard. The vertical axis shows the expression level relative to the expression level of RNU6B (normalized expression level). If no signal amplification was observed after 40 cycles of PCR, the result was recorded as "Not detected." In Figures 5A to 5D, "Mock" indicates the results for Calu-3 cells not infected with SARS-CoV-2, and "SARS-CoV-2-infected" indicates the results for Calu-3 cells infected with SARS-CoV-2.

[0140] [Experimental Example 3] (Secondary structure prediction of SARS-CoV-2 derived svRNA and its surrounding region) Generally, miRNA precursors have a hairpin-like stem-loop structure, from which mature miRNAs are excised by various proteins. To confirm whether the svRNA precursor has a stem-loop structure, we predicted the secondary structure of the svRNA and its surrounding regions using RNAfold (http: / / rna.tbi.univie.ac.at / cgi-bin / RNAWebSuite / RNAfold.cgi).

[0141] Figures 6 and 7 show the predicted secondary structures. Figure 6 shows the secondary structures of svRNA ORF1ab and the regions 100 nt upstream and downstream thereof. Figure 7 shows the secondary structures of svRNA ORF7a-1, svRNA ORF7a-2, and the regions 100 nt upstream and downstream thereof. The results revealed that svRNA ORF1ab, svRNA ORF7a-1, and svRNA ORF7a-2 are contained in a stem-loop structure.

[0142] [Experimental Example 4] (Production of svRNA inhibitors and svRNA mimetics) Inhibitors and mimics for svRNA ORF1ab, svRNA ORF7a-1, and svRNA ORF7a-2 were produced by Ajinomoto Bio-Pharma Services (https: / / www.ajioligos.com / products / mirna-mimic-inhibitor / ).

[0143] Figure 8 shows a schematic diagram of the structure of the svRNA inhibitor. The svRNA inhibitor we prepared was a 2'-O-methylated double-stranded RNA with two svRNA-binding sites, which bound to svRNA in cells and inhibited its function.

[0144] The inhibitor for svRNA ORF1ab was prepared by hybridizing an RNA strand having the nucleotide sequence 5'-GACGGCGCUAGGAUCAUCAACCCUUGUAUCCUAUGAUUUCACUUCAAGUAUUCUGGU-3' (SEQ ID NO: 13) with an RNA strand having the nucleotide sequence 5'-ACCAGAAUACAACCCUUGUAUCCUAUGAUUUCACUUCAAGAUGAUCCUAGCGCCGUC-3' (SEQ ID NO: 14). These RNA strands were 2'-O-methylated throughout their entire length.

[0145] The inhibitor for svRNA ORF7a-1 was prepared by hybridizing an RNA strand having the nucleotide sequence 5'-GACGGCGCUAGGAUCAUCAACUAGCGAGUGUUAUCAGUGCCAAGAAAAGCAAGUAUUCUGGU-3' (SEQ ID NO: 15) with an RNA strand having the nucleotide sequence 5'-ACCAGAAUACAACUAGCGAGUGUUAUCAGUGCCAAGAAAAGCAAGAUGAUCCUAGCGCCGUC-3' (SEQ ID NO: 16). These RNA strands were 2'-O-methylated throughout their entire length.

[0146] The inhibitor for svRNA ORF7a-2 was prepared by hybridizing an RNA strand having the nucleotide sequence 5'-GACGGCGCUAGGAUCAUCAACACUCUUGGUAGUGAUAAAGCUCACCAAGUAUUCUGGU-3' (SEQ ID NO: 17) with an RNA strand having the nucleotide sequence 5'-ACCAGAAUACAACACUCUUGGUAGUGAUAAAGCUCACCAAGAUGAUCCUAGCGCCGUC-3' (SEQ ID NO: 18). These RNA strands were 2'-O-methylated throughout their entire length.

[0147] The left side of Figure 9 is a schematic diagram showing the structure of the svRNA mimic. The svRNA mimic we created is a chemically modified double-stranded RNA that is incorporated into the RISC complex, as shown on the right side of Figure 9, and mimics the post-transcriptional gene expression regulatory function of natural miRNAs.

[0148] The mimics of svRNA ORF1ab, svRNA ORF7a-1, and svRNA ORF7a-2 were designed and synthesized by Gene Design based on the nucleotide sequences of svRNA ORF1ab, svRNA ORF7a-1, and svRNA ORF7a-2, respectively.

[0149] [Experimental Example 5] (Investigating the effects of svRNA inhibitors and svRNA mimetics on viral replication) We investigated the effects of svRNA inhibitors and svRNA mimics on viral replication. Figure 10 illustrates the experimental schedule. First, bronchial organoid-derived epithelial cells were transfected with SARS-CoV-2-derived svRNA inhibitors or svRNA mimics for 4 hours. Subsequently, each cell was infected with SARS-CoV-2 at an MOI of 0.01 for 2 hours. The infected bronchial organoid-derived epithelial cells were then cultured in differentiation medium for 48 hours. In Figure 10, "dpi" indicates days postinfection. Subsequently, the viral RNA copy number in the cell culture supernatant was measured by quantitative RT-PCR. Therefore, this experiment can be said to have investigated the preventive effect of svRNA inhibitors on SARS-CoV-2 replication.

[0150] Figure 11 is a graph showing the results of quantifying the number of viral genome copies contained in cell culture supernatants when svRNA inhibitors were introduced alone or in combination. In Figure 11, "NC" indicates the negative control, "7a-1" indicates an inhibitor against svRNA ORF7a-1, "7a-2" indicates an inhibitor against svRNA ORF7a-2, "1ab" indicates an inhibitor against svRNA 1ab, and "All" indicates a combination of an inhibitor against svRNA ORF7a-1, an inhibitor against svRNA ORF7a-2, and an inhibitor against svRNA 1ab. Data are shown as mean ± standard deviation (n = 3).

[0151] As a result, it was revealed that the copy number of the viral genome was reduced when cells were transfected with a combination of an inhibitor against svRNA ORF7a-1 and an inhibitor against svRNA 1ab, a combination of an inhibitor against svRNA ORF7a-2 and an inhibitor against svRNA 1ab, or a combination of an inhibitor against svRNA ORF7a-1, an inhibitor against svRNA ORF7a-2 and an inhibitor against svRNA 1ab.

[0152] Next, we performed a similar experiment using iPS cells overexpressing angiotensin-converting enzyme (ACE) 2 (ACE2-iPS) instead of bronchial organoid-derived epithelial cells. The results showed that the introduction of svRNA inhibitors also reduced the number of viral RNA copies in the cell culture supernatant when ACE2-iPS cells were used.

[0153] Also, TCID 50 The titer of infectious virus in the cell culture supernatant was measured using a median tissue culture infectious dose (MTCID) assay. The results confirmed that the virus titer was reduced in the presence of svRNA inhibitors compared to the negative control.

[0154] Similar experiments were also performed using multiple SARS-CoV-2 variants (α, β, γ, and δ types), and the results confirmed that the combined use of svRNA inhibitors was effective in inhibiting viral replication for all variants.

[0155] These results suggest that svRNA inhibitors may be used to suppress viral replication in virus-infected cells.

[0156] Figure 12 is a graph showing the results of quantifying the number of viral genome copies contained in cell culture supernatants when svRNA mimetics were introduced alone or in combination. In Figure 12, "NC" indicates the negative control, "7a-1" indicates a mimetic of svRNA ORF7a-1, "7a-2" indicates a mimetic of svRNA ORF7a-2, "1ab" indicates a mimetic of svRNA 1ab, and "All" indicates a combination of a mimetic of svRNA ORF7a-1, a mimetic of svRNA ORF7a-2, and a mimetic of svRNA 1ab. Data are shown as mean ± standard deviation (n = 3).

[0157] As a result, it was revealed that when the svRNA ORF7a-1 mimetic, the svRNA ORF7a-2 mimetic, or the svRNA 1ab mimetic was introduced into cells alone, and when the svRNA ORF7a-1 mimetic and the svRNA ORF7a-2 mimetic were introduced in combination into cells, the copy number of the viral genome increased compared to the negative control.

[0158] Furthermore, it was revealed that the copy number of the viral genome was more significantly increased when a combination of an svRNA ORF7a-1 mimetic and an svRNA 1ab mimetic, a combination of an svRNA ORF7a-2 mimetic and an svRNA 1ab mimetic, or a combination of an svRNA ORF7a-1 mimetic, an svRNA ORF7a-2 mimetic and an svRNA 1ab mimetic was introduced into cells.

[0159] [Experimental Example 6] (Investigating the therapeutic effects of svRNA inhibitors on COVID-19) We investigated the therapeutic efficacy of svRNA inhibitors for COVID-19. Figure 13 illustrates the experimental schedule. First, bronchial organoid-derived epithelial cells were infected with SARS-CoV-2 at an MOI of 0.1. The infected bronchial organoid-derived epithelial cells were then cultured in differentiation medium for 24 hours. Subsequently, they were transfected with a SARS-CoV-2 svRNA inhibitor for 4 hours. The svRNA inhibitor concentration was 300 nM. The bronchial organoid-derived epithelial cells transfected with the SARS-CoV-2 svRNA inhibitor were then cultured in differentiation medium for 48 hours. In Figure 13, "dpi" indicates days postinfection. Subsequently, the viral RNA copy number in the cell culture supernatant was measured by quantitative RT-PCR. Therefore, this experiment investigated the inhibitory effect of an svRNA inhibitor on SARS-CoV-2 replication after SARS-CoV-2 infection. In other words, this experiment examined the therapeutic effects of svRNA inhibitors on COVID-19.

[0160] Figure 14 is a graph showing the results of quantifying the number of viral genome copies contained in cell culture supernatants when svRNA inhibitors were introduced alone or in combination. In Figure 14, "NC" indicates the negative control, "7a-1" indicates an inhibitor against svRNA ORF7a-1, "7a-2" indicates an inhibitor against svRNA ORF7a-2, "1ab" indicates an inhibitor against svRNA 1ab, and "All" indicates a combination of an inhibitor against svRNA ORF7a-1, an inhibitor against svRNA ORF7a-2, and an inhibitor against svRNA 1ab. Data are shown as mean ± standard deviation (n = 3).

[0161] As a result, it was revealed that the copy number of the viral genome was reduced when cells were transfected with a combination of an inhibitor against svRNA ORF7a-1 and an inhibitor against svRNA 1ab, a combination of an inhibitor against svRNA ORF7a-2 and an inhibitor against svRNA 1ab, or a combination of an inhibitor against svRNA ORF7a-1, an inhibitor against svRNA ORF7a-2 and an inhibitor against svRNA 1ab.

[0162] These results indicate that svRNA inhibitors can be used as therapeutic agents to suppress viral replication in virus-infected cells.

[0163] [Experimental Example 7] (Confirmation of SARS-CoV-2 derived svRNA expression by quantitative RT-PCR 2) Using a reverse transcription primer specific for mature svRNA and a TaqMan probe, we quantified the expression levels of svRNA in bronchial organoid-derived epithelial cells uninfected with SARS-CoV-2 and those infected with SARS-CoV-2. Cells were infected with SARS-CoV-2 at an MOI of 0.1, and the expression levels of svRNA in each cell type were quantified over time up to day 4 post-infection.

[0164] Figures 15A to 15C are graphs showing the results of quantitative RT-PCR. Figure 15A shows the results of quantification of svRNA ORF1ab expression. Figure 15B shows the results of quantification of svRNA ORF7a-1 expression. Figure 15C shows the results of quantification of svRNA ORF7a-2 expression. In Figures 15A to 15C, circles indicate the average value of three different wells. RNU6B was used as an internal standard. The vertical axis shows the relative expression level to the expression level of RNU6B (normalized expression level). "Mock" indicates the results for bronchial organoid-derived epithelial cells not infected with SARS-CoV-2, and "SARS-CoV-2" indicates the results for bronchial organoid-derived epithelial cells infected with SARS-CoV-2. "dpi" indicates the number of days post-infection.

[0165] [Experimental Example 8] (Confirmation of SARS-CoV-2 derived svRNA expression by quantitative RT-PCR 3) An experiment similar to Experimental Example 7 was conducted using iPS cells (ACE2-iPS) that overexpressed angiotensin-converting enzyme (ACE) 2 instead of bronchial organoid-derived epithelial cells.

[0166] Using a reverse transcription primer specific for mature svRNA and a TaqMan probe, we quantified the expression levels of svRNA in ACE2-iPS cells that were not infected with SARS-CoV-2 and in those infected with SARS-CoV-2. Cells were infected with SARS-CoV-2 at an MOI of 0.1, and the expression levels of svRNA in each cell type were quantified over time up to day 4 post-infection.

[0167] Figures 16A to 16C are graphs showing the results of quantitative RT-PCR. Figure 16A shows the results of quantification of svRNA ORF1ab expression. Figure 16B shows the results of quantification of svRNA ORF7a-1 expression. Figure 16C shows the results of quantification of svRNA ORF7a-2 expression. In Figures 16A to 16C, circles indicate the average value of three different wells. RNU6B was used as an internal standard. The vertical axis shows the relative expression level to the expression level of RNU6B (normalized expression level). "Mock" indicates the results for ACE2-iPS cells not infected with SARS-CoV-2, and "SARS-CoV-2" indicates the results for ACE2-iPS cells infected with SARS-CoV-2. "dpi" indicates the number of days post-infection. [Industrial Applicability]

[0168] The present invention provides a technology for controlling the life cycle of coronaviruses, which can be applied to the prevention and treatment of coronavirus infections.

Claims

1. (i) a base sequence set forth in any one of SEQ ID NOs: 1 to 3, (ii) a base sequence in which 1 to 3 bases are deleted, substituted, inserted or added in any of the base sequences set forth in SEQ ID NOs: 1 to 3, or (iii) a nucleotide sequence having 90% or more sequence identity to any of the nucleotide sequences set forth in SEQ ID NOs: 1 to 3 and having an activity of promoting the replication of SARS-CoV-2 when present in a SARS-CoV-2-infected cell; Or, (i) a base sequence set forth in any one of SEQ ID NOs: 1 to 3; (ii) a base sequence in which 1 to 3 bases are deleted, substituted, inserted or added in any of the base sequences set forth in SEQ ID NOs: 1 to 3, or (iii) a nucleotide sequence having 90% or more sequence identity to any of the nucleotide sequences set forth in SEQ ID NOs: 1 to 3 A polynucleotide consisting of the above and having an activity of promoting the replication of SARS-CoV-2 when present in a SARS-CoV-2-infected cell; A SARS-CoV-2 replication promoter containing the active ingredient

2. (i) a base sequence set forth in any one of SEQ ID NOs: 1 to 3, (ii) a base sequence in which 1 to 3 bases are deleted, substituted, inserted or added in any of the base sequences set forth in SEQ ID NOs: 1 to 3, or (iii) a nucleotide sequence having 90% or more sequence identity to any of the nucleotide sequences set forth in SEQ ID NOs: 1 to 3 and having an activity of promoting the replication of SARS-CoV-2 when present in a SARS-CoV-2-infected cell; Or, (i) a base sequence set forth in any one of SEQ ID NOs: 1 to 3; (ii) a base sequence in which 1 to 3 bases are deleted, substituted, inserted or added in any of the base sequences set forth in SEQ ID NOs: 1 to 3, or (iii) a nucleotide sequence having 90% or more sequence identity to any of the nucleotide sequences set forth in SEQ ID NOs: 1 to 3 A polynucleotide consisting of the above and having an activity of promoting the replication of SARS-CoV-2 when present in a SARS-CoV-2-infected cell; A composition for promoting the replication of SARS-CoV-2, comprising a combination of two or more of the above as active ingredients.

3. (i) a base sequence set forth in any one of SEQ ID NOs: 1 to 3, (ii) a base sequence in which 1 to 3 bases are deleted, substituted, inserted or added in any of the base sequences set forth in SEQ ID NOs: 1 to 3, or (iii) a nucleotide sequence having 90% or more sequence identity to any of the nucleotide sequences set forth in SEQ ID NOs: 1 to 3 and having an activity of promoting the replication of SARS-CoV-2 when present in a SARS-CoV-2-infected cell; Or, (i) a base sequence set forth in any one of SEQ ID NOs: 1 to 3; (ii) a base sequence in which 1 to 3 bases are deleted, substituted, inserted or added in any of the base sequences set forth in SEQ ID NOs: 1 to 3, or (iii) a nucleotide sequence having 90% or more sequence identity to any of the nucleotide sequences set forth in SEQ ID NOs: 1 to 3 A polynucleotide consisting of the above and having an activity of promoting the replication of SARS-CoV-2 when present in a SARS-CoV-2-infected cell; The active ingredient is a mimic of The mimic is a double-stranded polynucleotide in which the polynucleotide and its complementary strand are hybridized, and is a replication-promoting agent for SARS-CoV-2.

4. A combination of an inhibitor for a polynucleotide consisting of the base sequence set forth in SEQ ID NO: 1 and an inhibitor for a polynucleotide consisting of the base sequence set forth in SEQ ID NO: 2, a combination of an inhibitor for a polynucleotide consisting of the base sequence set forth in SEQ ID NO: 1 and an inhibitor for a polynucleotide consisting of the base sequence set forth in SEQ ID NO: 3; or a combination of an inhibitor for a polynucleotide consisting of the base sequence set forth in SEQ ID NO: 1, an inhibitor for a polynucleotide consisting of the base sequence set forth in SEQ ID NO: 2, and an inhibitor for a polynucleotide consisting of the base sequence set forth in SEQ ID NO: 3; is the active ingredient, The inhibitor is a polynucleotide that binds complementarily to the polynucleotide, or an siRNA or shRNA that targets the polynucleotide.

5. A pharmaceutical composition for preventing and / or treating SARS-CoV-2 infection, comprising the replication inhibitor of claim 4.

6. A method for inhibiting the replication of SARS-CoV-2 in animal cells, comprising a step of contacting the animal cells in vitro with the replication inhibitor of claim 4.

7. A step of contacting animal cells in vitro with the replication promoter of claim 1 or the replication-promoting composition of claim 2; Infecting the animal cells with SARS-CoV-2 before or after the step; A method for promoting the replication of SARS-CoV-2 in the animal cell, comprising: (i) a base sequence set forth in any one of SEQ ID NOs: 1 to 3; (ii) a base sequence in which 1 to 3 bases are deleted, substituted, inserted or added in any of the base sequences set forth in SEQ ID NOs: 1 to 3, or (iii) a nucleotide sequence having 90% or more sequence identity to any of the nucleotide sequences set forth in SEQ ID NOs: 1 to 3 and having an activity of promoting the replication of SARS-CoV-2 when present in a SARS-CoV-2-infected cell; Or, (i) a base sequence set forth in any one of SEQ ID NOs: 1 to 3; (ii) a base sequence in which 1 to 3 bases are deleted, substituted, inserted or added in any of the base sequences set forth in SEQ ID NOs: 1 to 3, or (iii) a nucleotide sequence having 90% or more sequence identity to any of the nucleotide sequences set forth in SEQ ID NOs: 1 to 3 A polynucleotide consisting of the above and having an activity of promoting the replication of SARS-CoV-2 when present in a SARS-CoV-2-infected cell; Or a combination of two or more of the above polynucleotides, Infecting animal cells containing the antibody with SARS-CoV-2; and culturing the animal cells infected with SARS-CoV-2. Method for producing SARS-CoV-2.

9. Replicating SARS-CoV-2 by the method of claim 7; and isolating the replicated SARS-CoV-2 from the animal cells. Method for producing SARS-CoV-2.

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