# US 2022/0026428 A1 · Detection of antibodies to sarsr-cov

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- Number: US 2022/0026428 A1
- Document ID: US20220026428A1
- Status: Published application
- Kind: A1
- Application number: 17/444,223
- Filed: 2021-08-02
- Published: 2022-01-27
- Earliest claimed: 2020-03-25
- Applicants: National University of Singapore
- Inventors: Linfa WANG
- Web page: https://patentgrep.com/patent/US20220026428A1

## CPC

- G01N 33/56983: {Viruses}
- G01N 2333/165: Coronaviridae, e.g. avian infectious bronchitis virus
- G01N 2333/948: acting on peptide bonds (3.4)
- G01N: INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES (measuring or testing apparatus or processes other than immunoassay, involving enzymes or microorganisms C12M, C12Q)

## Abstract

A kit, composition and method for detection of antibodies to severe acute respiratory syndrome related coronavirus (SARSr-CoV), and for diagnosis of SARSr-CoV infection.

## Claims

### Claim 1

A method of analysing a sample for the presence of antibodies to a SARSr-CoV, comprising:
contacting the sample with: (i) a spike protein of a severe acute respiratory syndrome-related coronavirus (SARSr-CoV), a S1 subunit or a receptor binding domain (RBD) of a SARSr-CoV spike protein, wherein the spike protein or the S1 subunit comprises the RBD of the SARSr-CoV spike protein, and (ii) an ACE2 protein or an extracellular domain of an ACE2 protein or a fragment thereof which binds specifically to the spike protein, the S1 subunit or the RBD of (i), and
determining the level of interaction between the spike protein, the S1 subunit or the RBD of (i) and the ACE2 protein or the ACE2 protein extracellular domain of (ii),
wherein the spike protein, the S1 subunit or the RBD of (i) or ACE2 protein or the ACE2 protein extracellular domain of (ii) is conjugated to a) a detection entity, or b) a biotin which binds an avidin or streptavidin-conjugated detection entity, for determining the interaction between (i) and (ii); and
(a) the spike protein, the S1 subunit or the RBD of (i) is conjugated to the detection entity or the biotin, and wherein the ACE2 protein or the ACE2 protein extracellular domain of (ii) is immobilised on a solid support; or
(b) the ACE2 protein or the ACE2 protein extracellular domain of (ii) is conjugated to the detection entity or the biotin, and wherein spike protein, the S1 subunit or the RBD of (i) is immobilised on a solid support.

### Claim 2 (depends on 1)

The method according to claim 1, wherein the sample is a blood sample, a lymph sample, a saliva sample, or a synovial fluid sample.

### Claim 3 (depends on 1)

The method according to claim 1, wherein the SARSr-CoV is SARS-CoV-2 or a variant thereof.

### Claim 4 (depends on 1)

The method according to claim 1, wherein the spike protein, the S1 subunit or the RBD of (i) is conjugated to the detection entity or the biotin, and wherein the ACE2 protein or the ACE2 protein extracellular domain of (ii) is immobilised on a solid support.

### Claim 5 (depends on 1)

The method according to claim 1, wherein the ACE2 protein or the ACE2 protein extracellular domain of (ii) is conjugated to the detection entity or the biotin, and wherein the spike protein, the S1 subunit or the RBD of (i) is immobilised on a solid support.

### Claim 6 (depends on 1)

The method according to claim 1, wherein the detection entity is a horseradish peroxidase, an alkaline phosphatase, an acridinium compound, a phycoerythrin, or a fluorescein isothiocyanate.

### Claim 7 (depends on 1)

The method according to claim 1, wherein the detection entity is a horseradish peroxidase.

### Claim 8 (depends on 1)

The method according to claim 1, wherein the spike protein or the S1 subunit of (i) comprises the S1 subunit.

### Claim 9 (depends on 1)

The method according to claim 1, wherein the S1 subunit comprises an amino acid sequence having SEQ ID NO: 12 or 27.

### Claim 10 (depends on 1)

The method according to claim 1, wherein the RBD comprises an amino acid sequence having SEQ ID NO: 13 or 26.

### Claim 11 (depends on 1)

The method according to claim 1, wherein the extracellular domain of ACE2 protein comprises an amino acid sequence having SEQ ID NO: 17 or 30.

### Claim 12 (depends on 1)

The method according to claim 1, wherein the spike protein, the S1 subunit or the RBD of (i) is at a quantity that is:
(a) sufficient to produce a detectable signal of interaction between the spike protein, the S1 subunit or the RBD of (i) and the ACE2 protein or the ACE2 protein extracellular domain of (ii) in the absence of the sample, and/or
(b) less than or equal to, in molar ratio, the quantity of the antibodies to the SARSr-CoV in the sample, and/or
(c) a minimal quantity required to produce a detectable signal of interaction between the spike protein, the S1 subunit or the RBD of (i) and the ACE2 protein or the ACE2 protein extracellular domain of (ii) in the absence of the sample.

### Claim 13 (depends on 1)

The method according to claim 1, wherein the solid support is a microtiter plate or a bead.

### Claim 14 (depends on 13)

The method according to claim 13, wherein the detection entity is a horseradish peroxidase, an alkaline phosphatase, an acridinium compound, a phycoerythrin, or a fluorescein isothiocyanate.

### Claim 15 (depends on 13)

The method according to claim 13, wherein the quantity of the spike protein, the S1 subunit or the RBD of (i) immobilized on the solid support is regulated by adjusting the quantity of the spike protein, the S1 subunit or the RBD of (i) incubated with the solid support.

### Claim 16 (depends on 1)

The method according to claim 1, comprising:
contacting the sample with the spike protein, the S1 subunit or the RBD of (i),
immobilizing the spike protein, the S1 subunit or the RBD of (i) to the solid support,
contacting the spike protein, the S1 subunit or the RBD of (i) immobilized on the solid support with the ACE2 protein or the ACE2 protein extracellular domain of (ii), and
determining the level of interaction between the spike protein, the S1 subunit or the RBD of (i) and the ACE2 protein or the ACE2 protein extracellular domain of (ii),
wherein the ACE2 protein or the ACE2 protein extracellular domain of (ii) is conjugated to the detection entity, and
(a) the spike protein, the S1 subunit or the RBD of (i) is conjugated to a biotin, the solid support is a microtiter plate or a bead, and the solid support is conjugated with an avidin or a streptavidin, or
(b) the spike protein, the S1 subunit or the RBD of (i) is conjugated to an avidin or a streptavidin, the solid support is a bead, and the solid support is conjugated with a biotin.

### Claim 17 (depends on 1)

The method according to claim 1, comprising:
immobilizing the spike protein, the S1 subunit or the RBD of (i) to the solid support,
contacting the sample with the spike protein, the S1 subunit or the RBD of (i) immobilized on the solid support,
contacting the spike protein, the S1 subunit or the RBD of (i) immobilized on the solid support with the ACE2 protein or the ACE2 protein extracellular domain of (ii), and
determining the level of interaction between the spike protein, the S1 subunit or the RBD of (i) and the ACE2 protein or the ACE2 protein extracellular domain of (ii),
wherein the ACE2 protein or the ACE2 protein extracellular domain of (ii) is conjugated to a) the detection entity, or b) the biotin which binds an avidin or streptavidin-conjugated detection entity.

### Claim 18 (depends on 17)

The method according to claim 17, wherein the solid support is a microtiter plate or a bead.

### Claim 19 (depends on 18)

The method according to claim 18, wherein the solid support is a bead, and the quantity of the spike protein, the S1 subunit or the RBD of (i) immobilized on the bead is regulated by adjusting a) the quantity of the spike protein, the S1 subunit or the RBD of (i) incubated with the bead, b) the quantity of the bead incubated with the spike protein, the S1 subunit or the RBD of (i), and/or c) the surface area of a bead for conjugating the spike protein, the S1 subunit or the RBD of (i).

### Claim 20 (depends on 18)

The method according to claim 18, wherein the solid support is a bead, and the molar ratio of the spike protein, the S1 subunit or the RBD of (i) to the antibodies to a SARSr-CoV in the sample is optimized by adjusting the spike protein, the S1 subunit or the RBD of (i) immobilized on the bead.

### Claim 21

A method of determining whether a subject is or has been infected with a SARSr-CoV, comprising:
contacting a sample obtained from the subject with: (i) a spike protein of a SARSr-CoV, a S1 subunit or a RBD of SARSr-CoV spike protein, wherein the spike protein or the S1 subunit comprises the RBD of the SARSr-CoV spike protein, and (ii) an ACE2 protein or an extracellular domain of an ACE2 protein or a fragment thereof which binds specifically to the spike protein, the S1 subunit or the RBD of (i), and
determining the level of interaction between the spike protein, the S1 subunit or the RBD of (i) and the ACE2 protein or the ACE2 protein extracellular domain of (ii),
wherein the spike protein, the S1 subunit or the RBD of (i) or ACE2 protein or the ACE2 protein extracellular domain of (ii) is conjugated to a) a detection entity or b) a biotin which binds an avidin or streptavidin-conjugated detection entity, for determining the interaction between (i) and (ii); and
(a) the spike protein, the S1 subunit or the RBD of (i) is conjugated to the detection entity or the biotin, and wherein the ACE2 protein or the ACE2 protein extracellular domain of (ii) is immobilised on a solid support; or
(b) the ACE2 protein or the ACE2 protein extracellular domain of (ii) is conjugated to the detection entity or the biotin, and wherein spike protein, the S1 subunit or the RBD of (i) is immobilised on a solid support.

### Claim 22 (depends on 21)

The method according to claim 21, wherein the spike protein, the S1 subunit or the RBD of (i) is conjugated to the detection entity or the biotin, and wherein the ACE2 protein or the ACE2 protein extracellular domain of (ii) is immobilised on a solid support.

### Claim 23 (depends on 21)

The method according to claim 21, wherein the detection entity is a horseradish peroxidase, an alkaline phosphatase, an acridinium compound, a phycoerythrin, or a fluorescein isothiocyanate.

### Claim 24 (depends on 21)

The method according to claim 21, wherein the RBD comprises an amino acid sequence having SEQ ID NO: 13 or 26.

### Claim 25 (depends on 21)

The method according to claim 21, wherein the SARSr-CoV is SARS-CoV-2 or a variant thereof.

### Claim 26 (depends on 21)

The method according to claim 21, wherein the solid support is a microtiter plate or a bead.