Field of the Invention
5 The present invention relates to a diagnostic device and a kit comprising the diagnostic
device and also to a method of testing for the presence of an antibody specific for a
biological antigen.
10
Background of the Invention
Coronavirus disease 2019 (COVID-19) is an infectious disease caused by severe acute
respiratory syndrome coronavirus 2 (SARS-CoV-2). The disease was first identified in
December 2019 in Wuhan, the capital of China's Hubei province, and has since spread
globally, resulting in the ongoing 2019-20 coronavirus pandemic. As of 1 May 2020,
15 more than 3.27 million cases have been reported across 187 countries and territories,
resulting in more than 233,000 deaths. Left unchecked, it is estimated that 40-70% of
the global population of approximately 7.8 billion will contract the current form of the
virus. With an estimated mortality of 1-3%, 31-164 million lives are at risk.
20 Repeat testing, via detection of antibodies, and specifically lgG antibodies, for potential
immunity and post infection epidemiology data, and also testing for viral antigens, will
provide an essential tool to minimise the continued spread of disease, and risk of its
mutation into something even more deadly.
25 CO VI D-19 is most contagious during the first tt1ree days after the onset of symptoms,
although spread may be possible before symptoms appear and in later stages of tile
disease. Since the virus is highly contagious and since the incubation period in an
individual can be up to 14 days (and, indeed, certain infected individuals do not present
any noticeable symptoms at all) monitoring the progress of tt1e infection within a
30 community is challenging. It is widely accepted that a high degree of testing within
communities is desirable in order to identify individuals who are currently infected and to
identify individuals who have previously been infected and currently have antibodies
specific for the virus.
5
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A wide range of different techniques have been devised for testing for the COVID-19
virus. A typical test for the virus, itself, is a reverse transcription polymerase chain
reaction test which detects RNA from tile virus and for which results are generally
available within a few hours to 2 days. A related test is an isothermal amplification assay.
Another type of test is an antigen test which seeks to detect proteins (in some cases
proteins from tile surface spikes) from the surface of tile virus. The problem witil this type
of test is that often the amount of antigenic material present in a biological sample is not
enough to be readily detected. Based on the sensitivity of similar antigen tests for
10 respiratory diseases such as influenza, it is currently doubtful wt1ett1er a test of this type
could be made sufficiently reliable for tile detection of the CO VI D-19 virus.
A further type of test is a serology test in which antibodies, which are presumed to be
specific for epitopes of the COVID-19 virus, are detected in blood samples from an
15 individual. Typically, such tests are either lateral flow immunoassay tests (which are
invariably coated with nucleoprotein antigen) or are enzyme-linked immunosorbent
assay (ELISA) tests. The problem with lateral flow immunoassay tests is tl1at, although
they are suited for domestic use and use by non-medical practitioners, their accuracy
and reliability, in particular tt1eir sensitivity and specificity, in relation to the detection of
20 the COVID-19 virus is questionable. The inherent design limitations of lateral flow
immunoassay test devices and the lack of bonds to hold components together results in
the test strips in the devices invariably being loose and able to detach from the correct
position in relation to other components. The sample volume of lateral flow amino acid
test devices is also very limited due to design limitations and the way in which tile
25 molecular elements are stacked in a complex arrangement. Furtl1ermore, a lateral flow
immunoassay test can take 20 minutes to complete. The problem with ELISA tests is
that it can take 1 to 5 t1ours to give results and must typically be performed in an equipped
laboratory, with skilled staff working in controlled conditions
30 Another type of test which has hitherto not been applied to the COVID-19 virus is the
QuickCard (TM) test. The QuickCard test has predominantly been applied in the
detection of autoimmune diseases. In its typical form, the QuickCard test comprises a
rigid casing with an aperture therein and a nitrocellulose membrane located so as to
cover the aperture and being supported on a liquid-absorbent pad. The nitrocellulose
35 membrane has a biological antigen immobilised thereon. In use, a liquid, biological
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sample (typically a blood sample from an individual) is deposited on the nitrocellulose
membrane via the aperture in ttie casing such ttiat any relevant antibodies in the sample
bind to the biological antigen. Excess liquid from the sample is then absorbed through
tile nitrocellulose membrane and into the liquid-absorbent pad. In a subsequent step, a
5 detection reagent is deposited on the nitrocellulose membrane, via the aperture in the
casing. The detection reagent comprises a gold particle conjugated to an anti-lgG, antilgM
or anti-lgA antibody. If the biological sample contained relevant antibodies then tile
antibody in the detection reagent binds to the relevant antibodies, tl1us concentrating the
gold particles onto the nitrocellulose membrane such that a detectable spot is visible.
10 Thus the presence of the spot is indicative of the presence of relevant antibodies (lgG,
lgM or lgA) in the biological sample whereas the absence of the spot is indicative of the
absence of relevant antibodies from the biological sample. The presence of antibodies
is indicative either of prior infection by a micro-organism (e.g. virus) against which the
antibodies tiave been generated or immunity arising from prior vaccination.
15
While the QuickCard test is an effective test for many antibodies, it has been found that
in certain circumstances, such as the detection of anti-COVI 0-19 antibodies, the usual
configuration of the QuickCard test is not sufficiently sensitive to provide a reliable test.
20 Tile QuickCard test was developed in tile mid-1990s. Various iterations of the test have
been developed over the years. One such variant is disclosed in W095/19845, the
contents of which is hereby incorporated by reference.
25
The present invention seeks to alleviate one or more of the above problems.
Summary of the Invention
Tile present invention arises from the surprising finding ti1at, by providing a flow control
structure between the nitrocellulose membrane (or other porous membrane element)
30 and the casing of the QuickCard test, flow of the liquid, biological sample is better
controlled. In particular, Hie flow control structure limits or prevents Hie seepage of the
liquid sample around the outer surface of the nitrocellulose membrane (or other porous
membrane element) and directly to the liquid-absorbent pad, without coming into contact
with the biological antigen (or other member of a reporter-analyte pair) immobilised on
35 the nitrocellulose membrane. By avoiding such seepage, the variability between
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manufactured test kits is significantly reduced making the test kit more reproducible and
thus more reliable, In particular, the reliability of the test is such that detection of
antibodies specific for the COVID-19 virus in a biological sample is possible.
5 The present invention also arises from the surpns1ng finding that, when detecting
whether an individual has been exposed to the COVID-19 virus (Le. either through
infection or through vaccination), identifying the presence of antibodies against tile
COVID-19 spike protein and specifically the S1 spike protein is a much more accurate
indication of the exposure of the individual to the COVID-19 virus than is identifying the
10 presence of antibodies against other parts of the virus. In particular, the present invention
arises from the finding that the nucleoprotein of the CO VI 0-19 virus is not specific to the
CO VI D-19 virus and is also present in other coronaviruses, giving rise to the potential for
cross reactive results. Thus, by detecting the presence of antibodies against the spike
protein and, specifically, the S1 spike protein, false positive detection events are avoided,
15
The present invention also arises from the observation that in certain contexts (e.g.
wl1ere a detection device has to be produced rapidly) the quality of the biological antigen
that is provided in a detection device may be sub-optimal. For example, the biological
antigen may be contaminated with antigens from tt1e host species, which gives rise to
20 false positive detection events due to reactivity against other antigens of the host
species. Thus the present invention arises from tile realisation that providing multiple
versions of the biological antigen and detecting the presence of antibodies against all
versions of the biological antigen suct1 that only tt1e detection of antibodies against all
versions is regarded as a positive result gives rise to a more accurate detection device.
25
The present invention also arises from the realisation that providing a detection device
which gives an indication of the quantity of antibody present in a sample can be achieved
by providing multiple different concentrations of antigen in the detection device.
30 The present invention also arises from the recognition that, where only a low volume of
biological sample is available for testing in a detection device, funnelling the biological
sample such that all or almost all of the sample comes into contact with the detection
portion on which antigen is located ensures that tile biological sample is used to
maximum effect and does not bypass tile detection portion.
35
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The present invention also arises from the finding that, in a detection device, locating
biological antigen on a non-planar membrane facilitates greater control of detection of
antibodies in a biological sample. Such greater control includes managing low volumes
of biological sample by coalescing the biological sample on the biological antigen; and
5 managing a biological sample which contains visual contaminants by encouraging the
contaminants to flow away from the biological antigen.
According to one aspect of the present invention, there is provided a diagnostic device
for detecting a first member of a reporter-analyte pair comprising:
10 a casing comprising a testing portion having an aperture therein, the aperture having an
inlet for receiving a liquid, biological sample and an outlet for releasing the liquid,
biological sample;
a porous membrane element comprising a detection portion, a second member of the
reporter-analyte pair being immobilised on the detection portion, the outlet being in liquid
15 communication with the detection portion via a detection flow path; and
a flow control structure for limiting or preventing the flow of the liquid, biological sample
from the outlet along a bypass flow path, which bypasses the detection portion, instead
of the detection flow path.
20 Conveniently, the flow control structure comprises a liquid-tight seal present between the
testing portion and the porous membrane element, which prevents the liquid, biological
sample from flowing along the bypass flow path which bypasses the detection portion,
preferably wherein the liquid-tight seal surrounds the aperture.
25 Preferably, the liquid-tight seal is an ultrasonic weld or other controlled seal between the
testing portion and the porous membrane element.
Advantageously, the casing and the liquid-tight seal form a liquid-tight chamber around
the porous membrane element from which only the detection portion of the porous
30 membrane element is exposed from the chamber.
35
Alternatively, the flow control structure comprises an arrangement of gates or obstacles
which are present in the bypass flow path and which limit the liquid, biological sample
from flowing along the bypass flow path which bypasses the detection portion.
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Conveniently, the porous membrane element is located adjacent to the testing portion
such that the detection portion is visible through the inlet of the aperture.
Preferably, the diagnostic device further comprises a liquid-absorbent pad in liquid-
S communication with the detection portion of the porous membrane element, the detection
flow path being from the outlet of the aperture through the detection portion and into the
liquid-absorbent pad.
Advantageously, the bypass flow path is from the outlet of the aperture to the liquid-
1 0 absorbent pad, without passing through the detection portion of the porous membrane
element.
Conveniently, the liquid-absorbent pad comprises an opening therein, and the porous
membrane element is located between the liquid-absorbent pad and the aperture in the
15 testing portion, the opening in the liquid-absorbent pad being aligned with the aperture
in the testing portion.
Preferably, the porous membrane element comprises a nitro-cellulose membrane.
20 Advantageously, the second member of the reporter-analyte pair comprises a biological
antigen and the first member of the reporter-analyte pair comprises an antibody specific
for the biological antigen.
Conveniently, the biological antigen comprises a Coronavirus protein or fragment
25 thereof.
Preferably, the coronavirus protein is a Covid-19 protein, preferably a COVID-19 81
spike protein or fragment thereof. Advantageously, the biological antigen does not
comprise the Covid-19 nucleoprotein, or a fragment thereof, of COVID-19 but
30 conveniently does comprise the COVID-19 82 protein (which follows the RBD portion of
the 81 protein).
Advantageously, the coronavirus protein or fragment thereof is a polypeptide comprising
a sequence of at least 8, 10, 12, 14, 16, 18, 20, 30, 100, 200 or 300 amino acids from
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an amino acid sequence having at least 70%, 80%, 90%, 95%, 99% or 100% sequence
identity to the sequence represented in Figure 10 (SEQ I D NO: 4).
Alternatively, the first member of the reporter-analyte pair comprises a biological antigen
5 and the second member of the reporter-analyte pair comprises an antibody specific for
the biological antigen.
Conveniently, the biological antigen comprises a COVID-19 protein or fragment thereof.
10 Preferably, the casing comprises at least one securing structure for locating the porous
membrane element in a position covering the aperture.
Advantageously, the porous membrane element further comprises a reference element
for indicating a level of the first member of the reporter-analyte pair in the liquid, biological
15 sample, preferably wherein the reference element is a plurality of reference elements.
According to a second aspect of the present invention, there is provided a kit comprising
a diagnostic device according to the invention and a detection reagent, the detection
reagent comprising a molecular conjugate which comprises a detectable moiety bound
20 to a moiety capable of binding the first member of the reporter-analyte pair.
Conveniently, the moiety capable of binding the first member of the reporter-analyte pair
is an antibody.
25 Preferably, the molecular conjugate comprises a gold particle conjugated to an anti-lgG
or anti-lgM antibody.
According to a third aspect of the present invention, there is provided a method of testing
for the presence of a first member of a reporter-analyte pair in a liquid, biological sample,
30 comprising the steps of:
I) providing a diagnostic device according to the present invention;
II) depositing the biological sample onto the porous membrane element via the aperture
such that the biological sample contacts the second member of the reporter-analyte pair
immobilised on the porous membrane element and such that first member of the
35 reporter-analyte pair interacts with the second member of the reporter-analyte pair;
5
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Ill) depositing a detection reagent onto the porous membrane element via the aperture
such that the detection agent contacts the first member of the reporter-analyte pair, the
detection reagent providing a detectable signal when contacting the first member of the
reporter-analyte pair.
Conveniently, the detection reagent comprises a detectable moiety bound to a moiety
capable of binding the first member of the reporter-analyte pair.
According to a fourth aspect of the present invention, there is provided a diagnostic
10 device for detecting a first member of a reporter-analyte pair in a biological sample
comprising:
a porous membrane element comprising a detection portion, a second member
of the reporter-analyte pair being immobilised on the detection portion,
wherein one of the first or second member of the reporter-analyte pair comprises a
15 biological antigen and the other of the first or second member of the reporter-analyte pair
comprises an antibody specific for the biological antigen, and
wherein the biological antigen comprises a spike protein, or a fragment thereof, of
COVID-19 and wherein the device is for independent detection of the spike protein, or
the fragment thereof, or of an antibody specific for the spike protein, or the fragment
20 thereof, in the biological sample.
Preferably, the second member of the reporter-analyte pair is immobilisable on the
detection portion.
25 Conveniently, the diagnostic device comprises an inlet for receiving a liquid, biological
sample, wherein the inlet and the detection portion are in liquid communication.
30
35
Preferably, the spike protein or the fragment thereof is a COVID-19 81 spike protein or
a fragment thereof, optionally the COVID-19 81 spike protein receptor binding domain.
Conveniently, the COVID-19 81 spike protein or the fragment thereof is a polypeptide
comprising a sequence of at least 8, 10, 12, 14, 16, 18, 20, 30, 100, 200 or 300 amino
acids from an amino acid sequence having at least 70%, 80%, 90%, 95%, 99% or 100%
sequence identity to the sequence represented in Figure 10 (SEQ 10 NO: 4).
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Advantageously, the COVI0-19 S1 spike protein or the fragment thereof comprises the
COVI0-19 S1 spike protein receptor binding domain having the sequence of SEQ 10
NO: 3.
5 Advantageously, the reporter-analyte pair is a plurality of reporter-analyte pairs,
wherein one of the first or second member of each reporter-analyte pair comprises a
biological antigen and the other of the first or second member of each reporter-analyte
pair comprises an antibody specific for the biological antigen,
wherein the biological antigen of each reporter-analyte pair is a different biological
10 antigen.
Conveniently, the plurality of reporter-analyte pairs comprises a first, a second and
optionally a third reporter-analyte pair,
wherein the biological antigen of the first reporter-analyte pair is a COVI0-19 S1 spike
15 protein or a fragment thereof, and
20
wherein the biological antigen of the second reporter-analyte pair is a COVI0-19 S2
spike protein or a fragment thereof, and optionally
wherein the biological antigen of the third reporter-analyte pair is a COVI0-19
nucleoprotein or a fragment thereof.
Preferably, the COVI0-19 S2 spike protein or the fragment thereof is a polypeptide
comprising a sequence of at least 8, 10, 12, 14, 16, 18, 20, 30, 100, 200 or 300 amino
acids from an amino acid sequence having at least 70%, 80%, 90%, 95%, 99% or 100%
sequence identity to the sequence represented in Figure 11A (SEQ 10 NO: 5) or Figure
25 11 B (SEQ 10 NO: 6).
30
Advantageously, the COVI0-19 S2 spike protein or the fragment thereof comprises a
sequence in which the C-terminal six amino acids are deleted from the sequence
represented in Figure 11A (SEQ 10 NO: 5) or Figure 11 B (SEQ 10 NO: 6).

CLAIMS:
1. A diagnostic device for detecting a first member of a reporter-analyte pair or a
first member of each of a plurality of reporter-analyte pairs comprising:
an inlet for receiving a liquid, biological sample; and
a porous membrane element comprising a detection portion, the detection
portion being in liquid communication with the inlet and a second member of the or
each reporter-analyte pair being immobilisable on the detection portion,
wherein one of the first or second member of the or each reporter-analyte pair
comprises a biological antigen and the other of the first or second member of the or
each reporter-analyte pair comprises an antibody specific for the biological antigen,
and
wherein the biological antigen comprises:
(a) a COVID-19 S1 spike protein comprising the sequence of SEQ
ID NO: 4 (as represented in Figure 10) or a sequence having at least
99% or 100% sequence identity to the sequence of SEQ ID NO: 4 (as
represented in Figure 10); and/or
(b) a first biological antigen from a first reporter-analyte pair
comprising a COVID-19 S1 spike protein or a fragment thereof, and
a second biological antigen from a second reporter-analyte pair
comprising a COVID-19 S2 spike protein or a fragment thereof,
and wherein the device is for independent detection of a spike protein, or a fragment
thereof, or of an antibody specific for a spike protein, or a fragment thereof, in the
biological sample.
2. The diagnostic device according to claim 1, wherein the first biological antigen
comprising the COVID-19 S1 spike protein or the fragment thereof is a polypeptide
comprising a sequence of at least 8, 10, 12, 14, 16, 18, 20, 30, 100, 200 or 300 amino
acids from an amino acid sequence having at least 70%, 80%, 90%, 95%, 99% or
100% sequence identity to the sequence of SEQ ID NO: 4 (as represented in Figure
10), optionally wherein the COVID-19 S1 spike protein or the fragment thereof
comprises the COVID-19 S1 spike protein receptor binding domain having the
sequence of SEQ ID NO: 3.
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3. The diagnostic device according to claim 1 or 2, wherein the second biological
antigen comprising the COVID-19 S2 spike protein or the fragment thereof is a
polypeptide comprising a sequence of at least 8, 10, 12, 14, 16, 18, 20, 30, 100, 200 or
300 amino acids from an amino acid sequence having at least 70%, 80%, 90%, 95%,
99% or 100% sequence identity to the sequence of SEQ ID NO: 5 (as represented in
Figure 11A) or SEQ ID NO: 6 (as represented in Figure 11B).
4. The diagnostic device according to any one of claims 1 to 3, wherein the
COVID-19 S2 spike protein or the fragment thereof comprises a sequence in which the
C-terminal six or 62 amino acids are deleted from the sequence of SEQ ID NO: 5 (as
represented in Figure 11A) or SEQ ID NO: 6 (as represented in Figure 11B).
5. The diagnostic device according to any one of claims 1 to 4, wherein the
COVID-19 S1 spike protein or the fragment thereof and the COVID-19 S2 spike protein
or the fragment thereof are comprised within a single polypeptide chain, the single
polypeptide chain being immobilisable on the detection portion.
6. The diagnostic device according to any one of claims 1 to 5, wherein the
biological antigen further comprises a third biological antigen from a third reporteranalyte
pair and wherein the third biological antigen comprises a COVID-19
nucleoprotein or a fragment thereof, preferably comprises the sequence of SEQ ID NO:
7 (as represented in Figure 12).
7. The diagnostic device according to any one of claims 1 to 6, wherein the porous
membrane element further comprises a reference element for indicating a level of the
first member of the or each reporter-analyte pair in the liquid, biological sample,
preferably wherein the reference element is a plurality of reference elements.
8. The diagnostic device according to any one of claims 1 to 7, wherein the
second member of the or each reporter-analyte pair is immobilised on the detection
portion.
9. A kit comprising a diagnostic device according to any one of the preceding
claims and a detection reagent, the detection reagent comprising a molecular
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conjugate which comprises a detectable moiety bound to a moiety capable of binding
the first member of the reporter-analyte pair.
10. A kit according to claim 9 wherein the moiety capable of binding the first
member of the reporter-analyte pair is an antibody.
11. A kit according to claim 10 wherein the molecular conjugate comprises a gold
particle conjugated to an anti-IgG or anti-IgM antibody.
12. A method of testing for the presence of a first member of a reporter-analyte pair
in a liquid, biological sample, comprising the steps of:
I) providing a diagnostic device according to any one of claims 1 to 8;
II) depositing the biological sample onto the porous membrane element such that the
biological sample contacts the second member of the reporter-analyte pair
immobilisable on the porous membrane element and such that first member of the
reporter-analyte pair interacts with the second member of the reporter-analyte pair,
wherein an interaction between the first member of the reporter-analyte pair and the
second member of the reporter-analyte pair is detectable.
13. The method according to claim 12, wherein the method further comprises the
step of:
III) depositing a detection reagent onto the porous membrane element such that
the detection reagent contacts the first member of the reporter-analyte pair, the
detection reagent providing a detectable signal when contacting the first member of the
reporter-analyte pair.
14. The method according to claim 13, wherein the detection reagent comprises a
detectable moiety bound to a moiety capable of binding the first member of the
reporter-analyte pair.
15. The method according to any one of claims 12 to 14, wherein the second
member of the reporter-analyte pair comprises a biological antigen, the biological
antigen comprising a spike protein, or a fragment thereof, of COVID-19 and wherein
the first member of the reporter-analyte pair comprises an antibody specific for the
spike protein, or the fragment thereof, of COVID-19.
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16. The method according to any one of claims 12 to 15, wherein the diagnostic
device provided is a diagnostic device according to any one of claims 1 to 8, wherein
the reporter-analyte pair is a first and/or a second reporter-analyte pair,
wherein the second member of the first reporter-analyte pair is a COVID-19 S1 spike
protein or a fragment thereof and the first member of the first reporter-analyte pair is an
antibody specific for the COVID-19 S1 spike protein or a fragment thereof; and/or
wherein the second member of the second reporter-analyte pair is a COVID-19 S2
spike protein or a fragment thereof and the first member of the second reporter-analyte
pair is an antibody specific for the COVID-19 S2 spike protein or a fragment thereof,
and
wherein the presence of an antibody specific for the COVID-19 S1 spike protein or the
fragment thereof and/or the COVID-19 S2 spike protein or the fragment thereof in the
biological sample indicates current or prior infection by or vaccination against COVID-
19.
17. The method according to any one of claims 12 to 15, wherein the diagnostic
device provided is a diagnostic device according to any one of claims 6 to 8, wherein
the reporter-analyte pair is a first, a second and a third reporter-analyte pair,
wherein the second member of the first reporter-analyte pair is a COVID-19 S1 spike
protein or a fragment thereof and the first member of the first reporter-analyte pair is an
antibody specific for the COVID-19 S1 spike protein or a fragment thereof;
wherein the second member of the second reporter-analyte pair is a COVID-19 S2
spike protein or a fragment thereof and the first member of the second reporter-analyte
pair is an antibody specific for the COVID-19 S2 spike protein or a fragment thereof;
and
wherein the second member of the third reporter-analyte pair is a COVID-19
nucleoprotein or a fragment thereof and the first member of the third reporter-analyte
pair is an antibody specific for the COVID-19 nucleoprotein or a fragment thereof, and
wherein the presence of an antibody specific for the COVID-19 nucleoprotein, or the
fragment thereof, and the absence of an antibody specific for the COVID-19 S1 spike
protein, or the fragment thereof, and the absence of an antibody specific for the
COVID-19 S2 spike protein, or the fragment thereof, indicates current or prior infection
by or vaccination against a beta group coronavirus other than COVID-19.
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18. A diagnostic device for detecting a first member of a reporter-analyte pair
comprising:
a casing comprising a testing portion having an aperture therein, the aperture
having an inlet for receiving a liquid, biological sample and an outlet for releasing the
liquid, biological sample;
a porous membrane element comprising a detection portion, a second member
of the reporter-analyte pair being immobilised on the detection portion, the outlet being
in liquid communication with the detection portion via a detection flow path; and
a flow control structure for limiting or preventing the flow of the liquid, biological
sample from the outlet along a bypass flow path, which bypasses the detection portion,
instead of the detection flow path,
wherein the flow control structure comprises:
(a) a liquid-tight seal present between the testing portion and the porous
membrane element, which prevents the liquid, biological sample from flowing along the
bypass flow path which bypasses the detection portion; or
(b) an arrangement of gates or obstacles which are present in the bypass
flow path and which limit the liquid, biological sample from flowing along the bypass
flow path which bypasses the detection portion.
19. A kit comprising a diagnostic device according to claim 18 and a detection
create reagent, the detection reagent comprising a molecular conjugate which
comprises a detectable moiety bound to a moiety capable of binding the first member
of the reporter-analyte pair.
20. A method of testing for the presence of a first member of a reporter-analyte pair
in a liquid, biological sample, comprising the steps of:
I) providing a diagnostic device according to claim 18;
II) depositing the biological sample onto the porous membrane element via the
aperture such that the biological sample contacts the second member of the reporteranalyte
pair immobilised on the porous membrane element and such that first member
of the reporter-analyte pair interacts with the second member of the reporter-analyte
pair;
III) depositing a detection reagent onto the porous membrane element via the
aperture such that the detection agent contacts the first member of the reporter-analyte
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pair, the detection reagent providing a detectable signal when contacting the first
member of the reporter-analyte pair.
21. A diagnostic device for detecting a first member of a reporter-analyte pair
comprising:
an inlet for receiving a liquid, biological sample;
a porous membrane element comprising a detection portion, the detection
portion being in liquid communication with the inlet,
wherein the detection portion comprises a second member of the reporteranalyte
pair and a variant of the second member of the reporter-analyte pair
immobilisable thereon, and
wherein an interaction between the first member of the reporter-analyte pair and
the second member of the reporter-analyte pair is separately detectable from an
interaction between the first member of the reporter-analyte pair and the variant of the
second member of the reporter-analyte pair.
22. A diagnostic device for detecting a first member of a reporter-analyte pair or a
first member of each of a plurality of reporter-analyte pairs comprising:
an inlet for receiving a liquid, biological sample; and
a porous membrane element comprising a detection portion, the detection
portion being in liquid communication with the inlet and a second member of the or
each reporter-analyte pair being immobilisable on the detection portion,
wherein one of the first or second member of the or each reporter-analyte pair
comprises a biological antigen and the other of the first or second member of the or
each reporter-analyte pair comprises an antibody specific for the biological antigen,
wherein the biological antigen comprises a COVID-19 S1 spike protein or a fragment
thereof comprising a sequence in which one or more amino acids are substituted in a
sequence consisting of the N-terminal 100, 200, 300, 400, 500 or 600 amino acids of
the sequence of SEQ ID NO: 4 (as represented in Figure 10), and
wherein the device is for independent detection of the COVID-19 S1 spike protein, or
the fragment thereof, in which one or more amino acids has been substituted, or of an
antibody specific for the COVID-19 S1 spike protein, or the fragment thereof, in which
one or more amino acids has been substituted, in the biological sample.
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23. A diagnostic device for detecting a first member of a reporter-analyte pair
comprising:
an inlet for receiving a liquid, biological sample,
a porous membrane element comprising a detection portion, the detection
portion being in liquid communication with the inlet,
wherein the detection portion comprises a second member of the reporteranalyte
pair immobilised thereon at a plurality of different concentrations, and
wherein the plurality of different concentrations of the second member of the reportanalyte
pair extend between a first point on the detection portion, at which the
concentration of the second member of the reporter-analyte pair is highest, through to
a second point on the detection portion, at which the concentration of the second
member of the reporter-analyte pair is lowest and at sequential concentrations
therebetween.
24. A diagnostic device for detecting a first member of a reporter-analyte pair
comprising:
a casing comprising a testing portion having an aperture therein, the testing
portion having an inlet for receiving a liquid, biological sample and an outlet for
releasing the liquid, biological sample;
a membrane element having a detection portion on which a second member of
the reporter-analyte pair is immobilised, the outlet being in liquid communication with
the detection portion via a detection flow path;
the outlet of the testing portion contacting the membrane element and defining
a visible portion of the membrane element, the visible portion of the membrane element
comprising the detection portion,
and wherein the surface area of the detection portion is at least 60% but less
than 100% of the surface area of the visible portion.
25. A diagnostic device for detecting a first member of a reporter-analyte pair
comprising:
a casing comprising a testing portion having an aperture therein, the testing
portion having an inlet for receiving a liquid, biological sample and an outlet for
releasing the liquid, biological sample;
M&C PN841678IN
69
12688969-1
a porous membrane element having a detection portion on which a second
member of the reporter-analyte pair is immobilised, the outlet being in liquid
communication with the detection portion via a detection flow path;
the outlet of the testing portion contacting the membrane element and defining
a visible portion of the membrane element, the visible portion of the membrane element
comprising the detection portion,
wherein the detection portion is non-planar.