Immunoassay methods utilizing trapping conjugate
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Publication Number
US-10908158-B2
Publication Date
2021-02-02
Expiration Date
Abstract
Methods are provided for determining the presence of a first ligand in a sample. In some embodiments depletion conjugates are used to deplete the ligands different from but related to the first ligands from the sample. In some embodiments, interim binding agents are used to enhance the test signal.
Core Innovation
The invention relates to dual-path lateral-flow immunoassay test cells and methods for testing a sample for the presence of a first ligand. The device includes first and second sorbent strips that define a first migration path and a second migration path, with the sorbent strips touching each other at a test site location. A depletion conjugate is located on or in the second migration path and comprises depletion molecules bound to particles, and a marker conjugate is located on or in the first migration path and is adapted to bind to the first ligand.
The depletion molecules include ligand-binding elements adapted to specifically bind related but non-target ligands that are cross-reactive with the first ligand, to which the depletion molecules will not bind. After a sample is applied to the second location such that it migrates along the second migration path into contact with the depletion molecules, a solution is applied to the first location to cause the marker conjugate to migrate along the first migration path. The test site includes an immobilized ligand-binding mechanism for the first ligand, and inspecting the test site provides an indication of the presence or lack thereof of the first ligand in the sample.
The disclosed configurations include control lines and viewing windows, and device or housing structures in which the sample and buffer or conjugate solutions are provided to distinct openings removed from the test site such that the sample requires time to migrate and does not immediately wet the test site. The partial content also describes embodiments that include different particle types for the depletion conjugate, including white-latex antigen/antibody depletion conjugates and magnetic versus latex bead embodiments, with examples including flu detection and HIV p24 detection using interim binding agents such as streptavidin/biotin, anti-biotin, and double interim binding.
Claims Coverage
The partial content explicitly provides two independent claims (clm-00001 and clm-00005). Both independent claims share a multi-strip lateral-flow testing sequence that uses a depletion conjugate on a second migration path for cross-reactive but non-target ligands, followed by a marker conjugate on a distinct first migration path to produce an indication at a test site with an immobilized ligand-binding mechanism. Across the independent claims, there are 3 main inventive elements: (i) two distinct sorbent strips with separated migration paths, (ii) a depletion conjugate with cross-reactive related ligands that are not bound by the depletion molecules, and (iii) a sequential application and inspection structure where the sample is applied to a second location removed from the test site to prevent immediate wetting.
Two touching sorbent strips defining separated migration paths with a test site
A test device includes a first sorbent strip with a first location for receiving a solution defining a first migration path and a second sorbent strip distinct from the first and having a second location for receiving the liquid sample defining a second migration path, with a test site on or in at least one of the strips and the first and second sorbent strips touching each other at the test site location.
Depletion conjugate with cross-reactive related ligands that are not bound
A depletion conjugate located on or in the second migration path comprises depletion molecules bound to particles, where the depletion molecules include ligand-binding elements adapted to specifically bind to second ligands that are different from but related to the first ligand by being cross-reactive therewith to which the depletion molecules will not bind.
Marker conjugate migration to immobilized ligand-binding mechanism and inspection
A marker conjugate located on or in the first migration path binds to the first ligand, and after applying the sample to the second location and applying a solution to the first location to cause the marker conjugate to migrate along the first migration path, inspecting the test site determines an indication of the presence or lack thereof of the first ligand in the sample.
First flu antibody with second flu antibody depletion and sequential migration
In the flu-specific method, the first ligand is a first flu antibody and the depletion conjugate uses depletion molecules adapted to specifically bind second flu antibodies that are different from but related to the first flu antibody by being cross-reactive therewith to which the depletion molecules will not bind, using the same separated migration and sequential application and inspection structure.
Across the independent claims, the coverage centers on dual-path lateral-flow testing using separate sorbent strips or migration paths, a depletion conjugate configured to address cross-reactive related but non-target ligands, and a marker conjugate delivered later to produce an inspectable indication at a test site with an immobilized ligand-binding mechanism.
Stated Advantages
Not explicitly described in patent.
Documented Applications
Not explicitly described in patent.
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