Immunoassay utilizing trapping conjugate

Abstract

Test devices 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.

What is claimed is: 
     
         1 . A test device for determining the presence of a first ligand in a liquid sample, comprising:
 a) a first sorbent strip having a first location for receiving a solution and defining a first migration path;   b) a marker conjugate adapted to move along said first migration path and bind to said first ligand;   c) a second sorbent strip distinct from said first sorbent strip and having a second location for receiving the liquid sample and defining a second migration path;   d) depletion molecules located on or in said second migration path wherein said depletion molecules include a ligand-binding elements adapted to specifically bind to second ligands that are different from but related to said first ligand to which said depletion molecules will not substantially bind; and   e) a test site located on or in one at least one of said first sorbent strip and said second sorbent strip, said test site having an immobilized first ligand binding mechanism for said first ligand, and said first and second sorbent strips touching each other at the test site location, wherein said second location is removed from said test site such that sample applied to said second location requires time to migrate to said test site and does not immediately wet said test site.   
     
     
         2 . A test device according to  claim 1 , wherein: said first ligand is a first flavivirus antibody, said second ligands that are different from but related to said first ligand include at least one of a second flavivirus antibody and an alphavirus antibody, and said ligand-binding elements are antigens specific to at least one of a second flavivirus antibody and an alphavirus antibody. 
     
     
         3 . A test device according to  claim 2 , wherein: said first flavivirus antibody is a Dengue antibody, and said antigens specific to at least one of a said second flavivirus antibody and an alphavirus antibody are antigens specific to Zika antibodies. 
     
     
         4 . A test device according to  claim 2 , wherein: said antigens specific to at least one of a said second flavivirus antibody and an alphavirus antibody are antigens specific to at least one of West Nile and Yellow fever antibodies. 
     
     
         5 . A test device according to  claim 2 , wherein: said first flavivirus antibody is a Zika antibody, and said antigens specific to at least one of a said second flavivirus antibody and an alphavirus antibody are antigens specific to Dengue antibodies. 
     
     
         6 . A test device according to  claim 5 , wherein: said antigens specific to at least one of a said second flavivirus antibody and an alphavirus antibody are antigens specific to at least one of West Nile and Yellow fever antibodies. 
     
     
         7 . A test device according to  1 , wherein: said first ligand is a first flavivirus antibody, said second ligands that are different from but related to said first ligand include at least one alphavirus antibody, and said ligand-binding elements are antigens specific to at least one of a second flavivirus antibody and an alphavirus antibody include antigens specific to an alphavirus antibody. 
     
     
         8 . A test device according to  claim 7 , wherein: said first flavivirus antibody is one of a Dengue antibody and a Zika antibody, and said antigens specific to an alphavirus antibody are specific to a Chikungunya antibody. 
     
     
         9 . A test device according to  claim 8 , wherein said antigens specific to at least one of a said second flavivirus antibody and an alphavirus antibody are antigens specific to at least one of West Nile and Yellow fever antibodies. 
     
     
         10 . A test device according to  claim 2 , wherein said depletion molecules comprise conjugates of latex particles with antigens specific to at least one of a second flavivirus antibody and an alphavirus antibody. 
     
     
         11 . A test device according to  claim 2 , wherein said depletion molecules comprise conjugates of latex particles and either (i) recombinant antigens, (ii) synthetic peptides, or (iii) lysate antigens, specific to at least one of a second flavivirus antibody and an alphavirus antibody. 
     
     
         12 . A test device according to  claim 2 , further comprising: a housing defining a first opening adjacent said first location, a second opening adjacent said second location, and a window adjacent said test site through which said test site is viewable. 
     
     
         13 . A test device according to  claim 2 , wherein: said marker conjugate comprises an antigen or antibody for the first ligand and a marker coupled to the antigen or antibody. 
     
     
         14 . A test device according to  claim 13 , wherein: said marker is a colored marker viewable in the visible spectrum. 
     
     
         15 . A test device according to  claim 14 , wherein: said first sorbent strip and said second sorbent strip are arranged in a “T” configuration. 
     
     
         16 . A test device according to  claim 12 , wherein: at least one of said first sorbent strip and said second sorbent strip includes a control site, and either said window is sized to permit viewing of said control site or a second window is provided in said housing to permit viewing of said control site. 
     
     
         17 . A test device according to  claim 1 , further comprising: buffer solution, wherein said marker conjugate is disposed on or in said first migration path and said buffer solution is adapted to carry said marker conjugate to said test site. 
     
     
         18 . A test device according to  claim 12 , further comprising: a first adhesive backing card underlying or overlying said first sorbent strip, and a second adhesive backing card underlying or overlying said second sorbent strip, wherein said first sorbent strip includes a first membrane and a first backing and said second sorbent strip includes a second membrane and a second backing, and said first sorbent strip and said second sorbent strip are arranged such that said first membrane is in contact with said second membrane. 
     
     
         19 . A test device according to  claim 2 , wherein said first ligand is a first flavivirus IgM antibody, said second ligands that are different from but related to said first ligand include at least one of a second flavivirus antibody and an alphavirus antibody, and said ligand-binding elements are antigens specific to at least one of a second flavivirus antibody and an alphavirus antibody. 
     
     
         20 . A test device for determining the presence of a first IgM ligand in a liquid sample, comprising:
 a) a first sorbent strip having a first location for receiving a solution and defining a first migration path;   b) a marker conjugate adapted to move along said first migration path and bind to said first IgM ligand, said marker conjugate including anti-human IgM;   c) a second sorbent strip distinct from said first sorbent strip and having a second location for receiving the liquid sample and defining a second migration path;   d) depletion molecules located on or in said second migration path wherein said depletion molecules include anti-human IgG; and   e) a test site located on or in one at least one of said first sorbent strip and said second sorbent strip, said test site having an immobilized first ligand binding mechanism for said first ligand, and said first and second sorbent strips touching each other at the test site location, wherein said second location is removed from said test site such that sample applied to said second location requires time to migrate to said test site and does not immediately wet said test site.