Dual path immunoassay device
The systems of the invention include test cells with a first sorbent material defining a first flow path for a solution, a second sorbent material defining a second flow path distinct from the first flow path for a sample, and a test line or test site with immobilized antigens or antibodies or other ligand binding molecules such as aptamers, nucleic acids, etc. located at the junction of the first and second sorbent materials. The first and second sorbent strips touch each other at the test site location.
1. A test device for determining the presence of a 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 second sorbent strip having a second location for receiving the liquid sample and defining a second migration path distinct from said first migration path, said second migration path including a conjugate of an antibody bound to an interim binding agent, said antibody being selected to bind to the ligand when present in the sample;
c) a test site located on or in at least one of said first sorbent strip and said second sorbent strip, said test site having an immobilized binding agent, said interim binding agent and said immobilized binding agent chosen for their ability to selectively bind well to each other, said first and second sorbent strips touching each other at the test site location, and said second migration path extending laterally from said second location to at least said test site such that application of the liquid sample to the second location requires time for the liquid sample to laterally flow to the test site and does not immediately wet the test site upon application.
2. A test device according to claim 1 , wherein:
said first sorbent strip supports a conjugate of a marker coupled to a second antibody selected to bind to the ligand when present in the sample.
3. A test device according to claim 1 , wherein:
said ligand is a human immunodeficiency virus type 1 (HIV-1) p24 antigen, said conjugate of an antibody bound to an interim binding agent is a HIV-1 p24 monoclonal antibody bound to biotin, and said immobilized binding agent is streptavidin.
4. A test device according to claim 2 , wherein:
said ligand is a human immunodeficiency virus type 1 (HIV-1) p24 antigen, said conjugate of an antibody bound to an interim binding agent is a HIV-1 p24 monoclonal antibody bound to biotin, said immobilized binding agent is streptavidin, and said conjugate of a marker coupled to a second antibody is a colored latex conjugate with a monoclonal antibody.