Control Line Systems for Lateral Flow Assays
Lateral flow tests consist of a test line and a control line. The control line provides validation of a functioning test. If the control line does not appear after running the test, that test is deemed invalid. The choice of a control line antibody will depend on which detector antibody is used in the test.
If a mouse monoclonal antibody is used as the detector antibody, the control line of choice will be Goat anti-Mouse IgG. If a rabbit monoclonal antibody or rabbit polyclonal antibody is used as the detector antibody, Goat anti-Rabbit IgG may be utilized for the control line. If Protein A is conjugated to the detector particle, then Chicken anti-Protein A may be chosen for the control line.
In some cases, the manufacturer will decide to use a control line system that is different from the test line system. An example of this is the HIV test in the double antigen sandwich format. Double antigen sandwich assays generally have an independent control line system which must be compatible with the other test components. An HIV test may have a Goat anti-Mouse IgG control line, but Mouse IgG gold conjugate must be added to the HIV gold conjugate. The manufacturer could choose an anti-HIV antibody for the control line but that is cost-prohibitive. Instead, the manufacturer may add Mouse IgG gold conjugate to the HIV antigen conjugate and use Goat anti-Mouse IgG for the control line. Another option is to add Chicken IgY gold conjugate to the HIV gold conjugate and select Goat anti-Chicken IgY as the control line reagent.
Various control line systems available from Arista Biologicals, a Fortis Life Sciences company, are shown below:
Arista manufactures and purifies all secondary antibodies and IgG/IgYs in-house. Each lot is functionally tested in a lateral flow assay. The secondary antibodies are also suitable for other test platforms such as ELISA but require further conjugation to HRP or another enzyme.
