EIA detects low and high avidity anti-dsDNA antibodies, increasing its sensitivity and reducing its specificity. Similar to antibody, aptamers TBA and HD22 show avidity effect against thrombin after dimerization. Avidity (functional affinity) is the accumulated strength of multiple affinities. Avidity and affinity can be judged by the dissociation constant for the interactions they describe. The kinetoplast fluoresces if serum contains high avidity anti-dsDNA antibodies. As such, avidity is distinct from affinity, which describes the strength of a "single" interaction. Avidity effects of bivalent interactions redirecting transport to the lysosome . They are usually low avidity and are only detectable transiently after treatment. Pentamers offer enhanced brightness and avidity of staining compared with other multimer reagents. Currently there are two avidity assays in use. This changes the net surface charge of bound molecules, altering their avidity for the resin. These tests help to distinguish acute, recurrent or past infection by avidity of marker-specific IgG. In addition, the TBA-HD22 avidity can be examined by ecarin clotting time.