Abstract: Disclosed is a use of reaction kinetics to generate multiple dose-response curves from a single reaction, thus eliminating the need to run a second experiment with additional sample, reagents, and time to cover a broader measuring range than is available in a standard assay. Using a single protocol, the differences in the reaction kinetics for different sample concentrations yield different responses at different measurement times. Selection of the appropriate dose-response curve cross-section increases the measuring range and accuracy of the assay from a single reaction without substantially increasing imprecision. Several overlapping dose-response curves are pieced together to provide a standard curve to ensure continuity throughout the expanded measuring range.

Abstract: A Treponema pallidum triplet antigen construct is disclosed which includes three Treponema pallidum antigens (TP15, TP17, and TP47), as well as a ten amino acid leader sequence (tag 261) and human copper zinc superoxide dismutase (hSOD). This construct is optimized for in vitro diagnosis of syphilis infection. Plasmids containing DNA encoding the triplet antigen, host cells, production methods, detection methods, and kits are also disclosed.