A novel antibody avidity methodology for rapid point-of-care serological diagnosis.

A novel methodology is introduced for rapid serological diagnosis. This methodology combines the antibody bridging assay principle with the measurement of antibody avidity. The combination allows the determination of the infection phase with a single dilution of a single sample of serum. This is a significant improvement on current serological techniques which often require either paired-sample testing (IgG/IgM serology) or testing of the sample in several dilutions (IgG avidity testing). Assay methods were developed on two immunoassay platforms; the heterogeneous time-resolved fluoroimmunoassay and the separation-free two-photon excitation fluorometry. The new methods were compared to conventional class-specific IgG/IgM and IgG avidity techniques. The major findings were that the avidity results of the new methodology were independent of the sample dilution (specific antibody concentration in serum) and consistent between immunoassay platforms. This new methodology is simple, rapid, and quick to perform. It provides the possibility of running serodiagnostic tests at point-of-care with bench-top random-access analyzers.