Disclosed is a highly sensitive assay method and assay kit for HBsAg, which do not require treatment with a strong acid or alkali in the sample pretreatment, and which is less susceptible to influences by the autoantibodies. The assay method for hepatitis B virus s antigen in a sample separated from a living body includes: a pretreatment step of mixing a sample with a pretreatment reagent containing a reducing agent, to reduce hepatitis B virus s antigen; and an immunoassay step of subjecting the pretreated sample to an immunoassay of hepatitis B virus s antigen using at least one antibody or antigen-binding fragment thereof capable of antigen-antibody reaction with a reduced peptide composed of the amino acids at positions 98 to 179 of hepatitis B virus s antigen.

Methods, techniques, systems and compositions to reduce or prevent the aggregation and/or epitope masking of control/calibration peptides. The methods described herein may be particularly helpful for calibration and quantifying target proteins from immunoassays such as solid-phase enzyme immunoassays (EIAs).

This invention provides methods and compositions, e.g., to reduce interference from non-specific binding sample constituents in a migration shift assay. Interference due to non-specific binding of sample constituents to an affinity substance (e.g., an affinity molecule or a conjugate of an affinity molecule and a charged carrier molecule) is prevented by, e.g., binding the constituents to charged polymers such as heparin sulfate. The present invention also provides methods to concentrate an analyte of interest with high concentration and to detect the analyte with high sensitivity, and further to optimize the reaction conditions for easily concentrating the analyte. Such objects of the present invention are attained, for example, by concentrating a complex of the analyte and a conjugate which is formed by contacting the analyte in a sample with an affinity molecule bound to a charged carrier molecule such as DNA.

The invention concerns a fusion polypeptide comprising several molecules of folding helper polypeptides, comprising one multimerization domain, in particular Skp, and at least one molecule of SlyD or SlpA, wherein no further target polypeptide sequences are fused to said fusion polypeptide. The invention further concerns an immunoassay and the use of said fusion polypeptide in an immunoassay for reduction of interferences or minimizing false positive results or for stabilizing proteinaceous assay reagents. Further the invention concerns a reagent kit for use in an immunoassay comprising said fusion polypeptide.

Methods and kits for detecting antibodies (e.g., anti-drug antibodies). Such methods and kits permit the detection of, for example, anti-drug antibodies in human body fluids, such as blood, plasma and serum.

Blocking reagent compositions, as well as methods of making and using the same, are provided. Aspects of the composition include a blocking reagent that binds to the cell surface but does not specifically bind to a targeted first cell surface antigen. Also provided are system and kits that include the compositions.

Disclosed herein are compositions and methods for removing interfering substances from biological samples, biochemical assays, or reagents used in biological samples using porous liposomes that capture and in some instances enrich said interfering substances within the liposomes.

The present invention provides a technique for reducing contamination with impurities in a system of operating an extracellular vesicle. More specifically, the present invention provides a method of washing an extracellular vesicle and the like. The method includes washing the extracellular vesicle with a nonionic surfactant that is a chain compound containing a structure represented by —O—(—CH.sub.2—CH.sub.2—O—).sub.x—H, wherein x is a value defined in the description.

The present invention provides a method for increasing the sensitivity of LFIAs by using palladium nanoparticles, selecting appropriate dye chemistries, and improving the timing of the development chemistry. In the presence of a palladium nanoparticle, three reagents interact with a catalytic label to form a colored dye. The three reagents include a hydrogen peroxide source, a color developer (a substituted para-phenylenediamine), and a color coupler (e.g. a napthol or a phenol). The timing of the development chemistry is improved by any combination of using a reducing agent, delaying hydrogen peroxide application by diffusion, using dissolving materials as a time delay, using serpentine flow, and separating the color coupler and the color developer on the strip.

There is provided a method for preventing an occurrence of an irregular detection value and performing measurement with good reproducibility in an immunoassay using an automatic analyzer regardless of whether the reaction cuvette used is of a disposable type or a reusable type and whether the optical detection method used measures transmitted light or scattered light. There is also provided an immunoassay reagent for use in the method. A method for preventing the occurrence of irregular detection and enhancing the reproducibility of measurement includes using a reagent containing polyethylene glycol or the like having a weight-average molecular weight of 300 to 3000.