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"Gold Standard" for Neutralizing Antibody Detection in Kits

1. The "gold standard" for the neutralizing antibody rapid detection kit

Neutralizing antibody detection is one of the important indicators in the process of vaccine development and clinical evaluation. The laboratory gold standard for neutralizing antibody detection is infection inhibition test, which mainly includes a plaque reduction neutralization test using a living body and a trace cell neutralization test for analysis by detecting cytopathic variables.

Both of these two methods use quantitative live and different dilutions of equal amount of serum to inoculate pre-prepared monolayer cells, and evaluate the degree of cell pathology and neutralizing antibody titers through different indicators. Neutralization assays using live in vitro cultures reflect the titers of total neutralizing antibodies capable of blocking infection in human blood samples.

2. Standardization of detection methods for neutralizing antibody detection kits

Neutralizing antibody detection methods need to go through a strict standardization process and adequate performance evaluation, and determine the low protection level by establishing a suitable Cut-off value to establish a correlation with the protective power. For example, the relatively mature influenza vaccine, EV71 vaccine, rabies vaccine, polio vaccine, etc., have established standardized neutralizing antibody tests recognized by WHO, and have corresponding WHO standard products and recommended standard strains. A clear Cut-off value is set. For other vaccines, even if there is no internationally recognized reference method, each vaccine manufacturer needs to establish a relatively standardized test method for neutralizing antibodies.

In addition, for emerging severe infectious diseases, due to the limitation of the source of live strains and the need to operate in high-level biosafety laboratories, more and more laboratories have begun to develop pseudo-cell culture methods to detect neutralizing antibodies. The pseudomembrane protein structure in the method is similar to that of the living body, and it does not require a high-level biosafety laboratory. The operation is simple and the results are judged objectively. However, the method also needs to be standardized and should be verified with the method of live culture.

Experts widely believe that the above PRNT, CPE and pseudo-neutralization tests are the three commonly used and classic neutralizing antibody detection methods in vaccine evaluation. Methodologically sound, but requires a rigorous standardization process.

In response, many domestic and foreign research institutions and production companies are working on live or fake neutralizing antibody detection methods, including WHO laboratories. However, due to the limited period of vaccine development, relevant basic research is still insufficient. Coupled with the continuous emergence of mutant strains, no standardized neutralizing antibody test methods have been established so far; there are also considerable differences between the test methods established by various institutions.