Significance of neutralizing antibody detection
The principle of neutralizing antibodies to protect the body: binding to the surface protein of new coronavirus, and blocking the binding of viral protein with cell surface-specific receptor ACE-2, thus preventing the virus from invading cells (non-neutralizing antibody has no such function). When the titer of neutralizing antibody in antibody is insufficient, it may lead to the deterioration of ADE (antibody-dependent enhancement) type disease: the virus binds to Fc receptor on the cell surface through antibody, and then infects more kinds of cells including macrophages, leading to immune response disorder. The virus infection verification method is to verify the effectiveness of neutralizing antibodies at the cellular level, which is suitable for the vaccine development stage. In order to quickly evaluate the protective effect of neutralizing antibodies for the population after large-scale vaccination, a simpler and faster immune blocking verification method can be used.
Immune blocking validation uses the principle of neutralizing antibody blocking the binding of S-RBD protein to ACE-2. After adding neutralizing antibody, the titer of neutralizing antibody is calculated by detecting the reduction of ACE-2 binding on S-RBD protein. The vaccinated serum was dripped in the sample adding area, and the serum was chromatographed forward under the action of capillarity, and the colloidal gold-labeled ACE-2 on the binding pad was moved together. After the serum reaches the detection area, ACE-2 binds to the fixed S-RBD on the detection line and is fixed on the detection line. The neutralizing antibody in the serum will competitively inhibit the binding of S-RBD and ACE-2, thus reducing the ACE-2 fixed on the detection line. After the end of the reaction, the detection area, the detection line, and the quality control line was observed by the naked eye, and the colloidal gold was rich, and the purple-red band appeared. The inhibition effect of neutralizing antibodies can be judged by the intensity of the purplish-red band of the detection line and quality control line.