Neutralizing antibodies are antibodies that are produced when pathogenic microorganisms invade the body. When pathogenic microorganisms invade cells, they need to rely on the specific molecules expressed by the pathogen to bind to the receptors on the cells in order to infect the cells and further expand. Neutralizing antibodies are certain antibodies produced by B lymphocytes that can bind to antigens on the surface of pathogenic microorganisms, thereby preventing pathogenic microorganisms from adhering to target cell receptors and preventing cell invasion.
In the battle against the new crown pneumonia epidemic, the recovered plasma treatment has made great contributions. All parts of the country have collected recovery plasma from recovered patients for the treatment of severe and critically ill patients with new coronary pneumonia. So, what is the "magic power" that makes plasma therapy for recovered patients stand out among the many treatment methods? This is because patients who have experienced the new coronavirus infection and then recovered have already developed humoral immunity against specific pathogens in their bodies. The blood usually contains high titers of neutralizing antibodies, and patients who have been transfused with convalescent blood products can obtain passive immunity. And specific pathogens, eventually eliminate pathogens in blood circulation. Judging from current experience, this convalescent plasma therapy is generally safe.
However, plasma transfusion still has potential risks and adverse reactions of blood transfusion pathogens, including allergies. In the process of separation and preparation of convalescent plasma, strict pathogen inactivation and biosafety testing are required. The risk of infection is relatively small, but it does not rule out that individual donors in the window period have a negative pathogen test. Secondly, during the infusion of convalescent plasma, there is a risk of blood transfusion-related lung injury, especially in patients who have already experienced severe lung inflammation. So although this method is effective, it is not universal.
Neutralizing antibodies have attracted much attention because of their dual effects of treatment and prevention. Compared with vaccines or antiviral drugs, antibody drugs are unique because they can both treat and prevent new coronavirus infections. Compared with small molecule antiviral drugs, neutralizing antibodies are therapies developed for the new coronavirus and have very high specificity. At the same time, the stability of antibodies in the blood is high, and injection of neutralizing antibodies can provide passive immunity and achieve the effect of preventing new coronavirus infections.
After understanding the neutralizing antibody, let's talk about the research target of the new coronavirus S protein neutralizing antibody:
Researcher Li Bin from the Shanghai Institute of Immunology, Shanghai Jiaotong University School of Medicine, said, “Compared with vaccines, antibody drugs are more precise, and their target is usually the receptor domain of the spike protein on the surface of the new coronavirus.”
The spike-like S protein is the most important surface membrane protein of the new coronavirus, which determines the host range and specificity of the new coronavirus. The shape of S protein is somewhat similar to that of screws, but the head is larger and the handle is more slender. The S protein exists in the form of a trimer, which mainly includes three S1 head subunits and one trimer S2 subunit. The tip of the S1 subunit's head contains the Receptor Binding Domain (RBD), which can bind to the human receptor—Angiotensin Converting Enzyme 2 (ACE2). The genetic recombination or mutation of RBD can realize the spread between different hosts and lead to a higher mortality rate. The S2 subunit is closer to the viral membrane and is responsible for the fusion of the viral membrane and the host cell membrane. Therefore, the S protein is the key target of the new coronavirus neutralizing antibody. When the new coronavirus invades cells, first the S protein RBD binds to the surface receptor ACE2 of human cells, and then the viral membrane and the cell membrane fuse, the virus is internalized into the cell, transcribed and replicated in the cell, and reassembled into a large number of new viruses. Go to continue to infect other cells.
So, what are the neutralizing antibodies against the new coronavirus? Here are a few briefly:
1. The new coronavirus recombinant human antibody SARS-CoV/SARS-CoV-2S recombinant human antibody, clone CR3022, #RAB01043
The antibody recognizes human SARS-CoV and CoV-2 spike proteins with high affinity. The binding site is the 318-510 amino acids (RBD, receptor binding domain) of the S1 subunit of the spike protein.
2. New Coronavirus ECD recombinant human antibody SARS-CoV-2 S ECD recombinant human antibody, clone BHB04, #RAB01048
This antibody detects the endogenous level of S-ECD protein. Application: Neutralization reaction, WB (recombinant protein sample), ELISA
3. SARS-CoV-2 S monoclonal antibody (M01), clone 6F3, #MAB22854-M01
Antibodies that respond to recombinant proteins. Application: Neutralization reaction, WB (recombinant protein sample), ELISA.
New coronavirus S protein neutralizing antibody link:
http://www.amyjet.com/featured/sars-cov-2-s.shtml