The novel coronavirus gene encodes a variety of proteins, such as spike protein (S), small envelope protein (E), envelope protein (M), and nucleoprotein (N). The most significant difference between the S proteins of different coronaviruses is whether they are cleaved by host proteases during the assembly and release of the virus. The mature S protein is usually cleaved by host proteases (cysteine proteases, trypsin, etc.) into two subunits: S1 and S2. S1 contains the receptor binding domain (receptor binding domain, RBD).

The S protein is an important site for neutralizing antibodies in the host. It can be transmitted between different hosts through genetic recombination or mutation of RBD, leading to a higher fatality rate. The new coronavirus IgM and IgG antibodies target the nucleocapsid protein and spike glycoprotein (S protein) receptor binding domain (S-RBD) of the new coronavirus. The nucleocapsid protein wraps the genomic RNA of the new coronavirus, and S-RBD can bind to receptors on host cells. RBD is located on the S1 subunit and is responsible for recognizing cellular receptors, which determines the host range and specificity of the virus.

The earliest antibody IgM produced after the human body is stimulated by the virus does not appear until about a week after the body is stimulated and lasts for a short time; when stimulated by the antigen again, the human body will produce the antibody IgG with higher affinity. Unlike IgM, IgG will exist in the body for a long time, and some can even last for decades. By detecting IgG, it can not only identify whether the human body is infected or not, but also identify whether the patient has a recent infection or a past infection.

The new coronavirus (2019-nCoV) IgM and IgG antibody detection kits developed by Hecin are produced by our company under the guidance of Academician Zhong Nanshan’s team and in conjunction with the State Key Laboratory of Respiratory Diseases, and have unique platform advantages. Our company is the first company in China to add S protein to IgG-coated antigen for testing. The S protein has a receptor binding domain (RBD) that specifically binds to IgG and can detect antibodies that produce protective effects after COVID-19 infection. , thereby effectively judging the patient’s disease course. This product is a single card setup, and its technical design avoids the risk of non-specific reactions with IgM in the same card slot. It is easy to operate, does not require instruments, and can produce results in 15 minutes, enabling instant detection. This project can be combined with the IgM project for supplementary testing, or it can be used alone to determine the prognosis of the general population who have experienced fever of unknown origin. It can greatly improve prevention and control and effectively track groups who may be infected.