IgG antibodies to Spike protein, Corona virus (SARS-Cov-2), quantitative determination

Why this test?

For the quantitative determination of IgG antibodies to the spike protein of the SARS-CoV-2 coronavirus, which makes it possible to assess the protective antibodies presence.

In what cases is it prescribed?

After suffering from SARS-CoV-2 and after vaccination.

Test information

The COVID-19 coronavirus infection is an infectious disease caused by the new SARS-CoV-2 coronavirus, which has not been detected in humans before. The influence of this virus leads to the development of a respiratory flu-like disease with such symptoms as cough, fever, and in more severe cases, pneumonia develops. The average incubation period for COVID-19 is 6.5 days, and its extreme limits are from 3 to 21 days. The SARS-CoV-2 coronavirus is an RNA-containing virus with a characteristic envelope with processes in the form of a "crown". The main structural proteins of the virus include the envelope protein (E), the membrane protein (M), the adhesion (S) glycoprotein, and the nucleocapsid (N) protein. The S protein on the surface of the SARS-CoV-2 virion mediates receptor recognition and membrane fusion with ACE2 molecules, which are mainly expressed on type II pneumocytes, colon and kidney epithelial cells. It contains three fragments, namely an ectodomain, a transmembrane domain, and a short intracellular segment. The ectodomain consists of the receptor-binding subunit S1 containing the RBD domain and the envelope fusion subunit (S2). During viral infection, the C-terminal domain of the S1 fragment binds to the extracellular peptidase (PD) domain of ACE2 to allow attachment of the virus to the surface of the target cell. The N-terminal domain of the S1 fragment binds to glycans. Attachment causes the cleavage of the S protein between the S1 and S2 fragments by cellular proteases, which, in turn, initiates the fusion of the viral and cell envelopes with the help of the S2 subunit.

Although most viral proteins are capable of inducing the production of specific antibodies after infection with SARS-CoV-2, and the detection of antibodies to N- and S-proteins are widely used in the serological diagnosis of COVID-19, antibodies targeting the viral S-protein are more worthy of attention. as they can block the entry of SARS-CoV-2 into host cells. And given that most vaccines induce the formation of antibodies specifically to the spike protein, the determination of specific IgG to this antigen also makes it possible to assess the presence of protective antibodies after a disease or vaccination against COVID-19.