Structure of a Corona virus
The enveloped RNA Virus SARS-CoV-2 consists of 4 structural proteins and 16 non-structural proteins. The 4 structural proteins are spike (S), envelope (E), nucleocapsid (N) and membrane (M).
The N protein is associated with the RNA genome, the S, E and M proteins together form the virus envelope. The S protein is a glycoprotein consisting of two domains, the S1 domain, which contains the receptor binding domain (RBD), and the S2 domain including transmembrane and endodomain. On the virus surface, the S protein forms trimeric structures, with the RBD responsible for the virus being able to attach to and fuse with the ACE2 receptor of the host cell .
N and S protein are major immunogenic proteins of the virus family Coronaviridae and are very well suited for serological detection of anti-SARS-CoV-2 antibodies. Recombinant versions of both proteins are already widely used in different test systems [2, 3, 4, 5].
Neutralizing antibodies during host immune responses are predominantly directed against the S protein, which is supposedly suitable for very specific test settings as it is less conserved within the family of Coronaviridae than the other immunogenic antigens [2, 6].
However, recent studies have shown that antibodies against the N protein are detectable earlier in mild infections than antibodies directed against the S protein [3, 7]. As an acute marker in particular, it can be beneficial to use the N protein for the detection of IgA and IgM antibodies in order to enable early sensitive detection . In the further course of the immune response, the N protein antibody level decreases, whereas antibodies against the S protein are detectable for a longer time.
Four new recombinant SARS-CoV-2 antigens complement the growing SERION Immunologics raw material portfolio for the development of high quality IVD test systems. Learn more here