The Coronavirus SARS-Cov-2: the Characteristics of Structural Proteins, Contagiousness, and Possible Immune Collisions

Abstract

Relevance. Coronavirus SARS-Cov-2 is a novel virus demonstrating the ability to be trans¬mitted from human-to-human, via respiratory droplets or close contact, and cause the severe acute respiratory syndrome (SARS). The role of its structural proteins in the SARS pathogenesis is unknown.Aim is to characterize the features of the SARS-Cov-2 structural proteins and their changes associated with acquiring other way of transmission and analyze the possibility of heterologous immunity emergence in its infection. Materials and method. For the computer analysis and alignment, the gene sequences of SARS-Cov-2 , SARS-CoV , MERS-CoV и bat CoV HKU3 reference strains were used from the Internet. From the primary structure of their genes it were translated their structural proteins: spike (S), envelope (E),membrane (M), and nucleocapsid (N). The genetic code of structural proteins was also defined. The search of homologous sequences in the SARS-Cov-2 S-protein, surface proteins of other viruses, and human proteins was made to find immune epitope continuum of protein relationships.Results. In the SARS-Cov-2 structural proteins amino acid sequences of M, E, and N-proteins are conservative. The S1 subunit of the S-protein contains some large insertions, significant changes of the amino acid content with the predominance of arginine and lysine which is typical for the surface glycoproteins in the viruses possessing high contagiousness. The S2 subunit is rather conservative and retain negative polarity. The S-protein exhibits the immune epitope relationships with many proteins of viruses and human which may be associated with immune collisions.Conclusion: The SARSCov-2 features are determined by marked changes of the S1 subunit structure in the S-protein which may be responsible for its contagiousness and many immune collisions aggravating infection process.