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Given the global epidemic of COVID-19, it is important to design a vaccine for prevention. The virus belongs to the beta-coronavirus family and forms appendages on the surface of the glycoprotein spike virus membrane. Studies on SARS-CoV-1 and related MERS-CoV vaccines have shown that the spike protein on the virus surface is a suitable target for the vaccine. In this experimental study, we compare the recombinant fragment of spike protein (rfsp) expressed in the eukaryotic host CHO-K1 cell and prokaryotic  E. coli in terms of immunogenicity, neutralizing activity, and epitopes recognition Similar to the virus strain and the ability to bind to the serum of improved patients, in two types of alpha and delta variants. The results showed that both rfSP proteins are a potential new antigen candidate for the development of the Covid 19 vaccine, but the CHO cell maintains the biological activity of the protein by performing post-translational modification processes such as glycolysis. This increases the present likelihood of developing virus-like epitopes and increases the titer of rfsp-specific antibodies in the serum of immunized mice. Therefore, priority is given to rfsp expressed in CHO cells to evaluate vaccine efficacy.

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In the last month of 2019, an unknown virus appeared in Wuhan, China. Sequencing studies have shown that the virus is a new member of the coronavirus family, which mostly causes a respiratory disease with pneumonia-like symptoms. The new coronavirus consists of 25 proteins, including 4 important structural proteins and 15 non-structural proteins. Spike protein is one of the most important structural proteins on the surface of the virus; It is highly glycosylated and plays a key role in the virus binding to the host cells. The binding of glycans to proteins affects their structure and function in two ways; They lead to proper protein folding, and can play an important role in protein interactions, and also, by covering the surface of the protein, it causes the virus to escape from the immune system. So it is obvious that the study of glycan structures becomes more important when either a vaccine is going to be designed or glycan structures have important roles in the folding, activity, and interaction of a protein. Therefore, since the spike protein is a non-functional structural protein, the study of glycan structures is important for two goals of vaccine design and investigating the role of glycans in protein interactions. In this article, we are going to review the most important findings on spike protein glycosylation and compare the amount of glycosylation in different viruses, indicating the importance of glycan structures in designing an effective vaccine.