The S, E, M, and N genes encode structural proteins, whereas nonstructural proteins, such as 3-chymotrypsin-like protease, papain-like protease, and RNA-dependent RNA polymerase, are encoded by the ORF region.

Gene fragments express structural and nonstructural proteins. An RNA-based metagenomic next-generation sequencing approach has been applied to characterize its entire genome, which is 29,881 bp in length (GenBank no. SARS-CoV-2 is a single-stranded RNA-enveloped virus. As the epidemic spreads, it is critical to find a specific therapeutic for COVID-19, and vaccines targeting various SARS-CoV-2 proteins are under development. Conversely, the other three, SARS-CoV, MERS-CoV, and SARS-CoV-2, are able to cause severe symptoms and even death, with fatality rates of 10%, 37%, and 5%, respectively.Īlthough a large number of studies and clinical trials are being launched on COVID-19 around the world, no evidence from randomized clinical trials has shown that any potential therapy improves outcomes in patients. It is the seventh known coronavirus to infect humans four of these coronaviruses (229E, NL63, OC43, and HKU1) only cause slight symptoms of the common cold. The COVID-19 was quickly discovered to be caused by a coronavirus later named severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which belongs to the β coronavirus family. CT, cytoplasmic domain FP, fusion peptide HR1/2, heptad repeat 1/2 NTD, N‐terminal domain RBD, receptor‐binding domain SARS‐CoV‐2, severe acute respiratory syndrome‐coronavirus‐2 SP, signal peptide TM, transmembrane domain.The epidemic of novel coronavirus disease 2019 (COVID-19) was caused by a new coronavirus occurred in December 2019, and now has spread worldwide and turned into a global pandemic. The residue numbers of each region denote their positions in the S protein of SARS‐CoV‐2. Similar to SARS‐CoV, S protein of SARS‐CoV‐2 also consists of (a) a signal peptide (SP amino acids 1–19) located at the N terminus, (b) an extracellular domain (amino acids 20–1213) containing S1 (N‐terminal domain : amino acids 20–286 C‐terminal domain /RBD: amino acids 319‐541) and S2 (fusion peptide and Heptad repeat : amino acids 686–1213), (c) a transmembrane domain (TM: amino acids 1214–1236) and (d) a short cytoplasmic domain (CT: amino acids 1237–1273)., The D614G amino acid change in S protein is caused by an A‐to‐G nucleotide mutation at position 23,403 in the Wuhan reference strain. SARS‐CoV‐2 encodes four structural proteins spike (S), envelope (E), membrane (M), and nucleocapsid (N) and eight accessory proteins 3a, 3b, p6, 7a, 7b, 8b, 9b, and ORF14. The orf1a encodes the pp1a protein that contains ten nsps (nsp1‐nsp10). The orf1ab encodes the pp1ab protein that contains 15 nsps (nsp1‐nsp10 and nsp12‐nsp16). (a) The coding sequence for SARS‐CoV‐2 proteins. This manuscript reviews different characteristics of S protein, its potency and 'state of the art' of the vaccine development strategies and platforms using this antigen, for construction of a safe and effective SARS-CoV-2 vaccine.

Thus, S protein is an obvious candidate antigen for inclusion into vaccine platforms against SARS-CoV-2 viral infection. Moreover, T-cell responses against the SARS-CoV-2 'S' protein have also been characterized that correlate to the IgG and IgA antibody titres in Covid-19 patients. Furthermore, 'S' protein contains multiple neutralizing epitopes that play an essential role in the induction of neutralizing antibodies (nAbs) and protective immunity. The spike (S) protein of SARS-CoVs is the main determinant of cell entry and tropism and is responsible for facilitating zoonosis into humans and sustained person-to-person transmission. Therefore, development of second and third generation safer vaccines (by using modern vaccine platforms) is actively sought for this viral infection. Prior animal studies with first generation (whole virus-based) preparations of SARS-CoV vaccines (inactivated and attenuated vaccine modalities) indicated the possibility of increased infectivity or eosinophilic infiltration by immunization. The SARS-CoV-2 and SARS-CoV share a high degree of genetic and pathologic identity and share safety and immune-enhancement concerns regarding vaccine development. To prevent the worldwide spread of this highly pathogenic virus, development of an effective and safe vaccine is urgently needed. Coronavirus disease 2019 (Covid-19) is caused by severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2) which is responsible for a global pandemic that started in late 2019 in Wuhan, China.

Coronavirus spike protein