Genome structure of SARS-CoV-2 and its viral proteins. The genome of SARS-CoV-2 was about 29,903 bp, which encodes four structural proteins, S, M, E, and N, and nine auxiliary proteins (3a, 3b, 6, 7a, 7b, 8b, 9b, 9c, and ORF10). S protein exists in homotrimers bulging on the viral surface, M protein is a multitransmembrane protein and exists in the membrane in the form of the dimer. E protein is the smallest among the four structural proteins and exists in the membrane, and N protein is the only protein in the nucleocapsid with the main function to bind to viral RNA.