The most important structural proteins of CoV are spike (S) protein (trimeric), membrane (M) protein, envelop (E) protein, and the nucleocapsid (N) protein. Some of the viruses such as beta-CoVs also have hemagglutinin esterase (HE) glycoprotein.[3] The RNA genome of CoV has seven genes that are conserved in the order: ORF1a, ORF1b, S, OEF3, E, M, N in 5' to 3' direction. The two-third part of the RNA genome is covered by the ORF1a/b, which produces the two viral replicase proteins that are polyproteins (PP1a and PP1ab).[9] Sixteen mature nonstructural proteins (NSPs) arise from further processing of these two PPs. These NSPs take part in different viral functions including the formation of the replicase transcriptase complex. The remaining genome part of the virus encodes the mRNA which produces the structural proteins, i.e., spike, envelope, membrane, and nucleocapsid, and other accessory proteins.[9] Another important envelop-associated protein which is expressed by only some strains of CoV is the HE protein.[10] The RNA genome of CoV is packed in the nucleocapsid protein and further covered with envelope.[11]