Identity and Similarity Percentages of SARS-CoV-2 Proteins Can Be Used as Indicators of the Virus Origin

There are three types of proteins in the coronaviruses; nonstructural, structural and accessory proteins. The coronaviruses proteins are essential for the viral replication and for the binding, invasion and regulation of the host cells metabolism and immunity. This article investigated the amino acid sequence similarity and identity percentages of 10 proteins present in SARS-CoV-2, SARS-CoV and the Rhinolophus affinis bat coronavirus (BatCoV RaTG13). The investigated proteins were 1ab polyprotein, spike protein, orf3a, envelope protein, membrane protein, orf6, orf7a, orf7b, orf8, and ncleocapsid protein. The online sequence alignment service of The European Molecular Biology Open Software Suite (EMBOSS) was used to determine the similarity and identity percentages of the three viruses proteins. The results showed that the similarity and identity percentages of the SARS-CoV-2 and BatCoV RaTG13 proteins are above 95% while the identity and similarity percentages of the SARS-CoV-2 and SARS-CoV are above 38%. The proteins of the SARS-CoV-2 and the BatCoV RaTG13 are of high identity and similarity percentages compared to those of the SARS-CoV-2 and the SARS-CoV.