The Severe Acute Respiratory Syndrome 2 (COVID-19/SARS-CoV-2) has become the pandemic of the century due to its drastically infectious nature. SARS & MERS are the most notable of past coronaviruses infecting merely thousands compared to COVID-19s gigantic magnitude. COVID-19s global spread has been attributed to its high asymptotic transmission and explosive infectious nature, mainly due to mutational changes in the spike glycoprotein. The purpose of this research is to comprehend & evaluate the divergent evolution of the spike glycoprotein in COVID-19, and other coronaviruses, at the molecular level via bioinformatic analysis. A phylogenetic tree was constructed using spike glycoprotein sequences from viral genomes using MEGA X program. Nucleotide composition analysis and genome organization study were carried out. Dot plot comparisons were performed using EMBOSS Dot Matcher program. Phylogenetic analysis produced four distinct clades for each coronavirus genera with a common ancestral origin sometime in recent history. More importantly, COVID-19 and SARS formed their own subclade suggesting that evolution of sequence has taken place in the spike glycoprotein over the period time. Genome organization and nucleotide composition provided further evidence of mutational changes in the spike glycoprotein. The results from this study demonstrated the divergent evolution of coronaviruses. Mutational changes in the spike glycoprotein have resulted in more virulent forms of COVID-19.
Key words: COVID-19, spike glycoprotein, coronavirus, divergent evolution, mutation, phylogenetic analysis
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