Covid-19 is a highly contagious zoonotic disease of humans and animals caused by SARS-CoV-2. The WHO has declared the enduring outbreak of COVID-19 is a global public health emergency and pandemic. SARS-CoV-2 is a spherical positive sense, single‐stranded RNA viruses that belong to beta coronavirus, subgenus sarbecovirus. The genomes of the virus are mainly composed of four types of structural proteins that are spike glycoprotein, envelope protein, nucleocapsid protein, and membrane protein. The genetic sequence of the SARS-CoV-2 showed more than 80% identity to SARS-CoV and 50% to the MERS-CoV. RaTG13 is the only BatCoV that shows as high as 96% full genome homology with SARS-CoV-2. The virus is suggested to be originated from bats and most closely relating to beta coronavirus of bat origin since it has 87.9% and more nucleotide similarity.
The mutation is one of the driving factors for the evolution of the organisms. Community transmission, antiviral treatments, and ecological changes along with the genetic plasticity of RNA viruses facilitate the emergence of several new RNA viruses and the development of more virulent strains. The evolved strains may cause a high mortality rate and resistant to treatments. Therefore, systematic tracking of demographic, clinical patient information, and strain information is crucial to successfully combat COVID-19. Molecular methods, serology, and viral culture are used as diagnostic tools for isolation and identification of newly emerged viral disease. The RT-qPCR assay is regarded as the gold standard method for identification and surveillance of SARS-CoV-2 target sequences.
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