ABSTRACT
Worldwide outbreak of coronavirus disease 2019 (COVID-19) demonstrates clinical complications ranging from asymptomatic, mild to severe complication resulting into mortality. Coronaviruses not only cause respiratory and intestinal infections to humans but it also cause pathogenicity to animals. During mid of the 1960s human coronaviruses were first identified. At the beginning of the 21st century two transmissible and infectious viruses belonging to family Coronaviridae namely MERS and SARS that emerged in humans have been identified as the cause of a Middle East respiratory syndrome (MERS-CoV) outbreak in 2012 and a severe acute respiratory syndrome (SARS) outbreak in 2003. Although SARS-CoV-2 belongs to the same family and genus as SARS-CoV and MERS-CoV, genomic analysis revealed similarity between SARS-CoV-2 and SARS-CoV. This is because SARS-CoV-2 shares about 79.5% genomic similarity with SARS-CoV however approximately 50% resemblance with MERS-CoV. SARS-CoV-2 and SARS utilize angiotensin-converting enzyme 2 (ACE2) receptors to infect host cells whereas MERS-CoV uses dipeptidyl peptidase 4 receptor to infect the host. The genome of SARS-CoV-2 encodes polyproteins, four structural proteins and six accessory proteins. Clinical findings suggested that SARS Cov-2 show lethal result due to complications like severe pneumonia, acute respiratory distress syndrome, acute cardiac injury and septic shock. These complications prevailed mainly due to hyper-inflammatory state due to over production of cytokines (called as as a cytokine storm) mainly IL‐6, IL‐1β, IL‐10, TNF, GM‐CSF, IP‐10, IL‐17, MCP‐3, and IL‐1ra. Isolation and quarantine of suspected cases is suggested. Management is mainly supportive, with newer antiviral drugs/vaccines under investigation. 2021 begins with great news that CDC authorized and recommended two vaccines (Pfizer-BioNTech COVID-19 vaccine and Moderna’s COVID-19 vaccine) to prevent COVID-19. In the current section, we have reviewed origin, morphology, genome organization, growth, replication, and pathogenesis of SARS-CoV-2
