A Causal not Casual Approach to Coronavirus Disease 19. Tracing the Roots of Novel Virus

Abstract

Coronavirus disease (COVID-19) has generated extraordinary circumstances worldwide like never before; India is already reeling under the health issues caused by this disease. At this critical juncture, having insights into pathogenesis is important so that unwanted panic and uncertainty regarding causative mechanisms can be curtailed. The causative pathogen of COVID-19 has been identified to be SARS-CoV-2 or also known as novel Coronavirus (nCov), which is a variant of the Coronaviruses (CoV). Through this review, we intend to present phylogenetic analysis of nCoV, epidemiology and pathogenesis of COVID-19. On the basis of nucleotide sequencing, nCoV isolates from China and US were found to have the highest similarity index of about 88.2% with two “Bat-SARS-like CoV (Bat-SL-CoVZC45 and Bat-SL-CoVZXC21. Researchers think that bat might have initiated the outbreak and an unknown wild animal might have acted as an intermediate host prior to the transmission to humans. Nasal cavity is considered to be the entry point for nCoV. Initially, a defined RBD of nCoV will locate the ACE2 receptors of Type II Pneumocytes in the alveoli, and will attach and fuse together to form a receptor host membrane. This critical step is responsible for the susceptibility of the host. Blessing in disguise is that the mutation rate of “nCoV” is much slower than “SARS CoV” and “MERS CoV”. Thus, vaccines and antiviral agents developed will not be rendered ineffective early due to slow genetic drift. The live animal markets act as highly potential centres for spill over of viruses from their reservoirs to other species and in turn humans. Such markets need to be dealt with diligently in the wake of the high risk they pose for such outbreaks.