Image by Gerd Altmann from Pixabay 

Medical WriterSimpal Kumar Suman, Biotechnologist(Int. PhD., Research Scholar) and Scientific writer, Patna (Bihar), India

The causative agent of  COVID-19 pandemic is the SARS-CoV-2 (severe acute respiratory syndrome coronavirus-2), previously it was known as “2019 novel coronavirus”.  It was first reported in the Huanan Seafood Wholesale Market, Wuhan city , Hubei province, China, in December 2019. The International Committee on Taxonomy of Viruses  officially announced it SARS-CoV-2 on February 11, 2020  due to  its genetic relatedness  to SARS-CoV.  Initially, it was epidemic but soon it turned into global pandemic. Its R value is still in the morbidity and mortality range. It decides infection control, prevalence and recurrence of infectious diseases. Its value may vary from country to country. Medical supports(diagnostics, various therapies, vaccines) and public self-supports (mask wearing, physical distancing, hand washing, lockdown rules) may  reduce the value of R.  This pandemic stopped  economical wheel of the entire world. Due to rapid mutations and the presence of overlapping genes (“genes within genes” )  made it medically rigid and being puzzled for  scientists. Scientists are tirelessly working towards powerful therapeutics development. Human to human transmission is the main reason for the global transmissibility of this disease.

Genomic insights:

  • SARS-CoV-2 belongs to the family of Coronaviridae, the genus Betacoronavirus and the Sarbecovirus subgenus.

  • Containing  a single positive-sense‐stranded RNA.

  • SARS-CoV-2 Wuhan-Hu-1 was first time isolated and  sequenced.   (Ref-Wu et al. ), See-  NCBI Reference Sequence: NC_045512.2

  • Genome size- 29,881 bp in length, (GenBank no. MN908947), No. of encoding amino acid-  9860 (Ref-DOI: 10.1080/22221751.2020.1725399)

  • Large no. of glycosylated S(spike) protein(type I transmembrane protein) found on the surface  of the SARS-CoV-2 binds to Angiotensin-converting enzyme 2 (ACE2), the mammalian cell surface receptor that mediating viral cell entry.

  • The fragments of genes coding both structural and nonstructural proteins.

  • The four genes  S, E, M, and N  encode structural proteins which play critical roles in viral infection and viral cell entry in to mammalian cell. Scientists are finding powerful drug targets against  both structural and nonstructural proteins.

References:

1.Huang, Y., Yang, C., Xu, Xf. et al. Structural and functional properties of SARS-CoV-2 spike protein: potential antivirus drug development for COVID-19. Acta Pharmacol Sin 41, 1141–1149 (2020). https://doi.org/10.1038/s41401-020-0485-4

2.Wu F, Zhao S, Yu B, Chen YM, Wang W, Song ZG, Hu Y, Tao ZW, Tian JH, Pei YY, Yuan ML, Zhang YL, Dai FH, Liu Y, Wang QM, Zheng JJ, Xu L, Holmes EC, Zhang YZ. A new coronavirus associated with human respiratory disease in China. Nature. 2020 Mar;579(7798):265-269. doi: 10.1038/s41586-020-2008-3. Epub 2020 Feb 3. Erratum in: Nature. 2020 Apr;580(7803):E7. PMID: 32015508; PMCID: PMC7094943.

3.Chan JF, Kok KH, Zhu Z, Chu H, To KK, Yuan S, et al. Genomic characterization of the 2019 novel human-pathogenic coronavirus isolated from a patient with atypical pneumonia after visiting Wuhan. Emerg Microbes Infect. 2020;9:221–36.

4.Helmy YA, Fawzy M, Elaswad A, Sobieh A, Kenney SP, Shehata AA. The COVID-19 Pandemic: A Comprehensive Review of Taxonomy, Genetics, Epidemiology, Diagnosis, Treatment, and Control. J Clin Med. 2020;9(4):1225. Published 2020 Apr 24. doi:10.3390/jcm9041225

5.Sironi M, Hasnain SE, Rosenthal B, et al. SARS-CoV-2 and COVID-19: A genetic, epidemiological, and evolutionary perspective. Infect Genet Evol. 2020;84:104384. doi:10.1016/j.meegid.2020.104384

6.Hou, Y., Zhao, J., Martin, W. et al. New insights into genetic susceptibility of COVID-19: an ACE2 and TMPRSS2 polymorphism analysis. BMC Med 18, 216 (2020). https://doi.org/10.1186/s12916-020-01673-z

7.Chase W Nelson, Zachary Ardern, Tony L Goldberg, Chen Meng, Chen-Hao Kuo, Christina Ludwig, Sergios-Orestis Kolokotronis, Xinzhu Wei. Dynamically evolving novel overlapping gene as a factor in the SARS-CoV-2 pandemiceLife, 2020; 9 DOI: 10.7554/eLife.59633

8.https://www.who.int/emergencies/diseases/novel-coronavirus-2019/technical-guidance/naming-the-coronavirus-disease-(covid-2019)-and-the-virus-that-causes-it