Perspective Chapter: Tracking Trails of SARS CoV-2 – Variants to Therapy

*Ankur Kumar, Manju O. Pai, Gaurav Badoni, Arpana Singh, Ankit Agrawal and Balram Ji Omar*

### **Abstract**

A virus when replicates itself from one generation to another, tends to change a little bit of its structure. These variations are called mutations. History says that SARS CoV-2 originated from the virus reservoirs of animals, specifically non-human mammals like bats and minks. Since then, there are evolutionary changes in its genome due to recombination in divergent strains of different species. Thus, making the virus more robust and smarter to sustain and evade immune responses in humans. Probably, this has led to the 2019 SARS CoV-2 pandemic. This chapter tracks the evolutionary trails of the virus origin, its pathogenesis in humans, and varying variants with the coming times. Eventually, the chapter overviews the available vaccines and therapies to be followed for SARS CoV-2.

**Keywords:** evolution, pathogenesis, variant, SARS CoV-2, vaccine

### **1. Introduction**

At the end of the year, 2019 a pandemic was caused by a new human infecting coronavirus, also called severe acute respiratory syndrome coronavirus 2 or SARS CoV-2. The first case of this novel virus was reported in Wuhan city of China and later it spread all over the globe. COVID-19 is the disease caused by SARS-CoV-2, which is characterized by different levels of severity and a range of signs and symptoms mainly fever, cough epidemic, sore throat, sudden onset of anosmia, shortness of breath, nausea, vomiting, and diarrhea [1]. This was announced a 'public health emergency of international concern' by the International Health Regulations (IHR) Emergency Committee of the World Health Organization (WHO) [2]. To date, more than 6 million deaths are caused by this disease around the globe (WHO, Coronavirus Disease COVID-19 Dashboard, accessed on 14/04/2022). Coronaviruses are positivesense single standard RNA viruses that come under the family of *Coronaviridae* and *Orthocoronavirinae* subfamily. They are enveloped viruses having spherical, oval, or pleomorphic genomic shapes. The subfamily is further divided into four genera: Alpha, Beta, Gamma, and Deltacoronavirus [3]. Coronaviruses are not new to humans, and most of them cause minor respiratory infections in humans. They have

also been known to infect domesticated animals for decades [4]. However, since the beginning of the twenty-first century, they have emerged as a major threat to the human population. There were six coronaviruses (CoV) known till now, among which severe acute respiratory syndrome CoV (SARS CoV) and Middle East respiratory syndrome CoV (MERS CoV) outbreaks took the life of a large number of people in 2002 and 2012, respectively. SARS CoV first appeared in China in 2002, infecting 8422 people followed by 916 deaths. MERS CoV afterward emerged in Arabian nations and infected around 1800 people. In 2019, the seventh CoV produced a large-scale outbreak that affected nearly every country on the planet. The new coronavirus was called SARS CoV-2 since it is closely related to SARS CoV. SARS CoV-2 is spreading quicker than SARS CoV and MERS CoV, with an increasing number of deaths [5].
