The Inclusive Review on SARS-CoV-2 Biology, Epidemiology, Diagnosis, and Potential Management Options

Abstract

A novel coronavirus member was reported in Wuhan City, Hubei Province, China, at the end of the year 2019. Initially, the infection spread locally, affecting the Wuhan people, and then expanded rapidly throughout the world. On 11 March 2020, the World Health Organization (WHO) proclaimed it a global pandemic. The virus is a new strain most closely related to a bat coronavirus (RaTG13) which was not previously discovered in humans and is now formally known as the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Coronavirus disease 2019 (COVID-19) is the disease syndrome that the SARS-CoV-2 virus triggers. It is suggested that SARS-CoV-2 can be transmitted through aerosols, direct/indirect contact, and also during medical procedures and specimen handling. The infection is characterized by isolated flu-like symptoms, but there may be specific signs of fever, fatigue, cough, and shortness of breath, as well as the loss of smell and breathing difficulty. Within this report, we tried to review the most current scientific literature published by January 2021 on various aspects of the outbreak, including virus structure, pathogenesis, clinical presentation, epidemiology, diagnostic approaches, potential therapeutics and vaccines, and prospects. We hope this article makes a beneficial impact on public education to better deal with the SARS-CoV-2 crisis and push a step forward in the near term towards its prevention and control.

Fig. 1

The key reservoirs and cross-species transmission of coronaviruses. Coronaviruses have evolved from their ancestors in bat and bird hosts to new virus species that infect other animals

Fig. 2

The schematic structure of SARS-CoV-2 and its structural proteins. The spike, envelope, and membrane glycoproteins are embedded in the lipid bilayer, and nucleocapsid protein binds to genomic RNA

Fig. 3

Genome structure of SARS-CoV-2 and its encoded proteins. The open reading frame 1a (ORF1a) and ORF1b are shown as blue and orange boxes, respectively, that encode 15 non-structural proteins (NSPs). The genes encoding main structural proteins, including spike (S), envelope (E), membrane (M), and nucleocapsid (N), are represented as green boxes. The purple, red, and pink boxes on the 3′ end represent the secondary (accessory) proteins (Color figure online)

Fig. 4

The SARS-CoV-2 life cycle in the host cell. After attachment to its receptor, the virus enters the cytosol through the endosomal pathway. The next step in the coronavirus lifecycle entails the translation of the virion’s replicase gene from genomic RNA (gRNA), which forms two co-terminal polyproteins, pp1a and pp1ab. These proteins produce various non-structural proteins (nsps) following the proteolysis processes. Approximately all nsps merge into the Replicase-Transcriptase Complex (RTC) to render a region suitable for RNA synthesis and are unanimously responsible for replication and transcription of subgenomic RNA (sgRNA). The sgRNAs act as mRNAs for the structural as well as accessory genes that are located downstream of polyprotein replicase. Both gRNAs and sgRNAs are produced via ribosomal frameshifting that generates intermediate RNAs by discontinues transcription. Upon replication and synthesis of the (+) sgRNA, the viral structural proteins, including S, E, and M, are translated into the endoplasmic reticulum (ER), and pass through the secretory cycle into the endoplasmic Reticulum-Golgi intermediate compartment (ERGIC). Subsequently, the virus genome, covered by N protein, buds inside the ERGIS membrane, which is composed of other viral structural proteins. After assembly, the particles are transported to the cell exterior via vesicles and released by exocytosis