1. Introduction
OVID-19 is one of the most important viral diseases in the current decade, which has created a widespread pandemic in the world. This disease was first reported in patients with symptoms of acute respiratory distress syndrome in December 2019 in Wuhan, Hubei Province, China. On January 8, 2020, the Centers for Disease Control and Prevention (CDC) in China identified the virus and the World Health Organization (WHO) named it COVID-19. According to ICTV data, the virus of this disease is called SARS-CoV-2, which is a family of Coronaviridae. Viruses in this family in 2002 (SARS-CoV) and 2012 (MERS-CoV) spread to several countries and led to death and economic loss. The present study aims to evaluate COVID-19 from different aspects (evolutionary process and molecular biology of the virus), and review the effective drugs for fighting against this disease (Figure 1). 2. Materials and Methods
The articles were studied based on information available in the WHO database. SARS-CoV-2 proteins were identified molecularly and functionally using data analysis and bioinformatics methods, and then related drugs and their effect on virus replication and inhibition were investigated.
3. Results
Studies on the structure of SARS-CoV-2 and drug therapies to inhibit the progression of the disease showed that, depending on the rate of disease progression, the use of different drug strategies is effective in the treatment of COVID-19. Molecular studies showed that the use of viral protease inhibitors and nucleoside analogues can be effective in the course of the disease, and intravenous immunoglobulin, aminoquinoline compounds, TMPRSS2 inhibitors, and viral S protein can be effective in the early stages of the disease. In addition to these pharmacological treatments, the use of synthetic ACE2 proteins can be effective in the prevention of the disease, and molecular inhibitors of nucleic acid and host factors can be effective in the course of the disease (Figures 2 & 3).  4. Discussion and conclusion
The present study showed that the study of the structure of SARS-CoV-2 and its biology in the body is very important to control the virus. Identification of drugs that affect the virus based on its biological structure is essential. Due to the structural changes of the virus and successive mutations in the virus genome and the emergence of resistant strains or highly contagious strains, further studies in the field of SARS-CoV-2 structure and its changes in the body is needed for designing pharmaceutical and therapeutic strategies. The use of these strategies varies according to the stage of the disease, as some drugs prevent the virus from entering the target cells in the early stages of the disease, and others, in combination with the virus’s surface glycoproteins, block the binding of the virus antigen to receptors in the host cells. In the late stages of the disease, antiviral drugs, including protease inhibitors and nucleoside analogues, interfere with the replication and structure of the virus. Due to the intermittent changes of SARS-CoV-2 and the development of drug-resistant viruses, it is important to continuously review virological and clinical studies and the performance of existing drugs against this virus.

Ethical Considerations
Compliance with ethical guidelines
All ethical principles were observed in this study.

Funding
This research did not receive any grant from funding agencies in the public, commercial, or non-profit sectors. 

Authors' contributions
Conceptualization, data analysis, and text writing and review:Ali Hojbar Rajaeuni, Parvaneh Mehrbod; Study:Ali Hojbar Rajaouni.

Conflicts of interest
The authors declare no conflict of interest.


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