Virology & Mycology
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SARS-Cov-2 (COVID-19) Pandemic Outbreak: A Worldwide Challenge and Contemporary Situation

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Introduction

On dated December 8th, 2019, the novel SARS-CoV-2 coronavirus that expressed in Wuhan City of Hubei Province of China and became epidemic at large scale. The COVID-19 disease spreaded among more than 210 other countries. In March 2020, around 3300 deaths due to coronavirus and approximate, 96,000 corona positive (COVID-19) cases have been reported in China while in India reported 29 cases [1]. On dated 9th January 2020, coronavirus emerged as novel infectious viral agent [2,3] which has unique background of infection in human being in 1997 due to avian influenza A H5N1 [4] and SARSCoV in 2003 [5]. The origin of this infection was started from china. In Wuhan, the capital city of Hubei, December 2019, adult people started suffering from severe pneumonia-like unknown disease. The respiratory samples of the affected people sent to the labs for etiologic investigations and found the cause of this disease was coronavirus which had more than 95% homology with the bat coronavirus and more than 70% similarity with the SARSCoV which is further notified by World Health Organization (WHO). Many of the cases reported from the Huanan seafood wholesale market which also known to traded live animals. So, the surveillance system was activated after the knowing cause of infection and which signified that the virus was originated from the Huanan seafood market [6]. It has been declared the transmission of virus was found more rapidly by human-to-human contact [7]. Now a day’s, this disease (COVID-19) affected whole world and became anxiety. The epidemiology of this infection stated that the susceptibility of the coronavirus infection was found in all age people. It transmitted through the symptomatic patients to the healthy person by coughing and sneezing in the range of 1-2 m but now it also spread through asymptomatic people [8-10]. The virus can remain viable on surfaces and can be destroyed by some common disinfectants such as hydrogen peroxide, sodium hypochlorite, etc. [11].

Morphology and Genome Sequence Of Coronavirus

Coronaviruses are spherical particles (150 to 160 nm) which is enveloped and pleomorphic, and consist of constructive singlestranded RNA, un-segmented, nucleoprotein, capsid, matrix, and surface glycoprotein (S-protein) (Figure 1). Significant viral proteins comprises different type of proteins such as nucleocapsid protein (N), membrane protein (M), spike glycoprotein (S), and envelope small membrane protein (E). Glycoproteins such as acetyl esterase and Hemagglutination encoded by some beta coronaviruses eg. COVID-19 causing coronaviruses [12-14]. Glycoprotein (S) is the outermost covering of this virion which provides typical shape. Coronavirus name is given due to the homotrimers of these S proteins which resembles sun-like morphologies [15-17]. S proteins interact with the M proteins and virion membrane through C-terminal trans-membrane regions [18,19]. Regeneration of virions in the cell is governed by the M protein. There are three trans-membrane regions was found in M Glycoproteins which goes under modification of the virion to fuse with the cell and to make them antigenic by interacting with Endoplasmic Reticulum -Golgi Apparatus Intermediate Compartment (ERGIC) [20- 25]. Glycoproteins (E) composed of around 76 to 109 amino acids. Amino acids in the N-terminus allow the glycoprotein (E) attachment to the viral membrane [26]. It also helps in the assembly and morphogenesis of virions inside the cell. N proteins are phosphoproteins having a flexible structure of viral genomic RNA by binding to the helix. Due to locating in both the replication or transcriptional regions and the ERGIC region. It plays a key role in virion structure, replication and transcription [22,27-34].

Figure 1:Pictorial depiction of the leading structure of crown shaped COVID-19 coronavirus identical to the solar corona due to presence of spikes.

Evaluation of the genome arrangement showed that COVID-19 is more identical with SARS-CoV as compared to MERS-CoV6 and the RNA binding domain of the S-protein of COVID-19 also showed more homology with with SARS-CoV. Depending upon polyprotein and S-protein the arrangement of amino acid in COVID-19 coronavirus is differ from former coronaviruses completely. S-protein (consist two subunits) helps to binding of the coronavirus to the host cells. S protein binds with the receptor of host cell and enters inside the host cell. Most of the studies revealed that angiotensin-converting enzyme (ACE2 and mostly ACE29) works as receptor for the COVID-19 in human [35-37]. It has been noted that specific CoV do not need to have the full ensemble of structural proteins to make virons, highlighting that certain proteins maybe dispensable or compensated by the function of non-structural proteins [38]. Table 1 shows the structural proteins of coronavirus and their functional roles.

Table 1: Structural proteins of coronavirus and their functions (Adopted from [26]).

Covid -19 Symptoms

Understanding the symptoms of COVID-19 is a very important aspect. Common symptoms of COVID-19 are including fever, cough, and fatigueness. Few days prior to fever symptoms arises with diarrhea and nausea, it is suggested that fever is dominating symptoms but not the premier symptom of infection. Some patients also can suffer from hemoptysis or headache [39,40] and some even asymptomatic [41]. Severe alveolar damage due to respiratory failure affects commonly older men. The disease shows organ dysfunction such as Acute Respiratory Distress Syndrome (ARDS), shock, acute cardiac and kidney injury and in severe cases, it causes death [7,40]. The COVID-19 positive patients might show lower white blood cell counts, thrombocytopenia or lymphopenia, and increment in C-reactive protein level [7,39,40].

As it is clear through literature investigations, there are situations where patients affirmed with COVID-19 contamination have no chest CT irregularities, appearing differently in relation to subclinical disease giving positive imaging discoveries on CT. It is urgent that the clinical effects of screening asymptomatic patients with chest CT be resolved. A progressively careful examination about the presence of any possible advantage on clinical results should be tended to against the known monetary expenses and presentation to ionizing radiation related with CT checking. Overall, the symptoms of this virus are like pneumonia. According to WHO reports, based on 56, 000 lab cases the fit symptoms of coronavirus infection caused 14%, 5%, 14%, 88%, 5%, 19%, 15%, 38%, 11%, 4%, 33% and 68% of headache, runny nose, sore throat, fever, vomiting, shortness of breath, joint pain fatigue, chills, diarrhea, phlegm, dry cough, respectively.

Spreads Of Coronavirus and Prevention

The human coronavirus (COVID-2019) generally spreads from person to person through open-air coughing and sneezing, touching or shaking hands, touching a narrow object or surface, then touching your nose, eyes or mouth without washing or sanitizing your hands and use of an infected thing like vegetable and other food items. The basic and most important prevention of COVID-19 infections are such as clean your hands with soap and water or alcohol-containing hand bars, cover your nose and mouth with a tissue or bent elbow when coughing and sneezing, avoid making close contact with people who have cold or flu-like symptoms, always allow hello or greet at the place of hand contact, use the mask and dispose of it after using by burning of buried, avoid going to public places and crowds, avoid market food items which are cooked out of the house, after bringing the vegetable, wash it immediately with hot salt water, avoid courier or postal item it may carry the virus infection, do not let the children play or visit outside of the house, always prefer to take more fluids, do not invite guests or other outsiders to the house and also minimize the use of computers, and gadgets used by other persons. The most common target of the infection is elder or aged people so do not let them out of the house. There is one example of prevention is that Indian government put one-day ‘JANTA’ curfew on dated March 22, 2020, for the same. If you feel the symptoms of COVID-19 infection such as fever, cough and difficulty in breathing, immediately contact the doctor and follow the important information, and the advice is given by the doctors.

Existing Situation

According to World Health Organization (WHO) it is a pandemic disease and found 215 countries, areas or territories and till June 17th, 2020 total confirm cases 8,295,151, confirmed deaths 446,746 and recovered cases are 4,346,863. In India, total of 155,227 cases are confirmed out of 11,903 death and 186,934 get recovered till June 17th, 2020. The highest confirmed in Maharashtra state which is 113,445 and deceased 5,537. Here, we presented the worldwide report of confirmed cases and deaths by country, territory, or conveyance.

Confirmed Coronavirus Cases and Deaths By Country and Territory Or Conveyance

The coronavirus COVID-19 is affecting 213 countries and territories around the world and 2 international conveyances: the Diamond Princess Cruise ship harbored in Yokohama, Japan, and Holland America's MS Zaandam cruise ship. The day (June 17, 2020) is reset after midnight UTC+7. The list of countries and territories and their continental regional classification is based on the Countrycodex.COVID-19 affected countries report of coronavirus cases in globally (Table 2).

Table 2: COVID-19 affected countries report of total coronavirus cases, total deaths; total recovered and total active cases (Data obtained from June 17, 2020).

Conclusion

Through this review article, we infer that the disease framework of COVID-19 is dynamic and proceeds to quickly spread. The COVID-19 pandemic is dispersing transversely the world at a disturbing recurrence. It has caused more infections and deceases as contrasted to SARS and MERS. There are hitherto many open quarries that are pending about COVID-19. Maturing and immunocompromised patients are at the extraordinary danger of mortality. The brief degree of disease licenses exceptional examination and quarantine protocols to prevent further transmission. Till date, no prolonged drug or immunization has been created. Present treatment approaches are expected at symptomatic precaution and oxygen rehabilitation. In future, prophylactic vaccination will be obligatory for the impending prevention of COV-associated epidemic or pandemic.

Conflict Of Interest Statement

None declared

Funding Sources

There is no funding source available.

Authors's Contributions

MM and PS contributed to all chapters and had a key role in formulating the review. PS and MM wrote review, critically read and corrected the entire manuscript, and MM adjusted it to the required format. MM prepared the figures and the list of references.

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