Review on COVID-19: Rise of SARS-CoV-2 Pandemic Outbreak

Since the initial recognition of COVID-19 in the world in 2019, tremendous advances have taken place in the understanding of the dreaded diseases as regarding its epidemiology, etiology, immunology, Pathophysiology, clinical feature, and morphology changes in various tissues and organs of the body. Although antiretroviral therapy is being widely used all over the world for such patents, effects at finding a 2019 Novel Coronavirus (SARS-CoV-2) vaccine have not succeeded. Human pathogenic subtypes of a coronavirus are associated with mild clinical manifestations. However, SARS-CoV and MERS-CoV are two important exceptions. In 2012, MERS-CoV was first seen in Saudi Arabia. He was responsible for 2,494 confirmed cases, leaving 858 people dead. In 2002, a subtype of the Corona beta virus spread rapidly in Guangdong, China. This epidemic has claimed 8,000 deaths and 774 deaths in 37 countries (Lu et al., 2020). The epidemic of 2020 was detected as pneumonia of unknown etiologic in Wuhan, China. Extensive studies and laboratory research have identified the offender as a new strain of a coronavirus (Adhikari et al., 2020). Initially, this virus was classified as SARS-CoV-2. However, the virus was classified by the International Commission for Viruses Classification as CoV-2. On February 11th, 2020, the World Health Organization (WHO) announced that the disease caused by this new virus was Coronavirus 2019 (COVID-19). The emergence and outbreak of frequent coronaviruses pose a public health threat. This recommends that CoVs that originate from one animal to another can be transferred from one person to another. The ongoing changes in the Review on COVID-19: Rise of SARS-CoV-2 Pandemic Outbreak


INTRODUCTION
. The epidemic of 2020 was detected as pneumonia of unknown etiologic in Wuhan, China. Extensive studies and laboratory research have identified the offender as a new strain of a coronavirus (Adhikari et al., 2020  . The emergence and outbreak of frequent coronaviruses pose a public health threat. This recommends that CoVs that originate from one animal to another can be transferred from one person to another. The ongoing changes in the environment and climate make the emergence of such infections in the future more likely (Hassan et al., 2020).  is pandemic in the spread and is seen in all continents. As per the WHO global report 2019, a novel coronavirus recognizing SARS-CoV-2. This is likely the third time in three decades that a zoonotic coronavirus has fall from infecting animals to humans. As of May 25 th , 2020, 337,687 have died, and 5,204,508 have been infected globally with the center of the outbreak being located in Wuhan but now having spread, with confirmed cases 212 other countries (Worldometer, 2020). While the fatality rate of SARS-CoV-2 is less than other recent respiratory virus outbreaks, it rests much higher than other commonly encountered causes of respiratory infection but its full impact is yet undetermined. The WHO has now conformed the coronavirus outbreak to be a public health emergency of international concern (Long & Ehrenfeld, 2020). Most infected countries' data of COVID-19 are summarized in Figure 1. Many studies show more clearly that the death rate increases with age, and children younger than 9 years do not appear to be affected significantly, without symptoms or mild symptoms or none of them died due to a COVID-19 infection. For 80-year-olds, about 14.80%

EPIDEMIOLOGY
of people die as presented in Figure 2. Mortality  Control and Prevention has published specific guidelines for people in these categories (Hafeez et al., 2020). For people with cardiovascular disease, the death rate is 13.2%, for diabetes 9.2%, for chronic respiratory diseases (such as asthma and chronic lung disease) 8.0%, for high blood pressure (high blood level) 8.4%, and the cancer death rate 7.6%. The data is summarized in Figure 3.   (Dhama et al., 2014;Hui et al., 2020).

ETIOLOGICAL OF COVID-19
Thanks to the genome sequencing, the nCoV 2019 gene sequencing became available to the WHO, which enabled various laboratories to produce a diagnostic test for the reverse transcription of a polymerase chain reaction (RT-PCR) specifically for detection of 'viral DNA. The SARS-CoV-2 is the 2B β-CoV group. With genetic comparability of more than 70% with SARS-CoV . Coronaviruses have begun two large-scale pandemics in the past two decades, SARS and the Middle East respiratory syndrome (MERS) (Drosten et al., 2003;Zaki et al., 2012). It has commonly been thought that SARS-CoV-2 which is found in bats could cause a disease outbreak Schoeman & Fielding, 2019).

ORIGIN OF SARS-CoV-2
The source of the new coronavirus infection has been resolved as a racket. With the entire genome, the SARS-  Kumar et al., 2020).

COMPOSITION OF SARS-CoV-2
Coronary viruses are spherical with diameters of approximately 125 nm, as demonstrated in recent studies by microscopic tomography and electron microscopy. A major characteristic feature of coronaviruses is that clubdropping points emanate from the surface of the virion.
These nails are an explanatory feature of the virion and give it the appearance of a solar aura, which gave the name of a coronavirus. In the shell of the virion is the nucleus. Coronaviruses have a unified helical nucleocapsid, which is not unusual for positive RNA viruses but is more common for negative RNA viruses  Freon. It is a very weak protein (~25-30 kDa) with three membranous domains (Molenkamp & Spaan, 1997) and is supposed to transport virion in its shape. It is a low ectodomain N-terminal glycosylated and a much larger C-terminal endo domain extends 6 to 8 nm in the viral structure (Kuo & Masters, 2013). Although the translation is common to the ER membrane, most M proteins do not have the code sequence (Hurst et al., 2013).
Protein E (~8-12 kDa) is found in small quantities in the Freon. Coronavirus E proteins vary greatly but have a typical structure (Sturman et al., 1980). The membrane topology for protein E has not been completely resolved, but most data indicate that it is a transmembrane protein.
Protein E contains the ectoderm N-terminal field and the C-terminal endodomain and the ion channel activity.
Since they are hostile to other structural proteins, recombinant viruses that lack protein E are not always fatal, although this may depend on the type of virus (Klausegger et al., 1999).
Protein N is the only protein found in the nucleus. It  (Egloff et al., 2006).
The ORF1a/b consists of about two-thirds of the viral genome and codes for 16 non-structural proteins as summarized in Table I. There is a shift in Box-1 between ORF1a and ORF1b, which results in the production of two peptides (pp1a and pp1ab), which are then processed by the viral coded protease at 16 nsp.

TRANSMISSION ROUTES OF SARS-CoV-2
The coronavirus first announced in December 2019 is now a public health emergency of international concern.
Epidemiologists are working to update estimates the number of cases; genome samples of the pathogen are being sequenced and results are being shared (Zheng, 2020). Mechanisms of transmission are concluding to incorporate contact, droplet, and possibly airborne under certain circumstances supported on historical experiences associated with SARS-CoV outbreaks (Yu et al., 2020;Christian et al., 2004).

Respiratory droplet
Respiratory infection may be transmitted through droplets of varied sizes; when the droplet partials are smaller than 5-10 µm in diameter, they called respiratory droplets, and after they are smaller than 5 µm in diameter they're called as droplet nuclei, per present evidence, and is therefore in danger of getting his/her mucosa (mouth and nose) or conjunctive (eyes) exposed to potentially infective respiratory droplets. Transmission can also occur through fomites with the immediate environment around the infected parson (Dbouk & Drikakis, 2020).

Focal-oral routes
There is some evidence that COVID-19 infection may attend to intestinal infection and be present in fasces.
However, thus for just one study has cultured the COVID-19 virus from one stool specimen

PATHOGENESIS OF COVID-19
The pathogenesis of COVID-19 infection is mostly related to the depletion of type 2 respiratory pneumocyte cells resulting in profound alveoli destruction as visualized in Figure 5.

Selective tropism for pneumocyte molecular receptor
The first coronavirus receptors were identified by the MHV receptor as listed in  (Belouzard et al., 2012).

The intervention of the virus at the site of binding of receptors
The

Integration of viral DNA into the host cell
The primary association of virion with the host cell begins with interactions between protein S and its receptor.
Recipient binding domain (RBD) sites within the S1 protein S site of the coronavirus vary depending on the virus, some have RBD at the end N of S1 (MHV), while others SARS-CoV have an RBD at the C term of S1 (Krijnse-Locker et al., 1994). The interaction of S protein receptors is the primary determinant of coronaviruses to infect host species and also leads to polarization of the virus tissue. SARS-CoV and HCoV-NL63 use the ACE2 as a receptor, enter the MHV via mCEACAM1, and connect the newly identified MERS-CoV with dipeptidyl peptidase 4 (DPP4) to enter human cells as presented in Table II.

Repetition
The next step in the life cycle of a coronavirus is to translate the mimic gene from the viral genomic RNA.
The gene codes for two large ORFs, rep1a and rep1b, which connect to two homogeneous polypropylene proteins, pp1a and pp1ab. To deliver multiple proteins, the virus uses a sliding sequence (5'-UUUAAAC-3') and RNA pseudoknot that causes the displacement of the ribosome frame from the rep1a reading frame towards the ORF rep1b. In most cases, the ribosome breaks down the pseudoknot structure and extends the translation until it satisfies colonic stop code 1. Sometimes, the false node prevents the ribosome from continuing to elongate, resulting in a temporary stop in the slippery sequence, adjusting the reading frame by moving the nucleotide, and turning-1 frame before the ribosome can dissolve the pseudoknot structure and extend the translation to rep1b, which leads to an interpretation of pp1ab (Cheng & Shan, 2020;Yu et al., 2004).

Viral spread
After reproduction and synthesis of RNA without genome, viral structural proteins S, E, and M are translated and inserted into the endoplasmic reticulum (ER). These proteins travel along the secretory pathway in the endoplasmic reticulum -Golgi compartment (ERGIC) (Tooze et al., 1984;de Haan & Rottier, 2005).
There, viral genomes coated with N protein in ERGIC membranes contain viral structural proteins, forming mature virions (Arons et al., 2020).

SYMPTOMS OF COVID-19
The maximum number of patients infected with the virus will suffer from colds and influenza, while a few will remain asymptomatic. About 80% of patients will experience mild symptoms of the disease. Adults have the best immunity to fight infection, but the disadvantage is that they are more likely to spread infection and a recent study of nearly 140 patients at Zhong nan Hospital of Wuhan University has revealed two different. Types of symptoms that lead to a disease known as COVID-19.
Almost 99% of the patients developed a very hot fever, while more than half of them experienced fatigue and a dry cough. A third of the patients developed a dry cough and difficulty breathing (Yi et al., 2020;Fu et al., 2020).

DIAGNOSIS OF COVID-19
The diagnosis allows suspects to understand whether they are infected or not. Diagnosis can help get the care they need and can help them take steps to reduce the likelihood of injury to others. If a person develops symptoms of coronavirus 2019 and is exposed to the virus, he consults a doctor. The doctor can decide whether or not to test COVID-19 based on individual signs and symptoms. The doctor can also determine if the person is in close contact with a person diagnosed with COVID-19 or who has visited or lived in areas where the community has continued to spread COVID-19 in the past 14 days .

Direct detection
The SARS-CoV-2 infection is detected by special laboratory tests that require samples such as throat swabs or lung fluid. This method is called a PCR test and it takes 24 to 48 hours to get the final results. WHO recommends sampling the upper and lower respiratory tract. This can be done with sputum, bronchial lavage, or end-trachea sucking. These samples will then determine the viral RNA identity using a polymerase chain reaction (PCR).
If a positive test result is obtained, it is recommended to repeat the activation test. Negative tests with strong clinical suspicion are also recommended for repeated testing (Kumar et al., 2020;Hassan et al., 2020).

Serological test
The SARS-CoV ELISA and IgM ELISA Inner control kits were developed using IDR 3 N SARS-CoV as antigens, which share 90% amino acid alkene identity with all or all  (Okba et al., 2020).

RNA vaccines
Modern Biotechnology Company in Cambridge has prepared a test vaccine for coronavirus diagnosis. This rapid change is due to the unique advantages of RNA vaccines, says MIT Professor Daniel Anderson that the main advantage of the RNA message is the speed with which you can define and use a new sequence to find a new vaccine (World Health Organization, 2020).

Molecular examinations
Currently, many of the tests that reveal SARS-CoV-2 are prepared internally, commercially, or under development. Some tests can only detect the new virus, and some tests can also detect other strains that are genetically similar (Trafton et al., 2020).

TREATMENT OF COVID-19
Currently, there is no specific treatment, vaccine, or drug for the virus. However, healthcare professionals have many ways to help patients. First, early diagnosis helps stop the spread of the disease, making society a safer place for everyday life. Second, there are supportive care options that seem to work miracles with new coronavirus patients.

Oxygen therapy
The risk of hypoxia increases when the virus targets the lungs. A nasal catheter and an oxygen mask should be provided to the patient immediately. In an emergency, non-invasive or invasive mechanical ventilation should be provided to the patient .

Rhizoma Polygoni Cuspidati and Radix Sophorae
Tonkinensis contain certain active ingredients that were effective against COV-2 .

Antibiotic drugs
The third class of medicinal drugs is Azithromycin, a class of antibiotics known as macrolide that is used to treat infections such as bronchitis, pneumonia, and MAC infection (Mycobacterium avium complex). With the spread of SARS-CoV-2, many countries around the world have

Anti-coagulating therapy
Hospital patients with severe medical illness are at an increased risk of developing VTE up to 90 days after discharge. This result should apply to COVID-19 patients, although infection data don't seem to be yet available. Therefore, it is reasonable to think of long blood clots occurring after prolonged discharge using a regulated approved system (such as betrixaban 160 mg on the first day, followed by 80 mg once daily for 35 to 42 days; or rivaroxaban 10 mg daily for 31 to 39 Days) (Porfidia & Pola, 2020).

Boosts the immune system
In addition to basic disease prevention and true defense, there is a strong immune system. The human body is better able to fight disease when the immune system is impulsive and people have to get fit to get the perfect shape. In this critical condition, get enough sleep and a little fresh air and the sun every day. People also need to stay hydrated, reduce excessively processed foods, and make sure to eat enough micronutrients when they can do their best with what they can find in grocery stores right now (Taghizadeh-Hesary & Akbari, 2020).

COVID-19
This new virus often features a limited geographic spread (Zappa et al., 2009). However, there are the amounts of hygiene measures that are recommended to guard against the infection and for the spread the include following advisory are covering your mouth and nose with masks, avoiding close contact with those that are sick, stop shaking hand with one other, washing hands regularly after one hour with soap, avoiding unnecessary contact with animals and hand washing, use of masks and PPE (Personal protective equipment), drinking warm water daily, sanitize your hands time to time (Singhal, 2020).
Steps to protect yourself 1. Wash your hands regularly and completely with soap and water for at least 20 seconds or with an alcohol-based hand sanitizer (a hand sanitizer that contains at least 60% alcohol), rub the cover thoroughly together so that it does not dry out, especially after visiting a public place, or after blowing your nose or sneeze as well as cough.
2. Hands touch many surfaces and catch viruses, and these contaminated hands can spread the virus to your nose, eyes, or mouth. So, avoid touching these organs with unwashed hands. Because from there, the virus can enter the body and make people sick.
3. Maintain a social distance (keep at least 1 m or 3 feet between you and anyone) and avoid close contact with patients (who cough or sneeze). When infected or sneeze, they spray small drops from their nose or mouth that may contain the COVID-19 virus. A person can breathe these drops (Centers for Disease Control and Prevention, 2020).

Steps to protect others
1. Stay home if you are not feeling well unless you will get medical treatment.
2. If you have a cough, fever, and difficulty breathing, see your doctor online, see your doctor.
3. If you are sick, avoid using public transportation.