INFECTIOUS DISEASE - COVID-19PREFACE, From the formation stage of an embryo to human death, we have found a variety of diseases.in that some are not vulnerable but others are.Along with the information collected from history, there have been many outbreaks that have turned heaven earth into death catacombs.However, we can even infer that past outbreaks are not as serious as present outbreaks. Even though we found vaccines and drugs to use, we cannot control mortality. So T collected some information about COVID-19 as a biology student.HISTORY HOW DID CORONAVIRUS START: The first case of COVID-19 was reported Dec. 1, 2019, and the cause was a then-new coronavirus later named SARS-CoV-2. SARS-CoV-2 may have originated in an animal and changed (mutated) so it could cause illness in humans, In the past, several infectious disease outbreaks have been traced to viruses originating in birds, pigs, bats and other animals that mutated to become dangerous to humans. Research continues, and more study may reveal how and why the coronavirus evolved to cause pandemic disease.WHY IS IT CALLED AS CORONAVIRUS: The pathogen got its name due to the spiky crown (or corona in Latin) that you can see on i uurface when you take a look at it undemeath a microscope, explains Rishi Desai, MD, a former epidemic intelligence service officer in the division of viral diseases at the Centers for Disease Control and Prevention (CDC). And there isn't one sole coronavirus. Coronaviruses are actually a family of viruses that cause respiratory infections, according to the information, While many of the coronaviruses out there don’t give humans too much trouble (some strains are responsible for mild cases of the common cold, for example), other types that initially infect animals can evolve to infect humans with more severe diseases, like Middle East respiratory syndrome (MERS) and severe acute respiratory syndrome (SARS), says Dr. Desai. The latest coronavirus to make the leap from animals to humans is the one the world is SARS-CoV2. concemed about right no You may have also heard the coronavirus on everyone's radar right now referred to as the new or novel coronavirus—and that's simply because it’s the latest coronavirus to be discovered in humans, says Natasha Bhuyan, MD, a specialist in infectious diseases and family physician in Phoenix, Arizona. As such, it’s quite literally new to us.Why is it necessary to name new viruses and the diseases they cause? Too often when a health situation like this happens, the illness quickly gets nicknamed based on where it originated or the first animal species or human populations it infects, which can lead to misinformation and xenophobia (not cool). As Ghebreyestis said on Twitter, "having a name matters to prevent the use of other names that can be inaccurate or stigmatizing The WHO even has best practices for naming new human diseases. The aim of those guidelines is "to minimize unnecessary negative impact of disease names on trade, travel, tourism or animal welfare, and avoid causing offense to any cultural, social, national, regional, professional or ethnic groups." the organization states.TIMELINE TD-1 S1Dec 2019 Wuhan Municipal Health Commission, China, reported a eluster of eases of pneumonia in Wuhan, Hubei Province. A novel coronavirus was eventually identified. 1 January 2020 WHO had set up the IMST (Incident Management Support Team) across the three levels of the organization: headquarters, regional headquarters and country level, putting the organization on an emergency footing for dealing with the outbreak 4 January 2020 WHO reported on social media that there was a cluster of pneumonia eases — with no deaths — in Wuhan, Hubei province. S January 2020 WHO published our first Disease Outbreak News on the new virus. This is a flagship technical publication to the seientific and public health community as well as global media, It contained a risk assessment and advice, and reported on what China had told the organization about the status of patients and the public health response on the luster of pneumonia cases in Wuhan, 0. y 2020 WHO issued a comprehensive package of technical guidance online with advice to all countries on how to detect, test and manage potential eases, based on what was known about the virus at the time. This guidance was shared with WHO's reg ynal emergency directors to share withWHO representatives in countries. Based on experience with SARS and MERS and known modes of transmission of respiratory viruses, infection and prevention control guidance were published to protect health workers recommending droplet and contact precautions when caring for patients, and airborne precautions for aerosol generating procedures conducted by health workers. 22 January 2020 China publicly shared the genetic sequence of COVID-19. 13 January 2020 Officials confirm a case of COVID-19 in Thailand, the first recorded case outside of China. L4 January 2020 WHO's technical lead for the response noted in a press briefing there may have been limited human-to-human transmission of the coronavirus (in the 41 confirmed cases), mainly through family members, and that there was a risk of a possible wider outbreak. The lead also said that human-to-human transmission would not be surprising given our experience with SARS, MERS. and other respiratory pathogens. 20-21 Sanuary 2020 WHO experts from its China and Western Pacific regional offices conducted a brief field visit to Wuhan, 22. January 2020 The WHO mission to China issued a statement saying that there was evidence of human-to-human transmission in Wuhan but more investigation was needed to understand the full extent of transmission.(22-23 January 2020 The WHO Director- General convened an Emergency Committee (EC) under the Intemational Health Regulations (IHR 2005) to assess whether the outbreak constituted a public health emergency of international concern, The independent members from around the world could not reach a consensus based on the evidence available at the time, They asked to be reconvened within 10 days after receiving more information. 28 January 2020 A senior WHO delegation led by the Director-General travelled to Beijing to meet China's leadership, learn more about China's response, and to offer any technical assistance. Tedros agreed with Chinese government leaders that an international team of leading scientists would travel to China on a mission to better understand the context, the overall response, and exchange information and experience. 30 January 2020 The WHO Director-General reconvened the Emergency Committee (EC). This was earlier than the 10-day period and only two days after the first reports of limited human-to-human transmission were reported outside China, This time, the EC reached consensus and advised the Director-General that the outbreak cons uted a Public Health Emergency of International Concern (PHEIC). The Director-General accepted the recommendation and declared the novel coronavirus outbreak (2019-nCoV) a PHEIC. This is the 6th time WHO has declared a PHEIC since the International Health Regulations (IHR) came into force in 2005. WHO's situation report for 30 January reported 7818 total confirmed cases worldwide, with the majority of these in China, and 82 cases reported in 18 countries outside China. WHO gave a risk assessment of very high for China, and high at the global level. 3 Bebruary 2020FAMILY OF VIRUSES: The original ICTV viral classification, which is entirely separate from the wee of cellular life, included only the lower rungs of the evolutionary hierarchy, from species and genus up to the order level — a tier equivalent to primates or trees with cones in the classification of multicellular life, There were no higher levels. And many viral families floated alone, with no links to other kinds of virus. So in 2018, the ICTV added higher-order levels: classes, phyla and kingdoms. At the very top, it ADOING TO THEFAMEY, invented ‘realms’, Snore, instead of tevearchers having to culture the ve and aos intended. as 10000 counterparts to the I ‘domains’ of & 6.000 cellular life = — 3 i p06 Bacteria, Archaea aa and Eukaryota — but using a different eo te80~—=«2000=—«210-S=S« 2020 word to differentiate between the two trees, (Several years ago, some scientists suggested that certain viruses might fit into the cell-based evolutionary tree, but that idea has not gained widespread favour.) intoa The ICTV outlined the branches of the tree, and grouped RNA-based virus realm called Riboviria. SARS-CoV-2 and other coronaviruses, which have single-stranded RNA genomes, are part of this realm, But then it was up to thebroader community of virologists to propose further taxonomic groups. As it happened, Eugene Koonin, an evolutionary biologist at the National Center for Biotechnology Information in Bethesda, Maryland, had assembled a team to analyse all the viral genomes, as well as the latest research on viral proteins, to create a first-draft taxonomye, They reorganized Riboviria and proposed three more realms (see ‘Virus realms’). There was some quibbling over the details, Koonin says, but the taxonomy was ratified without much trouble by ICTV members in 2020. Two further realms got the green light in 2021, but the original four realms will probably remain the largest, he says. Eventually, Koonin speculates, the realms might number up to 25.MOLECULAR STRUCTURE OF CORONAVIRUS: Coronaviruses are members of the family Coronaviridae, onder Nidovirales. These enveloped viruses possess genomes in the fom of single-stranded RNA molecules of positive sense, that is, the same sense as the messenger RNA (mRNA). At present, four genera are known: Alphacoronavirus, __Betacoronavirus, Gammacoronavirus, — Deltacoronavirus. Members of the genera A lphacoronavitus and Betacoronavirus are identified to cause human disease, whereas those of the genera Gammacoronavinus and Deltacoronavirus are causative agents of animal disease Coronaviruses have a typical characteristic in negative-stain electron microscopy showing a fringe on their surface structure like a spike. This fringe resembles the solar corona, from which the name coronavirus was derived . These viruses ate roughly spherical with an average diameter of 80-120 nm. The surface spikes of the coronaviruses project about 17-20 nm from the surface of the virus particle and have been described as club-like, pear-shaped, or petal-shaped, having a thin base which swells to a width of approximately 10 nm at the distal extremity . A schematic visualization of the coronavirus virion is presented in. In infection, the coronavirus particle serves three important functions for the genome: first, it provides the means to deliver the viral genome across the plasma membrane ofa host cell; second, it serves asa means of escape for the newly synthesized genome; third, the viral particle functions as a durable vessel which protects the genome integrity on its journey between cells .The genome of the coronaviruses codes four main structural proteins: the spike (S) protein, the nucleocapsid (N) protein, the membrane (M) protein and the envelope (F) protein, each of which play primary roles in the structure of the virus particle as well as in other aspects of the viral replication cycle. Generally, all of these proteins are needed to form a structurally complete virion, Some coronaviruses, however, do not requit the full assemblage of the structural proteins to produce a complete, infectious viral particle. This indicates that some structural proteins are likely dispensable, or that those viruses may encode additional proteins with compensatory roles ‘The envelope of coronaviruses contains three or four viral proteins. The major proteins of the viral envelope are the S and the M proteins. In some, but not all coronaviruses, a third major envelope protein, the hemagglutinin esterase (HE) is found. Lastly, the small E protein constitutes a minor, however critical structural component of the viral envelope , Many of the coronavirus proteins are modified by post-translational modifications which change the protein structure by proteolytic cleavage and disulfide bond formation or extend the chemical repertoire of the 20 standard amino acids by introducing new functional groups. Functional groups are commonly added through phosphorylation, glycosylation and lipidation (such as palmitoylation and myristoylation). The post-translational modifications play critical roles in regulating folding, stability, enzymatic activity, subcellular localization and interaction of the viral protein with other proteins .ACCESSORY PROTEINS PRESENT IN CORONAVIRUS: Accessory proteins of human coronavirases” Alleoronavirus genomes contain accessory genes interspersed among the canonical Yiree Acceseory genes (Pretstes) genes, replicase, 8, E, M, N which vary HCOV-IDIE [rep] {3)4aS(E HOM] ephiS}5-B-M0-09 (rep 20H)1S}-4-(E (00-091, 76) (rsp) 22.26 GHE)(S)3 (129%).1M 1885 ‘Third plague Farsi pasett 12M 1889-1890 Russian flu ‘Infloenza HIN2? (RNA virus) IM LSLSASIS Span ds Tnlseaa HIN os ‘1957-1958 Asian fro Infloenea HIN? LIM ‘1968-1970 Hong Kong fu Influenza HIN IM ‘L9Sl-present AIDS HIV (RNA wars) 25-35M ‘002-2003 SARS SARS-CoV-1 (RNA vin) Oak 208-2010 Swine a Tnfcenss HIN 200K ZUIO6 Bhela hola ius GEA vis) nK ‘WlSprevant MERS MERS.C3V (RNA vin) oak ‘W1Sprasant COVID-19 SARS-CoV-2 (RNA virus) 205M‘The Top 10 Worst Affected Countries - Confirmed Cases M- Number of people in millions