Coronavirus

Coronaviruses are a group of related viruses that contain positive-sense, single-stranded RNA RNA Ribonucleic acid (RNA), like deoxyribonucleic acid (DNA), is a polymer of nucleotides that is essential to cellular protein synthesis. Unlike DNA, RNA is a single-stranded structure containing the sugar moiety ribose (instead of deoxyribose) and the base uracil (instead of thymine). RNA generally carries out the instructions encoded in the DNA but also executes diverse non-coding functions. RNA Types and Structure. Coronavirus derives its name from “κορώνα” in Greek, which translates as “crown,” after the small club-shaped proteins visible as a ring around the viral envelope in electron micrographs. Coronaviruses have large genomes, a propensity for mutation Mutation Genetic mutations are errors in DNA that can cause protein misfolding and dysfunction. There are various types of mutations, including chromosomal, point, frameshift, and expansion mutations. Types of Mutations, and frequent recombination events that have resulted in a diversity of species. These new species are capable of rapid adaptation to new hosts and ecologic environments. New coronavirus infections have appeared in both humans and animals. Coronaviruses are known to be the cause of some cases of the common cold, severe acute respiratory syndrome (SARS), Middle East respiratory syndrome (MERS), and coronavirus disease 2019 (COVID-19).

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Classification

Rna viruses flowchart classification

RNA RNA Ribonucleic acid (RNA), like deoxyribonucleic acid (DNA), is a polymer of nucleotides that is essential to cellular protein synthesis. Unlike DNA, RNA is a single-stranded structure containing the sugar moiety ribose (instead of deoxyribose) and the base uracil (instead of thymine). RNA generally carries out the instructions encoded in the DNA but also executes diverse non-coding functions. RNA Types and Structure virus Virus Viruses are infectious, obligate intracellular parasites composed of a nucleic acid core surrounded by a protein capsid. Viruses can be either naked (non-enveloped) or enveloped. The classification of viruses is complex and based on many factors, including type and structure of the nucleoid and capsid, the presence of an envelope, the replication cycle, and the host range. Virology: Overview identification:
Viruses can be classified in many ways. Most viruses, however, will have a genome formed by either DNA DNA The molecule DNA is the repository of heritable genetic information. In humans, DNA is contained in 23 chromosome pairs within the nucleus. The molecule provides the basic template for replication of genetic information, RNA transcription, and protein biosynthesis to promote cellular function and survival. DNA Types and Structure or RNA RNA Ribonucleic acid (RNA), like deoxyribonucleic acid (DNA), is a polymer of nucleotides that is essential to cellular protein synthesis. Unlike DNA, RNA is a single-stranded structure containing the sugar moiety ribose (instead of deoxyribose) and the base uracil (instead of thymine). RNA generally carries out the instructions encoded in the DNA but also executes diverse non-coding functions. RNA Types and Structure. RNA RNA Ribonucleic acid (RNA), like deoxyribonucleic acid (DNA), is a polymer of nucleotides that is essential to cellular protein synthesis. Unlike DNA, RNA is a single-stranded structure containing the sugar moiety ribose (instead of deoxyribose) and the base uracil (instead of thymine). RNA generally carries out the instructions encoded in the DNA but also executes diverse non-coding functions. RNA Types and Structure genome viruses can be further characterized by either a single- or double-stranded RNA RNA Ribonucleic acid (RNA), like deoxyribonucleic acid (DNA), is a polymer of nucleotides that is essential to cellular protein synthesis. Unlike DNA, RNA is a single-stranded structure containing the sugar moiety ribose (instead of deoxyribose) and the base uracil (instead of thymine). RNA generally carries out the instructions encoded in the DNA but also executes diverse non-coding functions. RNA Types and Structure. “Enveloped” viruses are covered by a thin coat of cell membrane Cell Membrane A cell membrane (also known as the plasma membrane or plasmalemma) is a biological membrane that separates the cell contents from the outside environment. A cell membrane is composed of a phospholipid bilayer and proteins that function to protect cellular DNA and mediate the exchange of ions and molecules. The Cell: Cell Membrane (usually taken from the host cell). If the coat is absent, the viruses are called “naked” viruses. Viruses with single-stranded genomes are “positive-sense” viruses if the genome is directly employed as messenger RNA RNA Ribonucleic acid (RNA), like deoxyribonucleic acid (DNA), is a polymer of nucleotides that is essential to cellular protein synthesis. Unlike DNA, RNA is a single-stranded structure containing the sugar moiety ribose (instead of deoxyribose) and the base uracil (instead of thymine). RNA generally carries out the instructions encoded in the DNA but also executes diverse non-coding functions. RNA Types and Structure (mRNA), which is translated into proteins. “Negative-sense,” single-stranded viruses employ RNA RNA Ribonucleic acid (RNA), like deoxyribonucleic acid (DNA), is a polymer of nucleotides that is essential to cellular protein synthesis. Unlike DNA, RNA is a single-stranded structure containing the sugar moiety ribose (instead of deoxyribose) and the base uracil (instead of thymine). RNA generally carries out the instructions encoded in the DNA but also executes diverse non-coding functions. RNA Types and Structure dependent RNA RNA Ribonucleic acid (RNA), like deoxyribonucleic acid (DNA), is a polymer of nucleotides that is essential to cellular protein synthesis. Unlike DNA, RNA is a single-stranded structure containing the sugar moiety ribose (instead of deoxyribose) and the base uracil (instead of thymine). RNA generally carries out the instructions encoded in the DNA but also executes diverse non-coding functions. RNA Types and Structure polymerase, a viral enzyme, to transcribe their genome into messenger RNA RNA Ribonucleic acid (RNA), like deoxyribonucleic acid (DNA), is a polymer of nucleotides that is essential to cellular protein synthesis. Unlike DNA, RNA is a single-stranded structure containing the sugar moiety ribose (instead of deoxyribose) and the base uracil (instead of thymine). RNA generally carries out the instructions encoded in the DNA but also executes diverse non-coding functions. RNA Types and Structure.

Image by Lecturio. License: CC BY-NC-SA 4.0

General Characteristics

Structure

  • Spherical
  • 120 nm in diameter 
  • Usually distinguished by its club-shaped or “crown-like” surface proteins
  • Enveloped, with the viral envelope containing the following proteins:
    • Spike (S) protein
    • Hemagglutinin esterase (HE) protein
    • Membrane (M) protein
    • Envelope (E) protein
  • The nucleocapsid is large and has helical symmetry.
  • Has a single-stranded RNA RNA Ribonucleic acid (RNA), like deoxyribonucleic acid (DNA), is a polymer of nucleotides that is essential to cellular protein synthesis. Unlike DNA, RNA is a single-stranded structure containing the sugar moiety ribose (instead of deoxyribose) and the base uracil (instead of thymine). RNA generally carries out the instructions encoded in the DNA but also executes diverse non-coding functions. RNA Types and Structure genome of approximately 26–31 kilobases
Envelope proteins are denoted coronavirus

Envelope proteins are denoted:
S: spike
HE: hemagglutinin esterase
M: membrane
E: envelope
N: nucleocapsid
(+)ssRNA: positive-sense single-stranded RNA RNA Ribonucleic acid (RNA), like deoxyribonucleic acid (DNA), is a polymer of nucleotides that is essential to cellular protein synthesis. Unlike DNA, RNA is a single-stranded structure containing the sugar moiety ribose (instead of deoxyribose) and the base uracil (instead of thymine). RNA generally carries out the instructions encoded in the DNA but also executes diverse non-coding functions. RNA Types and Structure

Image: “Structure of coronavirus” by Nongluk S et al. License: CC BY 4.0

Clinically relevant species

  • The family Coronaviridae comprises 2 subfamilies:
    • Letovirinae (has no medically relevant species)
    • Orthocoronavirinae is divided into 4 genera:
      • Alphacoronavirus and Betacoronavirus (infect mammals)
      • Gammacoronavirus and Deltacoronavirus (mainly infect birds)
  • Most of the human-infecting species of coronavirus are found within the Betacoronavirus genus. The most relevant ones include:
    • Human coronaviruses (HCoV-OC43, HCoV-HKU1, HCoV-2293)
    • Severe acute respiratory syndrome coronavirus (SARS-CoV)
    • Middle East respiratory syndrome-related coronavirus (MERS-CoV)
    • Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)

Pathogenesis

Transmission

  • Reservoirs:
    • Chiroptera (bats) are thought to be the origin host for all alphacoronaviruses and betacoronaviruses and, therefore, all human coronaviruses.
    • Camels can also be a reservoir for MERS.
    • Birds are the natural reservoirs and hosts for all of the gammacoronaviruses and deltacoronaviruses.
  • Routes of transmission:
    • Fecal–oral
    • Respiratory droplets and airborne spread
    • Contact with infected surfaces and fomites
    • Vertical transmission has been reported for SARS-CoV-2.

Virulence factors

Most coronaviruses have 4 structural proteins: S, E, M, and N.

  • S, E, and M proteins create the viral envelope. 
  • The N protein forms a complex with RNA RNA Ribonucleic acid (RNA), like deoxyribonucleic acid (DNA), is a polymer of nucleotides that is essential to cellular protein synthesis. Unlike DNA, RNA is a single-stranded structure containing the sugar moiety ribose (instead of deoxyribose) and the base uracil (instead of thymine). RNA generally carries out the instructions encoded in the DNA but also executes diverse non-coding functions. RNA Types and Structure (nucleocapsid) and aids in the regulation of viral RNA RNA Ribonucleic acid (RNA), like deoxyribonucleic acid (DNA), is a polymer of nucleotides that is essential to cellular protein synthesis. Unlike DNA, RNA is a single-stranded structure containing the sugar moiety ribose (instead of deoxyribose) and the base uracil (instead of thymine). RNA generally carries out the instructions encoded in the DNA but also executes diverse non-coding functions. RNA Types and Structure synthesis.
  • The M protein projects on the external surface of the envelope and is important for viral assembly. 
  • The E protein has an unclear function, although it may aid in virus Virus Viruses are infectious, obligate intracellular parasites composed of a nucleic acid core surrounded by a protein capsid. Viruses can be either naked (non-enveloped) or enveloped. The classification of viruses is complex and based on many factors, including type and structure of the nucleoid and capsid, the presence of an envelope, the replication cycle, and the host range. Virology: Overview release.
  • The S protein is a club-shaped surface projection that gives the virus Virus Viruses are infectious, obligate intracellular parasites composed of a nucleic acid core surrounded by a protein capsid. Viruses can be either naked (non-enveloped) or enveloped. The classification of viruses is complex and based on many factors, including type and structure of the nucleoid and capsid, the presence of an envelope, the replication cycle, and the host range. Virology: Overview its characteristic crown-like appearance on electron microscopy and is responsible for receptor binding and fusion with the host cell membrane Cell Membrane A cell membrane (also known as the plasma membrane or plasmalemma) is a biological membrane that separates the cell contents from the outside environment. A cell membrane is composed of a phospholipid bilayer and proteins that function to protect cellular DNA and mediate the exchange of ions and molecules. The Cell: Cell Membrane.

Replication cycle

  1. Coronaviruses bind to the host cell surface via the S proteins.
    • Viral entry occurs either by receptor-mediated endocytosis or through membrane fusion. 
    • The virus Virus Viruses are infectious, obligate intracellular parasites composed of a nucleic acid core surrounded by a protein capsid. Viruses can be either naked (non-enveloped) or enveloped. The classification of viruses is complex and based on many factors, including type and structure of the nucleoid and capsid, the presence of an envelope, the replication cycle, and the host range. Virology: Overview escapes the acidified environment of the endosomes by transporting itself to lysosomes. 
  2. Coronaviruses have single-stranded, positive-sense RNA RNA Ribonucleic acid (RNA), like deoxyribonucleic acid (DNA), is a polymer of nucleotides that is essential to cellular protein synthesis. Unlike DNA, RNA is a single-stranded structure containing the sugar moiety ribose (instead of deoxyribose) and the base uracil (instead of thymine). RNA generally carries out the instructions encoded in the DNA but also executes diverse non-coding functions. RNA Types and Structure that can directly produce the proteins and new genomes in the cytoplasm.
  3. The negative-sense strand template RNA RNA Ribonucleic acid (RNA), like deoxyribonucleic acid (DNA), is a polymer of nucleotides that is essential to cellular protein synthesis. Unlike DNA, RNA is a single-stranded structure containing the sugar moiety ribose (instead of deoxyribose) and the base uracil (instead of thymine). RNA generally carries out the instructions encoded in the DNA but also executes diverse non-coding functions. RNA Types and Structure is produced. 
  4. The new viral proteins are translated by the host’s ribosomes.
  5. The nucleocapsid protein binds with genomic RNA RNA Ribonucleic acid (RNA), like deoxyribonucleic acid (DNA), is a polymer of nucleotides that is essential to cellular protein synthesis. Unlike DNA, RNA is a single-stranded structure containing the sugar moiety ribose (instead of deoxyribose) and the base uracil (instead of thymine). RNA generally carries out the instructions encoded in the DNA but also executes diverse non-coding functions. RNA Types and Structure, and protein M is integrated into the membrane of the endoplasmic reticulum along with proteins S and HE. 
  6. An assembled nucleocapsid that contains the RNA RNA Ribonucleic acid (RNA), like deoxyribonucleic acid (DNA), is a polymer of nucleotides that is essential to cellular protein synthesis. Unlike DNA, RNA is a single-stranded structure containing the sugar moiety ribose (instead of deoxyribose) and the base uracil (instead of thymine). RNA generally carries out the instructions encoded in the DNA but also executes diverse non-coding functions. RNA Types and Structure moves into the endoplasmic reticulum to be encased and is released by exocytosis.
Coronavirus replication

Replication cycle of coronaviruses:
1. Coronaviruses bind to the host cell surface via the S proteins. Viral entry occurs either by receptor-mediated endocytosis or through membrane fusion. The virus Virus Viruses are infectious, obligate intracellular parasites composed of a nucleic acid core surrounded by a protein capsid. Viruses can be either naked (non-enveloped) or enveloped. The classification of viruses is complex and based on many factors, including type and structure of the nucleoid and capsid, the presence of an envelope, the replication cycle, and the host range. Virology: Overview escapes the acidified environment of the endosomes by transporting itself to lysosomes.
2. Coronaviruses have single-stranded, positive-sense RNA RNA Ribonucleic acid (RNA), like deoxyribonucleic acid (DNA), is a polymer of nucleotides that is essential to cellular protein synthesis. Unlike DNA, RNA is a single-stranded structure containing the sugar moiety ribose (instead of deoxyribose) and the base uracil (instead of thymine). RNA generally carries out the instructions encoded in the DNA but also executes diverse non-coding functions. RNA Types and Structure that can directly produce the proteins and new genomes in the cytoplasm.
3. The negative-sense strand template RNA RNA Ribonucleic acid (RNA), like deoxyribonucleic acid (DNA), is a polymer of nucleotides that is essential to cellular protein synthesis. Unlike DNA, RNA is a single-stranded structure containing the sugar moiety ribose (instead of deoxyribose) and the base uracil (instead of thymine). RNA generally carries out the instructions encoded in the DNA but also executes diverse non-coding functions. RNA Types and Structure is produced.
4. The new viral proteins are translated by the host’s ribosomes.
5. The nucleocapsid protein binds with genomic RNA RNA Ribonucleic acid (RNA), like deoxyribonucleic acid (DNA), is a polymer of nucleotides that is essential to cellular protein synthesis. Unlike DNA, RNA is a single-stranded structure containing the sugar moiety ribose (instead of deoxyribose) and the base uracil (instead of thymine). RNA generally carries out the instructions encoded in the DNA but also executes diverse non-coding functions. RNA Types and Structure, and protein M is integrated into the membrane of the endoplasmic reticulum (ER) along with proteins S and HE.
6. Assembled nucleocapsid that contains the RNA RNA Ribonucleic acid (RNA), like deoxyribonucleic acid (DNA), is a polymer of nucleotides that is essential to cellular protein synthesis. Unlike DNA, RNA is a single-stranded structure containing the sugar moiety ribose (instead of deoxyribose) and the base uracil (instead of thymine). RNA generally carries out the instructions encoded in the DNA but also executes diverse non-coding functions. RNA Types and Structure moves into the ER to be encased and is released by exocytosis.

Image: “The infection life cycle of coronavirus” by C. Michael Gibson et al. License: CC BY-SA 3.0

Diseases Caused by Coronaviruses

  • Common cold:
    • The common cold is usually caused by rhinoviruses.
    • However, coronaviruses cause 15% of common colds.
    • Incubation period: 3 days
  • GI infections:
    • Far less commonly caused by coronaviruses
    • Incubation period: 3 days
    • Usually presents as a very mild infection that causes diarrhea Diarrhea Diarrhea is defined as ≥ 3 watery or loose stools in a 24-hour period. There are a multitude of etiologies, which can be classified based on the underlying mechanism of disease. The duration of symptoms (acute or chronic) and characteristics of the stools (e.g., watery, bloody, steatorrheic, mucoid) can help guide further diagnostic evaluation. Diarrhea, diffuse abdominal pain Pain Pain has accompanied humans since they first existed, first lamented as the curse of existence and later understood as an adaptive mechanism that ensures survival. Pain is the most common symptomatic complaint and the main reason why people seek medical care. Physiology of Pain, and vomiting
    • Rarely, can lead to neonatal necrotizing enterocolitis Necrotizing enterocolitis Necrotizing enterocolitis (NEC) is an intestinal inflammatory process that can lead to mucosal injury and necrosis. The condition is multifactorial, with underlying risk factors that include prematurity and formula feeding. The clinical presentation varies in severity from feeding intolerance, acute findings on abdominal exam, and systemic symptoms. Necrotizing Enterocolitis
  • MERS:
    • Emerged in 2012 in Saudi Arabia from dromedary camels.
    • Incubation period: 5 days
    • Clinical presentation ranges from asymptomatic infection to acute upper respiratory illness.
    • Can lead to rapidly progressive pneumonitis, respiratory failure Respiratory failure Respiratory failure is a syndrome that develops when the respiratory system is unable to maintain oxygenation and/or ventilation. Respiratory failure may be acute or chronic and is classified as hypoxemic, hypercapnic, or a combination of the two. Respiratory Failure, septic shock Septic shock Organ dysfunction resulting from a dysregulated systemic host response to infection separates sepsis from uncomplicated infection. Patients commonly present with fever, tachycardia, tachypnea, hypotension, and/or altered mentation. Septic shock is diagnosed during treatment when vasopressors are necessary to control hypotension. Sepsis and Septic Shock, and multiorgan failure, resulting in death. 
  • SARS:
    • Emerged in 2003 in southern China from civet cats.
    • Incubation period: 4–6 days 
    • Clinical presentation ranges from mild, flu-like illness with full recovery (25% of cases), to severe respiratory infection (approximately 70%), to death from respiratory failure Respiratory failure Respiratory failure is a syndrome that develops when the respiratory system is unable to maintain oxygenation and/or ventilation. Respiratory failure may be acute or chronic and is classified as hypoxemic, hypercapnic, or a combination of the two. Respiratory Failure (approximately 10%).
    • Usually manifests as low-grade fever Fever Fever is defined as a measured body temperature of at least 38°C (100.4°F). Fever is caused by circulating endogenous and/or exogenous pyrogens that increase levels of prostaglandin E2 in the hypothalamus. Fever is commonly associated with chills, rigors, sweating, and flushing of the skin. Fever, muscle pain Pain Pain has accompanied humans since they first existed, first lamented as the curse of existence and later understood as an adaptive mechanism that ensures survival. Pain is the most common symptomatic complaint and the main reason why people seek medical care. Physiology of Pain, lethargy, cough, sore throat, and malaise
    • Can progress to dyspnea Dyspnea Dyspnea is the subjective sensation of breathing discomfort. Dyspnea is a normal manifestation of heavy physical or psychological exertion, but also may be caused by underlying conditions (both pulmonary and extrapulmonary). Dyspnea, pneumonia Pneumonia Pneumonia or pulmonary inflammation is an acute or chronic inflammation of lung tissue. Causes include infection with bacteria, viruses, or fungi. In more rare cases, pneumonia can also be caused through toxic triggers through inhalation of toxic substances, immunological processes, or in the course of radiotherapy. Pneumonia, respiratory failure Respiratory failure Respiratory failure is a syndrome that develops when the respiratory system is unable to maintain oxygenation and/or ventilation. Respiratory failure may be acute or chronic and is classified as hypoxemic, hypercapnic, or a combination of the two. Respiratory Failure, and death
  • Coronavirus disease 2019 (COVID-19):
    • Emerged in November 2019 in Wuhan, China, from horseshoe bats and caused a global pandemic
    • Incubation period: 2–14 days
    • Clinical presentation can range from asymptomatic or mild infections will full recovery (80% of cases), to severe respiratory infections (15%), to critical disease with multiorgan damage (5%) and death (2.2%). 
    • Usually presents as dry cough, malaise, and fatigue and may be associated with hemoptysis Hemoptysis Hemoptysis is defined as the expectoration of blood originating in the lower respiratory tract. Hemoptysis is a consequence of another disease process and can be classified as either life threatening or non-life threatening. Hemoptysis can result in significant morbidity and mortality due to both drowning (reduced gas exchange as the lungs fill with blood) and hemorrhagic shock. Hemoptysis, diarrhea Diarrhea Diarrhea is defined as ≥ 3 watery or loose stools in a 24-hour period. There are a multitude of etiologies, which can be classified based on the underlying mechanism of disease. The duration of symptoms (acute or chronic) and characteristics of the stools (e.g., watery, bloody, steatorrheic, mucoid) can help guide further diagnostic evaluation. Diarrhea, vomiting, headache, anosmia, dysgeusia, and chest pain Chest Pain Chest pain is one of the most common and challenging complaints that may present in an inpatient and outpatient setting. The differential diagnosis of chest pain is large and includes cardiac, gastrointestinal, pulmonary, musculoskeletal, and psychiatric etiologies. Chest Pain
    • Can progress to pneumonia Pneumonia Pneumonia or pulmonary inflammation is an acute or chronic inflammation of lung tissue. Causes include infection with bacteria, viruses, or fungi. In more rare cases, pneumonia can also be caused through toxic triggers through inhalation of toxic substances, immunological processes, or in the course of radiotherapy. Pneumonia, ARDS ARDS Acute respiratory distress syndrome is characterized by the sudden onset of hypoxemia and bilateral pulmonary edema without cardiac failure. Sepsis is the most common cause of ARDS. The underlying mechanism and histologic correlate is diffuse alveolar damage (DAD). Acute Respiratory Distress Syndrome, thrombosis, sepsis Sepsis Organ dysfunction resulting from a dysregulated systemic host response to infection separates sepsis from uncomplicated infection. The etiology is mainly bacterial and pneumonia is the most common known source. Patients commonly present with fever, tachycardia, tachypnea, hypotension, and/or altered mentation. Sepsis and Septic Shock, multiorgan failure, and death
Table: Epidemiology of respiratory coronavirus diseases
MERS-CoV SARS-CoV SARS-CoV-2
Date of first identified case June 2012 November 2002 December 2019
Location of first identified case Jeddah, Saudi Arabia Shunde, China Wuhan, China
Average age 56 years 44 years 56 years
Sex ratio (M:F) 3.3:1 0.8:1 1.6:1
Table: Frequency of symptoms in respiratory coronavirus diseases
MERS (caused by MERS-CoV) SARS (caused by SARS-CoV) COVID-19 (caused by SARS-CoV-2)
Fever 98% 99%–100% 87.9%
Dry cough 47% 29%–75% 67.7%
Dyspnea 72% 40%–42% 18.6%
Diarrhea 26% 20%–25% 3.7%
Sore throat 21% 13%–25% 13.9%
Ventilator use 24.5% 14%–20% 4.1%

Comparison of Similar Viruses

Table: Comparison of similar viruses
Organism SARS-CoV-2 Rhinovirus Rhinovirus Rhinovirus is an acid-labile, positive-sense RNA virus of the Picornavirus family. The virus, which causes the common cold, is most often acquired through the airway via the inhalation of aerosols containing rhinovirus and fomites. Rhinovirus Coxsackievirus Coxsackievirus Coxsackievirus is a member of a family of viruses called Picornaviridae and the genus Enterovirus. Coxsackieviruses are single-stranded, positive-sense RNA viruses, and are divided into coxsackie group A and B viruses. Both groups of viruses cause upper respiratory infections, rashes, aseptic meningitis, or encephalitis. Coxsackievirus
Characteristics
  • Spherical
  • 120 nm in diameter
  • Large nucleocapsid with helical symmetry
  • +ssRNA
  • Club-shaped S proteins
  • Icosahedral capsid
  • Non-enveloped
  • +ssRNA
  • Genomes 7200 to 8500 nucleotides in length
  • Icosahedral capsid
  • Small and non-enveloped
  • +ssRNA
Transmission
  • Aerosols
  • Respiratory droplets
  • Fomites
  • Vertical
  • Aerosols
  • Respiratory droplets
  • Fomites
  • Fecal–oral
  • Aerosols
  • Respiratory droplets
  • Fomites
Clinical
  • Fever
  • Dry cough
  • Shortness of breath
  • Anosmia
  • Hypoxia
  • Fever
  • Cough
  • Sneezing
  • Myalgia
  • Fatigue
  • Fever
  • Cough
  • Sore throat
  • Conjunctivitis Conjunctivitis Conjunctivitis is a common inflammation of the bulbar and/or palpebral conjunctiva. It can be classified into infectious (mostly viral) and noninfectious conjunctivitis, which includes allergic causes. Patients commonly present with red eyes, increased tearing, burning, foreign body sensation, and photophobia. Conjunctivitis
  • Herpangina
  • Vesicular rash
Diagnosis
  • RT-PCR
  • Serology
Clinical diagnosis Clinical diagnosis
Management
  • Careful observation
  • Hospitalization
  • Corticosteroids
  • Monoclonal antibodies Antibodies Immunoglobulins (Igs), also known as antibodies, are glycoprotein molecules produced by plasma cells that act in immune responses by recognizing and binding particular antigens. The various Ig classes are IgG (the most abundant), IgM, IgE, IgD, and IgA, which differ in their biologic features, structure, target specificity, and distribution. Immunoglobulins
  • Self-limited illness
  • Symptomatic treatment
  • Self-limited illness
  • Symptomatic treatment
Prevention
  • Social distancing
  • Vaccination Vaccination Vaccination is the administration of a substance to induce the immune system to develop protection against a disease. Unlike passive immunization, which involves the administration of pre-performed antibodies, active immunization constitutes the administration of a vaccine to stimulate the body to produce its own antibodies. Vaccination
  • Personal protective equipment
  • Respiratory hygiene
  • Social distancing
  • Respiratory hygiene
  • Social distancing
  • Respiratory hygiene
+ssRNA: positive-sense single-stranded RNA RNA Ribonucleic acid (RNA), like deoxyribonucleic acid (DNA), is a polymer of nucleotides that is essential to cellular protein synthesis. Unlike DNA, RNA is a single-stranded structure containing the sugar moiety ribose (instead of deoxyribose) and the base uracil (instead of thymine). RNA generally carries out the instructions encoded in the DNA but also executes diverse non-coding functions. RNA Types and Structure

References

  1. Lee N, Hui D, Wu A, Chan P, Cameron P, Joynt GM, et al. (2003). A major outbreak of severe acute respiratory syndrome in Hong Kong. N Engl J Med https://pubmed.ncbi.nlm.nih.gov/12682352/
  2. Tsang KW, Ho PL, Ooi GC, Yee WK, Wang T, Chan-Yeung M, et al. (2003). A cluster of cases of severe acute respiratory syndrome in Hong Kong. N Engl J Med 348:1977–1985. https://pubmed.ncbi.nlm.nih.gov/12671062/
  3. Centers for Disease Control and Prevention. (2003). Severe acute respiratory syndrome. Centers for Disease Control and Prevention. Retrieved January 31, 2021, from https://www.cdc.gov/sars/index.html
  4. Armed Forces Institute of Pathology. Severe acute respiratory syndrome (SARS). Armed Forces Institute of Pathology.
  5. Hsu LY, Lee CC, Green JA, Ang B, Paton NI, Lee L, et al. (2003) Severe acute respiratory syndrome (SARS) in Singapore: clinical features of the index patient and initial contacts. Emerg Infect Dis 9:713–717. https://pubmed.ncbi.nlm.nih.gov/12781012/
  6. Mole B. (2013). Deadly coronavirus found in bats. Nature. Retrieved 2019 Apr 10 from http://www.nature.com/news/deadly-coronavirus-found-in-bats-1.13597
  7. Hemida MG, Chu DKW, Poon LLM. (2017). MERS coronavirus in dromedary camel herd, Saudi Arabia. Emerging Infectious Diseases 20:1231–1234. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4073860/
  8. CDC. (n.d.). MERS in the U.S. Centers for Disease Control and Prevention. https://www.cdc.gov/coronavirus/mers/index.html
  9. Gallegos A. (2020). WHO declares public health emergency for novel coronavirus. Medscape Medical News. Retrieved January 30, 2020, from https://www.medscape.com/viewarticle/924596

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