6. •The name was coined by June Almeida and David Tyrrell who
first observed and studied human coronaviruses.
•The name refers to the
characteristic appearance of
virions (the infective form of
the virus) by electron
microscopy, which have a
fringe of large, bulbous
surface projections creating
an image reminiscent of the
solar corona or halo
7. •Coronaviruses were first discovered in the 1930s when an acute respiratory
infection of domesticated chickens was shown to be caused by infectious
bronchitis virus (IBV).
•In the 1940s, two more animal coronaviruses, mouse hepatitis virus (MHV) and
transmissible gastroenteritis virus (TGEV), were isolated.
•It was not realized at the time that these three different viruses were related
•Human coronaviruses were discovered in the 1960s
•Kendall, Malcom Byone, and David Tyrrell working at the Common Cold in 1960
isolated from a boy a novel common cold virus B814.
•Around the same time, Dorothy Hamre and John Procknow isolated a novel cold
virus 229E
•Almeida through electron microscopy was able to show that B814 and 229E were
morphologically related by their distinctive club-like spikes
•. Not only were they related with each other, but they were morphologically
related to infectious bronchitis virus (IBV).
8. •A research group at the National Institute of Health the same year was able to
isolate another member of this new group of viruses using organ culture and
named the virus strain OC43.
•The IBV-like novel cold viruses were soon shown to be also morphologically
related to the mouse hepatitis virus .
• This new group of IBV-like viruses came to be known as coronaviruses after
their distinctive morphological appearance.
•Human coronavirus 229E and human coronavirus OC43 continued to be studied
in subsequent decades
•The coronavirus strain B814 was lost.
•Other human coronaviruses have since been identified, including
•SARS-CoV in 2003
• HCoV NL63 in 2004
• HCoV HKU1 in 2005
• MERS-CoV in 2012
• and SARS-CoV-2 in 2019.
9. •Coronaviruses are large mostly spherical, sometimes pleomorphic, particles
with bulbous surface projections.
•The envelope is studded with projecting glycoproteins, and surrounds a
core consisting of matrix protein enclosed within which is a single strand of
positive-sense RNA (Mr 6 × 106) associated with nucleoprotein.
• The diameter of the envelope is 85 nm and the spikes are 20 nm long
•The average diameter of the virus particles is around 125 nm
•The viral envelope consists of a lipid bilayer where the membrane (M), envelope
(E) and spike (S) structural proteins are anchored.
•The ratio of E:S:M in the lipid bilayer is approximately 1:20:300.
10.
11. •The genome
•SS linear non segmented + ve sense RNA
•The largest among RNA viruses
•A crown-like Appearance when viewed by EM
•On the surface of the envelope are club shaped projections
that resemble a solar corona
•Coronaviruses (CoVs) are the largest group of viruses belonging to
the Nidovirales order, which includes Coronaviridae, Arteriviridae,
Mesoniviridae, and Roniviridae families.
12. **Coronaviridae is a family
of enveloped, positive-sense,
single-stranded RNA viruses.
**The Coronavirinae comprise one of two subfamilies in
the Coronaviridae family, with the other being the
Torovirinae.
**The Coronavirinae are further
subdivided into four groups, the
alpha, beta, gamma and delta
coronaviruses.
13.
14. •Coronaviruses contain a non-segmented, positive-sense RNA genome of
~30 kb. The genome contains a 5′ cap structure along with a 3′ poly (A)
tail, allowing it to act as an mRNA for translation of the replicase
polyproteins
•The 5′ end of the genome contains a leader sequence and untranslated
region(UTR) that contains multiple stem loop structures required for
RNA replication and transcription
• The 3′ UTR also contains RNA structures required for replication and
synthesis of viral RNA
15. Attachment and Entry
The initial attachment of the virion to the host cell is initiated by
interactions between the S protein and its receptor. The sites of receptor
binding domains (RBD) within the S1 region of a coronavirus S protein
vary depending on the virus, with some having the RBD at the N-terminus
of S1 (MHV), while others (SARS- CoV) have the RBD at the C-terminus of
S1.
•The S-protein–receptor interaction is the primary determinant for a
coronavirus to infect a host species and also governs the tissue tropism of
the virus.
• Many coronaviruses utilize peptidases as their cellular receptor
16. Attachment and Entry
•Following receptor binding, the virus must next gain access to the host cell
cytosol.
This is generally accomplished by aciddependent proteolytic cleavage of S
protein by a cathepsin, TMPRRS2 or another protease, followed by fusion of
the viral and cellular membranes.
•The mixing of viral and cellular membranes, resulting in fusion and
ultimately release of the viral genome into the cytoplasm.
17.
18. Replication
•A number of the nonstructural proteins coalesce to form a multi-
protein replicase-transcriptase complex (RTC). The main replicase-
transcriptase protein is the RNA-dependent RNA polymerase (RdRp).
•It is directly involved in the replication and transcription of RNA from an
RNA strand. The other nonstructural proteins in the complex assist in the
replication and transcription process
•The exoribonuclease nonstructural protein, for instance, provides extra
fidelity to replication by providing a proofreading function which the
RNA-dependent RNA polymerase lacks
19. Replication
•One of the main functions of the complex is to replicate the viral
genome
•Perhaps the most novel aspect of coronavirus replication is how the leader
and body TRS segments fuse during production of sub-genomic RNAs. This
was originally thought to occur during positive-strand synthesis, but now it is
largely believed to occur during the discontinuous extension of negative-
strand RNA
20.
21. Release
•The replicated positive-sense genomic RNA becomes the genome of the
progeny viruses.
•The mRNAs are gene transcripts of the last third of the virus genome after
the initial overlapping reading frame.
•These mRNAs are translated by the host's ribosomes into the structural
proteins and a number of accessory proteins
•RNA translation occurs inside the endoplasmic reticulum.
22. Release
•The viral structural proteins S, E, and M move along the secretory pathway
into the Golgi intermediate compartment.
•There, the M proteins direct most protein-protein interactions required for
assembly of viruses following its binding to the nucleocapsid
•Progeny viruses are then released from the host cell by exocytosis through
secretory vesicles.
23. • Several known
coronaviruses are
circulating in animals that
have not yet infected
humans.
•Coronaviruses are zoonotic,
meaning they are transmitted
between animals and people.
• Detailed investigations found
that – SARS-CoV was transmitted
from civet cats to humans and –
MERS-CoV from dromedary
camels to humans.
24.
25.
26. • In December 2019, a pneumonia outbreak was reported in Wuhan city of China
•On 31 December 2019, the outbreak was traced to a novel strain of corona
virus, which was given the interim name 2019-nCoV by the World Health
Organization (WHO), later renamed SARS-CoV-2 by the International
Committee on Taxonomy of Viruses .
27. • As of 15 March 2020, there have been at least 5,833 confirmed deaths and
more than 156,396 confirmed cases in the corona virus pneumonia pandemic
• The Wuhan strain has been identified as a new strain of Beta corona virus from
group 2B with approximately 70% genetic similarity to the SARS- CoV.
•The virus has a 96% similarity to a bat corona virus, so it is widely suspected to
originate from bats as well
• It is caused by SARS-CoV-2 is closely related to Sever Acute Respiratory
Syndrome Corona Virus which was outbreaks in 2003
28. •SARS-CoV-2, the virus, mainly spreads from person to person.
• Most of the time, it spreads when a sick person coughs or sneezes.
•They can spray droplets as far as 6 feet away.
• If you breathe them in or swallow them, the virus can get into your body.
•Some people who have the virus don't have symptoms, but they can still spread
the virus.
•You can also get the virus from touching a
surface or object the virus is on, then
touching your mouth, nose, or possibly
your eyes.
• Most viruses can live for several hours
on a surface that they land on.
29. study shows that the COVID-19
coronavirus can last for several hours
on various types of surfaces: Copper:
4 hours
Cardboard up to 24 hours
Plastic or stainless steel: 2 to 3 days
That’s why it’s important to disinfect
surfaces to get rid of the virus.
30.
31.
32. Signs and symptoms of coronavirus disease 2019 (COVID-19) may
appear two to 14 days after exposure. This time after exposure and before
having symptoms is called the incubation period.
Common signs and symptoms can include:
•Fever
•Cough
•Shortness of breath or difficulty breathing
34. Although most people with COVID-19 have mild to moderate symptoms,
the disease can cause severe medical complications and lead to death in
some people.
Older adults or people with existing chronic medical conditions are at
greater risk of becoming seriously ill with COVID-19.
Complications can include:
•Pneumonia in both lungs
•Organ failure in several organs
•Respiratory failure
•Heart problems, such as heart rhythm
problems and a disease of the heart muscle
that makes it hard for your heart to pump
blood to the body (cardiomyopathy)
•Acute kidney injury
•Additional viral and bacterial infection
35.
36.
37. Although there is no vaccine available to prevent COVID-19, you can take steps
to reduce your risk of infection. WHO and CDC recommend following these
precautions for avoiding COVID-19:
•Avoid large events and mass gatherings.
•Avoid close contact (within about 6 feet, or 2 meters) with anyone who is sick or
has symptoms.
•Stay home as much as possible and keep distance between yourself and others
(within about 6 feet, or 2 meters) if COVID-19 is spreading in your community,
especially if you have a higher risk of serious illness.
•Wash your hands often with soap and water for at least 20 seconds, or use an
alcohol-based hand sanitizer that contains at least 60% alcohol.
38. •Cover your face with a cloth face covering in public spaces, such as the grocery
store, where it's difficult to avoid close contact with others, especially if you're
in an area with ongoing community spread.
•Only use nonmedical cloth masks — surgical masks and N95 respirators
should be reserved for health care providers.
•Cover your mouth and nose with your elbow or a tissue when you cough or
sneeze.
•Throw away the used tissue.
•Avoid touching your eyes, nose and mouth.
•Avoid touching your eyes, nose and mouth.
•Avoid sharing dishes, glasses, bedding and other household items if you're
sick.
•Clean and disinfect high-touch surfaces daily.
39. •Stay home from work, school and public areas if you're sick, unless
you're going to get medical care.
•Avoid taking public transportation if you're sick.
40.
41.
42.
43. •vaccine development can take years, researchers aren't starting
from scratch to develop a COVID-19 vaccine. Past research on
SARS and MERS vaccines has identified potential approaches.
•Coronaviruses have a spike-like structure on their surface called
an S protein. (The spikes create the corona-like, or crown-like,
appearance that gives the viruses their name.) The S protein
attaches to the surface of human cells. A vaccine that targets this
protein would prevent it from binding to human cells and stop the
virus from reproducing.
44. Past research on vaccines for coronaviruses has also identified some
challenges to developing a COVID-19 vaccine, including:
•Ensuring vaccine safety.
Several vaccines for SARS have been tested in animals. Most of the
vaccines improved the animals' survival but didn't prevent infection.
Some vaccines also caused complications, such as lung damage. A
COVID-19 vaccine will need to be thoroughly tested to make sure it's
safe for humans.
•Providing long-term protection.
After infection with coronaviruses, re-infection with the same virus —
though usually mild and only happening in a fraction of people — is
possible after a period of months or years. An effective COVID-19
vaccine will need to provide people with long-term infection
protection.
•Protecting older people.
People older than age 50 are at higher risk of severe COVID-19. But
older people usually don't respond to vaccines as well as younger
people. An ideal COVID-19 vaccine would work well for this age
group.
45.
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organ culture". The Journal of General Virology
2. Mayo Foundation for Medical Education and Research (MFMER)./mayo
clinic /COVID-19 (coronavirus) vaccine: Get the facts
3. David A.J. Tyrrell and Steven H. Myint /Chapter 60Coronaviruses/Medical
Microbiology. 4th edition
4. Chapter of Gastroenterologists professional guidance for management of
patients with liver disease in Singapore during the COVID-19 pandemic
5. COVIDiagnosis-Net: Deep Bayes-SqueezeNet based diagnosis of the
coronavirus disease 2019 (COVID-19) from X-ray images Ferhat Ucara,⁎ ,
Deniz Korkmaz
6. Intracellular Antiviral Immunity Maria Bottermann, Leo C. James1 MRC
Laboratory of Molecular Biology, Cambridge, United Kingdo chapter13
47. 1. Hosts and Sources of Endemic Human Coronaviruses Victor M. Corman*,† ,
Doreen Muth*,† , Daniela Niemeyer*, Christian Drosten*Charite–
Universit€atsmedizin Berlin, corporate member of Freie Universit€at Berlin,
Humboldt-Universit€at zu Berlin, and Berlin Institute of Health, Institute of
Virology, Berlin, Germany
2. Coronaviruses: An Overview of Their Replication and Pathogenesis Anthony
R. Fehr and Stanley Perlman
3. International Committee on Taxonomy of Viruses (ICTV). October 2018.
4. Virus Taxonomy: 2019 Release international Committee on Taxonomy of
Viruses (ICTV). March 2019
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