Corona viruses

Dr. MOE YEE SOE

Assistant Lecturer

Department of Microbiology
• Members of a family of large, enveloped,
positive-sense, single stranded RNA viruses

• Replicates in cytoplasm of host cells

• Genomes range in length from 27 – 32 kb

(largest of RNA viruses)

• Virions about 100 – 140 nm in diameter

• Most but not all show characteristic appearance

of surface projections

(corona, Latin = crown)

• Spikes : 20 nm
Electron Microscopic picture of
SARCoV
 Group 1

• Canine, feline, porcine &

Human coronavirus 229 E

Group 2

• Bovine, murine, rat &

Human coronavirus OC 43

Group 3 ……Avian viruses

SEVERE ACUTE RESPIRATORY

SYNDROMES

(SARS)
• First originated in Guangdong (Southern China)
in November, 2002
• Internationally Reported on February 11, 2003
(WHO) (305 cases)
• Similar cases detected in Hong Kong, Vietnam
and Canada
• WHO issued a global alert – designated the
illness “Severe Acute Respiratory Syndrome”
(SARS)
In March 2003

• SARS recognized in healthcare workers and

household members who had cared for such
patients

WHO Physician, Dr. Carlo Urbani

• First recognized this new disease entity, himself

succumbed to this disease and died on March
29, 2003
Dr. Carlo Urbani
Countries Reporting SARS cases, WHO
29 countries through May 22, 2003
In March 17, 2003

• WHO organized collaboration of 11

laboratories in 9 countries

• ….To form network for multi-center

research into etiology of SARS and

• ….To develop a diagnostic test

• Etiologic agent of SARS was identified in
late March 2003 when labs in HK, US &
Germany found a novel Coronavirus in
patients with SARS

• Evidenced by cell culture, EM and RT-PCR,

microarray technology and indirect
immunofluorescent antibody tests
In April 16, 2003

• WHO announced that this new

Coronavirus was the causal agent of SARS
Structure of Coronavirus Virion

Holmes KV. NEJM 2003;348(20):1949.

 SARS Etiologic Agent

• Single-strand RNA enveloped virus

• Envelope

– S - spike protein

– M - matrix protein

– HE – hemagglutinin esterase protein

In animals

• Coronavirus cause highly virulent systemic

diseases

• Generally highly species-specific

• Human coronavirus associated only with

mild diseases ie., mild respiratory illness
• Occasionally cause serious infections of
the lower respiratory tract in children and
adults and necrotizing enterocolitis in
newborns

• SARS CoV – first coronavirus to cause

severe disease in humans
Genome shows that SARS CoV is

• neither a mutant of a known coronavirus

• nor a recombinant between known

coronaviruses
 Stability and Resistance

• Virus is stable in faeces and urine at room

temperature for at least 1 – 2 days

• Viability is better in diarrhoeic stools

(higher pH than normal)

• Heating to 56˙C inactivates SARS CoV

relatively quickly

• Loses its infectivity after exposure to

different commonly-used disinfectants

 Clinical Presentations

• Fever 38 °C ( 100.4° F)

• Chills and rigor

• Myalgia

• Cough

• Headache

• Dizziness
• Sore throat
• Coryza
• Nausea, vomiting
• Diarrhoea
diarrhea seemed to be a prominent
symptom in Amoy Garden’s outbreak in
H.K
 Laboratory Diagnosis
SARS CoV detected in
• Extracts of lung and kidney tissue by
virus isolation or PCR
• Broncho-alveolar larvage specimens by
virus isolation, E/M and PCR
• Sputum or upper respiratory tract swab,
aspirate or wash specimens by PCR
Viral RNA
Stool specimens
• viral RNA detected in 97% of patients 2
weeks after onset of illness
• Virus may be shed in faeces during the
late convalescent phase and for
prolonged periods of time
Urine samples

• 42% were positive for viral RNA

Plasma

• viral RNA detected at extremely low

concentrations during the acute phase
1. Virus isolation

By inoculating patient’s specimens

such as respiratory secretions,

blood or stool into Vero cells

2. Antibody Detection

By ELISA, IFA, NT

3. Polymerase Chain Reaction

SARS CoV specific RNA detected

from blood, stool, respiratory
secretions or body tissues by
RT-PCR
 Transmission
• spread by droplets shed from respiratory
secretions of infected persons
• By direct and indirect contact
• Oral-faecal route or aerosolization of
sewage
• Airborne transmission
• via ingestion of game animals
• Nosocomial transmission
• Source of infection

• Infected persons and animals

• A single individual has directly infected a large

number of other people (superspreaders)

• A common feature is nosocomial transmission

with hospitals serving as sources for disease

amplification .
Health care workers is probably related to
• increased contact with respiratory
secretions
• contact with patients during a more
contagious phase of critical illness
• contact with particular patients at increased
spreading of SARS (i.e. superspreaders)
• or exposure to aerosol -generating patient
care procedures
Diagnostic & therapeutic procedures inside
the hospitals such as
• Diagnostic sputum induction
• Bronchoscopy
• Endotracheal intubation
• Airway suction
• are potent aerosol generating procedures
 Animal Reservoirs
• Early SARS cases associated with animal
markets
• Coronavirus genetically related to SARS CoV
detected in wild animals sold for human
consumption in Southern China
• SARS-like viruses found in civet cats, racoon
dogs and badgers
 SARS-CoV
• Animal Host?
• Palm civets (Paguma larvata)
• Other
 Clinical course - triphasic
Week 1
• fever, myalgia, systemic symptoms that
improve after a few days
Week 2
• Fever returns, oxygen desaturation, CXR
worsens
Later
• 20% get ARDS needing ventilation
Peiris - Lancet 2003b; 361: 1767-72
 Chest X-ray

• Air space consolidation

• Unilateral focal involvement

• Unilateral multifocal or bilateral

involvement (indistinguishable from

other bronchopneumonia)
 Prevention and Control
• Early detection of suspect cases
• Containment of infection
- Quarantine and isolation measures
• Protection of personnel and environment
(a) Protect health care personnel
(b) Protect other patients
(c) Protect family & community members
• Personal hygiene and environmental

hygiene

(eg. Hand washing and precaution during

sneezing and coughing)

• Barrier nursing of infected persons in the

designated SARS hospitals

Personal Protective Equipment
(PPE)
• Cap
• Mask (N 95, N 100)
• Long-sleeved gowns
• Protective eye-wear eg, goggles
• Gloves
• Boots
What is the correct way to use

a mask?

First – How not to do it!

Could result in serious injury
Could result in suffocation
Could result in serious injury and
suffocation!
 Future Perspective
• SARS virus is capable of changing rapidly
and unpredictably by undergoing genetic
variation
• Management of disease and development
of drugs and vaccines will be difficult
• Control of SARS requires reliable diagnostic
kits to diagnose patients and to monitor its
spread
 VACCINES
Several vaccine approaches
• Live attenuated vaccines
• Live recombinant vaccines
…..similar to live attenuated vaccines
…..originate from the virulent pathogen
…..altered to decrease virulence by
genomic alterations
• Killed and inactivated vaccines are either
whole killed vaccines or subunit vaccines
• Recombinant subunit vaccines are
immunogenic proteins of virulent organisms
• Epitope-based vaccine
• Live recombinant viral vector vaccines
• Microencapsulated Antigen Vaccines
• Microencapsulated DNA vaccines
• Virus-Like Particles (VLPs)
SARS Containment Strategies :
Detect, Isolate, Quarantine

50
. SARS
• is caused by SARS Co Virus.
• is a noticeable disease.
• is associated with civet cat.
• is a chronic disease.
• is transmitted by inhalation and contact

.
Severe Acute Respiratory Syndrome:
• is caused by an adenovirus
• can be prevented by hand-washing
• causes fever, atypical pneumonia and sometimes
diarrhoea
• may be caused by eating game animals
• is caused by a Coronavirus
Regarding SARS:
• It is re-emerging infection in Asia starting from
China
• direct and indirect contact is important role in
transmission
• SARS Corona virus possesses crown like
projection on its surface
• Droplets transmission generates rapid spread
• It is prevented by personal protective
equipments during patient care

•
SARS is an acute respiratory illness

A. caused by adenovirus
B. first originated in Canada
C. spread by direct and indirect contact
D. present with the symptoms resemble other
form of atypical pneumonia
E. diagnosed definitely by PCR
Middle East Respiratory
Syndrome(MERS)
• Origin-Saudi Arabia
• Year -2012
• first reported in Saudi Arabia in 2012 -
presented with acute pneumonia and acute
renal failure and passed away on 24 June
2012
• - a second case in September 2012 in Qatar,
presented with symptoms similar flu symptoms
and a sequence of the virus was nearly
identical to that of the first case
• - similar cases in November in Qatar and Saudi
Arabia
• From September 2012 to date,
• WHO has been informed of a global total of 41
laboratory-confirmed cases of infection with
nCoV, including 20 deaths.
• Several countries in the Middle East have been
affected, including Jordan, Qatar, Saudi Arabia,
and the United Arab Emirates (UAE).
• Cases have also been reported by three
countries in Europe: France, Germany, and the
United Kingdom.
• recorded 502 fatalities and 1,171 reported
cases since June 2012 when the virus first
appeared

• An outbreak of Middle East respiratory

syndrome coronavirus occurred in South Korea
from May 2015 to July 2015. From the
outbreak, a total of 186 cases have been
infected, with a death toll of 36.
Natural reservoirs

- blood from camels had protein-specific

antibodies against the MERS-CoV spike protein
- bats may also be the ultimate reservoir of the
virus
• until now, MERS-CoV does not spread in a
sustained person to person way at all

• - however, there is potential danger in that it is

possible for the virus to mutate into a strain that
does transmit from person to person

• -infection of healthcare workers (HCW) leads to

concerns of human to human transmission.
Transmission of MERS CO V
THE END