Coronavirus
28 December 2020 16:52
Common cold coronavirus
• Positive strand enveloped viruses divided into alpha and beta subgroups.
• Coronaviruses 229E, OC43, HKU1 and NL63 usually give rise to mild upper respiratory tract
disease and account for 15-30% of common colds.
• Epithelial cells primary site of infection but dendritic cells also important and infection can
lead to syncytia formation and cell death.
• Immunity relatively short lived (~2 years) so reinfection common.
SARS-CoV-1:
Coronaviruses associated with UTRI and GI infections of mammals and birds.
Major global outbreak of SARS in China in 2002 exacerbated by extensive global human travel.
Molecular epidemiology reveals that SARS-CoV-1 arose by recombination between two bat CoVs.
• 6% bats positive for CoVs in China
Bat CoV first transmitted to palm civets then to human via live animal markets in China. Increased
transmission due to rapid adaptation of virus spike protein and travel of population worldwide.
Mutations in spike gene of SARS-CoV essential for human transmission
SARS-CoV targets the ACE2 to receptor.
MERS-CoV:
Camel is an important host for this species of coronavirus.
Middle East respiratory syndrome associated coronavirus (MERS-CoV) was first isolated from a
patient with severe, fatal pneumonia in Saudi Arabia in Sep, 2012.
• Retrospectively identified in Jordan in April 2012
To date majority of the 2,468 confirmed cases and 851 deaths (10 Nov 2019)
• Have been in the kingdom of Saudi Arabia and one large travel-associated outbreak occurred
in South Korea.
Case fatality rate: 34.3%
Virus uses dipeptidyl peptidase 4 as a receptor (CD26)
Origins of MERS CoV:
• Likely source is a zoonoses from bats
• Infections in camels appear to be the closest link with human infections
• Serology of serum dating back to 1983 indicates extensive camel infection (80% positive)
– Mainly upper respiratory tract
• Despite many deaths pathophysiology is not well defined
• Transmission likely through contact with camels but human cases reported with no camel
contact (human to human transmission?)
• 27 countries have reported cases of MERS-CoV
SARS-CoV-2:
○ Emerged at end of 2019
○ Cluster of pneumonia cases of unidentified origin in Wuhan, Hubei Province
○ Origins in "seafood" market in Wuhan
> But cases now identified 2 months prior to this infection cluster
○ Member of the beta-coronaviruses (as is MERS)
○ Spike protein binds to the human angiotensin converting enzyme 2 (ACE2) [cf SARS-CoV-1]
○ As of October 13th 2020 cases worldwide have reached 36 million and the death of 1.05
million people.
○ Many countries experiencing a second wave of infection.
Origins of SARS:
• Bats are likely source of zoonotic coronaviruses
Coronavirus Page 1
28 December 2020 16:52
Common cold coronavirus
• Positive strand enveloped viruses divided into alpha and beta subgroups.
• Coronaviruses 229E, OC43, HKU1 and NL63 usually give rise to mild upper respiratory tract
disease and account for 15-30% of common colds.
• Epithelial cells primary site of infection but dendritic cells also important and infection can
lead to syncytia formation and cell death.
• Immunity relatively short lived (~2 years) so reinfection common.
SARS-CoV-1:
Coronaviruses associated with UTRI and GI infections of mammals and birds.
Major global outbreak of SARS in China in 2002 exacerbated by extensive global human travel.
Molecular epidemiology reveals that SARS-CoV-1 arose by recombination between two bat CoVs.
• 6% bats positive for CoVs in China
Bat CoV first transmitted to palm civets then to human via live animal markets in China. Increased
transmission due to rapid adaptation of virus spike protein and travel of population worldwide.
Mutations in spike gene of SARS-CoV essential for human transmission
SARS-CoV targets the ACE2 to receptor.
MERS-CoV:
Camel is an important host for this species of coronavirus.
Middle East respiratory syndrome associated coronavirus (MERS-CoV) was first isolated from a
patient with severe, fatal pneumonia in Saudi Arabia in Sep, 2012.
• Retrospectively identified in Jordan in April 2012
To date majority of the 2,468 confirmed cases and 851 deaths (10 Nov 2019)
• Have been in the kingdom of Saudi Arabia and one large travel-associated outbreak occurred
in South Korea.
Case fatality rate: 34.3%
Virus uses dipeptidyl peptidase 4 as a receptor (CD26)
Origins of MERS CoV:
• Likely source is a zoonoses from bats
• Infections in camels appear to be the closest link with human infections
• Serology of serum dating back to 1983 indicates extensive camel infection (80% positive)
– Mainly upper respiratory tract
• Despite many deaths pathophysiology is not well defined
• Transmission likely through contact with camels but human cases reported with no camel
contact (human to human transmission?)
• 27 countries have reported cases of MERS-CoV
SARS-CoV-2:
○ Emerged at end of 2019
○ Cluster of pneumonia cases of unidentified origin in Wuhan, Hubei Province
○ Origins in "seafood" market in Wuhan
> But cases now identified 2 months prior to this infection cluster
○ Member of the beta-coronaviruses (as is MERS)
○ Spike protein binds to the human angiotensin converting enzyme 2 (ACE2) [cf SARS-CoV-1]
○ As of October 13th 2020 cases worldwide have reached 36 million and the death of 1.05
million people.
○ Many countries experiencing a second wave of infection.
Origins of SARS:
• Bats are likely source of zoonotic coronaviruses
Coronavirus Page 1
