L15 Coronavirus Infections Flashcards
(42 cards)
What is the taxonomy of coronavirus?
Order : nidovirales
Family : coronaviridae
Subfamily : coronavirinae
Genera : Alphacoronavirus (mammalian + human)
Betacoronavirus (mammalian + human)
Deltacoronavirus (mammalian + avian)
Gammacoronavirus (avian)
What is the genome made up of in coronavirus?
A single stranded, positive-sense RNA virus
- genome can act as a mRNA
What is coronavirus made up of?
- genome : single strand positive-sense RNA virus
- enveloped vision
- enveloped proteins
- internal nucleocapsid
What are the key proteins in COVID?
Spike protein
M protein
Nucleoprotein
E protein
What is the role of the spike protein?
Binds to the cellular receptor
The major immunogenicity target for the current vaccines
What is the role of the M protein?
Important for vision assembly
What is the role of the nucleoprotein?
Binds to and protects the RNA genome
what is the role of the E protein?
It’s needed for efficient viral release from the cell
What are subgenomic mRNAs needed for?
They are needed for replication/assembly stages
- this includes spike protein mRNA
What is the genome translated into and why?
Translated into polyprotein which is needed for early stages of replication
Why is RNA replication error prone?
RNA polymerase does not proofread or correct errors
What enzyme is involved in RNA replication and transcription?
Virally encoded RNA-dependant RNA polymerase
Where does RNA replication take place?
In the cytosol and buds into the ER/golgi
How does RNA exit the cell after replication?
Exits the cell by exocytosis
How does the Covid virus attatch and enter the cell?
- the spike protein binds to ACE2 on the cell surface
- transmembrane protease, serine 2 cleaves the spike protein which reveals the fusion domain on the protein
- the viral and cellular membrane fuse and the nucleocapsid can enter (RNA genome)
Explain the process of viral fusion
1) the viruses spike roteins have receptor binding domains which bind to cell receptors
2) the virus fuses with the host cell which allows the RNA to enter the cell
3) the cellular machinery is hijacked to duplicate viral RNA and translate viral RNA into proteins
4) viral particles exit the cell and can infect other cell
Where is ACE2 highly expressed?
- lung type II alveolar cells
- gastrointestinal tract
- kidney
- heart
What are the three novel coronaviruses that have emerged since 2003?
- SARS-CoV
- MERS-CoV
- SARS-CoV-2
They are all betacoronviruses and they cause severe respiratory disease
What are the symptoms of SARS-CoV?
Initial fever which is followed by a few days of a non-productive cough and shortness of breath
Pneumonia develops - fatal in around 10% of cases
How is SARS-CoV diagnosed?
Infrared thermography is used to detect those with high temperatures at airports
RT-PCR and serological tests eventually became available to test for SARS-CoV
What are the symptoms of MERS-CoV?
Fever
Cough
Shortness of breath
Pneumonia
Outline MERS-CoV
Middle East respiratory syndrome-related coronavirus
First case in Jeddah, Saudis, Arabia
Case fatality of 37%
Humans are largely infected from camels
Limited spread between humans as it requires prolonged close contact
Outline SARS-CoV
Severe acute respiratory syndrome
Appeared in the Guangdong province of southern china in November 2002
8 hotel guests carried the virus to other countries including Vietnam, Singapore and Canada
Incubation period of 2-10 days
What are the symptoms of COVID-19?
High temperature - hot to touch on chest and back
Continuous cough - more than 3 coughing episodes in 24 hours
A loss or change to your sense of smell or taste
