Micro - Coronavirus Flashcards
CoV is (enveloped, nonenveloped) (segmented, nonsegmented) (RNA+, RNA-, DNA)
Eveloped segmented RNA+
Two main organ systems affected by CoV
Respiratory + GI
What is unique about CoV genome?
Largest known RNA genome to date
Characteristic of all RNA+ genomes
Don’t have own RNA polymerase although their genome codes for it
CoV genome resembles ___ b/c:
Eukaryotic mRNA
Has 5’methyl cap and 3’ PolyA tail
Two major diseases caused by CoV
Common cold
SARS
How to treat common cold caused by CoV
Don’t – self-limited
Pathophys of SARS-CoV infection
Infects type II pneumocytes causing diffuse alveolar damage and ARDS
First sx of SARS
Fever
Describe progression of SARS sx
Fever
Flu-like sx for 2-7 days
Hypoxemia, dyspnea, dry cough at 3-7 days
Respiratory failure +/- GI sx with lymphopenia
Incubation period for SARS-CoV
2-10 days
Transmission of SARS-CoV
Human-to-human via droplets
Contaminated surfaces
Fecal
Virulence factors of CoV
- S (spike) protein
- HE (hemagg-esterase)
- E (envelope) protein
- M (membrane) protein
- N (nucleocapsid) protein
- RdRp (RNA-dependent RNA polymerase)
- PL-pro (papain-like protease)
- 3CL-pro (3C-like protease)
How does S (spike) protein contribute to CoV virulence?
Aids in attachment and viral membrane + host membrane fusion
like F protein of paramyxoviruses
How does HE protein contribute to CoV virulence?
Aids in viral entry and exit
How does E protein contribute to CoV virulence?
Integral part of viral membrane involved in morphogenesis, assembly, budding, and has an ion channel important in replication
How does M protein contribute to CoV virulence?
Budding + part of envelope
How does N protein contribute to CoV virulence?
Binds to viral genome + M protein and assists in assembly and budding
How does RdRp contribute to CoV virulence?
It doesn’t proofread, so allows a lot of variation
How do PL-pro and 3CL-pro contribute to CoV virulence?
Cleave immature viral polypeptides into mature viral proteins
Steps in RNA+ genome replication
- Entry and uncoating
- Transcribe RdRp + PL-pro + 3CL-pro
- RdRp + PL-pro + 3CL-pro transcribe antigenomic RNAs
- These RNAs used as templates for transcribing RNA- in a discontinuous fashion
- RNA- strands serve as templates for transcribing mRNAs
- mRNAs transcribed into non-replicase proteins
Two ways in which CoV can produce variable genomes
- High error rate of RdRp
2. Reassortment (remember: CoV genome is segmented) when two strains infect same cell
Seasonality of CoV
Winter-spring
same as influenza and hPIV3
Who gets pneumonia due to CoV?
Infants, elderly, immunocompromised
Who gets GI infection due to CoV?
Infants < 1 year
SARS-CoV was transmitted to humans via:
Bats
Who is most likely to get a CoV infection and when?
Children in winter
What history on top of respiratory symptoms might suggest SARS-CoV?
Recent travel to China, Taiwan
