M2-Picornaviridae Flashcards
What Baltimore group are Picornaviridae in?
Group 4: (+)ssRNA
True or false: Picornaviridae are enveloped viruses
FALSE
-non-enveloped
How do viruses in Picornaviridae family get out of cells?
Cell Lysis
Are viruses in Picornaviridae family environmentally stable?
Yes
-non-enveloped
-can live in GI tract/harsh environments
What are pathogens in Picornaviridae
-Poliovirus
-Rhinovirus
-Hepatitis A
-Coxsackieviruses
-Enterovirus
-Foot and mouth disease
-Norovirus
True or false: Most poliovirus infections are symptomatic
False
-most are asymptomatic
-poliovirus enters the nervous system around 1% of the time
What is the normal route of Poliovirus and which route does it take for pathogenesis
Oral to fecal route
-goes off target to brain and meninges which causes paralysis
What did rising concern and public fear of poliovirus lead to?
Two vaccines:
-Salk vaccine
-Sabin vaccine
What are the main differences between the Salk and Sabin poliovirus vaccine?
Salk:
-Inactivated/killed virus
-does not induce antibodies at natural route of infection (intestine/GI)
-needs to be injected
-no chance of reactivation
Sabin:
-live attenuated
-natural route of infection
-Given orally
-Small chance of reactivation
True or false: Picornaviruses are non-enveloped lytic viruses
True
-Can release 10^5 viruses per infected cell
Instead of a cap at the 5’ end what do Picornaviruses have?
-IRES
-Vpg
True or false: These viruses degrade eIF4E to block host translation
True
Where does replication occur?
Replication occurs at cytoplasm and membranes
What are some things we learned from studying Picornaviruses?
-1st animal virus discovered (foot & mouth disease)
-1st evidence of RNA dep RNA pol
-Polyprotein & cleaved by protease
-IRES mediated cap independent translation
-Vaccine research
-Evolution of RNA viruses
What is error catastrophe?
Ribavirin will bind which pushes virus over error threshold
-a way to inhibit virus
-leads to mutations–>high error freq
What does R0 measure?
How many people a single infected person will infect
What does it mean when R0 > 1?
Epidemic continues
What does it mean when R0 < 1?
Epidemic dies out
What are 2 ways to reduce R0?
- # if contacts in a given time –>Encounter less people
- Transmission probability per contact –> reduce transmission
How to calculate R0?
(# of contacts in a given time) x (Transmission probability per contact) x (duration of infection)
What is the basis of herd immunity?
Effective R
What is Effective R?
Tells us how much of the population needs to be vaccinated
-needs to equal 1
How to calculate Effective R?
R0 x Fraction of susceptible population
What is one way to reduce the effective R?
Vaccinate people
-reduce the # of people who have never seen a virus
True or false: All vaccines have an effective vaccine rate
False
-not all vaccines are effective, people could get the vaccine and still not reach the desired % rate
What is forward genetics?
Mutating the virus, looking for a phenotype change and sequencing the virus
What is reverse genetics?
Make specific individual mutations and test whether it makes a given phenotype
Which Baltimore group of RNA viruses do you think will be easiest to do reverse genetics on?
Group 4–> (+)ssRNA
-b/c all we need is an RNA
What are the 5 types of different vaccines and Covid 19 vaccine example?
1.Whole Inactivated –>sinovac
2. Recombinant –>Novavax
3. Live attenuated –>none
4. mRNA vaccines –> Moderna and Pfizer
5. Viral Vector vaccines–>Astrazeneca & J&J
