Flashcards in L79 Deck (34):
What disease does rhinovirus cause? Transmission?
The common cold is transmitted by resp droplets
What are unique replication requirements of rhinovirus?
Prefers the cold
Nose > lungs
Why does rhinovirus make asthma worse?
Turns on Th2 response
Describe the rhinovirus genome - what is unique?
IRES = internal ribosome entry site
- Ribosome knows to start here, don't need to scan the genome for start codon
Means rhinovirus RNA genome doesn't need to be capped like human RNA does
Rhinovirus pathogenesis - how does it change host cell processes? Where in the host cell does it replicate?
Infects nasal epithelium
Shuts off all host translation to push viral translation - preferential replication
RNA genome = replicate in cytoplasm
How does rhinovirus leave host cells
Describe the timeframe of rhinovirus cold - what immunity is responsible for clearing the cold?
0 = infected
Day 2 = viral peak in serum
Day 3-4 = symptom peak
Day 5 = virus gone from serum
Innate immunity clears - entire infection moves too fast for Ab to be produced/effective
Why isn't there a rhinovirus vaccine?
Too many strains - recombination
What bug causes flu?
- or +
ss or ds
Helical or icosahedral capsid
-ssRNA in 8 indep segments
Where does Orthomyxoviridae replicate in host cells?
Which proteins are present on Orthomyxoviridae envelope?
Describe flu nomenclature:
A = type of flu (A, B or C)
Cali = where first isolated
07 = isolate #
2001 = year of isolation
H1N1 = major HA & NA type
What receptor does flu bind to enter host cells?
HA + sialic acid
How is the flu genome release after being endocytosed?
Endosome turns ACIDIC via M2 channel
HA triggered virus/endosome membrane fusion
Release genetic material alone
How does Orthomyxoviridae leave host cells?
How does Tamiflu work?
Block the release of new virions
How does flu effect ciliated epithelium?
No cilia - mucus isn't moving to clear infection
What is antigenic drift?
Minor HA & HA variations year to year
Due to mistakes made by RNA pol
What is antigenic shift?
If 2 flu viruses infect a person at the same time, the virus that buds out has a combo the RNA genomes of both
Pandemic: antigenic shift or drift?
Shift = pandemic
Epidemic: antigenic shift or drift?
Drift = epidemic
What aspect of Orthomyxoviridae would a universal flu vaccine target?
Which bugs fall under the umbrella of Paramyxoviridae? Which diseases do they cause?
RSV - pna & bronchiolits
Parainfluenza - croup
- or + RNA
Helical or icosahedral capsid?
All have -ssRNA -> has viral RNA pol to transcribe viral genome on own
2 major proteins on Paramyxoviridae envelope - describe the fxn of both
HN = binds sialic acid on ciliated epithelial cells
F protein = fusion
*Must be at NEUTRAL pH
Which parainflu serotypes cause croup? What is croup?
Croup = distinct barking cough
Which parainflu serotype causes bronchiolitis?
How does Paramyxoviridae leave host cells?
Therefore envelope is derived from host cell membrane
Where in the host cell does viral replication and assembly take place for Paramyxoviridae?
RNA virus --> cytoplasm
1. Uncoat genome
2. Viral RNA transcribed
3. +sense amde
4. Viral proteins through ER/Golgi --> surface
5. RNA to PM site --> budding
How does Paramyxoviridae interact with host immunity?
Inhibits innate immunity
Cells cant fight the infection against them --> increases spread
P2P - small infectious dose
What 2 diseases does RSV cause?