Final; Respiratory Viruses Flashcards
What are the three types of influenza
A, B , and C (the most rare)
type A is the most common and associated with the greatest concern
What is the genome of influenza
-ssRNA in 8 segments
What type of virion is influenza
enveloped
What are the special surface antigens of influenza
16 HA (hemagglutinin) serotypes 9 NA (neuraminidase) serotypes
What is a major determinant for human to human transmission of influenza
HA
Which type of influenza has an animal reservoir
type A; mostly waterfowl
the pig is a key between bird and human transmission
True or False
HAs role is cell attachment and entry is poorly understood
False; it is well understood
What triggers the conformation change after virus and host cell membrane attachment
pH change of the endosome
The conformation change of the membranes triggered by the pH change causes what
membrane fusion; this is a model for all enveloped viruses
Where does transcription of influenza take place
in the nucleus; exception to the rule (it has -ssRNA)
The protected genome (RNP core) escapes the nucleus and buds from the cell via the use of this protein
NA
How is influenza transmitted
aerosol, large and small droplets
When is the infectivity the greatest for influenza particles
When they are the smallest, they can penetrate the deep lung
What is the incubation period of influenza
1-4 days
contagious days before symptom onset to 5 days letters; children infectious for longer
What are the symptoms of the seasonal flu
fever, malaise, nonproductive cough, sore throat
lasts 3 to 7 days after symptoms develop
What are the current circulating strains of influenza and its contagiousness
H3N2, H1N1
reproductive numer = 1:2
What are some complications of influenza
viral pneumonia
bacterial pneumonia
reye synrome (type B + aspirin)
otitis media
What type of vaccine is the influenza vaccine
attenuated live; donor virus with wild type HA/NA epitopes
Why is a new influenza vaccine required each year
antigenic shift, the vaccine usually contains H3N2, H1N1, and type B
What is used to prevent/control influenza
antiviral treatment
tamiflu
supportive care
What are the 4 major pandemics of influenza
1918 Spanish Flu (H1N1)
1957 Asian Flu (H2N2)
1968 Hong Kong Flu (H3N2)
2009-2010 H1N1
Highly pathogenic avian influenza (HPAI) contains what strains (and low pathogenic)
H5 or H7; has multi-basic residues at HA cleavage sites allowing replication throughout the body (of birds)
What are the symptoms of HPAI
skin lesions, necrotic and swollen combs, systemic infection (of birds)
True or False
H5 and H7 strains can mutate to HPAI strains
True
What is so controversial about the Dutch study involving H5N1
They used ferrets to model how H5N1 could infect humans which has a high mortality rate
What is used to characterize the adenovirus
serotype; different serotypes are associated with different diseases
What are the two most studied adenovirus serotypes
2 and 5
What is the genome of adenovirus
dsDNA
What is the virion of adenovirus
non-enveloped
How does adenovirus enter the cell
entry is triggered by coxsackie-adenovirus receptor (CAR)
pH triggers capsid disassembly
What is the method of gene expression of adenovirus
intermediate - early
early
late
What takes place during the intermediate-early phase of gene expression in adenovirus
E1A portion of genome
2 transcriptional regulators (cell and virus)
What takes place during the early phase of gene expression in adenovirus
5 genome sections
DNA replication and post transcriptional events
What takes place during late phase of gene expression in adenovirus
take over of cellular mRNA synthesis
What takes place during genome replication of adenovirus
it can be initiated at either end of the genome
5’-3’
displaced strand circularizes allowing template to be made
primed by the protein pTP
What is involved with cell cycle regulation of adenovirus
DNA replication occurs during S phase
not all cells are actively replicating
What does the E1A portion of adenovirus do to gene expression
it inactivates pRb leading to S phase
What does the E1B portion of adenovirus do to gene expression
it inactivates p53 leading to S phase and preventing apoptosis
The E3 gene of adenovirus produces what
proteins important to host immune evasion; blocks MHC-1 expression
E3 gene blocks what cytokines
TNF induced apoptosis
IFN-α and IFN-β keeping protein translation alive
With adenovirus, what disease is common
respiratory infections; 5-10% of all viral infections
What are the symptoms of adenovirus infections
common cold symptoms
nasal congestion, inflammation, cough
adenovirus also causes this disease which causes severe pneumonia in military troops (vaccine available for them)
actue respiratory disease
What makes adenovirus important involving research
it is frequently used as a vector
This is a frequent cause of mild upper respiratory infections
rhinovirus
Why is it impractical to develop a vaccine against rhinovirus
it has a large antigenic diversity; humans are the only reservoir
What does rhinovirus use to attach to host cells
attached to intercellular adhesion molecule 1 or the very low density lipoprotein receptor and extrudes its genome into the cell
What is the incubation/duration of rhinovirus
incubation is 1-4 days
duration 2-3 days with virus shedding sometimes up to 3 weeks
What are the symptoms of rhinovirus diseases
red nose, nasal discharge, epithelial damage due to immune response
What are the prevention strategies against rhinovirus
no vaccine
no antivirals; resistant mutants
