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Micro unit 2 > L6 > Flashcards

L6 Flashcards

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1
Q

Influenza type

A

Orthomyxoviridae

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2
Q

Influenza genome

A

Segmented (-)ssRNA

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3
Q

Influenza virion

A

Enveloped

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4
Q

Adenovirus type

A

Adenoviridae

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5
Q

Adenovirus genome

A

dsDNA

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6
Q

Adenovirus virion

A

Non-enveloped

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7
Q

Rhinovirus type

A

Picornavirus*

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8
Q

Rhinovirus genome

A

(+)ssRNA

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9
Q

Rhinovirus virion

A

Non-enveloped

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10
Q

Three types of influenza virus:

A

A, B, and C

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11
Q

Type A most common and associated

Influenza

A

with greatest concerns

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12
Q

Influenza Identified by

A

surface antigens HA and NA

16 HA serotypes
9 NA serotypes

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13
Q

Influenza Avian vs. Human Strains

A

HA major determinant (a.a. 138 & 227 key role)
a2,3 sialic acid linkage = Avian
a2,6 sialic acid linkage = Human

NA specificity (like HA) & PB2 (point mutation) 
HA major determinant for human to human transmission
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14
Q

Type A has

Influenza

A

animal reservoir

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15
Q

Influenza HA protein’s role in cell

A

attachment and entry is well understood

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16
Q

Influenza Attachment brings cell and virus

A

membranes into proximity (A)

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17
Q

Conformation change triggered after

A

cell attachment by pH change in endosome

Causes membrane fusion (B)
Model for all enveloped viruses

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18
Q

Influenza Transcription and replication take place in

A

nucleus

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19
Q

Protected genome (RNP core) escapes

A

nucleus and buds from cell surface

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20
Q

NA critical to

A

budding

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21
Q

Influenza Transmission by

A

aerosol, large and small droplets

Infectivity greatest for particles <10 microns
ID50 as low as 0.3 to 6, 50% egg infectious doses (EID50)

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22
Q

Influenza Incubation time

A

1-4 days

Contagious day beforesymptom onset to 5 days later, children are infectious for longer

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23
Q

Influenza Seasonal (interpandemic) flu

A

Fever, malaise, nonproductive cough, sore throat

Lasts 3 to 7 days after symptoms develop

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24
Q

Influenza Currently circulating strains:

A

H3N2, H1N1

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25
Influenza Contagiousness | Reproductive number:
1 to 2
26
Influenza complications
Viral pneumonia Bacterial pneumonia Reye syndrome (Type B + aspirin) Otitis media
27
Influenza Attenuated live vaccine
Virus mutations require newvaccine development every year – antigenic shift Long lead time Usually contains an H3N2, H1N1, and Type B strain Type A strain generated through reassortment via coinfection with PR8 strain
28
Influenza Antiviral treatment
Amantidine, rimantidine Blocks entry, inhibits M2 activity Development of resistance common
29
Influenza Zanamivir or oseltamivir (Tamiflu)
Blocks release of budding virions | Development of resistance is not common
30
1918 Spanish Flu
H1N1 strain 20-40 million deaths Virulent in healthy adults; cause “cytokine storm” in lethal cases
31
1957 Asian Flu
H2N2 strain | 6 million deaths, mostly elderly and young children
32
1968 Hong Kong Flu
H3N2 | 2 million deaths
33
2009-2010 H1N1
8,000 to 18,000 deaths
34
Influenza Pandemics are thought to arise from
avian strains
35
Highly Pathogenic Avian Influenza
H5 or H7 strains Lethal in >75% of 6-8 week old susceptible chicks HPAI strains have multi-basic residues at HA cleavage site allowing replication throughout the body Skin lesions, necrotic & swollen combs, systemic infection
36
Low Pathogenic Avian Influenza
Asymptomatic to slight respiratory infection, no lesions
37
H5 and H7 strains can mutate to
HPAI strains
38
Dutch research caused great
controversy | Used H5N1 strain, high mortality rate in people
39
Could H5N1 adapt to
humans? Passaged virus in ferrets Model for human infection After 10 generations virus was capable of airborne transmission between animals Five mutations in two genes UW-Madison research identified mutations in HA that alter sialic acid binding Mortality still high for infected animals
40
Adenoviruses characterized by their
serotype | Different serotypes associated with different diseases – Ad 2 & 5 most frequently studied
41
Entry via | Adenovirus
coxsackie-adenovirus receptor (CAR)
42
Adenovirus have pH triggered
capsid disassembly | then Moves to nucleus
43
Adenovirus Gene expression in three phases
``` Immediate-early: E1A portion of genome 2 transcriptional regulators (cell & virus) Necessary to reach early stage Early: 5 genome sections E1B, E2, E3, E4, and L1 DNA replication & post transcriptional events Late Take over of cellular mRNA synthesis ```
44
Genome replication | Adenovirus
Initiated on either end, identical end sequences Replication in 5’ to 3’ direction, one strand displaced Displaced strand circularizes to allow template copy to be made Primed by the protein pTP, unusual priming strategy
45
Adenovirus Cell Cycle Regulation
DNA replication occurs during S phase Not all cells are actively replicating E1A inactivates pRb leading to S phase gene expression E1B inactivates p53 leading to S phase and preventing apoptosis Similar to oncogenic processes
46
Adenovirus E3 gene produces
proteins important to host immune evasion
47
Adenovirus Blocks
MHC class I expression reducing CTL cell killing
48
Blocks TNF
induced apoptosis
49
Adenovirus Blocks IFN-α & IFN-β action keeping
protein translation active
50
Respiratory infections very common
5 to 10% of all viral infections | 75% occur before the age of 14
51
Adenovirus Typical symptoms same as the common cold
Nasal congestion, inflammation, cough | Serotypes 1, 2, 5, & 6
52
Acute respiratory disease (ARD) | adenovirus
Severe pneumonia - seen in military recruits, crowded conditions & fatigue are risk factors Serotypes 4 & 7 Vaccine available for military personnel 17-50 yrs old
53
Rhinovirus Frequent cause of
mild upper respiratory infections
54
Rhinovirus Large antigenic diversity
Over 100 serotypes | Makes vaccine development impractical
55
Rhinovirus Humans only known
reservoir
56
Rhinovirus Attaches to intercellular
adhesion molecule 1 (ICAM-1) or the very low density lipoprotein (VLDL) receptor
57
Rhinovirus Incubation period
1 to 4days
58
Rhinovirus Duration
2 to 3 days withdetectable virus shedding | Virus shedding sometimesdetected up to 3 weeks afterwards
59
Rhinovirus Symptoms
``` Red nose (hyperemic), blood vessel dilation Nasal discharge that becomes mucopurulent (neutrophils) Epithelial damage likely due to the immune response ```
60
Rhinovirus Prevention
No vaccines: too many serotypes | No antivirals: resistant mutants
61
Ebola Virus
Filovirus Polymorphic particle, enveloped -RNA genome Helical nucleocapsid
62
Ebola transmission
Transmission Primarily body fluids Some evidence for inhalation
63
Ebola disease
Viral hemorrhagic fever Fever, headache, vomiting,diarrhea, bleeding Incubation 2-21 days
64
Ebola treatment
Supportive care Experimental treatments Vaccine – ChAd3-ZEBOV,VSV-EBOV, others

Micro unit 2 (12 decks)

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