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Micro unit 2 > L6 > Flashcards

L6 Flashcards

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
Q

Influenza Contagiousness

Reproductive number:

A

1 to 2

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26
Q

Influenza complications

A

Viral pneumonia
Bacterial pneumonia
Reye syndrome (Type B + aspirin)
Otitis media

27
Q

Influenza Attenuated live vaccine

A

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
Q

Influenza Antiviral treatment

A

Amantidine, rimantidine
Blocks entry, inhibits M2 activity
Development of resistance common

29
Q

Influenza Zanamivir or oseltamivir (Tamiflu)

A

Blocks release of budding virions

Development of resistance is not common

30
Q

1918 Spanish Flu

A

H1N1 strain
20-40 million deaths
Virulent in healthy adults; cause “cytokine storm” in lethal cases

31
Q

1957 Asian Flu

A

H2N2 strain

6 million deaths, mostly elderly and young children

32
Q

1968 Hong Kong Flu

A

H3N2

2 million deaths

33
Q

2009-2010 H1N1

A

8,000 to 18,000 deaths

34
Q

Influenza Pandemics are thought to arise from

A

avian strains

35
Q

Highly Pathogenic Avian Influenza

A

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
Q

Low Pathogenic Avian Influenza

A

Asymptomatic to slight respiratory infection, no lesions

37
Q

H5 and H7 strains can mutate to

A

HPAI strains

38
Q

Dutch research caused great

A

controversy

Used H5N1 strain, high mortality rate in people

39
Q

Could H5N1 adapt to

A

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
Q

Adenoviruses characterized by their

A

serotype

Different serotypes associated with different diseases – Ad 2 & 5 most frequently studied

41
Q

Entry via

Adenovirus

A

coxsackie-adenovirus receptor (CAR)

42
Q

Adenovirus have pH triggered

A

capsid disassembly

then Moves to nucleus

43
Q

Adenovirus Gene expression in three phases

A 
Immediate-early: E1A portion of genome
2 transcriptional regulators (cell &amp; virus)
Necessary to reach early stage
Early: 5 genome sections
E1B, E2, E3, E4, and L1
DNA replication &amp; post transcriptional events
Late
Take over of cellular mRNA synthesis
44
Q

Genome replication

Adenovirus

A

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
Q

Adenovirus Cell Cycle Regulation

A

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
Q

Adenovirus E3 gene produces

A

proteins important to host immune evasion

47
Q

Adenovirus Blocks

A

MHC class I expression reducing CTL cell killing

48
Q

Blocks TNF

A

induced apoptosis

49
Q

Adenovirus Blocks IFN-α & IFN-β action keeping

A

protein translation active

50
Q

Respiratory infections very common

A

5 to 10% of all viral infections

75% occur before the age of 14

51
Q

Adenovirus Typical symptoms same as the common cold

A

Nasal congestion, inflammation, cough

Serotypes 1, 2, 5, & 6

52
Q

Acute respiratory disease (ARD)

adenovirus

A

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
Q

Rhinovirus Frequent cause of

A

mild upper respiratory infections

54
Q

Rhinovirus Large antigenic diversity

A

Over 100 serotypes

Makes vaccine development impractical

55
Q

Rhinovirus Humans only known

56
Q

Rhinovirus Attaches to intercellular

A

adhesion molecule 1 (ICAM-1) or the very low density lipoprotein (VLDL) receptor

57
Q

Rhinovirus Incubation period

A

1 to 4days

58
Q

Rhinovirus Duration

A

2 to 3 days withdetectable virus shedding

Virus shedding sometimesdetected up to 3 weeks afterwards

59
Q

Rhinovirus Symptoms

A 
Red nose (hyperemic), blood vessel dilation
Nasal discharge that becomes mucopurulent (neutrophils)
Epithelial damage likely due to the immune response
60
Q

Rhinovirus Prevention

A

No vaccines: too many serotypes

No antivirals: resistant mutants

61
Q

Ebola Virus

A

Filovirus
Polymorphic particle, enveloped
-RNA genome
Helical nucleocapsid

62
Q

Ebola transmission

A

Transmission
Primarily body fluids
Some evidence for inhalation

63
Q

Ebola disease

A

Viral hemorrhagic fever
Fever, headache, vomiting,diarrhea, bleeding
Incubation 2-21 days

64
Q

Ebola treatment

A

Supportive care
Experimental treatments
Vaccine – ChAd3-ZEBOV,VSV-EBOV, others

Micro unit 2 (12 decks)

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