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Virology > Orthomyxoviruses > Flashcards

Orthomyxoviruses Flashcards

1
Q

Orthomyxovirus shape

A

pleomorphic

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2
Q

Orthomyxoviruses cause ___ and ____ infections

A

URI and LRI

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3
Q

______ is the most common complication of Orthomyxovirus

A

Pneumonia

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4
Q

Orthomyxovirus types

A

Influenza A, B, C

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5
Q

Influenza type ___ is the most virulent

A

A

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6
Q

Who does Influenza A infect?

A

humans and wide variety of animals (Birds, swine, seals, horses)

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7
Q

Who does Influenza B infect?

A

Only humans

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8
Q

Who does Influenza C infect?

A

Humans and Swine

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9
Q

Rarest Influenza is…

A

C

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10
Q

Influenza B epidemics are ____ because they ____

A

Mild, mutate slowly

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11
Q

Most people have antibodies against the ___ strain of Influenza

A

B

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12
Q

Types of Influenza that are included in the vaccine

A

A + B

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13
Q

Types of Influenza that cause human epidemics

A

A + B

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14
Q

Influenza virus genome (type and segmentation)

A

ss(-)RNA, segments = 8 for A/B, 7 for C

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15
Q

Influenza surface proteins

A

M1/2, Neuraminidase + Hemagglutinin

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16
Q

Influenza M1 protein function

A

forms a layer under the host cell membrane

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17
Q

Influenza Capsid shape

A

helical

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18
Q

Influenza enveloped or non?

A

Enveloped

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19
Q

Hemagglutinin functions by…

A

binding to sialic acid

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20
Q

Neuraminidase function

A

Hydrolyze sialic acid

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21
Q

Influenza B doesn’t have ____

A

M2 Protein

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22
Q

Locations of Influenza replication, assembly, and budding

A

Replicates in NUCLEUS, assembles in CYTOPLASM, buds at PLASMA membrane

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23
Q

Influenza steps of replication (6)

A

hemagglutinin BINDS to sialic acid —– virus is internalized in ENDOSOME —— endosome ACIDIFIES and capsid and vRNA are released —— vRNA goes to NUCLEUS —– mRNA is SYNTHESIZED —- mRNA TRANSPORTED to cytoplasm for protein synthesis.

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24
Q

Viral RNA polymerase type and subunits

A

vRNA-dependent RNApol, PA/PB1/PB2

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25
Q

Naked influenza virus assembles in the ____ after undergoing _____

A

nucleus, secondary transcription

26
Q

Why does influenza replicate in the nucleus

A

it doesn’t Cap or Polyadenylate it’s mRNA (it has to steal the machinery from the host cell)

27
Q

Incubation time for influenza

A

2 days

28
Q

Primary complication of influenza

A

PNA

29
Q

Who is especially at risk for influenza

A

Women in third trimester of pregnancy —– elderly —–people with CVD

30
Q

Primary influenza PNA is further complicated by…

A

secondary bacterial PNA

31
Q

Bacterial PNA from influenza… what pathogens?

A

S aureus, Strep Pneumo, H. Influenzae

32
Q

Which type of bacterial PNA is most serious?

A

Staphylococcal PNA

33
Q

Sx of Bacterial PNA

A

elevated WBC, bloody cough, CAVITARY infiltrate on chest Xray

34
Q

Non pulmonary complications of influenza

A

Myositis—-Cardiac—-Reye’s—-Encephalitis

35
Q

Reyes Sx

A

swelling of liver and brain, neuro sx and loss of consciousness

36
Q

Encephalitis is a complication of ________

A

influenza B

37
Q

Who is extremely susceptible to influenza-induced encephalitis

A

people younger than 7 or older than 55

38
Q

Influenza pathogenesis

A

establish URI by killing epithelial cells (mucus and ciliated) —- NA cleaves Sialic acid giving access to tissue —- Desquamation —– inflammatory cell response —- Interferon & cytokine responses

39
Q

Influenza spread by

A

AIR (droplets) and FOMITES

40
Q

Influenza is stabile in…

A

low temp and low humidity

41
Q

Seasonal Influenza is a result of…

A

antigenic DRIFT. New strain may require a different vaccine.

42
Q

Pandemic Influenza is a result of…

A

antigenic SHIFT of surface proteins. Whole population at risk.

43
Q

There are __ subtypes of HA and __ subtypes of NA

A

16 HA 9 NA

44
Q

Which subtypes (for HA and NA) are known to circulate widely in humans

A

H-1,2,3 N-1&2

45
Q

The only influenza HA strains known to cause pandemics are…

A

H1, H2, H3

46
Q

Ag Drift results from

A

point mutations

47
Q

Antigenic shift results from

A

exchange of a gene segment (REASSORTMENT) – Due to recombination with another genome of a different antigenic type

48
Q

Three ways Antigenic shift can occur

A

Example = Strain jumps through intermediate without changing…. Strain jumps to humans without changing…… or the intermediate gets strain from BOTH humans and bird and reassortment occurs

49
Q

Hemagglutinin binds to

A

sialic acid

50
Q

Human flu HA binds to…

A

alpha 2,6 sialic acid

51
Q

Bird flu HA binds to

A

alpha 2,3 sialic acid

52
Q

___ have both types of sialic acid receptors, which allows for greater chance of _____ to occur

A

Pigs……Reassortment

53
Q

Humans do, in fact, carry SOME _____, mostly in the trachea

A

alpha 2,3 sialic acid sequences

54
Q

Influenza antiviral drugs

A

Zanamivir, Oseltamivir…. Adamantanes

55
Q

Zaltamivir and Oseltamivir are active against what?

A

Influenza A + B

56
Q

Difference in administration of Zaltamivir and Oseltamivir

A

Zan = inhalation……. Oselt = Oral

57
Q

Adamantanes block

A

M2 protein — entry into the endosome & viral release

58
Q

Influenza vaccine types

A

Trivalent and Live attenuated

59
Q

Trivalent flu vaccine is what type?

A

inactivated.

60
Q

Trivalent vax made how? How does it protect?

A

egg grown virus, protects via IgG

61
Q

Live attenuated influenza vaccine approved for ____ administration to ________ (patients)

A

nasal……..non-pregnant 2 - 49 year olds

Virology (13 decks)

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