Mhd5 Influenza Virus

Front 1

Influenza is classified as what type of virus

Back 1

orthomyxovirus

Front 2

Major sx of influenza infection

Back 2

resp disease w/ fever and myalgia

Front 3

Mostclinically significant serotype of influenza

Back 3

Influenza A (cause epidemics and infect same host more than once in lifetime)

Front 4

Describe the ultrastructure of the Influenza A virus

Back 4

-enveloped

-very polymorphic particles

-different shapes (spherical and others filamentous)

-contain glycoprotein spike projections

-helical Ribonucleoprotein assemblage

Front 5

Describe the genome of the influenza A virus

Back 5

-RNA
-segmented
-minus-strand (need to be made to mRNA first)

Front 6

What proteins form the projecting spikes on the influenza envelope

Back 6

hemagluttin (HA)

and

neuraminidase (NA)

Front 7

Describe the oles of M1, M2, and Nucleoprotein (NP) for the flu virus

Back 7

-M1: under envelope and associates with NP

-NP: coats the RNA segment

-M2: tetrameric membrane spanning complex

Front 8

What is the roles of PB1, PB2, and PA enzymes for the flu virus?

Back 8

present in virion, bound to helical ribonucleoproteins

participate in viral RNA replication

Front 9

What does HA bind to on cell surfaces?

Back 9

sialic acid

Front 10

Describe the synthesis of HA in virus infected cells

Back 10

cotranslational insertion into ER

protein folding and oligomerization

3 units are made (for a trimer)

each monomeric unit is proteolytically cleaved (generates amino terminal and membrane anchored fragments)

Front 11

General roles of HA and NA in influenza infection

Back 11

HA: promote virus binding

NA: promote virus release and dissemination

Front 12

Describe general shape of NA

Back 12

four identical molecules form a box-shaped tetramer

box tetramer attaches to particle membrane by a slender stalk

outer surface of NA tetramer recognizes sialic acid and cleaves it

Front 13

Initial step in influenza infection

Back 13

HA attachment to sialic acid receptors

multiple trimers (up to 500) involved

entire particles are internalized into endosome

Front 14

Describe endosome acidification, and how this plays a role in influenza infection

Back 14

endosome pH is low (5-6)

acid environment alters flu particle in 2 ways:

1. protons bleed thorugh M2 pores = acidify virion interior. This frees ribonucleoprotein complexes and gets them ready for transport into the nucleus

2. alters charge of HA spike, changes their shape, and promotes fusion between flu and endosome membranes.

End result = delivery of nucleocapsids into cell cytosol

Front 15

Where are nucleocaspids targeted to in influenza infection? What is the goal of this?

Back 15

nucleus

for transcription to occur

Front 16

What to PB2, PB1, and PA form at the cell nucleus?

Back 16

RNA transcriptase

Front 17

What is "cap-snatching"?

Back 17

virulent form of parasitism, involved in flu transcription

virus-encoded endonuclease cleaves 5' terminal 10-13 nucldotides from host transcript

short RNAs used to prime viral transcription

End result: promotes VIRAl transcription (and thus translation), but disables cellular protein synthesis

Front 18

How do the newly synthesized HA, NA, and M2 get to the infected cell surface? where are the rest of the proteins targeted to?

Back 18

utilize the normal cellular exocytic pathway

rest- go back to the nucleus

Front 19

Describe the replication of the virion genome

Back 19

late in infection

virion RNAs of flu serve as templates for synthesis of cRNA (templates for minus strand virion RNAs)

Front 20

Describe packaging process of RNA virions during infection. Which proteins are involved?

Back 20

RNAs are packaged in conjunction with NP, transcriptase proteins, and M1.

Core migrates toward cell surface, acquire envelope, and later HA, NA, and M2. = BUDDING

Front 21

BIG THREE important things regarding influenza epidemiology

Back 21

1. Influenza A infection prevented by antibody to HA protein. Lots of HA proteins however, so antibodies form prior infection is not always useful (in cases of novel influenza)

2. Broad range of hosts for influenza provides transmission from animals to humans

3. 2 flu viruses can infect the same cell, and RNA segments from parent viruses can reassert = novel gene constellations in progeny.

Front 22

Mechanism responsible for influenza pandemics

Back 22

antigenic shift

flu antigen (HA) in one strain is shifted to a type not previously observed in human populations. shift is from reassotment of RNA segments = pathogenic assortment.

Front 23

Mechanism responsible for influenza epidemics

Back 23

occur more frequently vs pandemics

results from ANTIGENIC DRIFT.

Flu antigen (HA) drifts to a marginally altered form (due to inherently error prone flu replication) = escape immune surveilance

Front 24

Mechanism responsible for influenza endemics

Back 24

infection of individuals who escaped infection during previous epidemics

Front 25

Major sx of influenza infection

Back 25

fever

sore throat

nonproductive cough

ha

Front 26

where does the influenza virus replicate?

Back 26

ciliated columnar epithelium of resp tract

Front 27

describe major risk with influenza infection

Back 27

secondary pneumonia from bacterial infection (s. aureus) can occur

Front 28

Describe age group/risk factors for most influenza related deaths

Back 28

>65+ yo

risk increased in those suffering from chronic pulm or cardiac diseases

Front 29

Lab diagnosis of influenza is made how?

Back 29

throat swabs by virus cultivation in cell lines


viral antigen identification in infected cells by EIA

SEROLOGY NOT HELPFUL (PRIOR ANTIBODIES CONFUSING)

Front 30

Major classifications of influenza

Back 30

1. Serotypes (A,B,C)

2. Host of origin

3. geographic location of isolate

4. strain number, yr of isolation

5. HA and NA subtypes

Front 31

What is the critical immunogen for influenza vaccines?

Back 31

HA

Front 32

How are influenza vaccines made?

Back 32

virus is grown in embryonated chicken egg

purified and inactivated with formalin

usually standarized for immunoreactive HA

Front 33

Describe the concept of the live attenuated influenza vaccination

Back 33

administered via nasal spray

virus vaccine replicates enough to elicit powerful immune response

does not replicate enough to cause disease

Front 34

How does Amantadine work?

Back 34

antiviral against influanza A

blocks M2 protein ==> stops flow of protons into virion interior during penetration

nucleocapsids are incompetent for migration due to this

Front 35

How to oseltamivir and zanamizir work?

Back 35

block activity of NA, and limit dissemination of infection in resp tract

block influenza A and B

Front 36

What type of virus is the rhinovirus?

Back 36

picornavirus

Front 37

Describe major sx and optimal conditions for the rhinovirus

Back 37

acute upper resp disease

particles = acid labile (no enteric infection), and growth os optimal in low temps found in nasopharynx

Front 38

When do rhinovirus epidemics peak? incubation and sx duration?

Back 38

spring and fall peaks

incubation 2-3 days

sx for 3-7 days

Front 39

illnesses associated with adenovirus

Back 39

upper resp disease

conjunctivitis/pink eye

Front 40

Adenovirus is what type of virus?

Back 40

non-enveloped

DNa virus

lots of serotypic diversity

Front 41

population most frequently infectd with adenovirus?

major spread routes?

epidemic periods?

Back 41

infants

resp or fecal-oral

late winter = epidemic time

Front 42

Is there a vaccine for addenovirus?

Back 42

live attenuated vaccine against serotypes 4 and 7

only given to military recruits