Class #6 - Infection (part2) - Influenza

Question 1

Affinity of influenza virus is to ….cells?

Answer 1

Tracheobronchial epithelial cells, specifically the ciliated epithelial cells

Question 2

Difference between influenza and cold?

Answer 2

Influ: resp and systemic Sx, with sudden onset

Cold only throat and nose Sx, gradual onset

Question 3

Common complication of influenza in child?

Answer 3

Otitis media

Question 4

Sx of influenza?

Answer 4

Headaches, fever, myalgia, sore throat, runny nose.

Question 5

Biggest influenza pandemic?

Answer 5

1918:Spanish flu, 50 millions died

Question 6

Most recent influenza pandemic?

Answer 6

H1N1 209

Question 7

20th century flu Pandemics?

Answer 7

1918, 1957 (asian flu 1-2millions), 1968 (hong-kong flu, 700 000), 2009 (Swine flu, 280 000)

Question 8

Influenza DNA or RNA virus?

Answer 8

RNA

Question 9

What are the types of flu virus?

Answer 9

A,B,C

Question 10

What allows flu virus to recognize epithelial cells?

Answer 10

Hemagglutinin

Question 11

Influenza type A and B difference with type c?

Answer 11

A/B: 8 RNA, neurominidase and hemagglutinin

C: 7 RNA and no neurominidase. Once you get infected you retain immunity, which is not true of A/B

Question 12

What is RNP?

Answer 12

Ribonucleoprotein that contains coiled RNA in flu virus

Question 13

What make influenza virus special and dangerous?

Answer 13

Potential for cross species connection

Question 14

Different type of antigenic variations?

Answer 14

drift and shift

Question 15

Antigenic drift?

Answer 15

Small mutation in RNA of virus overtime as virus replicates, happens all the time. This can make Ig less effective with time

Question 16

Antigenic shift?

Answer 16

Different RNA strains inside a cell recombine resulting in abrupt major change resulting in new hemagglutinin or neuraminidase or both, rare.

Question 17

Difference between influenza A/B, which is more dangerous?

Answer 17

A: Drift and Shift, more dangerous.
B: Drift

Question 18

Influenza life cycle? + complete time?

Answer 18

1) Absorption: H binds to sialic acid on epithelial cells
2) Endocytosis
3) Fusion: M2 p+ proton ion channel acidify interior, weakening bond between cell and virus
4) Replication/transcription of RNA
5) Assembly
6) Release: Neuraminidase frees the new virus by breaking bond with sialic acid on cell membrane
- > 4-6 hours

Question 19

Hemagglutinin recognize…..linkage in human and ….linkage in birds?

Answer 19

human: alpha 2-6
birds: alpha 2-3

Question 20

Specificity of virus is due to?

Answer 20

sialic acid uniqueness in the epi. cell of upper airways

Question 21

Why can birds spread virus in their feces?

Answer 21

Because they have sialic acid bonding site in their GIT

Question 22

Drugs blocking (M2p+) release of virus from endosomic vesicule?

Answer 22

A”mantadine” and Ri”mantadine”

But, virus can be resistant

Question 23

Drugs blocking release of virus from cell?

Answer 23

Oselt”amivir” and Zan”amivir”

Question 24

Influenza nomenclature?

Answer 24

type/geographic origin/isolate #/year discovered/HA:NA

Eg: A/Fujian/411/2002/H3N2

Question 25

Why H5N3 dangerous?

Answer 25

Birds to human with 55% death. Rare spreading human to human, but if it did, really dangerous.

Question 26

ASA in children with flu?

Answer 26

Rare Reye Syndrome

Question 27

M2 channel only present on?

Answer 27

Type A