Orthomyxoviruses Flashcards Preview

Microbiology Exam #1 > Orthomyxoviruses > Flashcards

Flashcards in Orthomyxoviruses Deck (49):
1

What shape are orthomyxoviruses?

Pleomorphic

2

Symptoms of Orthomyxo?

Febrile illness of upper and lower respiratory tract
Sudden onset of fever, cough, soreness, malaise, etc.

3

Most common serious complication of orthomyxo?

Pneumonia

4

Types of Influenza?

A, B, and C

5

Describe Influenza Type A

Most virulent human pathogen
Infect many animal species
Wild aquatic birds are a natural reservoir

6

Describe Influenza Type B

Milder than Type A
Only Humans
Mostly milder, mutate slowly

7

Describe Influenza Type C

No epidemics
Rarely causes disease
Nobody really cares...

8

What is an influenza proton pump called?

M2

9

What is M2 used for?

Uncoating

10

Describe the influenza genome?

-ssRNA, 8 segments

11

Influenza caspid? Envelope?

Helical
Yes

12

Where does influenza replicate?

The nucleus

13

Why does influenza rep. in the nucleus?

To hijack protons used to add the protective RNA cap

14

How does influenza enter a cell?

Binding of hemaaglutinin to cell surface

15

What targets neurominidase?

Tamiflu

16

Components of ribosomal RNA?

PA, PB1, PB2

17

Typical clinical manifestation of influenza?

Fever, Sore throat, myalgia, headache
Ocular symptoms (photophobia, tears, ache)
Weakness, fatigue, cough, GI probs

18

Two influenza complications...

Primary influenza pneumonia and secondary bacterial pneumonia

19

Describe primary influenza pneumonia.

Progressive cough, dypnea, and cyanosis
Infiltrative patterns without consolidation on radiograph

20

Who is at risk for primary influenza pneumonia?

3rd trimester women
elderly patients

21

Causes of secondary bacterial pneumonia?

Staph Aureus
Strep pneumoniae
Haemophilus influenza

22

What is the most serious complication of secondary bacterial pneumonia?

Staphylococcal pneumonia

23

Symptoms of staphylococcal pneumonia?

Severely ill
Hypoxemia, Elevated WBC, productive bloody cough, cavitary infiltrates on radiograph

24

Potential non-pulmonary complications of influenza?

Myositis
Cardiac Complications
Reye's syndrome
Encephalitis

25

What is myositis?

Muscle inflammation

26

Examples of cardiac complications.

Myocarditis, pericarditis

27

What is Reye's syndrome?

Swelling in Liver and Brain
Confusion, Seizures, Loss of Consciousness
Approx. 40% fatal in children/teens

28

What is contraindicated for childhood of adolescent fevers because of Reyes?

Asprin

29

What is encephalitis?

Fever, Headache, Seizures, Confusion, Loss of Consciousness, Coma

30

Groups at risk for encephalitis?

Esp. children younger than 7, adults older than 55

31

Pathogenesis of Influenza?

Virus establishes a local URT infection and kills epithelial cells
NA cleaves sialic acid residues in the mucus, providing tissue access
If into LRT, severe desquamination or epithelium
Immune/Inflammatory response triggered

32

How is influenza transmitted?

Mostly droplets, human-to-human
Also contaminated surfaces, pass to mouth

33

T or F. Influenza is stable at low temperatures and humidity.

True

34

What is seasonal influenza?

Inf. caused by antigenic drift
Closely related to the old ones
Could require opsinization or boost if large drift or immunocompromised

35

What is pandemic influenza?

Result of antigenic shift
Serious threat to global health, no pre-existing immunity

36

How many HA subtypes?

16

37

How many NA subtypes?

9

38

What carrier can hold all influenza viruses?

Birds

39

What HA and NA subtypes can humans carry?

H1-H3 and N1-N2

40

What is the difference between genetic drift and shift.

Drift -- Minor change, same subtype
Shift -- Major change, new subtype

41

How does antigenic shift happen?

Two viruses infecting a single cell, recombination on genome

42

What are the three ways antigenic shift can occur?

1. Aquatic bird to host to human
2. Intermediate host gets inf. from bird and human. New reassortment passes to humans
3. Bird to human

43

How do influenza As all bind?

HN binding to proteins with sialic acid species

44

What sialic acids do human inf. prefer?
What sialic acids do bird inf. prefer?

alpha 2-6
alpha 2-3

45

Why can the bird and people share?

They both have some of both sialic acid residues

46

How to treat influenza?

Vaccine and Antivirals

47

What antivirals work against influenza?

Zanamivir and Oseltamivir
Rimantidine and Amantadine (only A)

48

What are the available vaccines for influenza?

Trivalent Inactivated Vaccine
Live attenuated vaccine

49

Cold or Flu? Fever, Headache, Fatigue, Cough

Flu