Ch. 15 - Viral Infections of URT Flashcards Preview

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Flashcards in Ch. 15 - Viral Infections of URT Deck (17):
1

Rhinovirus

Common cold

(+) ss RNA
Naked
Icosahedral

Cooler temp (in nares) - 33C --> better in drier environments - prevail in winter, everyone inside more

>100 strains (50% URT) --> why so difficult to develop vaccine: too many strains to immunize against

Transmission via airborne respiratory droplets or contaminated objects

No antibiotics; antihistamines to treat symptoms

Vaccine: identified core set of genes; develop vaccine against protein product from core set?

2

Adenovirus

DNA ds - encodes up to 40 genes

First found in adenoid tissue

Transmission via respiratory droplets

Infection cause: acute febrile pharyngitis, conjunctivitis, acute respiratory disease (military recruits - crowded places) --> all can progress to viral pneumonia

3

Laryngitis

Hoarse, sore throat

From any common cold virus

4

Influenza - general

Communicable, acute infection

Transmission via airborne respiratory droplets

1918 pandemic - Spanish flu

Symptoms: fever, body-wide aches, dry cough
vs. cold - productive cough

Preschoolers first infected

No cure, trivalent vaccine available every year

5

Influenza A

8 (-) ss RNA
Segments
Helical
Enveloped
Matrix protein

Subtypes based on spike proteins:
(H) Hemagglutinin - help virions attach and penetrate host cell
(N) Neuraminidase - help virions release from host cell after replication

Cause of most pandemics
New strain every year
Reservoir: humans, pigs, birds

6

Influenza B

New strain every year
Less common
Reservoir: humans

7

Influenza C

Mild respiratory illness

Not cause of epidemics

8

Influenza vaccine

Trivalent: 2 subtypes A, 1 subtype B

Quadrivalent: 2 subtypes A, 2 subtypes B

Each year's vaccine based on predominant strain from previous years' viruses

9

Antigenic variation

Chemical and structural changes in spike proteins every year

10

Antigenic drift

Small changes from point mutations during translation (A,B)

11

Antigenic shift

Major, abrupt changes in structure (A)

1. Jump directly to new species (Ex: Avian flu)

2. Gene swapping - reassortment between different flue viruses; swine = mixing vessel; intermediate host - can be infected by both avian and human flu viruses

12

Complication from the flu

Pneumonia, or other secondary bacterial infections

Most the immunocompromised

H. Influenza, S. Aureus, S. Pneum

13

Guillan-Barre Syndrome

Body mistargets infection

Damages own peripheral nerves

14

Reyes Syndrome

Children who take aspirin

Nausea, vomiting

May progress to brain and liver --> progressive mental challenges

15

Antiviral Flu Therapies

No longer prescribed: antiviral; most strains show resistance
Amantidine
Rimantadine

Currently perscribed: target N spikes --> prevent release of new virions, but not replication
Tamilfu
Relenza

15

Respiratory Syncytial Virus (RSV)

Children under 1 year

Infects bronchioles and alveoli --> cause cells to fuse to syncytia

Infected lung cells appear as large multi-nucleated cells

16

SARS (SARS-CoV)

Coronaviridae

Transmission: person-to-person or contaminated objects

Reservoir - Bats

Moderate URT --> severe illness and pneumonia

10% mortality rate

All pts isolated at least 10 days once fever breaks - to contain

2003 outbreak: 114 day epidemic
China-->Hong Kong-->Canada and US
Spread of disease through air travel