Ch. 15 - Viral Infections of URT

Question 1

Rhinovirus

Answer 1

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?

Question 2

Adenovirus

Answer 2

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

Question 3

Laryngitis

Answer 3

Hoarse, sore throat

From any common cold virus

Question 4

Influenza - general

Answer 4

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

Question 5

Influenza A

Answer 5

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

Question 6

Influenza B

Answer 6

New strain every year
Less common
Reservoir: humans

Question 7

Influenza C

Answer 7

Mild respiratory illness

Not cause of epidemics

Question 8

Influenza vaccine

Answer 8

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

Question 9

Antigenic variation

Answer 9

Chemical and structural changes in spike proteins every year

Question 10

Antigenic drift

Answer 10

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

Question 11

Antigenic shift

Answer 11

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

Question 12

Complication from the flu

Answer 12

Pneumonia, or other secondary bacterial infections

Most the immunocompromised

H. Influenza, S. Aureus, S. Pneum

Question 13

Guillan-Barre Syndrome

Answer 13

Body mistargets infection

Damages own peripheral nerves

Question 14

Reyes Syndrome

Answer 14

Children who take aspirin

Nausea, vomiting

May progress to brain and liver –> progressive mental challenges

Question 15

Antiviral Flu Therapies

Answer 15

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

Question 15

Respiratory Syncytial Virus (RSV)

Answer 15

Children under 1 year

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

Infected lung cells appear as large multi-nucleated cells

Question 16

SARS (SARS-CoV)

Answer 16

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