Viruses - Intro

Question 1

How are Virus families classified?

Answer 1

Virion Structure
Prescence/abscence of an envelope
Host Range
Mode of Replication

Question 2

What is a Virion?

Answer 2

The entire virus particle.
The outer protein capsid & inner nucleic acid.

Question 3

What part of the virus replication process occurs in the nucleus of host cell?

Answer 3

mRNA synthesis

Question 4

Where is the genomic nucleic acid synthesised?

Answer 4

the cytosol

Question 5

Why must viruses be cultured in live cells?

Answer 5

Because viruses can only reproduce within a host cell

Question 6

How are cells grown for virus cultures?

Answer 6

In a nutrient containing medium in a 5% CO2 atmosphere.

Question 7

How are HIV & HEP B transmitted?

Answer 7

Blood-Borne
Sexual
Vertical

Question 8

How is Polio transmitted?

Answer 8

Faecal-oral transmission.

Question 9

What is droplet transmission + an example.?

Answer 9

Transmission by large particels like sneeze or cough particles, has a very short range.
Influenza & RSV

Question 10

How is the herpes simplex virus transmitteD?

Answer 10

By close-contact

Question 11

What is zoonotic transmission?

Answer 11

direct transmission from animals to humans via air (influenza) or bites (rabies)

Question 12

What are examples of airborne virus’?

Answer 12

Measles & chickenpox

Question 13

What is vector-borne transmission?

Answer 13

virus’ transmitted by anthropods like mosquitoes & ticks.

Question 14

What does host range mean?

Answer 14

The range of hosts a virus can infect.
E.g. smallpox & measles only infect humans

Question 15

How can a novel virus be transmitted to humans?

Answer 15

Coinfection of human & animal/bird strains in one organism can lead to recombination & generation of a new strain trasmittable to both.

Question 16

What is viral latency & examples

Answer 16

Expression of the viral genome is restricted within the hostcell until reactivated.
E.g. Herpes Simplex

Question 17

What is transformation of a viral infection?

Answer 17

Long term infection with altered cellular gene expression.
e.g. Epstein-Barr

Question 18

What common virus’ result in chronic infection?

Answer 18

HIV, HEP B & HEP C

Question 19

Example of a virus cleared with no lasting immunity?

Answer 19

Hepatitis C

Question 20

Example of a virus cleared with long term immunity?

Answer 20

Measles

Question 21

What 3 things can be dected to diagnose a virus?

Answer 21

Full organism
PArts e.g. antigen or nucleic acid
The immune response toa apthogen e.g. antibodies

Question 22

How is a whole virus oranism detected?

Answer 22

By microscopy & culture, neither of which are used anymore

Question 23

How is part of an organism detected?

Answer 23

Antigen or DNA/RNA detection
(reacts with a coatin, e.g. antibody coating reacts with antigen)

Question 24

What is immune resposne detection used to determine?

Answer 24

Acute infection and prior infection.

Question 25

What two reasons are there for the low use of anti-virals?

Answer 25

There are often side effects (toxicity to host cell) There are limited viral protiens to target because they use host cell enzymes.

Question 26

What 4 things are antivirals used for?

Answer 26

- Prophylaxis (prevents infection) - Pre-emptive Therapy (when infection detected but no symptoms) - Overt disease treatment - Suppressive Therapy (Keeps viral replication below tissue damae rates)

Question 27

In what 3 ways do viruses cause cancer?

Answer 27

- Drives cell proliferation - Prevents programmed cell death - persistent inflammatory process leads to cancer via reactive oxygen species

Question 28

Examples of respiratory viral infection:

Answer 28

Influenza A Rhinovirus Respiratory Syncytial Virus

Question 29

Examples of Gastrointestinal viral infection?

Answer 29

Rotavirus

Question 30

Examples of neurological viral infections?

Answer 30

Enterovirus Herpes Simplex Virus

Question 31

Examples of viruses causing tumours?

Answer 31

Papillomavirus Retroviruses