Viruses

Question 1

Describe why viruses can not be described as cells.

Answer 1

Cannot replicate independently of a host cell

Question 2

What are the 3 types of virus shapes?

Answer 2

Icosahedral - 20 equilateral triangle faces

Helical

Complex

Question 3

Most viruses have tissue tropism. What does this mean?

Answer 3

Specific host range

Only infect specific type of host cell

Question 4

What is the name given to the extracellular form of a virus?

Answer 4

Virion

Question 5

Describe the structure of a virion.

Answer 5

Nucleic acid genome and associated polymerases surrounded by protein capsid (coat)

This is surrounded by a lipid envelope (sometimes) with attachment proteins

Question 6

How does a virus synthesise it’s protein coat?

Answer 6

It doesn’t

It steals it from the host cell that produced it

Question 7

What are the 3 routes of transmission for HIV?

Answer 7

Blood-borne
Sexual
Vertical

Question 8

What other viral infection has the same transmission routes as HIV?

Answer 8

Hepatitis B

Question 9

Aside from HIV and Hep B, what virus is transmitted via blood?

Answer 9

Hepatitis C

Question 10

What viruses are transmitted via the faecal-oral route?

Answer 10

Hepatitis A
Hepatitis E
Polio

Question 11

What viruses can be caught via droplet infection?

Answer 11

Influenza

RSV (Respiratory syncytial virus)

Question 12

What is the method of transmission of measles?

Answer 12

Airborne

Question 13

Aside from measles, what other virus undergoes airborne transmission?

Answer 13

Chickenpox

Question 14

Herpes simplex, CMV and EBV are transmitted through what?

Answer 14

Close contact

Question 15

Vector borne viruses are spread by bugs. Give 3 examples of vector borne viruses, and what insect spreads them.

Answer 15

Dengue
Yellow fever
Chikungunya

All 3 spread by mosquitoes

Question 16

Rabies, MERS and Ebola are viruses spread through what route of transmission?

Answer 16

Zoonotic

Question 17

What is viral latency?

Answer 17

The virus lying dormant in the cells of the organism

Few viral antigens and no viral particles are produced

Question 18

Give an example of a virus that undergoes latency.

Not HIV

Answer 18

Herpes simplex

Varicella zoster

Question 19

Viral infection can often lead to cancer. What 3 ways can this occur?

Answer 19

Affects cell cycle modulation - drives cell proliferation

Prevention of apoptosis (programmed cell death)

Reactive oxygen species mediated damage
(Persistent inflammatory processes can lead to cancer via reactive oxygen species)

Question 20

There are 3 basic ways to detect a virus, what are they?

Answer 20

Detect the whole virus

Detect part of the virus - antigens / nucleic acids

Detect an immune response to a pathogen - antibodies

Question 21

One way of detecting ‘the whole virus’ is through microscopy. What is the other way?

Answer 21

Culture

Question 22

‘All antiviral agents are virustatic, and not virucidal.’

What does this mean?

Answer 22

Virustatic agents prevent the growth and development of viruses, whereas virucidal agents destroy viruses.

So treatment only aims to prevent viruses from replicating, but will not kill the viruses themselves.

Question 23

Some antiviral therapy is prophylactic. What does this mean?

Answer 23

To prevent infection = prophyaxis

Question 24

Some antiviral therapy is utilised when there is evidence of infection/replication, but no symptoms are yet present. What is this called, and when is it often done?

Answer 24

Pre-emptive therapy

Often done after surgery and/or on immuno-suppressed patients

Question 25

What is the purpose of suppressive therapy?

Answer 25

Keep viral replication below the level that would cause tissue damage in an asymptomatic infected patient

Question 26

Summarise what types of antiviral therapy there are...

Answer 26

Prophylactic Pre-emptive Overt Suppressive

Question 27

What major viruses have been eradicated recently?

Answer 27

Measles | Polio

Question 28

Use a single word to describe the consequence of viral infection...

Answer 28

Syndromes

Question 29

Respiratory syndromes are caused by what?

Answer 29

Influenza Measles Chickenpox

Question 30

What viruses cause neurological syndromes to develop?

Answer 30

``` Rabies Polio Enterovirus HSV VZV ```

Question 31

Dengue fever, rubella, parvovirus and chikungunya cause arthralgia. What is arthralgia?

Answer 31

Joint pain

Question 32

Gastroenteritis sydromes are causes by what?

Answer 32

Norovirus Rotavirus Adenovirus

Question 33

Aside from Haepatitis A, B, C, D & E, what viruses are responsible for the development of Hepatitis syndromes?

Answer 33

CMV EBV Yellow fever

Question 34

Enteroviruses cause neurological syndromes and what else?

Answer 34

Skin infections

Question 35

What does HSV cause?

Answer 35

Neurological syndromes Skin infections Eye infections

Question 36

CMV, Rubella, VZV and parvovirus are responsible for causing what syndromes?

Answer 36

Congenital abnormalities (birth defects)

Question 37

Lymphadenopathy refers to disease causing abnormalities in the size of lymph nodes. What viruses can cause this?

Answer 37

HIV CMV EBV

Question 38

What viruses are responsible for causing eye infections?

Answer 38

HSV VZV Adenovirus

Question 39

What are the 3 mechanisms for which a viral infection can lead to cancer

Answer 39

Modulation of cell cycle control Modulation of apoptosis Reactive oxygen species mediated damage