CMB1003/L12 Intro to Virus Structure

Question 1

Are viruses single-stranded, double-stranded RNA or DNA?

Answer 1

They can be all of them

Question 2

Why do some viruses have a capsid?

Answer 2

To protect the genome

Question 3

What is a nucleocapsid?

Answer 3

The genome and the capsid protein

Question 4

Why are viruses described as obligate cellular parasites?

Answer 4

They can only grow in appropriate host cells

Question 5

What is a virion?

Answer 5

A purified virus particle

Question 6

Give the 5 basis structural forms of viruses.

Answer 6

Naked isosahedral
Naked helical
Enveloped icosahedral
Enveloped helical
Complex

Question 7

Give an example of a naked icosahedral virus.

Answer 7

Poliovirus

Question 8

Give an example of a naked helical virus.

Answer 8

Tobacco mosaic virus

Question 9

Give an example of an enveloped icosahedral virus.

Answer 9

Herpes

Question 10

Give an example of an enveloped helical virus.

Answer 10

Measles

Question 11

Give an example of a complex virus.

Answer 11

Poxvirus

Question 12

Explain the mechanism by which the Oxford/Astrazeneca COVID-19 vaccine delivers the gene for COVID-19 spike protein.

Answer 12

Via a harmless adenovirus vector

Question 13

Explain the difference between an oncolytic and an oncogenic virus.

Answer 13

Oncolytic viruses can be used to treat cancer
Oncogenic viruses which can cause cancer

Question 14

Describe, simply, the cycle of viral infection, starting with transmission. (5)

Answer 14

Transmission
Entry
Primary site replication
Spread within host
Shedding

Question 15

What are the 2 modes of viral transmission?

Answer 15

Horizontal
Vertical
Zoonosis

Question 16

Describe the modes of horizontal transmission. (2)

Answer 16

Respiratory
Faecal-oral

Question 17

Give an example of a respiratory transmitted virus.

Answer 17

Rhinovirus
Influenza
Measles
Coronavirus

Question 18

How can droplets cause infection? (3)

Answer 18

Inhalation
Through conjunctiva (eyes)
Fall onto surfaces and transfer
Be dessicated

Question 19

Give an example of a faecal-orally transmitted virus.

Answer 19

Rotaviruses
Hepatitis A
Poliovirus

Question 20

Why is faecal-oral a very efficient mode of viral transmission?

Answer 20

Viruses can grow to high titres in faeces

Question 21

Give an example of a sexually transmitted virus.

Answer 21

HIV/AIDS
Hepatitis B
Human Papilloma Virus (HPV)
Herpes simplex virus (HSV)

Question 22

Why can HSV re-emerge when a host is vulnerable?

Answer 22

It lies dormant in nerves that supply the original area of infection

Question 23

Give 2 less common modes of horizontal viral transmission.

Answer 23

In urine
Mechanical transmission

Question 24

Give 2 examples of vertical infection.

Answer 24

Mother-to-child
Primary infection during pregnancy
Reactivation of persistent infection

Question 25

Give an example of transplacental vertical transmission.

Answer 25

Rubella
Congenital defects

Question 26

Give an example of a virus transmitted during birth.

Answer 26

Herpes simplex virus

Question 27

Give an example of a virus transmitted from mother to child after birth.

Answer 27

HIV-1 in breast milk
Hepatitis B in saliva

Question 28

What is a reservoir and a vector with regards to zoonosis?

Answer 28

Reservoir - animal in which virus replicates
Vector - animal which transmits the virus

Question 29

Give 3 ways of breaking the chain of viral transmission.

Answer 29

Education
Barrier nursing
Quarantine/isolation/containment