Viral Properties

Question 1

What is the size range of viruses?

Answer 1

20-300 nm

Question 2

What is the shape of the Adenovirus?

Answer 2

Icosahedron

Question 3

What is the shape of the Rotavirus?

Answer 3

Icosahedron

Question 4

What is the shape of the Ebola virus?

Answer 4

Filamentous

Question 5

Can viruses generate their own energy?

Answer 5

Not independently, but can when inside the host and when it utilises its machinery

Question 6

Describe the two features of a virus

Answer 6

Nucleocapsid: The genome contained within a protein capsule

Virion: The infective viral particle

Question 7

Describe the differences between a Naked virus and an Enveloped virus

Answer 7

In a naked virus, the virion is the nucleocapsid itself

In an enveloped virus, the virion is the nucleocapsid plus the envelope

Question 8

Where does the viral envelope come from?

Answer 8

Derived from the host cell

Question 9

What are the role of “spikes” found on the surfaces of viruses?

Answer 9

They protrude from the surface of the virus particles and are involved in contact with the host cell

Question 10

Describe the structure of the Influenza virus

Answer 10

• Enveloped

- Has spikes: H - Haemaglutinin receptor and N - Neuaminidase

Question 11

Describe the structure of the Norovirus

Answer 11

• Non enveloped, naked

Question 12

Give two examples of naked viruses

Answer 12

Rotavirus

Norovirus

Question 13

Give three examples of enveloped viruses

Answer 13

HIV
Ebola
Influenza virus

Question 14

What are the consequences of being a naked or enveloped virus?

Answer 14

Naked viruses are more stable under environmental stress, spread more easily and can survive the gut / poor water treatment

Enveloped viruses must stay wet to remain infectious, are sensitive to detergents, spreads through large droplets

Question 15

Is Rabies an RNA or DNA virus?

Answer 15

It is a -sense RNA virus

Question 16

The viral genome encodes for 3 classes of proteins - what are they?

Answer 16

1. Proteins for viral progeny
2. Enzymes machinery for replication
3. Proteins to interfere with host immune defence

Question 17

Outline how a Rabies viral particle is made

Answer 17

Negative sense ssRNA is turned into Positive sense mRNA. Some Positive sense mRNA is translated into proteins, and some is translated back into negative sense ssRNA. This negative ssRNA then becomes RNA

Question 18

Give two examples of drugs which are Nucleoside analogues to inhibit Viral Polymerase

Answer 18

AZT (RT inhibitor)

Acyclovir (DNA polymerase inhibitor)

Question 19

The Zika virus is primarily transmitted by which vector?

Answer 19

Aedes mosquito