Introduction 1

Question 1

What is a negative sense RNA virus?

Answer 1

The RNA forms a complementary strand which acts as the messenger.

Question 2

What are the four functions of viral proteins?

Answer 2

1) protective coat 2) attachment 3) enzymes 4) antigens

Question 3

What are the five functions of viral lipids?

Answer 3

1) derived envelope from host 2) fusion 3) viral maturation processes 4) replication processes 5) subcellular localisation

Question 4

What are the three functions of viral carbohydrates?

Answer 4

1) glycosylation 2) influence antigens 3) Intracellular transportation

Question 5

What are three methods to detect virus growth?

Answer 5

1) culture in cell monolayers in HeLa and Vero cell and measure the cytopathic effects (CPE) 2) embryonated hens eggs (vaccinations) 3) intact living animal

Question 6

What are two methods to assay for viruses?

Answer 6

1) plaque assay - measure infectious virus particles 2) HA assay - measures levels of surface protein so less effective

Question 7

Describe a virus plaque assay.

Answer 7

Use try an blue to distinguish between live and dead cells, foci form where cell has been infected, calculate infectious units.

Question 8

Describe the HA assay.

Answer 8

Add red blood cells to various dilutions of viral suspension, infectious unit when red blood cells clump.

Question 9

What are the five stages of virus replication?

Answer 9

1) attachment 2) penetration and uncoating 3) replication 4) assembly 5) release via lysis or leakage

Question 10

What are the six basic properties of a virus?

Answer 10

1) small size 2) visualised only in EM 3) either RNA or DNA 4) outer protein coat (+ lipid membrane) 5) inert outside host but enzyme function upon entry 6) antigens for attachment