2-1 Virus Structure and Classification

Question 1

T/F: To culture viruses, you grow them on agar plates with specific nutrient media

Answer 1

False: Viruses are obligate intracellular parasites, which means that they can only grow and replicate within living cells…which agar plates or nutrient media are not composed of. Viruses must be grown and studied in tissue culture.

Question 2

What is the definition of a virus?

Answer 2

A virus is simply a capsid enclosing organism.
A virus refers to a host cell that is infected with viral DNA. Therefore, a host cell and viral DNA are the basic components

Question 3

What is a capsid? What “kind” of proteins are capsid proteins?

Answer 3

a Capsid is a protein shell that encapsulates the nucleic acid genome.
Capsid proteins are structural proteins because they form the virion…some replication proteins may also be included in the virion, but not always. Similarly, the host interacting factors are usually “non-structural” because they are left behind in the infected cell and not packaged into the virion.

Question 4

What is a virion?

Answer 4

the particle encoded by a virus genome

Question 5

What 3 basic modules do all viruses have?

Answer 5

1. Capsid proteins
2. The replicon which encodes the nucleic acid polymerase and accessory proteins to copy the genome
3. Multifunctional proteins that interact with the host cell

Question 6

What are structural and non-structural proteins?

Answer 6

Capsid proteins are structural proteins because they form the virion…some replication proteins may also be included in the virion, but not always. Similarly, the host interacting factors are usually “non-structural” because they are left behind in the infected cell and not packaged into the virion.

Question 7

T/F: the capsid shape is indicative of the genome it encloses

Answer 7

False…they are independent of one another

Question 8

T/F: The virion contains genetic material to create the lipid bilayer in enveloped viruses

Answer 8

False: The virions obtain a lipid bilayer from the host cell

Question 9

How do you classify a virus? (3)

Answer 9

1. Host Cell (kingdom: eukaryotic/prokaryotic, plant, insect, animal)
2. Genome Type (DNA/RNA, single/double stranded)
3. Virion structure (enveloped/naked, helical/icosahedral/complex)

Question 10

Describe the structure of adenovirus in terms of virion structure and genome type

Answer 10

ADIN (ADDIN-ovirus)
Icosahedral
naked
dsDNA

Question 11

Describe the structure of influenza in terms of virion structure and genome type

Answer 11

Helical
Enveloped
Segmented ssRNA

Question 12

Describe the structure of Herpesvirus in terms of virion structure and genome type

Answer 12

HIDDE (You want to HIDDE (Hide) from herpes…Herpesvirus_Icosahedral_DsDNA_Enveloped)

Icosahedral
Enveloped
dsDNA