Virus Structure and Classification

Question 1

What is a virus?

Answer 1

Small, obligate intracellular parasites with an eclipse phase in the replication cycle.
Metastable packages that carry a genome.

Question 2

What happens if you destroy the host cell during the virus eclipse phase?

Answer 2

There is a loss of infectivity. The virus is not infective at the eclipse phase.

Question 3

What are the different kinds of genome a virus can have?

Answer 3

DNA or RNA
ds or ss
Segmented or non-segmented
Linear or circular

Question 4

What is the viral packaging composed of?

Answer 4

Protein and sometimes lipids.

Question 5

What are the functions of the viral packaging polypeptides?

Answer 5

Structure
Enzymes and activities that assist with replication

Question 6

What is a capsid?

Answer 6

Protein shell surrounding genome. Made up of capsomeres.

Question 7

What is the nucleocapsid?

Answer 7

Combination of nucleic acid and the capsid

Question 8

What is an envelope?

Answer 8

A lipid membrane with embedded glycoproteins that surrounds the capsid

Question 9

Define a virion

Answer 9

Virus particle

Question 10

What are the two main criteria for virus classification?

Answer 10

Structure and Mode of Replication

Question 11

List of Enveloped DNA Viruses

Answer 11

Herpesvirus
Asfarviridae
Poxviridae
Hepadnaviridae
Iridoviridae

Question 12

Give an example of herpesviridae

Answer 12

Infectious bovine rhinotracheitis

Question 13

Describe the structure of Herpesvirus

Answer 13

dsDNA
Linear, large

Question 14

Describe the structure of Poxviridae

Answer 14

dsDNA
Complex virion with one or two envelopes
Large, ‘dumbbell’ shape

Question 15

Give an example of poxviridae

Answer 15

SmallPox
ORF

Question 16

List some common Enveloped RNA viruses

Answer 16

Orthomyxovirus
Paramyxoviridae
Coronaviridae
Arterivirus
Retroviridae
Rhabdoviridae

Question 17

Describe the structure of Orthomyxoviridae

Answer 17

ss(-)RNA
Small, segmented
NO capsid

Question 18

Give an example of orthomyxovirus

Answer 18

Influenza -
ie. avian, multiple antigenic subtypes with high and low pathogenicity

Question 19

Describe the structure of paramyxoviridae

Answer 19

ss(-)RNA
Non-segmented
NO capsid
Lack of distinct shape

Question 20

Give examples of paramyxoviridae

Answer 20

Newcastle disease
Canine distember

Question 21

Describe the structure of coronoviridae

Answer 21

ss(+)RNA
Small, Non segmented
No capsid

Question 22

Give examples of disease caused by coronaviridae

Answer 22

FIP

Question 23

Describe the structure of Arteriviridae

Answer 23

ss(+)RNA
Small, non segmented
No capsid

Question 24

Give an example of disease caused by arteriviridae

Answer 24

Porcine respiratory and reproductive symptom virus

Question 25

Describe the structure of retroviridae

Answer 25

ss(+)RNA
Small
Capsid present

Question 26

Give an example of disease caused by retroviridae

Answer 26

Sheep and goat lung cancer

Question 27

List non-enveloped DNA viruses

Answer 27

Adenoviridae
Parvoviridae
Circoviridae

Question 28

Describe the structure of circoviridae

Answer 28

ssDNA
Unenveloped, capsid
tiny

Question 29

List some examples of non-enveloped RNA viruses

Answer 29

Caliciviridae
Picornoviridae

Question 30

Describe the structure of calicivirus

Answer 30

ss(+)RNA
Unenveloped, capsid
small
Very env stable

Question 31

Describe the structure of picornoviridae

Answer 31

ss(+)RNA
Unenveloped, capsid
small

Question 32

Give an example of disease caused by caliciviridae

Answer 32

Feline calicivirus

Question 33

Give an example of disease caused by picornoviridae

Answer 33

Foot and mouth disease