General virology and lab diagnostic methods

Question 1

In what form do viruses contain nucleic acids?

Answer 1

In the form of linear or circular RNA in a single strand (most RNA viruses) and DNA in a double strand (most DNA viruses) in a (+) or (-) sense direction

Question 2

What is the nucleic acid typically surrounded by? What is this made of?

Answer 2

Protein coat (caspid), made of subunits that form a helical, icosahedral or complex structure

Question 3

What may nucleic acid complex with?

Answer 3

Nucleoprotein

Question 4

Describe uneveloped viruses

Answer 4

• Typically resistant to acid and desiccation

- Typically cause infection via the oro-faecal route

Question 5

What size are viruses?

Answer 5

Mostly 20-300nm

Question 6

Are viruses visible by light microscope?

Answer 6

No

Question 7

What is the viral envelope derived from?

Answer 7

It is a lipid bilayer derived from the host cell

Question 8

What determines the Baltimore classification of the virus?

Answer 8

Nucleic acid type (and replication strategy)

Question 9

What are methods of detecting virus or virus fragments in the blood or CSF?

Answer 9

ELISA
PCR (or RT-PCR)
Plaque (or other infectious centre) assays
Hemagglutination

Question 10

What are methods for detecting specific antibody?

Answer 10

ELISA, hemagglutination inhibition

Question 11

Baltimore class I

Answer 11

Double-stranded DNA viruses

Question 12

Baltimore class II

Answer 12

Single-stranded DNA viruses

Question 13

Baltimore class III

Answer 13

Double-stranded RNA viruses

Question 14

Baltimore class IV

Answer 14

Single-stranded RNA viruses - postive-sense

Question 15

Baltimore class V

Answer 15

Single-stranded RNA viruses - negative-sense

Question 16

Baltimore class VI

Answer 16

Positive-sense single-stranded RNA viruses that replicate through a DNA intermediate

Question 17

Baltimore class VII

Answer 17

Double-stranded DNA viruses that replicate through a single-stranded RNA intermediate

Question 18

Draw the structure of a virus

Answer 18

See folder with notes

Question 19

describe B1

Answer 19

Nuclear replication
Requires host polymerase
Dependent on cell cycle
Cancer

Question 20

Describe b2

Answer 20

Nuclear replication

Question 21

Describe B3

Answer 21

Cytoplasmic replication
Little dependence on polymerase
Segmental genome
Monocistronic

Question 22

Describe b4 and b5

Answer 22

cytoplasmic replication
+ can directly access ribosomes
- RNA must be transcribed to mRNA

Question 23

Describe b6

Answer 23

reverse transcribed DNA intermediate with integration

Question 24

Describe b7

Answer 24

gapped DNA requiring RT step

Question 25

Example of B1

Answer 25

Herpes

Question 26

Example of 4

Answer 26

Polio

HCV

Question 27

Examaple of V

Answer 27

Influenza

Question 28

Example of VI

Answer 28

HIV

Question 29

Example of VII

Answer 29

HBV

Question 30

Examples of enveloped viruses

Answer 30

HIV
Influenza
HepC
Herpes

Question 31

Examples of non-enveloped viruses

Answer 31

Adeno and papilloma

Question 32

What is eclipse phase?

Answer 32

Period immediately after infection before new virus production

Question 33

What is burst size?

Answer 33

Number of new infectious particles produced by an infected cell