5. Intro to Viruses

Question 1

What kind of microscope do you use to see a virus?

Answer 1

Electron

Question 2

Which virus family does influenza belong to?

Answer 2

Orthomyxovirus

Question 3

Through which mechanism do retroviruses, such as HIV, spread from one cell to another in an infected host?

Answer 3

Nuclear

Question 4

Traditionally, which approach was used to detect viruses in specimens from infected patients?

Answer 4

Tissue culture and light microscopy

Question 5

How are viruses classified?

Answer 5

Phenotype
Nucleic acid
How they replicate
Host
Disease

Question 6

What type of capsid does herpes simplex virus have?

Answer 6

Icosahedral

Question 7

What is a capsid?

Answer 7

Protein shell made of capsomers

Question 8

What are the 3 types of capsids?

Answer 8

Icosahedral
Helical
Complex

Question 9

What is the structure of an icosahedral capsid?

Answer 9

20 equilateral triangles

Question 10

What type of capsid do coronaviruses have?

Answer 10

Helical

Question 11

What parts of the virus interact with host cell receptors and contains antigens?

Answer 11

Capsid

Envelope

Question 12

What are the advantages to capsids?

Answer 12

Resistant to drying, heat, acids, proteases

Survive in GIT and in environment

Question 13

What are the disadvantages to capsids?

Answer 13

Humoral response may be enough to kill the virus

Needs to kill cells to spread

Question 14

What is a virus envelope made up of?

Answer 14

Phospholipids and glycoprotein

Taken from host cell membranes

Question 15

What surface polypeptide helps influenza to bind to sites on the host cell?

Answer 15

Haemaglutinins

Question 16

What are the disadvantages of envelopes?

Answer 16

Can’t survive in GIT

Need to stay wet in transmission, so spread through large droplets

Question 17

What are the advantages of envelopes?

Answer 17

Don’t need to kill cells to spread

Need both the humoral and cellular response

Question 18

What are the methods of virus acquisition?

Answer 18

Vector
Inhalation
Faecal oral
Blood borne
Sexual
Congenital

Question 19

What is tropism?

Answer 19

Virus is specific for a certain cell type

Question 20

What factors influences the tropism of a virus?

Answer 20

Cell receptor
Cell transcription factors (recognise viral promoters etc)
Ability to support viral replication
Physical barriers
Environment
Digestive enzymes and bile

Question 21

What are the 5 stages in virus replication?

Answer 21

Adsorption
Penetration
Uncoating
Synthesis and assembly
Release

Question 22

What are the 2 methods of viral penetration?

Answer 22

Internalised via endocytosis

Envelope fuses with membrane

Question 23

What is the purpose of uncoating?

Answer 23

Makes the virus’s genome available

Question 24

How does a non-enveloped virus get released?

Answer 24

Lysis or exocytosis

Question 25

How does an enveloped virus get released?

Answer 25

Budding

Question 26

What effect do viruses have on host cells?

Answer 26

Cell death Tranformation to malignant or pre-malignant Latent infection

Question 27

What ways can viral infections spread within the body?

Answer 27

Intracellular Extracellular (blood and lymph) Neural (PNS to CNS) Nuclear (virus genome added to host's)

Question 28

What 3 ways can viral infections be combatted?

Answer 28

Directly inactivate Increase host response Inhibit viral replication

Question 29

Name a drug that inhibits viral replication

Answer 29

Aciclover

Question 30

What ways can viruses be identified in culture?

Answer 30

Immunofluorescence Neutralisation Haemabsorption inhibition

Question 31

What does serology test for?

Answer 31

Viral antigens | Antibody produced against viral antigen

Question 32

What is used to detect viral antibodies?

Answer 32

ELISA

Question 33

What method can be used to detect resistance to antivirals?

Answer 33

PCR

Question 34

What is the cytopathic effect?

Answer 34

The way the presence of a virus can be seen in culture Ballooning or shrivelling of cells Disruption of cell monolayer

Question 35

What virus is associated with liver cancer?

Answer 35

Hep B and C

Question 36

What virus is associated with cervical cancer?

Answer 36

Papillomavirus

Question 37

What virus is associated with lymphoma and nasopharyngeal cancer?

Answer 37

Epstein Barr

Question 38

What virus can spread along neurons?

Answer 38

Rabies

Question 39

What type of virus is hepatitis B?

Answer 39

Hepadna DNA virus

Question 40

What type of virus is influenza?

Answer 40

Orthomyxo RNA virus

Question 41

What type of viruses are polio and hepatitis A?

Answer 41

Picorna RNA

Question 42

What type of virus is HIV?

Answer 42

Retro RNA virus

Question 43

Name a virus that spreads intracellularly

Answer 43

HSV

Question 44

Name a virus that spreads extracellularly

Answer 44

Influenza

Question 45

Name a virus that spreads in neurons

Answer 45

Rabies, HSV

Question 46

What can be seen in hippocampal cells in rabies?

Answer 46

Negri bodies