L23 Viruses

Question 1

Attributes for virus classification

Answer 1

Particle structure
genome
replication
serology 
stability

Question 2

Theories of virus orgin

Answer 2

Cellular

Autopoietic

Question 3

Nucleocapsid

Answer 3

RNA/DNA core protected by protein coat (capsid)

Question 4

Types of nucleocapsid structure

Answer 4

helical
pleomorphic
Icosahedral

Question 5

Nucleocapsid is comprised of repeating protein subinits called

Answer 5

capsomeres

Question 6

Advantage, disadvantage of large structure

Answer 6

advantage: carry a lot of stuff
Disadvantage: longer to replicate

Question 7

Virus particle size ranges from ___ to ___

Answer 7

18nm to 300nm

Question 8

Plus sense
Minus sense
Ambisense

Answer 8

Only for ssRNA

Need a plus sense before translation

Question 9

Virus replication

Answer 9

Attachment
Entry
Transcription
Translation
Replication
Assembly
Release

Question 10

True or false: Viruses mimic cell receptor’s nomral ligands

Answer 10

False

Question 11

Major determinant of tropism (host range)

Answer 11

Attachment

Question 12

Virus entry pathways

Answer 12

receptor mediated endocytosis
Direct penetration
Pores
Membrane disruption

Question 13

Mebrane disruption viruses

Answer 13

Adenovirus

Reovirus

Question 14

Influenza entry

Answer 14

Membrane fusion

HA protein causes Low pH and receptor conformational change

Question 15

Which genome viruses never release their material from the entering particle

Answer 15

dsRNA

Question 16

Which genome viruses must bing their own polymerase into the cell

Answer 16

(-)ssRNA

dsRNA

Question 17

Non structural proteins are seen

Answer 17

only inside the infected cell

Structural are produced in high quantities

Question 18

(+)ssRNA

Answer 18

Template for translation (mRNA)
Polymerase makes (-)ssRNA copy as template for new genomes

Question 19

(-)ssRNA

Answer 19

Virus must include viral polymerase
Polymerase makes mRNA for tranlation
Genome replicationt thru (+)ssRNA intermediate

Question 20

DNA viruses must gain access to nucleus except

Answer 20

Poxviruses

Question 21

Adenovirus assembly

Answer 21

epmty protein coat imports genome

Question 22

Reovirus assembly

Answer 22

RNA packaged during capsid assembly

Question 23

Retrovirus assembly

Answer 23

preassembly on a membrane

Question 24

Types of viruses that bud

Answer 24

Enveloped only

Question 25

Lysis is best know for

Answer 25

bacteriophages

Question 26

One step growth curve has a multiplicity of infection of

Answer 26

greater than 5

Question 27

Phases of kinetics

Answer 27

Eclipse: attachment and uptake
Exponential growth: replication and assembly
Plateau: cell death

Question 28

Virus kinetics are useful to assess

Answer 28

mutation
cell entry
process design

Question 29

Bacteriophage kinetics

Answer 29

Extremely fast

30 min

Question 30

What to look for in Cytopathic Effect

Answer 30

Look for cells dying
Cell rounding
Syncytia formation
inclusion bodies

Question 31

What to look for in plaque assay

Answer 31

Monolayer
inoculate with dilute virus
Infected cells die leaving clear area: plaque

Question 32

What to look for with infectious dose

Answer 32

Inoculate with different dilutions of virus

Calculate conc. based on number of infected cells

Question 33

Types of particle assays

Answer 33

Electron microscopy: latex bead standard

Hemagglutinin: bind to RBC. No red=virus

Question 34

Types of infection assays

Answer 34

Cytopathic effect
Fluorescent focus assay
Plaque assay
Infectious dose

Question 35

Types of Genome assays

Answer 35

Polymerase chain reaction
Southern (DNA) blot
Northern (RNA) blot

Question 36

Serological assays

Answer 36

Virus neutralization
Enzyme Link Immunosorbant Assay
Western (protein) Blot