Virus/cell interactions

Question 1

what are permissive cells?

Answer 1

cells supporting viral infection and this leads to productive infection

Question 2

what effects to productive infections usually have?

Answer 2

cytopathic

Question 3

what are non permissive cells?

Answer 3

if the virus does manage to get in it leads to abortive or restrictive infection

Question 4

What are persistent infections?

Answer 4

infections that last for long periods of time and occur when primary infection is not cleared by the adaptive immune response. Two types-chronic and latent

Question 5

what are chronic infections?

Answer 5

infections where there are low levels of virus to escape immune (can be reactivated)

Question 6

define a latent infection?

Answer 6

the virus has the ability to lie dormant within a cell and this is denoted at lysogenic part of the viral infection

Question 7

How can viruses transform cells?

Answer 7

abortive/restrictive infection and/or oncogenesis

Question 8

what is an acute viral infection?

Answer 8

short term infection no more than 6 months in which lots of viruses are present and leads to the death of many cells.

Question 9

how long can an acute infection be up to?

Answer 9

6 months

Question 10

are all effects intended and beneficial to viruses?

Answer 10

no for example polio and cervical cancer (but most effects are intended)

Question 11

What main 4 effects can viruses have on cells?

Answer 11

1) morphological effects
2) Syncitia/giant cell formation
3) Biochemistry effects
4) genetic effects`

Question 12

why are physical effects useful for detection?

Answer 12

they are visible under a microscope so allow quick detection, the cell looks visibly different

Question 13

How can viruses affect the cytoskeleton?

Answer 13

virus factors with associated tubules can change the cytoskeleton enough to bend it and therefore cause a change in cell shape

Question 14

how can viruses affect the nucleus?

Answer 14

can cause perinuclear inclusions with microtubule bundles

Question 15

what are inclusion bodies?

Answer 15

Nuclear or cytoplasmic aggregates of stainable substances, usually proteins. They typically represent sites of viral multiplication.

Question 16

Where are inclusion bodies usually for DNA virus and RNA?

Answer 16

in nucleus for DNA virus and in cytoplasm for RNA virus

Question 17

what was the cauliflower mosaic virus?

Answer 17

the first DNA plant virus to be reported

Question 18

how is the CAMV transmitted?

Answer 18

CaMV is transmitted between host plants by several aphid species

Question 19

CAMV is “circulative”, what does this mean?

Answer 19

to viruses that are transmitted only if the virus is transported across cell membranes and carried internally within the vector body cavity or fungal cells

Question 20

what are syncitia?

Answer 20

they are giant cells with many nuceli caused by fusion of a viral envelope with infected cells e.g measles and retroviruses (proteins on membrane can act as viral fusion ones and fuse cells together)

Question 21

what are giant cells called?

Answer 21

syncitia

Question 22

what effects do viruses have on cell biochemistry?(3)

Answer 22

a) activation of cellular protein
kinases and transcription
factors

b) activation of cellular
oncogenes, cell cycle arrest

c) inhibition of DNA synthesis as switching host DNA replication and synthesis to virus synthesis etc

Question 23

what type of effect on cells is activation of cellular
oncogenes, cell cycle arrest
and inhibition of DNA synthesis ?

Answer 23

biochemical

Question 24

What genetic effects do viruses have on cells? (3)

Answer 24

1) chromosome rearrangement and mutations
2) generalised chromosomal damage
3) transformation

Question 25

what are 2 morphological affects viruses can have on cells? and due to what?

Answer 25

effects on cytoskeleton and nucleus due to virus factors and inclusion bodies

Question 26

what viruses produce syncitia?

Answer 26

measle virus and retoviruses

Question 27

define briefly latent,chronic and acute.

Answer 27

Acute is sudden and severe, latent is dormant or recessive and chronic is on-going and long term.