5.2 Gastrointestinal viruses Flashcards

1
Q

What are the general features of viruses that cause acute gastroenteritis?

A

Small but very tough - non enveloped, resistant to drying and hard to disinfect

Rapid disease course - incubation down to 24 hours and symptoms from 24 hours to 7 days

Spectacular replication - low minimal infectious dose and massive yield

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2
Q

What kinds of viruses are rota, noro and adenovirus?

A

rotavirus: double stranded RNA virus

Norovirus: single stranded RNA virus

Adenovirus: DNA virus

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3
Q

How many types of rotavirus are there and which causes infantile diarrhoea?

A

Seven (A-G) with A being the major cause of infantile diarrhoea

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4
Q

What is the typical course of rotavirus?

A

3 days of vomiting that starts first and 5 days of diarrhoea that overlaps

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5
Q

What are the pathological changes in rotavirus?

A

Direct viral damage to enterocytes at the tips of the vili and shortening of the vili, malabsorption and secretion

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6
Q

What virus protein is thought to play a role in rotavirus and how?

A

NSP4
mess with IC Ca
Direct impact on tight junctions
interacts with the CNS

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7
Q

What is the transmission of rotavirus?

A

Fecal-oral, environmental contamination

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8
Q

What is the rotavirus structure?

A

genome in 11 segments with VP4 and VP7 encoding the major surface proteins G and P giving rise to the serotypes

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9
Q

What are the most common serotypes of rotavirus?

A

G1-4 and now G9

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10
Q

What are the vaccinations for rotavirus?

A

Live attenuated vaccine
Rotarix: single genotype

Rotateq: collection covering G1-4 and P1

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11
Q

How can you minimise the risk from rotavirus immunisation?

A

Stick to schedule, don’t vaccinate risk groups (immunocomprimised or ill), vigilance, advise parents of side effects

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12
Q

What is the structure of norovirus?

A

Capsid composed of one major and one minor protein with the major capsid protein (VP1) forming virus like particles

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13
Q

What is the genome of norovirus?

A

single stranded RNA with 3 open reading frames

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14
Q

What is the role of the open reading frame 1 (ORF1)?

A

polyprotein that encodes the proteinase to cleave this into active units

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15
Q

What is the replication strategy for norovirus?

A

‘hit and run’ massive replication before the innate immunity kicks in

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16
Q

What is the pathogenesis of norovirus?

A

Villus of SI shortened and blunted, some evidence of mononeuclear infiltration

17
Q

What is the disease course of norovirus?

A

Incubation from 1/2 - 2 day then acute symptoms for 1/2 to 2.5 days

18
Q

What is the transmission of norovirus?

A

Fecal-oral

Food borne

19
Q

What virus is the main cause of epidemic gastro?

A

Norovirus

20
Q

What types of adenovirus infect humans?

A

40 and 41

21
Q

What are the features of norovirus?

A

non enveloped virion that replicates in the nucleus

22
Q

What is the diagnosis of gastro?

A

Stool sample for rotavirus and adenovirus

23
Q

What kind of parasites cause gastro?

A

obligate with no metabolic processes