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CELL MICRO S1 > Viruses causing GE > Flashcards

Viruses causing GE Flashcards

1
Q

what is the worldwide mortality from GE?

A

4-10 million p/a

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2
Q

what is the 2nd most common cause of child death globally?

A

GE

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3
Q

what is viral GE?

A

inflammation of the lining of the stomach, small and large intestine

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4
Q

what causes complications in GE?

A

dehydration: fluid intake needs to be higher than that lost through vomiting and diarrhoea

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5
Q

how contagious is GE? how common?

A

Highly contagious and extremely common

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6
Q

what is necessary for a virus to be cause GE?

A
  • the gut has to be both the portal of entry and the target tissue
    (ie must replicate in gut and induce symptoms in gut)
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7
Q

how is GE spread?

A

oral-faecal route

  • enter via food–> food poisoning
  • excreted in faeces (poor hygiene, sanitation, clean water availability)
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8
Q

why are GE causing conditions poorly characterised?

A
  • don’t grow well/ at all in tissue culture
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9
Q

do GE viruses infect at low or high doses?

A

low (10-100vp)

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10
Q

are GE viruses detectable in food?

A

rarely, only in Bivalbia shellfish

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11
Q

why is routine food screening is not feasible?

A

most food contamination is identified RETROSPECTIVELY

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12
Q

how are GE viruses detected/diagnosed?

A

1) electron microscopy
2) genomic tests (RT-PCR)
3) immunological tests (antigenic detection, ELISA)

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13
Q

what method CANNOT be used to detect viral GE causing viruses?

A

CELL CULTURE

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14
Q

what are the problems with the methods of detecting GE viruses?

A
  • don’t tell us about infectivity

- lead to underestimation of GE infection

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15
Q

how can GE be prevented?

A

follow HACCP guidelines for food handling and safety management

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16
Q

what are the general features of Rotavirus?

A

spokes radiate from the central hub

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17
Q

which of the GE causing viruses are the largest?

what do their genomes have in common?

A

Rotavirus and Adenovirus

- both have double stranded genetic info (Adeno has DNA, Rota has RNA)

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18
Q

which of the GE causing viruses are the smallest? what do their genomes have in common?

A

Caliciviruses and Astroviruses

- both are positive sense RNA

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19
Q

what are the general features of Adenoviruses?

A
  • icosahedral

- may have long fibres extending from the apices

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20
Q

what are the general features of Caliciviruses?

A

32 ‘cup-like’ indentations on the surface

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21
Q

what are the general features of Astroviruses?

A

arrangements of capsomeres gives the appearance of 5/6 pointed STAR on surface

22
Q 
describe Astroviruses?
which group of baltimore 
transmission route
what does it infect
what does it cause
A
  • non enveloped
  • 30nm icosahedral virus
  • 5-6 pointed star like appearance
  • group 4 Baltimore
  • worldwide distribution
  • transmitted through oral-faecal route
  • infects epithelial cells of intestinal tract
  • cuases diarrhoea
23
Q

who does Astrovirus mostly affect?

how is it diagnosed?

A
  • young children and elderly & instituionalised patients
  • diagnosed using EM, ELISA, NAAT
24
Q 
describe Rotavirus
which family
genome
what type of virus 
what does it infect
A
  • members of Reoviridae
  • non-enveloped, 70nm icosahedral w/ spikes from central hub
  • double stranded RNA divided into 11 segments, codes for 12 proteins( 1 in each segment and 2 in segment 11)
  • genome protected by 3 protein shells
  • hit and run virus
  • infects TIPS OF MICROVILLI in intestine
25
Q

what is the major cause of viral GE in infants & young children?

A

Rota

- 1 million deaths pa

26
Q

how does Rotavirus have high transmission?

A
  • high stability to inactivation
  • quick infection (2-4 days)
  • high prod of viral particles in stools
27
Q

what is the target of Rota?

A

children

28
Q

what is the treatment for Rota?

A

children: fluid therapy
adults: rehydration

29
Q

why is Rota a hit and run virus?

A

poor immunity that does not protect against future infections

30
Q

how are neonates protected from Rota?

A

Maternal passive immunity can protect for few months

31
Q

are vaccines available for Rota?

A

now live attenuated vaccines approved for use in the US: routine vaccination with 3 doses at ages of 2, 4 and 6 months

32
Q

what is the single major cause of non bacterial GE?

A

Noro

33
Q

why is Noro so common?

A

v. high transmissibility
(guidelines state that those working with food (or nurseries) should not return to work for 48h after symptoms disappear)

34
Q

can Noro reinfect?

A

yes, there is no lasting immunity

35
Q

Noro is part of which family?

which genera infect humans?

A

Caliciviridae (consists of Vesivirus, Lagovirus, Sapovirus and Norovirus)
- Sapovirus and Norovirus infect humans causing winter vomiting disease

36
Q

describe the genome of Noro? which Baltimore group

A
  • non enveloped
  • positive sense RNA genome
  • Baltimore group 4
37
Q

what is the function of VPg protein in Noro?

A

works as primer, so protein can be made from the genome

38
Q

in Noro, what is the role of the SUBGENOMIC RNA?

A

produce only structural proteins

39
Q

how quickly do symptoms appear for Noro? how long do they last?

A
  • appear 12-48 hrs after infection

- lasts 2-3 days

40
Q

how is Noro transmitted?

A

Transmitted via oral-faecal route:

  • consumption of contaminated food
  • person/fomite-to-person contact- airborne droplets (vomit)
41
Q

what are the symptoms of Noro?

A

nausea, vomiting, diarrhoea, abdominal cramps and pain

42
Q

how do the drugs used for Noro work?

A

Drugs against protein synthesis, protease and polymerase

43
Q

is there a vaccine for Noro?

A

difficult because there are many serotypes and antigenic drift

VLPs (virus like particles) are under development

44
Q

describe the genome of Adenovirus?

Baltimore group

A
  • non enveloped
  • icosahedral
  • double stranded DNA
  • Baltimore group 1
45
Q

how is Adeno diagnosed?

A

electron microscopy

46
Q

other than GE, what can Adeno cause?

A
  • resp and eye inf

serotypes 40&41 specialise in infecting cells in the intestine

47
Q

how does Adeno replicate

A
  • enter cell
  • deliver its DNA into nucleus
  • make structural and non structural proteins
    LONG PROCESS (~2 days)
48
Q

what is defining about Adeno?

A

unlike the others, it is transmitted not by FOODBORNE, but by WATERBORNE

49
Q

who does Adeno mostly affect?

A

children <2 years

50
Q

what symptoms does Adeno cause?

A

WATERY diarrhoea

CELL MICRO S1 (16 decks)

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