L5 Viral pathogenesis 1 Flashcards

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1
Q

how can humans transmit to other humans

A

direct contact e.g.sexual

environmental e.g. faecal oral, aerosols

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2
Q

what is a chronic carrier

A

shed virus for long period, can be for life – persistent, virus actively replicating

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3
Q

what is an acutely infected individual

A

over short period spread virus

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4
Q

how do animals spread viruses to humans

A

direct bite
insect transmission
environmental
zoonosis – transmission across species barrier, e.g. SIV=HIV

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5
Q

what is the respiratory route of infection

A

sneezing, coughing
inhale the aerosol droplets
contaminated surface - touch mouth/nose/eyes (rhinovirus esp)

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6
Q

what protects against airborne viruses

A

cilia and mucus provide important physical protection

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7
Q

what is the best environment for virus survival

A

dry and cool e.g.steel

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8
Q

how is the GI tract infected

A

faecal oral route

food and water contamination

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9
Q

what virsues are faecal oral infectors of GI tract

A

Enteroviruses (Coxsackie, Polio etc.), Small Round Structured Viruses, norovirus

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10
Q

what must the virus be like to survive in the GI tract

A

acid stable

non-enveloped (bile salts)

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11
Q

why cant GI tract viruses be enveloped

A

duodenum – bile salts released here, they’re emulsifiers (kill envelope viruses)

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12
Q

how is rotavirus activated in the body

A

rotavirus isn’t infective until it gets activated by acid – pH changes, protein changes

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13
Q

how do viruses infect via the transcutaneous route

A

insect/animal bite

IDVA, needle stick injury, transfusion

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14
Q

how is the transcutaneous route protected

A

skin

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15
Q

how does the bite location affect infection

A

If bitten in the neck isn’t as far to travel to head but leg is longer for infection – replicates in brain and changes the behaviour of the animal

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16
Q

how does HIV risk change with genitial tract infection

A

more at risk as already compromised
up-regulation of virus receptors
infiltration of permissive cells

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17
Q

genital tract or rectal mucosa infections

A
HSV2 (and HSV1)
CMV
HBV
HPV
HIV
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18
Q

what is an acute infection

A

short lived

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19
Q

what is a persistent/chronic infection

A

virus always replicating and releasing

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20
Q

what is a latent infection

A

infected and virus becomes dormant, expresses latency genes – eventually immune response isn’t sufficient to keep virus under control - remerges

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21
Q

why are you susceptible to re-infection by some acute viral infections

A

short-lived immunity

immune escape due to mutations, genetic drift, genetic shift

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22
Q

examples of genetic drift

A

RSV and influenza

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23
Q

examples of genetic shift

A

influenza A

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24
Q

what is genetic shift

A

two viruses e.g. human and a chicken virus infect e.g. pig = genes moved between and lead to new viruses – new pieces of material

25
Q

what is genetic drift

A

mutated via point mutations that the immunity doesn’t recognise it anymore

26
Q

what does hep B virus cause

A

chronic liver disease and occasionally hepatocellular carcinoma

27
Q

how many can clear the hep B virus

A

90%

28
Q

how many will die from hep B

A

<1%

29
Q

how many will be chronic hep B carriers

A

10%

30
Q

what virus is hep B

A

RT DNA virus

31
Q

what virus is hep C

A

+ strand RNA virus

32
Q

how many have chronic hep C infection

A

~80% cases

33
Q

what can 10-30 years chronic hep C infection cause

A

cirrhosis and HCC

34
Q

what is hep C associated with

A
non-hepatic disease
mixed cryoglobulinaemia (don’t make same number of antibodies as normal)
35
Q

what is the chronic infection of HIV

A

100%

36
Q

what does HIV cause

A

AIDS

37
Q

what are the progression rates of HIV

A

1-15 years

38
Q

what is the primary infection of herpesvirus

A

varicella- chickenpox

39
Q

examples of latent infection

A

varicella zoster virus

epstein barr virus

40
Q

what is the latent site for varicella zoster virus

A

neurones

41
Q

what is the latent site for epstein barr virus

A

B lymphocytes

42
Q

what causes secondary or reactivation of latent viruses

A

host/environmental factors, usually associated with suppression of immune system

43
Q

what viruses are associated with cancer

A

papillomaviruses - cervical
human herpesvirus 8
chronic hepatitis - hepatocellular carcinoma

44
Q

what does human herpes virus 8 cause

A

EBV immortalisation of B cells

45
Q

what does chronic hepatitis cause

A

inhibition of apoptosis

46
Q

what is CPE

A

cytopathic effect

viruses grow some cells morphologically change

47
Q

examples of virus cells that can undergo CPE

A

primary cell cultures

continuous (cancer) cell lines

48
Q

what are diagnostics of CPE

A

syncytia or multinucleated cells
cell lysis
inclusion bodies

49
Q

what do influenza viruses cause

A

epithelial cell death

50
Q

what is the effect of epithelial death in influenza

A

give rise to opportunistic secondary bacterial infections (pneumonia)

51
Q

what are the types of acute infection

A

symptomatic

asymptomatic

52
Q

what is a factor of infection risk

A

age dependent

53
Q

what are the early acute symptoms

A

fever aches shivers

54
Q

what are the symptoms of HSV, VZV, hand foot and mouth

A

vesicles

55
Q

what are the symptoms of MMR

A

rash

56
Q

what are the clinical symptoms of human papilomavirus

A

warts

genital warts - associated to cancer

57
Q

how is human papillomavirus transmitted

A

direct contact

contaminated surfaces/fomites

58
Q

what is the effect of congenital rubella

A

severe life threatening disease
infected infant has abnormalities
infect fetus in the placenta
TORCH syndrome