viruses and their hosts (4) (Leanne) Flashcards

1
Q

pathogenicity

A

how virulent

diff strains have diff virulence

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2
Q

pathogenesis

A

mode of development of disease - mechanism by which pathogen causes disease

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3
Q

systemic effect

A

whole body affected if virus enters lymphatic/circulatory system

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4
Q

measles

A
respiratory system
systemic effect
enveloped virus
single stranded
non segmented
negative sense RNA genome
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5
Q

what cells are susceptible to viruses?

A

cell with receptors

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6
Q

intrinsic features of immune system

A

gender

MHC molecules - show viral particles

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7
Q

physiological variation

A

nutrition
age
stress
physical health

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8
Q

how does age affect immune system?

A

thymus gland vanishes over time

can’t produce new T cells

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9
Q

3 outcomes of infection

A

acute + death
acute + recovery
persistent

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10
Q

persistent infection

A

continuous virus production with or without chronic disease
because virus changes - antigenically stable virus types, surface protein slightly diff version (serotypes)
constantly diversifying virus population
chronic - constant virus production
or latent - no detectable virus but production may re-activate

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11
Q

herpes simplex virus

A

type 1 - cold sores
type 2 - genital
2 processes can trigger it from latent stage

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12
Q

human papilloma virus

A

can lead to cervical cancer
can be asymptomatic
latent infections may occur
in epithelial stem cells in basal layer of epithelium
cells driven into cell cycle, genome amplification and new virion production
low level protein production by virus allows it to evade immune detection
immune regression, infiltration of predominantly T cells, viral gene expression shut off, lesion regression occurs

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13
Q

horizontal transmission

A

host to host
direct or indirect
has recognised routes like respiratory, oral-faecal, sexual, conjunctival (eye)

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14
Q

respiratory route

A

airborne transmission like cold/measles

humidity affects desiccation rate

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15
Q

oral-faecal

A

direct or indirect
contaminated water, poor hygiene, swimming pools
e.g. poliovirus, rotavirus, hepatitis A

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16
Q

saliva and urine transmission

A

aerosols, zoonotic

e.g. CMV

17
Q

fomites, skin, conjunctiva

A

objects, surfaces, money, skin damage, hand-to-eye contact

18
Q

indirect transmission

A

1 or more species, vectors

19
Q

reservoir species

A

host for pathogen but survives without disease (asymptomatic)

20
Q

insect-borne viruses

A

yellow fever, West Nile, dengue fever

21
Q

yellow fever

A

replicates in mosquitoes and monkeys
sylvatic cycle - between these 2 species
urban cycle - to humans
but can’t transmit human to human

22
Q

vertical transmission

A

mother to child

intrauterine - across placenta, congenital rubelle syndrome
perinatal - during delivery because blood, HIV
postnatal - breast feeding, HIV

23
Q

2 types of vaccine

A

live attenuated

killed non-replicating

24
Q

serial passage

A

passed along hosts, growth in wrong host selects variants which are no longer virulent but still replicate in autologous (the usual host for specific virus)

25
epidemic vs pandemic
rapid spread over short time | cross borders and affect huge populations
26
influenza subtypes
``` 18 haemagglutinin (H) - aids in viral entry, binds to RBC 11 neuraminidase (N) - aids in viral exit ```
27
why do viruses have high mutation rates?
poor proofreading
28
antigenic drift vs shift
drift - small change shift - big difference, 2 viruses combine to mosaic, genome segments exchanged during replication
29
5 techniques in studying viruses
``` cell culture and viral propagation plaque assays haemagglutination assay antibody detection - IMF, ELISA molecular techniques - PCR, RT-PCR, detect nucleic acids ```
30
primary cell lines
taken from organ tissue | actual cells that virus targets
31
passage
cells differentiate limited times
32
cell lines
less differentiated so more capability of dividing and growing, more passages
33
continuous cell lines
HeLa, immortal
34
cpe
cytopathic effect - phenotypic effect of infection
35
PFU
plaque forming unit