viruses and their hosts (4) (Leanne)

Question 1

pathogenicity

Answer 1

how virulent

diff strains have diff virulence

Question 2

pathogenesis

Answer 2

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

Question 3

systemic effect

Answer 3

whole body affected if virus enters lymphatic/circulatory system

Question 4

measles

Answer 4

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

Question 5

what cells are susceptible to viruses?

Answer 5

cell with receptors

Question 6

intrinsic features of immune system

Answer 6

gender

MHC molecules - show viral particles

Question 7

physiological variation

Answer 7

nutrition
age
stress
physical health

Question 8

how does age affect immune system?

Answer 8

thymus gland vanishes over time

can’t produce new T cells

Question 9

3 outcomes of infection

Answer 9

acute + death
acute + recovery
persistent

Question 10

persistent infection

Answer 10

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

Question 11

herpes simplex virus

Answer 11

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

Question 12

human papilloma virus

Answer 12

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

Question 13

horizontal transmission

Answer 13

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

Question 14

respiratory route

Answer 14

airborne transmission like cold/measles

humidity affects desiccation rate

Question 15

oral-faecal

Answer 15

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

Question 16

saliva and urine transmission

Answer 16

aerosols, zoonotic

e.g. CMV

Question 17

fomites, skin, conjunctiva

Answer 17

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

Question 18

indirect transmission

Answer 18

1 or more species, vectors

Question 19

reservoir species

Answer 19

host for pathogen but survives without disease (asymptomatic)

Question 20

insect-borne viruses

Answer 20

yellow fever, West Nile, dengue fever

Question 21

yellow fever

Answer 21

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

Question 22

vertical transmission

Answer 22

mother to child

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

Question 23

2 types of vaccine

Answer 23

live attenuated

killed non-replicating

Question 24

serial passage

Answer 24

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)

Question 25

epidemic vs pandemic

Answer 25

rapid spread over short time

cross borders and affect huge populations

Question 26

influenza subtypes

Answer 26

18 haemagglutinin (H) - aids in viral entry, binds to RBC
11 neuraminidase (N) - aids in viral exit

Question 27

why do viruses have high mutation rates?

Answer 27

poor proofreading

Question 28

antigenic drift vs shift

Answer 28

drift - small change

shift - big difference, 2 viruses combine to mosaic, genome segments exchanged during replication

Question 29

5 techniques in studying viruses

Answer 29

cell culture and viral propagation
plaque assays
haemagglutination assay
antibody detection - IMF, ELISA
molecular techniques - PCR, RT-PCR, detect nucleic acids

Question 30

primary cell lines

Answer 30

taken from organ tissue

actual cells that virus targets

Question 31

passage

Answer 31

cells differentiate limited times

Question 32

cell lines

Answer 32

less differentiated so more capability of dividing and growing, more passages

Question 33

continuous cell lines

Answer 33

HeLa, immortal

Question 34

cpe

Answer 34

cytopathic effect - phenotypic effect of infection

Question 35

PFU

Answer 35

plaque forming unit