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viruses Flashcards

(57 cards)

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1
Q

what makes up a virion

A

genome
capsid
envelope
matrix

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2
Q

what is matrix

A

protein layer connecting capsid and envelope glycoproteins

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3
Q

what capsid symmetry do DNA viruses causing human disease have

A

icosahedral (or complex - pox)

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4
Q

DNA viruses

A

HHAPPP

hepada, herpes, adeno, parvo, pox, papova

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5
Q

what do all helical RNA viruses have

A

an envelope

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6
Q

difference between eclipse and latent period

A

eclipse - no increase in virus

latent - no extracellular virus

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7
Q

stages of replication

A 
attachment 
penetration 
uncoating 
amplification of genome and viral proteins
assembly 
release
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8
Q

where do RNA adn DNA viruses typically replicate

exceptions

A 
DNA - nucleus 
RNA - cytoplasm 
exceptions: 
- HIV RNA but nucleus 
- Pox is DNA but cytoplasm
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9
Q

what does -ve RNA viruses carry

A

RNA dependent RNA polymerase

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10
Q

inclusion bodies

A

accumulated viral proteins at site of viral assembly

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11
Q

3 ways viral genomes continually changing

A

mutation
recombination
reassortment

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12
Q

drug for herpes, why, type of drug

A

acyclovir - herpes virus has herpesvirus thymidine kinase required for activation/adding of P
nucleoside analogue

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13
Q

barriers to viruses in resp tract

A 
mucous 
cilia
alveolar macs
temp gradient (cooler at top)
IgA
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14
Q

what is characteristic of RSV on microscopy

A

multi-nuclear giant cell s

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15
Q

what causes croup

A

parainfluenza

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16
Q

koplick spots

A

diagnostic of measles early on

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17
Q

lifecycle of measles

A

primary viral replication in URT epithelium, infects macs, lymphs, DCs
these drain to lymph nodes and circulation - systemic infection

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18
Q

characteristics of GIT viruses

A

no envelope and bile resistant

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19
Q

reasons for diarrhoea in rotavirus

A

secretion of NSP4 from infected cells

decreased absorption due to enterocyte destruction

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20
Q

major characteristic of EBV

A

polyclonal B cell activation

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21
Q

what produces IFNalpha/beta

A

virally infected mac or DC or normal cell

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22
Q

what activates NK cells

A

IFNalpha/beta

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23
Q

what produces IFNgamma

Study These Flashcards
A

only NK cells and T cells wa

24
Q

what do type 1 vs type 2 interferons do

Study These Flashcards
A

type 1 (IFNalpha/beta) - inhibit viral replication, enhance MHCI expression, activates NK cells

type 2 - gamma - inhibit viral replication, enhances MHCI and II expression

25
ways to evade CD8 T cell recognition
antigenic variation induce apoptosis of MHCI bind TAP on ER - prevents processing adn presentation on MHCI bind MHCI and retain in ER latency - not producing proteins so not susceptible to CD8 attack
26
how do NK cells work
have activating R - recognises molecules on cell surface as result of viral infection - KILL inactivating R - if bind MHCI - OVERIDES KILL --> so if MHC absent or aberrantly expressed - KILL
27
what activates NK cells a
IL12 or IFNalpha/beta
28
what genes does IFN cause upregulation of
MHCI and PKR
29
how does PKR work
two PKR molecules hook over dsDNA and autophosphorylate | bind to eIF2alpha and phosphorylate - cause inhibition of translation
30
how do viruses evade PKR
- excessive production of small dsDNA - proteins that bind to dsDNA to protect - virus encoded homologue of eIF2alpha - binds PKR
31
where does influenza virus bind
sialic acid R on non-ciliated epithelial cells of RT
32
type of virus influenza
enveloped, -ve RNA
33
which flu can infect other species
a
34
which flu cause human disease
a and b
35
function of haemagglutinin
gripper - binds SA containing Rs - initiates entry
36
function of neuraminidase
snipper - binds SA and cuts it off
37
difference between different type a flu subtypes
different HA and NA
38
current scary forms of flu
H1N1 H3N2
39
why is flu virus localised to resp tract
needs enzyme tryptase clara to cleave HA to be able to undergo conformational change to escape endosome
40
why do we get reinfected with influenza
ab response is lifelong to a particular strain, but flu has antigenic drift
41
flu vaccine conformation
trivalent inactivated vaccine
42
antivirals to influenza
M2 channel blockers | NA blockers - zanamavir
43
antigenic shift vs drift
shift = sudden appearance of new subtype of A (new HA and NA not just mutations in epitope regions (drift))
44
when would you get a flu epidemic
when all 5 epitopes of subtype have mutated and vast majority of population has no abs
45
when would you get a flu pandemic
when get antigenic shift happens and get sudden appearance of new subtype
46
whats a way to create new influenza subtype
reassortment - pig infected with human and avian flu bc has both types of R in RT and get reassortment
47
lifecycle of hep a
contaminated water/food - ingestion - replication in intestinal epithelia - blood - rep in liver - bile/faeces
48
hep a vaccine conformation
inactivated whole virus
49
hep e lifecycle
same as a
50
can you give immunoglobulin to hep a and e
no just a - pre and post exposure
51
hep b lifecycle
- partial dsDNA made into cccDNA by viral polymerase - host RNA polymerase makes pregenomic RNA (lots of different reading frames) - reverse transcription into partial dsDNA
52
what does it mean if HBsAg+
chronic carrier
53
strategies of HBV to ensure persistence
1. HBeAg - essential for persistent infection 2. excess production of HBsAg 3. HBV cccDNA - can evade a lot of immunity
54
why HCC more common in chronic carriers
due to partial integration of HBV genome into hepatocyte genome
55
HBV treatments
peg-IFNalpha - for HBeAg+ carriers w chronic active infection nucleoside analogues - adenfovir
56
can you give hep b vaccines post exposure
yes in needle stick injury for e.g.
57
untreated HCV how many become chronic carriers
70-90%

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