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cellular basis of immunity > 8 - viral infection > Flashcards

8 - viral infection Flashcards

1
Q

most common recurrent infection in humans

A

viral

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2
Q

transient

A

feature of viral infections

last only for a short time

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3
Q

zoonotic

A

jumped species barrier

viral infection caused in humans, originally from another animal

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4
Q

why do zoonotic infections have high mortality rates in humans

A

new to humans so have not co-evolved

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5
Q

examples of zoonotic infection s

A

HIV –> originally from chimpanzees in africa
hantavirus –> originally from rodents in N/S america
severe acute respiratory sydrome (SARS) –> coronavirus from bats in china

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6
Q

viral replication

A

depend on host proteins and machinery

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7
Q

features of viral genomes

A

3 –> 300 genes
single or souble stranded RNA/DNA
enclosed within capsid

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8
Q

capsid

A

coat protein

recognised by immune cells

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9
Q

cytopathic effect

A

virus infects cell and causes lysis

induces autophagy or apoptosis on exit of cell

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10
Q

example of cytopathic virus

A

polio virus

influenza

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11
Q

latent virus

A

infect cells but only activated when immunity wanes

activation prodces infectious virions

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12
Q

example of latent virus

A

herpes

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13
Q

non-cytopathic virus

A

replicate without destruction of cells

e.g. Hep B

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14
Q

how do viruses cross epithelial barriers in intestinal infections
example

A

using antigen-sampling M cells

HIV
poliovirus

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15
Q

how do viruses cross epithelial barriers in respiratory viruses
example

A

establish infection in airway lining

INfluenza
rhinovirus

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16
Q

other methods to cross epithelial barriers

A 
insect vectors
physical trauma (causes bloodborne viruses)
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17
Q

what mediates viral innate immunity

A

type 1 interferons
complement
NK cells

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18
Q

type 1 interferons

A

host proteins that interfere with viral gene transcription

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19
Q

viral invasion

A

viruses exploit specific molecules on cells as receptors for invasion
(tissue tropsim)

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20
Q

HIV tropism

A

tissues support growth of virus
CD4 important
chemokine receptor CXCR4 and CCR5

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21
Q

indirect antibody binding

A

couples antibody binding to classical pathway of complement

C1 q/r/s complex

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22
Q

direct antibody binding

A

Fc receptors bind directly to neutralising antibody which is an opsonising virus particle

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23
Q

role of NK cells on antibody binding

A

Fc receptors on surface of NK cell bind to antibody as virus leaves infected cell
stimulated to kill infected cell using using perforins and granzymes

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24
Q

epidemic

A

new case of disease in a population at a higher rate than expected

25
outbreak
disease in one location | can be contained
26
global epidemic
pandemic
27
main mech of AIDS
infects and destroys CD4+ T cells
28
Gay-Related ImmunoDeficiency (GRID)
1980s | original name for HIV
29
prevalence of AIDS
39+ million deaths globally since 1st clinically recognised
30
AIDS patients show symptoms of ...
PCP pneumonia
31
PCP pneumonia
pneumocystic pneumonia common lung infection bad in immunocompromised patients trreatable if found early
32
HIV-1 retrovirus spread
zoontoic requires high risk transmission for human to human spread spread due to prostitution in african colonies
33
when was HIV-1 first seen in humans
congo 1959
34
HIV protein structures
GP 120 - Docking glycoprotein | GP 41 - transmembrane glycoprotein
35
HLA-DR
human leukocyte antigen - antigen D related MHC class II receptor ligand for the T cell receptor
36
HIV epithelial entry mechanisms
M cells epithelial damage langerhan cells chemokine receptor CCR5
37
M cells used by HIV for epithelial entry
transfer through and present to dendritic cells
38
importance of langerhan cells
projections stick out to sample antigens
39
where is the chemokine receptor CCR5 found
small intestine
40
HIV-1 binds to chemokine receptor CCR5 | mechanism
HIV-1 binds via gp120 | virus is transcytosed across membrane and exposed to dendritic cells
41
consequences of HIV infection
dendritic cells translocate HIV from mucosa i viral proliferation and viremia loss of helper T activities therefore no maintenance of CD8 cels and no antibody response of `b cells
42
timescale of HIV infection
dendritic cells translocate HIV from mucosa in 30 mins - quick by 3 weeks all lymphoid tissues are infected
43
why flu symptoms shown in HIV
loss of CD4 T cells in the blood | opportunistic infection when CD4 T cells <200ul
44
3 classes of influenxa
A B C
45
influenza A
most common | responsible for pancdemic outbreaks
46
flu is zoonotic
bird (avian) virus that adapts to humans | spread via aerosol droplets
47
influenza cytolytic effects
infections created in respiratory tract epithelium
48
structure of influenza virus
spherical or rod enveloped 2 x spike glycoproteins on surface (HA and NA)
49
HA
trimeric haemaglutinin mediates binding to cell surface (sialic acid) mediates internalisation of viral particles (endocytosis)
50
NA
tetrameric haemaglutinin cleaves sialic and promotes viral release from cells using ennzymes
51
bird genotypes
diverse
52
HA subtypes
H1 to H5
53
NA subtypes
N1 to N9
54
importance of pigs in influenza virus transfer to humans
pigs carry both types of linkage (e.g. alpha-2,6) pigs infected by both linkages and exhange viral genomes crucial for transfer
55
antigenic drift in influenza virus
point mutations in HA and NA means virus is no longer recognised by neutralising antibodies common cause of antibiotic
56
antigenic shift in influenza virus
reassortment of human/bird genomes inside pig whole cell change therefore highly transmissable pandemic caused
57
3 major pandemics
1918 - spanish flu 1957 - asian flu 1968 - hong kong flu
58
spanish flu
1918-1920 H1N1 subtypes brought over by US after WWI targets active immune systems (20-40 yr olds) high infection rates - 5% population died
59
hypercytokinemia
response of immune system to spanish flu cytokine storm release of over 150 inflammatory mediators

cellular basis of immunity (21 decks)

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