populate the concept map with terms from the lecture PowerPoint and draw/label any connections between terms.
Dr. Sean Murray
Mid-70s, Children in Lyme, CT
arthritis
Mid-70s, Children in Lyme, CT
arthritis
rash
Mid-70s, Children in Lyme, CT
arthritis
rash
conjunctivitis
Mid-70s, Children in Lyme, CT
arthritis
rash
conjunctivitis
fatigue/fever
headache
stiff neck
Mid-70s, Children in Lyme, CT
arthritis
rash
pain
numbness
weakness
conjunctivitis
fatigue/fever
headache
stiff neck
Mid-70s, Children in Lyme, CT
arthritis
facial
paralysis
rash
pain
numbness
weakness
conjunctivitis
fatigue/fever
headache
stiff neck
Mid-70s, Children in Lyme, CT
arthritis
facial
paralysis
rash
pain
numbness
weakness
conjunctivitis
fatigue/fever
headache
stiff neck
cardiac and/or neurological symptoms
What caused this illness
?
Early 1980’s: the gram-negative
bacterium
Borrelia
burgdorferi
Identification of Borrelia as
causative agent of Lyme
disease
• Isolate single colonies of Borrelia from ticks
• Grow up colonies, feed to ticks
• Let ticks bite rabbits
• See rash
• Isolate Borrelia from people with Lyme
disease
How were the children exposed to
this bacterium?
Dime
Photos by John VanDyk, Iowa State Univ.
How were the children exposed to
this bacterium?
Dime
Photos by John VanDyk, Iowa State Univ.
…via tick saliva (yuck!)
Tick after feeding….
Must feed for at least 24 hours to pass
on Borrelia burgdorferi bacteria to its host
How did ticks get infected with
Borrelia bergdorferi?
?
How did ticks get infected with
Borrelia bergdorferi?
How did ticks get infected with
Borrelia bergdorferi?
reservoirs
Life cycle of Borrelia burgdorferi in
the tick (Ixodes)
What we’ve discussed so far…
Lyme disease is NOT a new disease
• 1883 Lyme-related symptoms reported
in Germany
• 1909 Linked Lyme-related symptoms
with tick bites in Sweden
• ~1950 Treat symptoms with
antibiotics in Europe
• 1970 First tick-related rash reported in
USA
2002 Lyme Disease Cases by State as Reported to CDC
n=23,76
3
3989
3
7
219
26
1
1807553
5
85
2
4631
2349
19
4
D.C.
25
259
137
82
2
79
2
6
26
21
25
28
11
12
5
3
41
47
109
0
867
42
1
2
6
7
0
139
1
1
4
0
11
4
5
4
4
12
97
0 3
26
738
Ecological conditions in the northeast
maintain lyme disease
• Reforestation of northeast (after being previously
deforested for farmland); contiguous forested
area allows for mice, deer, birds, and ticks to
spread to new areas
• Residential development of reforested areas
(suburbs)
• Borrelia burgdorferi’s ability to infect multiple
species
How does Borrelia evade the immunity
of very different species?
reservoirs
Study Borrelia at the molecular level
Some Basic Immunology
• White blood cells recognize pathogen surface structures
(innate immunity)
• Pathogen is internalized and degraded to peptide
fragments
White Blood Cell Presents short
internalizes Pathogen degraded; peptides on surface
Pathogen peptides produced for Antibody production
Some Basic Immunology
• White blood cells recognize surface pathogen surface
structures (innate immunity)
• Pathogen is internalized and degraded to peptide
fragments
White Blood Cell Presents short
internalizes Pathogen degraded; peptides on surface
Pathogen peptides produced for Antibody production
Secretion molecules
to attract more WBCs;
inflammation
Some Basic Immunology
• White blood cells recognize surface pathogen surface
structures (innate immunity)
• Pathogen is internalized and degraded to peptide
fragments
White Blood Cell Presents short
internalizes Pathogen degraded; peptides on surface
Pathogen peptides produced for Antibody production
e.g. YVLEGTLTA
Secretion molecules
to attract more WBCs;
inflammation
Antibodies
• Bind to targets with
high affinity
• Trigger WBCs to
ingest pathogens and
destroy them
• Help complement
make holes in
pathogen membranes
Activated complement
Bacterial pathogens
bacterial
pathogen
intracellular
extracellular
Bacterial pathogens
bacterial
pathogen
intracellular
extracellular
Hide within host
cells, don’t worry
about hiding
surface protein
Avoid killing by
WBCs by living
inside them
Survival Strategies
Bacterial pathogens
bacterial
pathogen
intracellular
extracellular
Hide antigens to avoid immune response
Vary surface proteins by mutation
Survival Strategies
Hide in immune privileged sites
Hide within host
cells, don’t worry
about hiding
surface protein
Avoid killing by
WBCs by living
inside them
Bacterial pathogens
bacterial
pathogen
intracellular
extracellular
Hide antigens to avoid immune response
Vary surface proteins by mutation
Survival Strategies
Hide in immune privileged sites
Hide within host
cells, don’t worry
about hiding
surface protein
Avoid killing by
WBCs by living
inside host cells
Borrelia
Host-pathogen interactions
Tick saliva
inhibits immunity
Borrelia lacks or hides
common bacterial
surface structures
Bacterial cell envelopes
Gram-negative
Gram-positive
inner
membrane
(phospholipids)
peptidoglycan
(sugars)
lipopolysaccharide
asymmetric outer
membrane
phospholipids
lipids with chain of
sugars attached
endotoxin
Borrelia’s outer membrane has no
lipopolysaccharide endotoxin
Benefit: Borrelia doesn’t
trigger septic shock
in its hosts, which could kill
the host when Borrelia
travels though the host
bloodstream
outer membrane
inner membrane
periplasm
peptidoglycan
Borrelia’s flagella lie between the
inner and outer membranes
Benefit: Flagellar antigens hidden from the host immune system
Caulobacter
Tick saliva
inhibits immunity
Borrelia lacks or hides
common bacterial
surface structures
Borrelia prevents
attack by complement
Host-pathogen interactions
Complement evasion mediated by lipoproteins
outer
membrane
Borrelia is resistant to host-
complement
Borrelia has lipoproteins on its surface that recruit
a host protein that prevents pores from being
made in its membrane
Tick saliva
inhibits immunity
Borrelia lacks or hides
common bacterial
surface structures
Borrelia prevents
attack by complement
Borrelia adapts
to very different hosts
Host-pathogen interactions
Borrelia must adapt to its
environment
• Temperature
cold-blooded warm-blooded
Borrelia must adapt to its
environment
• Temperature
• pH
cold-blooded warm-blooded
Unfed tick
pH 7.4
Fed tick
pH 6.8
Borrelia must adapt to its
environment
• Temperature
• pH
• Cell density
cold-blooded warm-blooded
Unfed tick
pH 7.4
Fed tick
pH 6.8
Borrelia only expresses proteins
when needed
• OspA (Outer Surface Protein) lipoprotein is
adhesin used to bind to tick midgut – expressed
only in ticks
• OspC helps Borrelia migrate into salivary gland
• Feeding tick vs Unfed tick
OspA
OspC
OspA
OspC
How does Borrelia modulate OspA/
OspC?
• Temperature change regulates
topoisomerase enzymes, which control
supercoiling of DNA
• High Temp: decreased supercoiling
OspA OspC
• Low Temp: increased supercoiling
OspA OspC
DNA Supercoiling
Transcription factor binding promoter
OspA and OspC accumulation and ospA and ospC
transcription levels change in response to temperature
Alverson et al., Mol. Microbiol. 2003
Western blot
with anti-OpsA
or anti-OspC
RNA agarose gel
Plasmid supercoiling in Borrelia changes in
response to temperature
Alverson et al., Mol. Microbiol. 2003
Increased
supercoiling
Decreased
supercoiling
DNA agarose
gel of uncut
plasmid DNA
Plasmid supercoiling in Borrelia changes in
response to temperature
Alverson et al., Mol. Microbiol. 2003
supercoiling
supercoiling
ospA transcription
ospA transcription
Plasmid supercoiling in Borrelia changes in
response to temperature
Alverson et al., Mol. Microbiol. 2003
supercoiling
supercoiling
ospC transcription
ospC transcription
What happens to OspC if we change DNA
supercoiling with topoisomerase mutant?
• Gyrases increase DNA supercoiling
• gyrB mutants
– Reduced gyrase activity
– Decreased DNA supercoiling
OspC synthesis increases in gyrB mutant
Alverson et al., Mol. Microbiol. 2003
Wild type gyrB mutant
Western blot with anti-OspC
Tick saliva
inhibits immunity
Borrelia lacks or hides
common bacterial
surface structures
Borrelia prevents
attack by complement
Borrelia adapts
to very different hosts
Borrelia changes
its surface proteins
to stay one step ahead
of host antibodies
Host-pathogen interactions
Alter exposed antigens
Generate
antibodies
against specific
amino acid
sequences
Change amino acid sequence
of lipoproteins exposed on surface
original infection
original
Borrelia is now mixed population
Originals die
Variants 1 & 2 live
Cycle repeats
variant 1
variant 1 variant 2
When Borrelia faces a tough fight, it has
been proposed to hide…
• Immune privileged sites
– brain
– eye
– ovary/testis
• Immune system does not function in these
sites because inflammation there could
cause irreversible damage
• Borrelia may hide in these areas waiting to
surface again
Treatment
• antibiotics
• Chronic arthritis may develop after infection
clears………Why?
molecular mimicry
Molecular mimicry
• antibiotics
• Chronic arthritis may develop after infection
clears………Why?
White Blood Cell Presents short
internalizes Pathogen degraded; peptides on surface
Pathogen peptides produced for Antibody production
e.g. YVLEGTLTA
may resemble self-peptide
How can the immune system attack
itself?
Protein Sequence
OspA 165-173 YVLEGTLTA
Human Protein 332-340 YVIEGTSKQ
Associated with chronic arthritis
Prevention
• Don’t leave head or skin exposed in high-
risk areas
• Shower and inspect head or skin for ticks
afterwards and remove any ticks with
tweezers
• Get tested for Borrelia antibodies if you
have Lyme-disease-like symptoms
Lyme cycle: temperature, pH, cell density
ADAPT
OspA
#1
#2#3
Lyme cycle: temperature, pH, cell density
ADAPT
OspA
ADAPT
OspC
OspA
#1
#2#3
Lyme cycle: temperature, pH, cell density
ADAPT
OspA
ADAPT
OspC
OspA
OspA
ADAPT
ADAPT
OspC
OspA
#1
#2#3
Lyme cycle: temperature, pH, cell density
ADAPT
OspA
ADAPT
OspC
OspA
OspA
ADAPT
ADAPT
OspC
OspA
ADAPT AND FACE
IMMUNE ATTACK:
change antigens
hide in IP sites
#1
More symptoms
#2
Lyme cycle: temperature, pH, cell density
ADAPT
OspA
ADAPT
OspC
OspA
OspA
ADAPT
ADAPT
OspC
OspA
IMMUNE ATTACK
AND ADAPTION:
change antigens
hide in IP sites
#1
More symptoms
ADAPT AND FACE
IMMUNE ATTACK:
change antigens
hide in IP sites
More
symptoms
#2#3
Lyme cycle: temperature, pH, cell density
ADAPT
OspA
ADAPT
OspC
OspA
OspA
ADAPT
ADAPT
OspC
OspA
ADAPT AND FACE
IMMUNE ATTACK:
change antigens
hide in IP sites
#1
More symptoms
ADAPT AND FACE
IMMUNE ATTACK:
change antigens
hide in IP sites
More
symptoms
#2#3