Borellia burgdorferi and its role in Lyme Disease

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Borellia burgdorferi and its role in Lyme Disease

• Luke Collins
• Bacteriology 330
• 4/24/07

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Borellia burgdorferi

• Gram negative
• Obligate parasite
• Slow growing
• Microaerophilic
• Complex Life Cycle

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History of Lyme disease

• First discovered in Lyme, Connecticut by Dr. Alan
  Steere 1977
• Burgdorferi first isolated by Willy Burgdorfer at
  the National Institute of Health, who named it
  after himself

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Borellia morphology

• Spirochete
• Corkscrews through water and tissue
• Can live in viscous conditions

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Borellia Genome

• Borellia burgdorferi is an obligate parasite and
  has a small, simple genome.
• Chromosome is 910,725 base pairs long
• 17 plasmids, which add up to about 533,000 bp
• Estimated to have only 853 genes (E. coli has
  4288 genes)?

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Borellia Life Cycle Part 1

• Tick acquires spirochete from mice while in its
  nymphal stage
• Recent studies show that songbirds may also serve
  as a reservoir

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Borellia life cycle Part 2

• When the tick becomes an adult, it may bite
  humans or deer and allow Borellia to infect a new
  host.

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Borellia life cycle Part 3

• When infecting a human host, it causes the
  well-known Bullseye welts
• Severe infection may result in muscle pain,
  arthritis, fatigue and brain damage
• Autoimmune response is thought to cause such
  symptoms

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One Disease, Many Species

• Although Borellia burgdorferi was the first
  species known to cause Lyme disease (and still
  considered to be the primary cause) many other
  species have been identified as causing Lyme
  disease.
• B. andersonii, B. japonica, B. valaisiana, B.
  lusitanie, B. turdae. B. tunakii, B. bissettii,
  and B. lonestari have all been found to cause
  Lyme disease.

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Lateral Gene Transfer

• Borellia was thought to not be vulnerable to
  phage, but recent study shows that phiBB-1
  targets Borellia species and may cause lateral
  gene transfer.
• This may contribute to virulence

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Progression of Disease

• After infection, the spirochetes migrate from the
  source of infection, producing the famous
  bulls-eye rash.

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Progression of the Disease

• Once the infection spreads, it causes paralysis
  in various parts of the body.
• May lead to meningitis, joint pain, heart trouble
  or Bell's Palsy

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Prevention

• There is no Lyme vaccine on the market today, so
  the only effective means of protection is to
  avoid ticks.
• Avoiding wooded areas, wearing repellent and
  protective clothing are the best means of
  prevention.

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Treatment

• Use of doxycycline and amoxicillin has been
  proven effective in early stages.
• Treatment becomes more difficult as the disease
  progresses.
• Ceftriaxone is used in late-diagnosed patients,
  and Minocycline is used to treat burgdorferi
  which has crossed the blood-brain barrier.

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Potential Alternative Therapies

• Hyperbaric oxygen therapy has been used on many
  patients.
• Some research indicates that bee venom may have
  an effect on burgdorferi, although this treatment
  is painful.
• Neither of these treatments have undergone
  rigorous scientific study.

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Spread of Lyme Disease
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Advanced Immunology Research

• T-cells are known to combat Borellia infections
  of all sorts.
• Therefore, research has focused on T-cells and
  the inflammation process.

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Advanced Immunology Research

• Borellia toxins appear to induce unregulated
  release of interleukins, which explains the
  redness and swelling
• Borellia also causes local immunosuppression when
  becoming chronic
• It is hoped that study of Borellia infections and
  spread will help advance our understanding of the
  human immune system.

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Conclusions

• Lyme disease is caused by Borellia burgdorferi
  and many other Borellia species.
• Lyme disease requires a complex series of
  interactions between ticks and Borellia over the
  length of the tick's life cycle.
• Lyme disease is difficult to treat, and so
  preventive measures are best.
• Studying the spread and behavior of Lyme disease
  may help us understand our immune system.

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References