Therapy of human rabies: lessons from experimental studies in a mouse model

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Therapy of human rabies lessons from
experimental studies in a mouse model

• Alan C. Jackson, MD
• Courtney A. Scott, BSc
• James Owen, BSc
• Simon C. Weli, PhD
• John P. Rossiter, MB, PhD
• Departments of Medicine (Neurology)
• Microbiology and Immunology
• Centre for Neuroscience Studies
• Queens University, Kingston, ON, Canada

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Medical complications of rabies

• multisystem organ failure
• respiratory
• failure, hyperventilation, aspiration pneumonia
• cardiac
• failure, arrhythmias
• gastrointestinal hemorrhage
• hyperthermia or hypothermia
• endocrine SIADH, DI

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Recovery from rabies

• 6-yr-old male from Ohio. Hattwick et al.
  Ann
  Intern Med (1972)
• 45-yr-old female from Argentina. Porras et al.
  Ann Intern Med
  (1976)
• 32-yr-old male lab worker from New York.
  Tillotson et al. MMWR (1977)
• 9-yr-old male from Mexico. Alvarez et al.
  Pediatr Infect
  Dis (1994)
• 6-yr-old female from India. Madhusudana et al.
  Int J Infect
  Dis (2002)

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Clinical Infectious Diseases 3660-63, 2003
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Specific therapies

• rabies vaccine
• human rabies immune globulin (or mabs)
• ribavirin
• interferon-?
• ketamine
• role of combination therapy?

Jackson et al. Clinical Infectious Diseases
3660-63, 2003
6
N Engl J Med
3522508-14, 2005
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Survival Case

• healthy 15-year-old in Wisconsin
• bitten by bat probable bat rabies virus (no
  virus isolated, no antigen or RNA identified)
• antibodies on presentation (RFFIT 1102)
• midazolam infusion to produce burst suppression
  pattern on EEG with supplemental phenobarbital
• IV ketamine infusion 2 mg/kg/hr
• antiviral therapy with ribavirin (IV) and
  amantadine

N Engl J Med 3522508-14, 2005
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Survival Case

• Did specific therapy play important role in
  recovery?
• therapeutic coma??
• ketamine?
• antiviral therapy?
• Attenuated bat rabies virus strain?
• Early antibody response
• Lack of detection of viral antigen and RNA,
  suggests that effective viral clearance was in
  progress

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Ketamine

• dissociative anesthetic agent
• ketamine (1-2 mM) inhibits in vitro replication
  of rabies virus by inhibiting genome
  transcription
• with stereotaxic inoculation of fixed rabies
  virus into neostriatum of rats, ketamine 60 mg/kg
  IP q12h reduced infection in multiple brain
  regions (hippocampus, cerebral cortex, and
  thalamus)

Lockhart et al. Antiviral Chem Chemother 1991
and 1992
Antimicro Agents Chemother 1991
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Journal of Virology 8010270, 2006
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Toluidine blue-stained plastic sectionscerebral
cortex 48 hrs

• Mock-infected CVS-infected

J Virol 8010270, 2006
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Trypan blue exclusioncerebral cortex 72 hrs

• Mock-infected CVS-infected

J Virol 8010270, 2006
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Trypan Blue Staining Cerebral Cortex
Hippocampus
J Virol 8010270, 2006
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Effects of 125 µM ketamine on viability of
cortical neurons in CVS infection
J Virol 8010270, 2006
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Cumulative mortalityketamine 60 mg IP q12h or
vehicle

• intracerebral
  footpad
• log rank test p 0.50 log rank
  test p 0.53

J Virol 8010270, 2006
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Therapy with Ketamine

• Ketamine did not
• reduce mortality
• attenuate the clinical neurologic illness or
  prolong survival
• reduce viral spread or the number of infected
  neurons
• reduce the amount of infectious virus
• reduce neuronal apoptosis after intracerebral
  inoculation

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Lancet Neurology 3744, 2004
multiple sclerosis spinal cord injury Parkinsons
disease Huntingtons disease amyotrophic lateral
sclerosis viral diseases of CNS reovirus, SIV,
Sindbis v.
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Journal of Virology 816248, 2007
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log rank test p0.003
J Virol 816248, 2007
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Summary

• Therapy with minocycline (50 mg/kg/d) was
  associated with more severe neurologic disease
  and higher mortality than with vehicle in rabies
  virus infected mice.
• The number of rabies virus-infected neurons was
  similar with vehicle and minocycline.
• Neuronal apoptosis was more marked in infected
  mice that received vehicle than minocycline
  (minocycline was anti-apoptotic).
• There were smaller numbers of CD3 positive cells
  in the brainstem of mice that received
  minocycline than vehicle, indicating an
  anti-inflammatory effect of the drug.

J Virol 816248, 2007
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Conclusions

• Therapy of rabies with minocycline in an
  experimental mouse model did not provide
  neuroprotection and aggravated the neurological
  disease.
• Caution should be taken before using minocycline
  for empirical therapy of rabies or other viral
  encephalitis in humans before more experimental
  data become available.

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Therapeutic approach similar to the Willoughby
protocol has been unsuccessful in at least 8
cases

• United States 3 (TX, IN, CA)
• Canada (Alberta)
• Germany 2
• India
• Thailand

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Conclusions Ketamine

• Lack of efficacy of ketamine in about 8 human
  cases since the Milwaukee case
• Lack of efficacy of ketamine in primary neuronal
  cultures and in vivo in mice at 120mg/kg/d
• More experimental evidence is needed that
  supports the use of ketamine in rabies virus
  infection before recommending its use for the
  therapy of human rabies.

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Therapeutic coma

• useful for therapy of status epilepticus
• efficacy in other neurologic disorders is
  unproven
• no experimental evidence of efficacy in rabies or
  any other infectious disease
• potential serious adverse effects
• lack of effective neuroprotective agents even in
  common acute neurologic disorders (e.g., stroke),
  despite numerous clinical trials
• no scientific rationale for use in rabies
• does not work
• risks outweigh benefits
• should not be used for human rabies

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Willoughby protocol

• Multiple failures of the protocol in developed
  and developing countries.
• It is now highly questionable that therapy using
  this protocol was directly responsible for the
  favorable outcome.
• This protocol should not be repeated
  indefinitely.
• Experimental work should be performed in cell
  culture and in animal models to identify
  promising therapeutic agents.
• New approaches should be taken for future rabies
  patients.

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Acknowledgments
Queens University Violet E. Powell Fund
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