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

Alan C. Jackson, MD Courtney A. Scott, BScJames Owen, BScSimon C. Weli, PhDJohn P. Rossiter, MB, PhD

Departments of Medicine (Neurology) Microbiology and ImmunologyCentre for Neuroscience StudiesQueen’s University, Kingston, ON, Canada

Medical complications of rabies

multisystem organ failure respiratory

failure, hyperventilation, aspiration pneumonia

cardiac failure, arrhythmias

gastrointestinal hemorrhage hyperthermia or hypothermia endocrine – SIADH, DI

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)

Clinical Infectious Diseases 36:60-63, 2003

Specific therapies rabies vaccine

human rabies immune globulin (or mabs)

ribavirin

interferon-

ketamine

role of combination therapy?

Jackson et al.: Clinical Infectious Diseases 36:60-63, 2003

N Engl J Med 352:2508-14, 2005

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 1:102) 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

amantadineN Engl J Med 352:2508-14, 2005

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

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

Journal of Virology 80:10270, 2006

Toluidine blue-stained plastic sectionscerebral cortex – 48 hrs

Mock-infected CVS-infected

J Virol 80:10270, 2006

Trypan blue exclusioncerebral cortex – 72 hrs

Mock-infected CVS-infected

J Virol 80:10270, 2006

Trypan Blue StainingCerebral Cortex Hippocampus

J Virol 80:10270, 2006

Effects of 125 μM ketamine on viability of cortical neurons in CVS infection

J Virol 80:10270, 2006

Cumulative mortalityketamine 60 mg IP q12h or vehicle

intracerebral footpad

log rank test p= 0.50 log rank test p= 0.53

J Virol 80:10270, 2006

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

Lancet Neurology 3:744, 2004

multiple sclerosisspinal cord injuryParkinson’s diseaseHuntington’s diseaseamyotrophic lateral sclerosisviral diseases of CNS – reovirus, SIV, Sindbis v.

Journal of Virology 81:6248, 2007

log rank test p=0.003

J Virol 81:6248, 2007

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 81:6248, 2007

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.

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

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.

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

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.

Acknowledgments

Queen’s University Violet E. Powell Fund