Rhabdovirus

Summary

Rhabdoviruses are a class of RNA viruses that contain negative-sense RNA. They utilize a helical capsid, and are further surrounded by a viral envelope.

The most common rhabdovirus is rabies, which is a bullet shaped virus that is transmitted through bats and other wild animals like racoons. Rabies binds to neuronal nicotinic acetylcholine receptors in the peripheral nervous system, and travel in a retrograde fashion back to reach the brain or central nervous system. A rabies infection that reaches the brain causes encephalitis, which manifests clinically as hypersalivation, photophobia, and hydrophobia. To diagnose a rabies infection, clinicians do a brain biopsy and then search brain tissue for intracellular inclusions called Negri bodies. It is crucial that a patient who may be exposed to a rabid animal receive a killed rabies vaccine and rabies immunoglobulin as soon as possible to prevent the spread of the virus to the brain.

Key Points

• Rhabdoviruses
  • Characteristics
    • RNA viruses
      • replicate in the cytoplasm of cells
      • Single-stranded
      • - sense
        • Must be translated into +RNA for translation and replication
      • Linear genome
    • Enveloped
    • Helical capsid
  • Presentation
    • Rabies virus
      • Characteristics
        • Bullet-shaped virus
      • Transmission
        • bat, raccoon, and skunk bites
          • More common than dog bites in US
        • Aerosol transmission (bat caves) also possible
      • Pathophysiology and Presentation: Rabies
        • Long incubation period (weeks to months) before symptom onset
        • Binds to ACh receptors
          • Travels to CNS by migrating in retrograde fashion (via dynein motors) up nerve axons
        • Prodrome (Fever, malaise, pharyngitis, pain around bite site)
        • Encephalitis
          • hypersalivation
          • photophobia
          • hydrophobia
          • paralysis
          • agitation, coma, focal neurological deficits, death
      • Diagnosis
        • Brain Biopsy
          • Usually diagnosed post-mortem
          • Negri bodies
            • Round eosinophilic cytoplasmic inclusions found in
              • Purkinje cells of cerebellum
              • pyramidal hippocampal neurons
        • RT-PCR can also be used
      • Post-exposure Prophylaxis
        • Wound cleaning
        • Killed (inactivated) vaccine
          • Active immunization
        • Rabies immunoglobulin
          • Passive immunization
      • Treatment
        • Supportive