Rhabdovirus Characteristics

Rhabdovirus (Rabies)

• Rhabdovirus is a negative sense RNA virus with a helical nucleocapsid and a bullet-shaped capsule.
• It is an enveloped virus that can be transmitted through the saliva of infected animals such as bats, foxes, and squirrels.

Mechanism of Infection

• The virus binds to nicotinic acetylcholine receptors in the neuromuscular junction (NMJ) using its glycoprotein.
• Initial infection occurs at the synaptic receptors in the motor end plate.
• The virus replicates in motor neurons and moves in a retrograde fashion to the central nervous system (CNS).

Pathogenesis

• The virus replicates in the dorsal root ganglia and ascends in the spinal cord, eventually spreading to the brain.
• The virus can remain in ACH receptors for days to months before symptoms appear.

Stages of Disease

• Incubation: Asymptomatic, low titer, with virus in muscle.
• Prodrome: Fever, nausea, vomiting, headache, low titer, virus in CNS/brain.
• Neurologic: Hydrophobia, hallucination, delirium, paralysis, antibodies found in serum and CSF.
• Coma/Death: Coma, hypotension, hypoventilation, cardiac arrest (14 days after symptoms).

Diagnosis and Treatment

• Diagnosis is clinical and can be confirmed with Negri bodies, eosinophilic cytoplasmic inclusions found in the hippocampus or cerebellum.
• Treatment involves passive preformed antibodies (IgG) prior to symptoms, and a killed vaccine can be given as a post-exposure prophylaxis.
• Antidote involves administering antibodies prior to symptoms, and killed vaccine can be given even if symptoms have not yet appeared.

Negri Bodies

• Negri bodies are eosinophilic cytoplasmic inclusions found in the hippocampus or cerebellum.
• They are characteristic of rabies infection and can be found in pyramidal cells of the hippocampus and Purkinje cells of the cerebellum.