Rabies, Prion disease and Herpes Flashcards
(51 cards)
Why is rabies a more common cause of death in the developing world?
more exposure to animals
What group of viruses is rabies included in?
rhabdovirus, subtype lyssavirus
What are the key proteins in rabies virus?
viral glycoprotein/envelope (G)
nucleocapside (N)
matrix (M)
NS and L proteins rarer
What type of genome does rabies have?
- ss RNA
What can envelope (G) bind?
nicotinic ACh receptor in muscle, gangioside and CD56 in neurons
How does rabies virus enter cells?
is endocytosed and envelope fuses at low pH with endosomal membranes to release nucleoprotein
What switch must occur in order for rabies genome production to occur?
viral polymerase switches from mRNA mode to making full length + RNA which will serve as a template for - genome production
due to a buildup of N protein
Does rhabdovirus budding usually kill cells? Does it kill cells in the case of rabies?
yes
no
Which rabies molecule eleicits neutralizing antibodies?
G glycoprotein
is not protective
allows for vaccine production
How does rabies typically enter the body?
through a wound or ski abrasion via a bite and introduction to infected saliva
-also, rarely via infected cornea/organ transplants
Where does virus replicate during the “incubation” period?
muscle or connective tissue
How quickly does rabies virus travel in the CNS?
8-20mm/day
When is rabies intervention effective?
before spread to the nerves/CNS
Where does the rabies virus disseminate to after replicating in high levels in the brain?
eye, salivary glands, innervated ski (ie/hair follicles)
How long does the incubation period usually last?
3-8wks
patients usually asymptomatic
*the closer a bite is to the brain the shorter this period
What is the prodrome phase of rabies infectioin?
early after infection of brain
nervousness, headache, anxiety, pain at bite site, fever, nausea
progresses to myoclonus, slurred speech and tingling
presents to brain at end of this period, patients usually still Ab negative
Describe the acute neurological phase of rabies infection
high virus titer in brain and elsewhere
Ab present in serum and CNS
Progression from here can be “furious”/fulminant, or “dumb”/paralytic
Describe furious/fulminant progression of rabies
classic rabies
bizarre behavior, hallucinations, seizures, hydrophobia
fury later gives way to paralysis, then either coma or sudden fatal cardiac or respiratory arrest
Descirbe the paralytic or dumb progression of rabies
ascending flaccid paralysis, leads to fatal paralysis of respiratory muscles
What is the “hydrophobia” associated with rabies?
violent spasms of respiratory muscles triggered by drinking water
sight sound or mention of water can trigger it
What are “negri bodies”?
virus vactories, seen in some but not all cases of rabies
What is Dr. Wiloughby’s theory on the pathology of rabies?
that it is a metabolic disease
(a disease of ‘software’, not ‘hardware)
based on observation that patient’s brains are normal on gross path, there are Abs during final acute phase, and there is often little virus remaining at end stages
How is rabies diagnosed?
neurologic sx in living person w/suspected exposure
confirmed by detecting virus in CSF, saliva, skin or PCR
How are animals tested for rabies?
brain tissue tested by dFA
