Viruses affecting the CNS Flashcards

1
Q

Under what circumstances do lymphocytes cross the BBB?

A

During inflammation of the CNS

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2
Q

At what point does HIV become neurovirulent?

A

Once immunodificiency presents

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2
Q

Is it more common for alpha herpes viruses to travel to the CNS via the blood or through peripheral nerves?

A

Peripheral nerves

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3
Q

How does the rabies virus interact with the immune system?

A

It doesn’t try to hide, rather its glycoprotein is displayed on the cell surface

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4
Q

What is Guillain-Barre syndrome?

A

An acute inflammatory demyelinating disease following viral infection - commonly EBV, CMV, and HIV

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4
Q

T/F Viral replication occurs at the synapses in the nerve cells so they can quickly infect other cells

A

False, they replicate in the cell body as they require the protein synthesis machinery

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4
Q

What type of virus is rabies?

A

-sense RNA virus

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5
Q

Where is a common location for viral entry into the parenchyma of the CNS?

A

The choroid plexus

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5
Q

How does poliovirus get into the spinal cord?

A

Gut > regional lymph nodes > blood > spinal cord

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6
Q

How do young children with HSV 1 present?

A

Gingivostomatitis (cold sores)

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7
Q

In which is the virus still present, postinfectious encephalomyelitis or postinfectious encephalitis.

A

Postinfectious encephalitis

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8
Q

What type of virus is poliovirus?

A

+RNA with isosahedral capsid and no envelope

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9
Q

Does Guillain-Barre syndrome require an active infection?

A

No, as show by the outbreak that followed a vaccination program for influenza that used an inactivated virus

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9
Q

T/F Growth in nerve cells is obligatory part of the lifecycle or alphaherpes viruses and poliovirus

A

False, not for poliovirus

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10
Q

How does rabies virus get to the salivary glands?

A

Travels via the peripheral nerves and brain and down into them

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12
Q

What is the case fatality rate of HSV encephalitis?

A

70%

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13
Q

In which structure do HSV typically establish a latent infection?

A

Sensory nerve ganglia of the trigeminal or sacral nerve

14
Q

What is Reye’s syndrome?

A

Post-infectious cerebral oedema in children. Influenza or chicken pox

16
Q

What are the most common causes of viral encephalitis?

A

HSV 1 and 2

Rabies virus

Arboviruses

Enteroviruses

17
Q

In what form is the HSV genome maintained in latent infections?

A

Episome coated with histones

19
Q

What is secondary encephalitis (aka post-infectious encephalitis)

A

Secondary viral infection of the CNS, usually via the blood

19
Q

True or false, rabies replicates in the salivary glands only

A

False, it also replicates in the muscle adjacent to its entry point

21
Q

What is so problematic about viruses traveling in peripheral nerves?

A

They’re protected from attack by CTLs

22
Q

How does varicella-zoster virus enter the body?

A

Respiratory transmission

24
What is the sequelae of viral infection of oligodendrocytes?
Demyelination
24
In which cells does poliovirus infect in that leads to paralysis?
Anterior horn cells in the spinal cord
25
Why aren't peripheral nerves targeted by CTLs?
They don't MHC class I
26
What are neuroinvasive viruses capable of?
Entering or infecting the CNS
27
What immune mechanism may be responsible for keeping the HSV genome in a latent state?
CD8+ T cells
28
Why is the fear of water in rabies?
Evolutionary adaptation of the virus to avoid dilution of the virus in the saliva
29
What are neurotropic viruses?
Viruses capable of replicating in nerve cells
31
Describe HSV 1 and 2 in terms of neuroinvasiveness and neurovirulence
Low neuroinvasiveness High neurovirulence
32
What is myelitis?
An infection of the spinal cord
33
Are alpha herpesviruses non-enveloped or enveloped?
Enveloped
34
How is HSV 1 transmitted?
Via saliva
35
What are neurovirulent cells capable of?
Causing disease within the nervous system
36
What are two stategies of entering the CNS used by viruses?
Traveling up peripheral nerves Crossing the BBB
38
Which virus causes a mild encephalitis?
Mumps virus
39
At what point during varicella-zoster infection does virus enter peripheral nerves?
After entering rashes
40
What is the mechanism of damage postulated to cause postinfectious encephalomyelitis?
Autoimmune demyelination
41
Does rabies infect neurones or oligodendrocytes?
Neurones, it's highly neuroinvasive and neurovirulent
42
Coronavirus and herpes simplex virus share this route of entry to the CNS, what is it?
Via the olfactory bulbs