Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Neuro Histology & Pathology > CNS Viruses > Flashcards

CNS Viruses Flashcards

1
Q

Neuroinvasive viruses

A

are capable of entering or infecting the CNS (rather than just peripheral nerves i.e. neurotropic viruses)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Neurovirulent viruses

A

are capable of causing disease within the CNS

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Neurotropic viruses

A

are capable of replicating in nerve cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Meningitis

A

infection of the meninges surrounding brain and spinal cord

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Encephalitis

A

inflammation of the brain

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Myelitis

A

infection of the spinal cord

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Encephalomyelitis

A

inflammation of brain and spinal cord

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Primary viral encephalitis (acute)

A

direct viral infection of the spinal cord and brain; focal or diffuse

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Secondary encephalitis (post-infectious)

A

results from complications of a current viral infection where the virus spreads to the brain via blood

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is the most common cause of viral meningitis?

A

enteroviruses eg echo, coxsackie

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What are less common viral causes of meningitis?

A

mumps, VZV, influenza, HIV< HSV2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

How does the presentation of viral encephalitis differ from viral meningitis?

A

as viral meningitis plus personality and behavioural changes, seizures, partial paralysis, hallucinations, and altered levels of consciousness, ultimately coma and death

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What are the common causative viruses of encephalitis?

A

HSV1 and 2, rabiesvirus, arboviruses (insect-borne) or enteroviruses most common; mumps can cause meningitis that mildy infects brain parenchyma

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What is postinfectious encephalomyelitis?

A

infection of the brain and spinal cord following infection such as measles, chicken pox, rubella, or mumps - no virus is actually present but there is inflammation and demyelination that is possibly autoimmune in nature (cross-reactivity bc parts of virus look like myelin sheath)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is Guillain-Barré syndrome?

A

acute inflammatory demyelinating disease resulting in partial or total paralysis following infection with EBV, CMV, HIV

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Reye’s syndrome

A

occurs post-infection with influenza or VZV in children; cerebral oedema but no inflammation; related to aspirin administration for fever

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Chronic demyelinating disease

A

very rare e.g. subacute sclerosing panencephalitis post-measles later in life

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

AIDS encephalopathy/dementia complex

A

once HIV progresses to AIDS, it becomes neurovirulent and causes dementia

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

How do viruses spread to the brain?

A

peripheral nerves or ganglia connecting to the CNS; via blood stream (viremia)

20
Q

Why are viruses ‘protected’ by axons and dendrites?

A

Nerve fibres do not have MHC class I molecules and therefore cytotoxic T cells cannot attack them

21
Q

Which viruses can travel via peripheral axons to the CNS?

A

rabies, yellow fever, HSV1 & 2

22
Q

Replication of viruses travelling in peripheral nerves must take place

A

in the body of the nerve cell as this is where protein synthesis takes place; progeny cross synaptic junctions

23
Q

Retrograde viral spread occurs

A

from peripheral nerves to the CNS; progeny cross synaptic junctions

24
Q

Anterograde viral spread occurs

A

from the CNS to peripheral nerves; progeny cross synaptic junctions

25
Q

How do viruses spread to the brain via the blood stream?

A

commonly through the choroid plexus into CSF (eg mumps); cerebral vessels; meningeal vessels

26
Q

Which viruses can spread to the brain via blood?

A

poliovirus, mumps, measles, coxsackie, HIV in monocytes

27
Q

Viruses affecting the nasopharynx can travel to the brain via

A

the olfactory bulb (coronavirus, HSV, H5N1)

28
Q

How do viruses cause damage in the brain?

A

directly killing neurons (causes inflammatory response as tight junctions open up and allow lymphocytes, antibodies, immune effectors usually blocked by BBB); or replicate in non-neuronal cells (eg oligodendrocytes) triggering demyelination

29
Q

What is obligatory in the life cycle of rabiesvirus?

A

growth in nerve cells

30
Q

Rabiesvirus has (neuroinvasiveness, neurovirulence)

A

high neuroinvasiveness, high neurovirulence

31
Q

What is the structure of rabiesvirus?

A

bullet shaped -ve RNA virus w/helical capsid and envelope (tf must bud from cells to get its envelope glycoproteins - these are a target for antibodies)

32
Q

What is the nature of damage in rabiesvirus?

A

because it has an envelope it must bud from the cell to get its glycoproteins which are expressed on the cell - these are targets for antibodies to kill the cells

33
Q

What is the pathogenesis of rabiesvirus?

A

infected animal bite breaks skin; virus replicates in myocytes (1-60); virus enters peripheral nerve endings and carried to spinal cord (10-60); travels in CNS, causes neuronal dysfunction (12-60); clinical rabies, death (50-70); travels from CNS to salivary glands (30-70); replicates in salivary acinar cells (40-70)

34
Q

What are the symptoms of rabiesvirus?

A

aggression (hence biting), thirst but muscle spasm and fear of drinking water

35
Q

What is obligatory in the life cycle of alpha herpesviruses (HSV1 & 2, VZV)?

A

growth in nerve cells

36
Q

Alpha HSV viruses (neuroinvasiveness, neurovirulence)

A

low neuroinvasiveness, high neurovirulence

37
Q

What is the structure of alpha herpesviruses?

A

linear dsDNA, icosahedral, surrounded by envelope

38
Q

What is the pathogenesis of HSV?

A

infected saliva enters break in skin or mucous membranes (HSV1: mouth, throat, eye; HSV2: genitals) and multiplies locally; in 90% of cases it goes on to multiply in regional lymph nodes as an inapparent infection and resolve; 10-15% develop primary disease that enters adjacent nerve endings (occurs directly in 5%) where it then migrates along axons to sensory nerve ganglia where it resides as a latent infection until immunity is compromised and it is reactivated; on reactivation get localized multiplication and disease reoccurrence; *= rarely it enters the blood and travels to organs causing severe sporadic encephalitis of the temporal lobe

39
Q

What happens in the latent phase of HSV infection?

A

20% of people harbour genome episome (closed circular dsDNA) covered in histones w/latency activated mRNA transcripts (LATs); it is maintained in the latent phase by CD8 T cells killing infected cells (this is why you get reoccurrence in old age/when the immunity wanes)

40
Q

What is the pathogenesis of VZV?

A

infection of conjunctiva and/or URT; replicates in regional lymph nodes; primary viraemia in bloodstream (4-6); further replication in liver and spleen; secondary viraemia; infection of skin + vesicular rash (10); scratching aeresolizes virus and cycle repeats; in 10-20% of cases, from the RASH the virus can go up to dorsal root ganglia and become latent

41
Q

What is different about the life cycle of poliovirus vs the alpha herpesviruses and rabiesvirus?

A

growth in nerve cells is NOT an obligatory part of the life cycle

42
Q

Poliovirus (neuroinvasiveness, neurovirulence)

A

low neuroinvasiveness, high neurovirulence

43
Q

What is the structure of poliovirus?

A

+ve RNA, icosahedral capsid, no envelope - kills cells in which it replicates

44
Q

What is the pathogenesis of poliovirus?

A

ingested from faecally contaminated food or water; replicates in tonsils, then Peyer’s patches of GIT (0-3) - excreted in faeces (5-45, normal); replicates in regional lymph nodes (3-5); enters blood (5-15) and crosses BBB (8-12) to anterior horn cells of spinal cord (10-30), destroying them and causing paralysis (12-30)

45
Q

What is the pathogenesis of enteroviruses (coxsackie A & B, echoviruses, poliovirus)?

A

faecal-oral route; primary and secondary viraemia via lymphoid tissues into the blood

Neuro Histology & Pathology (6 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions