Viral Neuropathogenesis

Question 1

Which barriers does the CNS have to viral invasion?

Answer 1

Blood brain barrier
Lack of lymphatic drainage
Presence of insusceptible cells
Presence of macrophages
Isolation from systemic immune responses.

Question 2

What are the different routes of viruses to the CNS?

Answer 2

Animal bite
Blood transfusion
Transplantation
Vaccination
Droplet (respiratory)
Saliva (respiratory)

Question 3

Which factors determine neural cell susceptibility to viruses?

Answer 3

1. Presence of viral receptors on neural cells.
2. State of differentiation of neural cells
3. Mitotic activity of neural cells
4. Neural cell site.
5. Density of neural cells and supporting cells.
6. Immune responses in CNS

Question 4

What are the various effects viruses could have on host cells?

Answer 4

1. Lysis
2. Transformation
3. Latent infection
4. Persistent infection
5. Chronic dysfunction
6. No pathological effects

Question 5

What can reactivate herpes virus?

Answer 5

Trauma
Fever
Sunlight
X-ray irradiation
Immunosuppression
Malignancy
Drugs/chemicals

Question 6

Which transcripts are present during herpes latency?

Answer 6

HSV-1 transcripts

Question 7

What drives expression of latency associated transcripts?

Answer 7

Latency active promotor elements.

Question 8

What is neurovirulence of polio determined by?

Answer 8

5’ non-coding region of genome

Question 9

Which change confers polio neurovirulence?

Answer 9

Uridine to cytidine at position 472 in 5’ non coding region.

Question 10

What does rabies neurovirulence require?

Answer 10

Arginine or lysine in position 333 of viral glycoprotein.

Question 11

What are the immunopathological mechanisms in CNS in viral disease?

Answer 11

1. Induction of cytotoxic T cells.
2. Infection of immune cells.
3. Viral induction of cytokines.
4. Viral triggering of autoimmune responses.
5. Antigen presentation by neural cells.
6. Role of immunosuppression.

Question 12

What are some common causes of encephalitis in the UK?

Answer 12

Herpes simplex
Varicella-Zoster
EBV
CMV
Mumps
Measles
Rubella
Enterovirus infection
Influenza

Question 13

What is the neuropathogenesis of HSE?

Answer 13

1. Host defence/immune system are deficient.
2. HSE caused by very neurovirulent HSV.
3. Subclinical brain involvement is followed by later clinical or subclinical reactivation.
4. HSE is a rare change event occurring via a neurotropic route.