CSIM1.19: Herpes viruses I

Question 1

List the members of the Herpesviridae virus family.

Answer 1

1. Herpes Simplex Virus (HSV) 1 and 2
2. Varicella Zoster Virus (VZV)
3. Cytomegalovirus (CMV)
4. Epstein Barr Virus (EBV)
5. Human Herpes Virus 6 (HHV6)
6. HHV 7
7. HHV8 [Kaposi’s sarcoma associated herpes virus)

Question 2

Describe the structure of a typical Herpesviridae virus.

Answer 2

It is a DS DNA virus with a lipid envelope derived from cell nuclear membrane and also has spherical capsid.

Question 3

Describe the life cycle of Herpesviridae.

Answer 3

Primary infection followed by latency (only viral DNA persists, no replication and no intact virus) followed by reactivation (intermittent and depends on the status of the immune system of the host).

Question 4

Define primary infection of HSV

Answer 4

First infection with either HSV1/2

Question 5

Define initial infection of HSV

Answer 5

Usually first HSV2 infection in patient who has been infected by HSV1 or vice versa

Question 6

Define latency of HSV

Answer 6

Viral DNA persists in nerve cell bodies

Question 7

Define reactivation of HSV

Answer 7

Latent virus reactivates

Question 8

What causes HSV reactivation

Answer 8

Immunosuppression

Question 9

What is the seroprevalence of HSV1/2 in UK?

Answer 9

HSV1: around 80%
HSV2: around 10%

Most primary infections before 5 years of age

Question 10

How is HSV transmitted?

Answer 10

Mucosal contact:

1. oral - close social contact (kissing, nurseries etc)
2. genital - sexual

Question 11

Describe the primary infection of HSV1 and HSV2

Answer 11

Usually asymptomatic but can be severe gingivostomatitis

Question 12

Describe the reactivation of HSV 1

Answer 12

Usually asymptomatic / cold sores (orally)

Question 13

Describe the reactivation of HSV 2

Answer 13

Can be asymptomatic but symptomatic at genital area -> painful -> as latent virus sits in sacral ganglia

Question 14

What are the main complications of HSV?

Answer 14

1. Secondary bacterial infection
2. Corneal ulcers -> loss of vision (scarring)
3. Meningitis that is self-limited usually, can be recurrent Mollaret’s meningitis [usually HSV2]
4. Herpes Simplex Encephalitis, can be life threatening [HSV1]

Question 15

What are the risk groups for HSV?

Answer 15

1. neonates

2. immunocompromised