11. Human Herpesvirus

Question 1

HHV 1 & 2 (aka herpes simplex virus/HSV) remain latent in the..

Answer 1

Trigeminal ganglia

Question 2

HHV3 is also known as..

Answer 2

Varicella-Zoster Virus (VZV)
Aka Chicken Pox / Shingles

Question 3

Chicken pox remains latent in the..

Answer 3

Dorsal Root Ganglia

Question 4

HHV3 remains dormant in the..

Answer 4

Dorsal Root Ganglia

Question 5

What is the nucleic structure of Herpesviruses?

Answer 5

dsDNA
- encapsulated in a capsid and envelope
- has viral glycoproteins inserted on envelope surface

Question 6

How do human herpesvirus replicate?

Answer 6

• via DNA polymerase (target of antiviral drugs!!)
• they integrate into the host cell DNA n get translate tgt

Question 7

HHV4 is otherwise known as..

Answer 7

Epstein Barr Virus (EBV)

Question 8

HHV8 is responsible for..

Answer 8

Kaposi Sarcoma (pigmented tumours in mouth & other sites)
- HHV8 is an oncovirus (cancer causing virus)

Question 9

What are the symptoms of HHV 6 & 7?

Answer 9

Childhood rash

Question 10

How long does it take for the Chicken pox to appear as a rash upon infection?

Answer 10

Roughly 2 weeks (10-21days)
- called vesicular rash

Question 11

List out the Human Herpesviruses.

Answer 11

HHV1 & 2 => HSV-1 & HSV-2
HHV3 => Varicella-Zoster Virus (VZV)
HHV4 => Epstein-Barr Virus (EBV)
HHV5 => Human Cytomegalovirus (CMV)
HHV6 & 7 => childhood rash
HHV8 => Kaposi Sarcoma

Alpha: 1,2,3
Beta: 5,6,7
Gamma: 4,8

Question 12

Where do alpha HHVs stay latent in?

Answer 12

Sensory Neurons

HSVs stay latent in trigeminal ganglia
VZV stays latent in dorsal root ganglia

Question 13

Where do beta HHVs stay latent in?

Answer 13

WBCs

HHV6 & 7 stay latent in T cells

Question 14

Where do gamma HHVs stay latent in ?

Answer 14

Lymphocytes

HHV4 immortalises/latent in B cells
Immortalises B cells => tumour/cancer

Question 15

What drug should not be given in a chickenpox patient?

Answer 15

Aspirin
- can cause Reye’s syndrome (liver affected, buildup of ammonia)

Question 16

Human Herpesvirus infections can be..

Answer 16

1. Lytic
2. Persistent
3. Latent
4. Immortalizing (EBV)

Question 17

HSV lesions tend to appear in what region?

Answer 17

Oral & Genital mucosa

Mostly,
HSV-1 ‘above the waist’ => oral
HSV-2 ‘below the waist’ => genital
- but both can cause lesions on both areas (overlap)

Question 18

HSV is lytic in the _______ and latent in the ___________.

Answer 18

Lytic in mucoepithelial cells
Latent in neurons (Trigeminal ganglia)

Question 19

List the clinical syndromes of HSV:

Answer 19

1. Mucocutaneous: gingivostomatitis, cold sores
2. Herpetic keratitis (eye): small branching epithelial dendrites on cornea surface
3. Herpetic whitlow: blisters/sores on finger (nurses, physicians, dentists)
4. Genital herpes
5. Herpes encephalitis: inflammation of brain due to HSV
6. Neontal herpes

Question 20

Laboratory diagnosis of HSV thru?

Answer 20

1. Tzanck smear, immunofluorescence on clinical sample
2. Virus isolation
3. PCR
4. Serology not so useful

Question 21

How can HSV be treated?

Answer 21

Acyclovir (n later derivatives: valacyclovir, penciclovir, famciclovir)
- phosphorylation by viral thymidine kinase activates the drug, prevents elongation of viral DNA synthesis

Question 22

Who is most susceptible to VZV?

Answer 22

In decreasing severity:
1. Immunocompromised
2. Newborns
3. Elderly
4. Adults
5. Children

• elderly n immunosuppressed are most at risk of recurrence (zoster/shingles)

Question 23

How is VZV prevented?

Answer 23

Live attenuated vaccine

Question 24

Treatment for VZV?

Answer 24

Acyclovir

Question 25

What cells do EBV infect?

Answer 25

Infects B lymphocytes & immortalizes them

Question 26

EBV causes..

Answer 26

1. Asymptomatic shedding 2. Pharyngitis, infectious mononucleosis (spectrum of disease) 3. African Burkitt’s lymphoma (rare but highly aggressive (fast-growing) B-cell non-Hodgkin lymphoma (NHL)) 4. Hodgkin lymphoma (cancer that affects lymphatic system) 5. Nasopharyngeal carcinoma 6. EBV-induced lymphoproliferative disease in 1. post-transplant 2. HIV

Question 27

Lab diagnosis of EBV infection

Answer 27

1. Serology 2. EBV PCR in lymphoproliferative disease 3. Histology

Question 28

Treatment for EBV:

Answer 28

- no effective treatment or vaccine - acyclovir doesnt work well for EBV

Question 29

How is HHV8 transmitted?

Answer 29

Sexually transmitted

Question 30

HHV6&7 stays latent in the..

Answer 30

T cells

Question 31

Most adults carry ________ in its latent form, transmission is very common at _____%

Answer 31

Cytomegalovirus, 40-90% transmission

Question 32

Treatment for CMV:

Answer 32

Ganiciclovir, Foscarnet, Cidofovir

Question 33

Nasopharyngeal carcinoma is related to?

Answer 33

EBV

Question 34

What most commonly causes post-transplant organ rejection and fatal pneumonia?

Answer 34

CMV - cuz too many immuno-suppressive drugs, patient comes down w CMV

Question 35

Postherpetic neuralgia can come about due to?

Answer 35

Recurrent Zoster/Shingles - pain usually goes away in 1-3 months - cuz nerve fibres get damaged during the shingles outbreak

Question 36

EBV is found in..

Answer 36

Found in saliva

Question 37

EBV is reactivated when..

Answer 37

B cell is activated

Question 38

What is asymptomatic shedding?

Answer 38

Asymptomatic shedding occurs when the herpes virus is present on the skin but no visible symptoms develop. The virus “sheds'' from the skin and can be spread to others.

Question 39

Which herpes virus stays latent in 90% of adult population

Answer 39

CMV (& EBV too actually)

Question 40

What pathogen is responsible for Oral Hairy Leukoplakia?

Answer 40

EBV