11. Human Herpesvirus Flashcards
HHV 1 & 2 (aka herpes simplex virus/HSV) remain latent in the..
Trigeminal ganglia
HHV3 is also known as..
Varicella-Zoster Virus (VZV)
Aka Chicken Pox / Shingles
Chicken pox remains latent in the..
Dorsal Root Ganglia
HHV3 remains dormant in the..
Dorsal Root Ganglia
What is the nucleic structure of Herpesviruses?
dsDNA
- encapsulated in a capsid and envelope
- has viral glycoproteins inserted on envelope surface
How do human herpesvirus replicate?
- via DNA polymerase (target of antiviral drugs!!)
- they integrate into the host cell DNA n get translate tgt
HHV4 is otherwise known as..
Epstein Barr Virus (EBV)
HHV8 is responsible for..
Kaposi Sarcoma (pigmented tumours in mouth & other sites)
- HHV8 is an oncovirus (cancer causing virus)
What are the symptoms of HHV 6 & 7?
Childhood rash
How long does it take for the Chicken pox to appear as a rash upon infection?
Roughly 2 weeks (10-21days)
- called vesicular rash
List out the Human Herpesviruses.
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
Where do alpha HHVs stay latent in?
Sensory Neurons
HSVs stay latent in trigeminal ganglia
VZV stays latent in dorsal root ganglia
Where do beta HHVs stay latent in?
WBCs
HHV6 & 7 stay latent in T cells
Where do gamma HHVs stay latent in ?
Lymphocytes
HHV4 immortalises/latent in B cells
Immortalises B cells => tumour/cancer
What drug should not be given in a chickenpox patient?
Aspirin
- can cause Reye’s syndrome (liver affected, buildup of ammonia)
Human Herpesvirus infections can be..
- Lytic
- Persistent
- Latent
- Immortalizing (EBV)
HSV lesions tend to appear in what region?
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)
HSV is lytic in the _______ and latent in the ___________.
Lytic in mucoepithelial cells
Latent in neurons (Trigeminal ganglia)
List the clinical syndromes of HSV:
- Mucocutaneous: gingivostomatitis, cold sores
- Herpetic keratitis (eye): small branching epithelial dendrites on cornea surface
- Herpetic whitlow: blisters/sores on finger (nurses, physicians, dentists)
- Genital herpes
- Herpes encephalitis: inflammation of brain due to HSV
- Neontal herpes
Laboratory diagnosis of HSV thru?
- Tzanck smear, immunofluorescence on clinical sample
- Virus isolation
- PCR
- Serology not so useful
How can HSV be treated?
Acyclovir (n later derivatives: valacyclovir, penciclovir, famciclovir)
- phosphorylation by viral thymidine kinase activates the drug, prevents elongation of viral DNA synthesis
Who is most susceptible to VZV?
In decreasing severity:
1. Immunocompromised
2. Newborns
3. Elderly
4. Adults
5. Children
- elderly n immunosuppressed are most at risk of recurrence (zoster/shingles)
How is VZV prevented?
Live attenuated vaccine
Treatment for VZV?
Acyclovir
What cells do EBV infect?
Infects B lymphocytes & immortalizes them
EBV causes..
- Asymptomatic shedding
- Pharyngitis, infectious mononucleosis (spectrum of disease)
- African Burkitt’s lymphoma (rare but highly aggressive (fast-growing) B-cell non-Hodgkin lymphoma (NHL))
- Hodgkin lymphoma (cancer that affects lymphatic system)
- Nasopharyngeal carcinoma
- EBV-induced lymphoproliferative disease in 1. post-transplant 2. HIV
Lab diagnosis of EBV infection
- Serology
- EBV PCR in lymphoproliferative disease
- Histology
Treatment for EBV:
- no effective treatment or vaccine
- acyclovir doesnt work well for EBV
How is HHV8 transmitted?
Sexually transmitted
HHV6&7 stays latent in the..
T cells
Most adults carry ________ in its latent form, transmission is very common at _____%
Cytomegalovirus, 40-90% transmission
Treatment for CMV:
Ganiciclovir, Foscarnet, Cidofovir
Nasopharyngeal carcinoma is related to?
EBV
What most commonly causes post-transplant organ rejection and fatal pneumonia?
CMV
- cuz too many immuno-suppressive drugs, patient comes down w CMV
Postherpetic neuralgia can come about due to?
Recurrent Zoster/Shingles
- pain usually goes away in 1-3 months
- cuz nerve fibres get damaged during the shingles outbreak
EBV is found in..
Found in saliva
EBV is reactivated when..
B cell is activated
What is asymptomatic shedding?
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.
Which herpes virus stays latent in 90% of adult population
CMV
(& EBV too actually)
What pathogen is responsible for Oral Hairy Leukoplakia?
EBV
