Herpesviruses Flashcards
All herpes infections begin with ___________.
primary infection
After primary infection, herpes viruses can do one of two things: _____________.
lytic replication or latency
Lytic replication can manifest as _____________.
disease or asymptomatic shedding
What structure do herpes viruses (all of them) have?
Enveloped dsDNA with outer glycoproteins that allow infection
Herpes viruses can present with _____________ inclusions.
nuclear and cytoplasmic
Briefly describe the three subgroups of herpes viruses.
Alpha: establish latent infections in neurons (HSV1, HSV2, and VZV)
Beta: establish latent infections in myeloid cells (CMV, HH6, and HHV7)
Gamma: establish latent infections in B cells and myeloid cells (EBV, KSV)
What shape does the herpes capsid have?
It is icosahedral.
The viral capsid is ______ to the envelope.
deep
The fastest herpes virus subgroup (that is, fastest to develop) is ______________.
alpha (12 - 24 hours)
Alpha herpes viruses (HSV1, HSV2, and VZV) reside in _____________ neurons.
sensory ganglia
What part of the virus stimulates adaptive immunity?
The envelope glycoprotein
_________ is the only herpes virus to be transmitted via respiratory secretions.
VZV
Herpes viruses transcribe proteins in three stages: _______________.
- Immediate early: proteins that help create a favorable intracellular environment
- Early: proteins needed for replication (e.g., viral DNA polymerase)
- Late: structural proteins
What mechanism allows for very fast replication of viral genomes?
Rolling circle replication –a process like unraveling toilet paper
Acyclovir requires ___________ to become active.
thymidine kinase (as such, organisms such as beta herpes viruses – like CMV – that do not use thymidine kinase are resistant to acyclovir)
Ganciclovir requires _______ to become active.
UL97
Why are cidofovir and foscarnet more toxic?
They are activated by cellular kinases and thus inhibit host DNA as well.
True or false: the viral envelope comes from the nuclear envelope.
False. Viruses do acquire an envelope at the nucleus, but they lose it and regain another in the Golgi.
What is the difference between Cowdry bodies and CMV inclusions?
Cowdry bodies are eosinophilic – pink –and CMV bodies are basophilic.
HSV1 is typically latent in _______________, while HSV2 is typically latent in ______________.
the trigeminal ganglion; the sacral ganglia
There are, of course, exceptions.
Once an HSV lesion ____________, it is no longer infectious.
scabs over
By age 50, ________ percent of people are seropositive for HSV1.
90
Severe primary infection with HSV or immuno- compromisation can lead to a painful oral symptom: _____________
gingivostomatitis (swelling of the gingiva)
Because of ______________, secondary HSV is not as severe –often presenting with cancre sores.
T-cell memory
A patient presents with _____________ and you say “I know, they have herpetic encephalitis!”
fever, confusion, focal neurologic findings, and mononuclear cells in their CSF
HSV2 often presents with ___________ superinfection.
candida
Explain the clinical terminology for VZV.
Primary: chickenpox
Reactivation: zoster
Where does primary VZV replicate?
In lymph nodes
What is the classic description of primary VZV infection?
Crops of vesicles of varying age
What are some complications of VZV?
- Bacterial superinfection (most common problem)
- Severe adult infection (including pneumonia and sepsis)
- Encephalitis
- Congenital
What is Hutchinson sign?
Reactivation of VZV in the V1 dermatome of the face that leads down to the tip of the nose
Note: if you see this, consult an ophthalmologist because the V1 also enters the eye.
How can shingles be treated?
Acyclovir is effective if given in the first 3 or 4 days of symptoms.
What complications can result from shingles?
- Motor deficits
- Encephalitis
- Eye involvement
- Post-herpetic neuralgia
Part of why the elderly are at increased risk of shingles is ____________.
decreased T-cell immunity
The shingles vaccine is recommended for those ___________.
60 and older
Beta herpesviruses infect _________-positive cells.
CD34 (hematopoietic stem cells)
Most neonatal CMV results from __________.
breast milk
CMV in adolescents can cause ______________.
a mononucleosis-type syndrome
How should CMV be treated?
With ganciclovir or foscarnet (if the virus has UL97 mutations)
The “slapped-cheek” disease is caused by __________ and has two names: ____________.
parvovirus B19; 5th disease and erythema infectiosum
A mother tells you her child had a fever yesterday and a rash today. What virus is this? What is the most common pattern of virus?
Roseola; a maculopapular rash that starts on the trunk and moves to the face
The most important gamma herpesvirus is _____________.
EBV
What do EBVNA1 and EBVNA2 do?
EBVNA1: links EBV DNA to host genome
EBVNA2: activates viral genes and c-myc (hence Burkitt)
What is the pathogenesis of EBV?
B cells get infected in the tonsils and spread throughout the body. T cells kill the B cells, and the inflammation from that causes systemic symptoms.
Why do heterophile antibodies develop from EBV infection?
EBV stimulates B cells to proliferate regardless of antigen presentation. As such, the blood of someone actively infected with EBV will display agglutination to random antigens.
How sensitive is the monospot test?
~85%
What virus causes Kaposi’s sarcoma?
HHV8 (gamma herpes virus)
The virus that causes Kaposi’s sarcoma resides latent in ________________.
B cells
Why do herpesviruses typically require close contact?
Because they are easily killed in the environment
The envelope around herpesviruses (all of them) is derived from _____________.
the host cell’s Golgi apparatus
When the rash from a herpesvirus has __________, it is usually not contagious anymore.
crusted over
True or false: primary herpes infections are most often asymptomatic.
True. Only about 20% of cases present with symptoms.
Even people without herpes symptoms can ______________.
spread the virus to others
A classic finding of CMV infection in an adult is ______________.
interstitial pneumonia
Remember the lung stains on the butcher’s apron.
The acute test for EBV tests ________, while _________ will appear after an infection.
IgM; IgG
It takes about __________ days for VZV to present as chickenpox.
10-20
The two most common congenital herpes infections are ___________________.
CMV (40,000 per year) and HSV (1,200 per year)
