VZ + HHV 6/7 Flashcards
Describe HHV 6/7 and VZV
They are all linear, enveloped, dsDNA large genome (150-250 kbp) with an icosahedral capsid and about dozen of glycoproteins inside; they are all herpesviruses
What do the glycoproteins of HHV6/7 and VZV do?
They are for attachment, penetration, and release
Where are the HHV6/7 and VZV viruses assembled inside the cell?
In the nucleus
What kind of infections to the herpesviruses produce?
Generally self limiting, but life threatening infections can occur in ICP’s
Describe the life cycle of a Herpesvirus? (3 phases)
Establishment, Maintenance, and Reactivation; First the initial infection, then goes into latent period in which no virus is produced and the genome is maintained extrachromasomally (undetectable), then it is reactivted usually due to a lapse in host immune status
Where does VZV go latent?
Neural cells (it is a alphaherpesvirus)
Where do HHV 6/7 go latent?
Lymphocytes (it is a betaherpesvirus)
What is the primary infection of VZV? secondary?
Chickenpox; shingles
How is VZV spread?
It is highly communicable and by aerosol, late winter and early spring
What are the symptoms of chickenpox?
Fever and then itchy rash starting on scalp and trunk, can radiate from there
Describe adult chickenpox
Usually more severe, less rash, chance of pneumonia
Describe the infection of chickenpox in a child
Initial respiratory infection leads to replication in mucosa of URT, virus then spreads and replicated in regional lymph nodes which results in primary viremia around day 4-6. Virus progresses to liver and spleen and leads to secondary viremia around day 12-14
When does the rash appear in chickenpox for a child?
Only after the secondary viremia (around 12-14 day post exposure)
When is a child good to go back to school after a bout of chickenpox?
Only after the rash has scabbed over, before they are still contagious
What is the reactivated form of chickenpox (Varicella) called?
Shingles (Zoster)
What is shingles characterized by?
Sudden onset of pain and rash along a single dermatome (unilateral) or forehead; rash can last 2-4 weeks with pain lasting longer (postherpetic neuralgia) and most people only have it ONCE
How is VZV diagnosed?
Clinically
Describe the VZV vaccine
Approved live attenuated vaccine recommended as part of MMR regimen, there is no evidence of reactivation to shingles
What other drugs can treat chickenpox?
In immunocompromised kids use Acyclovir
What may adult pneumonia require?
VZV Ig
What do you exactly “treat” for chickenpox?
Symptoms
How is Zoster treated?
Oral ACV and steroids (faster the better)
What is the Zoster vaccine?
Booster to prevent or lessen zoster for patients 50 years or older
What do HHV 6/7 cause?
Roseola (exanthem subitum)
