varicella-zoster virus and HHV 6 and 7 Flashcards
varicella zoster, HHV-6, and HHV-7 are all ______ viruses.
herpes viruses
describe genome of herpes viruses
linear, ds DNA genome of 150-250kbp
what type of capsid do herpes viruses have?are they enveloped? what is contained in the capsid?
icosahedral capsid, enveloped, dozen glycoproteins(involved in attachment, penetration, and release of virus from cells)
where is viral DNA replicated in the cell? how about viral assembly?
nucleus of host cell
in general, what type of infection do herpes viruses produce?
self-limiting infections, but life-threatening infections can occur especially in immunocompromised hosts
what are the three classifications of herpesviruses?
alpha(HSV-1, HSV-2, VZV) , beta(CMV, HHV-6, HHV-7), gamma(EBV, HHV8)
which class of herpes virus does varicella belong to? what is its tropism?
alphaherpesvirus and it is neurotropic (stays latent in neurons)
which class do HHV-6 and HHV-7 belong to? In which cells do they become latent?
betaherpesviruses
lymphocytes
what is the hallmark of herpes infections?
latency
when does latency occur?
soon after initial infection
during latency are virus particles produced? what is the location of the genome? are viral genes expressed
no virus particles produced
ENTIRE genome maintained extrachromosomally
few viral genes are expressed
what are the three stages of latency? think: EMR
establishment, maintenance, reactivation
the primary infection of varicella results in ______?
chicken pox
varicella mode of tranmission?
highly communicable, spread by aerosol
during which time of year is varicella most common?
late winter/early spring
presentation of varicella zoster?
fever followed by itchy rash starting on scalp and trunk
what do adult cases of varicella result in?
adult cases can be more severe, resulting in pneumonia
describe timecourse of varicella infection
Day 0 = infection of conjuctivae and/or mucosa of URT –>viral replication of regional lymph nodes
Day 4-6=primary viremia –> viral replication in liver, spleen, and other organs –> secondary viremia
Day 14 = infectio nand appearance of vesicular rash
what does the reactivation of VZV cause?
shingles = zoster
presentation of shingles
sudden onset of pain and rash along thoracic dermatome or forehead
what is peculiar about the pain in shingles?
rash in shingles may last 2-4 weeks, but pain can last much longer: postherpetic neuralgia
how is VSV diagnosed?
clincially
is there a vaccine for VSV?
yes, FDA approved live attenuated vaccine (recommended as part of MMR regimen)
how is chickenpox treated?
treat symptoms: aches and pains
what may the tx of adult pneumonia require?
VZV Ig
how is zoster treated?
with oral acyclovir and steroids
what is the VSV vaccine designed for?
designed to boost immunity to prevent or lessen zoster
HHV-6 and HHV-7 cause ____
roseola (exanthem subitum)
symptoms of roseola
mild respiratory illness followed by high fever
t/f. after roseola fever, as few as 25% of kids will exhibit rash on face and body that will last 2-3 days
true
at which ages do HHV-6 and HHV-7 mostly infect kids
both viruses infect at 3 months - 6 years of age
what percentage of ppl in US are seropositive for HHV-6 and HHV-7?
> 90%
how are infections of HHV-6 and HHV-7 treated?
infections only treated if symptomatic
