varicella-zoster virus and HHV 6 and 7

Question 1

varicella zoster, HHV-6, and HHV-7 are all ______ viruses.

Answer 1

herpes viruses

Question 2

describe genome of herpes viruses

Answer 2

linear, ds DNA genome of 150-250kbp

Question 3

what type of capsid do herpes viruses have?are they enveloped? what is contained in the capsid?

Answer 3

icosahedral capsid, enveloped, dozen glycoproteins(involved in attachment, penetration, and release of virus from cells)

Question 4

where is viral DNA replicated in the cell? how about viral assembly?

Answer 4

nucleus of host cell

Question 5

in general, what type of infection do herpes viruses produce?

Answer 5

self-limiting infections, but life-threatening infections can occur especially in immunocompromised hosts

Question 6

what are the three classifications of herpesviruses?

Answer 6

alpha(HSV-1, HSV-2, VZV) , beta(CMV, HHV-6, HHV-7), gamma(EBV, HHV8)

Question 7

which class of herpes virus does varicella belong to? what is its tropism?

Answer 7

alphaherpesvirus and it is neurotropic (stays latent in neurons)

Question 8

which class do HHV-6 and HHV-7 belong to? In which cells do they become latent?

Answer 8

betaherpesviruses

lymphocytes

Question 9

what is the hallmark of herpes infections?

Answer 9

latency

Question 10

when does latency occur?

Answer 10

soon after initial infection

Question 11

during latency are virus particles produced? what is the location of the genome? are viral genes expressed

Answer 11

no virus particles produced
ENTIRE genome maintained extrachromosomally
few viral genes are expressed

Question 12

what are the three stages of latency? think: EMR

Answer 12

establishment, maintenance, reactivation

Question 13

the primary infection of varicella results in ______?

Answer 13

chicken pox

Question 14

varicella mode of tranmission?

Answer 14

highly communicable, spread by aerosol

Question 15

during which time of year is varicella most common?

Answer 15

late winter/early spring

Question 16

presentation of varicella zoster?

Answer 16

fever followed by itchy rash starting on scalp and trunk

Question 17

what do adult cases of varicella result in?

Answer 17

adult cases can be more severe, resulting in pneumonia

Question 18

describe timecourse of varicella infection

Answer 18

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

Question 19

what does the reactivation of VZV cause?

Answer 19

shingles = zoster

Question 20

presentation of shingles

Answer 20

sudden onset of pain and rash along thoracic dermatome or forehead

Question 21

what is peculiar about the pain in shingles?

Answer 21

rash in shingles may last 2-4 weeks, but pain can last much longer: postherpetic neuralgia

Question 22

how is VSV diagnosed?

Answer 22

clincially

Question 23

is there a vaccine for VSV?

Answer 23

yes, FDA approved live attenuated vaccine (recommended as part of MMR regimen)

Question 24

how is chickenpox treated?

Answer 24

treat symptoms: aches and pains

Question 25

what may the tx of adult pneumonia require?

Answer 25

VZV Ig

Question 26

how is zoster treated?

Answer 26

with oral acyclovir and steroids

Question 27

what is the VSV vaccine designed for?

Answer 27

designed to boost immunity to prevent or lessen zoster

Question 28

HHV-6 and HHV-7 cause ____

Answer 28

roseola (exanthem subitum)

Question 29

symptoms of roseola

Answer 29

mild respiratory illness followed by high fever

Question 30

t/f. after roseola fever, as few as 25% of kids will exhibit rash on face and body that will last 2-3 days

Answer 30

true

Question 31

at which ages do HHV-6 and HHV-7 mostly infect kids

Answer 31

both viruses infect at 3 months - 6 years of age

Question 32

what percentage of ppl in US are seropositive for HHV-6 and HHV-7?

Answer 32

> 90%

Question 33

how are infections of HHV-6 and HHV-7 treated?

Answer 33

infections only treated if symptomatic