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Test 4: Virology > HSV 1 & 2 and VZV > Flashcards

HSV 1 & 2 and VZV Flashcards

1
Q

What type of virus is herpesvirus?

A
  • dsDNA
  • linear
  • icosahedral
  • enveloped
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2
Q

T/F: Herpesvirus can have lytic or latent infections and all have systemic/generalized infections

A

True!

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3
Q

What response in all herpes infections is critical to keeping virus in check?

A

CD8-CTL

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4
Q

What are the antivirals for herpesvirus?

A

acyclovir:
- stop viral DNA replication
- activated by viral thymidine kinase to cause viral DNA chain termination
(vacylclovir used bc it is a prodrug and metabolized in body to acyclovir and has a longer half life in to body so less pills need to be taken)

famciclovir:
- oral prodrug of topical ointment penciclovir used interchangeably with acyclovir and vacyclovir

ganciclovir:
- used for CMV infection
- prodrug: valganciclovir with more side effects than acyclovir

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5
Q

Where does resistance to acyclovir class usually occur?

A
  • viral thymidine kinase
  • if resistance happens, drugs that are NOT phosphorylated by viral kinase can be used
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6
Q

T/F: HSV-1 and 2 can infect a person at the same time

A

True!
- the 2 are similar but not identical with 50% genetic identity

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7
Q

What do HSV-1 and 2 both infect?

A
  • mucosal epithelial cells, lesions
  • become latent in nerve ganglia: trigeminal ganglia in oral infections and sacral ganglia in genital infections
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8
Q

What occurs in latency of HSV-1 and 2?

A
  • miRNA prevents viral lytic gene expression
  • does not produce any viral proteins so no presentation of viral proteins in MHC1 and no killing by CTL’s
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9
Q

How will HSV and VZV travel to lay dormant?

A
  • go up nerve retrograde axial transport and lay dormant
  • cell can eventually reactivate and produce virus
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10
Q

Which HSV (1 or 2) cause genital herpes and oral herpes?

A

They both can be caused by each.
HSV-2 causes 70% of all genital herpes (HSV-1 causes 30%)

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11
Q

What is herpes labialis?

A
  • any reactivation/re current oral herpes after primary infection
  • usually less severe, fewer lesion, same place as primary lesion
  • triggered by: stress, UV light, menstruation, dental procedures
  • oral asymptomatic shedding of HSV-1 common in people who have been infected
  • HSV-1 way more common
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12
Q

T/F: Asymptomatic infections of genital herpes are common

A

True!
- it is most common to get HSV from an asymptomatic shedding of a sexual partner

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13
Q

What are characteristics of genital herpes?

A
  • majority is HSV-2 (now more 50%)
  • HSV-2 infections have more reoccurrence and asymptomatic shedding than genital HSV-1 (meningitis common with HSV-2)
  • infections/lesions present in genital epithelium, upper thighs, and anal area
  • -clovir drugs can be taken prophylactically or daily to prevent outbreaks and transmission but don’t entirely stop asymptomatic shedding
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14
Q

What is Herpetic Whitlow?

A
  • herpetic lesions on fingers
  • common in dentists and other health care workers due to patients secreting herpes in salvia without visible sores
  • can also be caused by autoincilation (HSV-1 or 2)
  • reoccurrence is common
  • gloves/handwashing are preventive
  • -clovir for tx
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15
Q

What is ocular herpes?

A
  • cause by reactivated oral herpes going to eye or spread by touching the eye and contaminating it with HSV-1 (more common in contact wearers)
  • usually resolves without a problem but can cause more severe infection that scar the cornea
  • reoccurrence is common with higher chance of some permanent vision loss so use ophthalmologist and antiviral eyedrops for tx
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16
Q

Who does herpes simplex encephalitis infect?

A
  • 1/3 children
  • 50% in pt over 50
17
Q

What are the characteristics of herpes simplex encephalitis?

A
  • almost all cases are HSV-1
  • travels up olfactory or trigeminal nerves to temporal or frontal lobes of brain (can happen during primary infection or during reactivation of virus)
  • virus replicates, causing necrosis of brain tissue
  • prompt tx is needed (in 1-2 days) with acyclovir
    (without acyclovir, high mortality)
  • survivors can have neurological defects
18
Q

How is neonatal herpes spread?

A
  • vertically
  • most cases are due to primary infection while pregnant but can also be due to reactivation of infection close to labor
  • most causes due to HSV-2 (HSV-1 cases are rising)
19
Q

What is the tx of neonatal herpes?

A
  • acyclovir in an infant can drastically reduce mortality
  • if genital lesions close to delivery, deliver by C-section and acyclovir recommended starting 36 weeks of pregnancy
19
Q

How contagious is varicella zoster/chickenpox?

A
  • very. 90% of susceptible people in household will contract chickenpox
20
Q

How is Varicella/chicken pox spread?

A
  • respiratory droplets and lesions are contagious
  • most lesions on face and trunk and less on extremities
21
Q

What are characteristics of Varicella/chicken pox?

A
  • more severe in adults and pregnant woman and immunocompromised (pneumonia)
  • defining feature: vesicular rash. lesions present in all stages
  • latent in dorsal root and cranial nerve and trigeminal ganglia
  • do not give aspirin to children with chickenpox or influenza because can cause Reye’s syndrome
22
Q

What is there a high risk of with varicella in pregnancy?

A
  • high risk for pneumonia with high mortality
  • can be lowered with tx: CFR, VeriZig and acyclovir
23
Q

What are the characteristics of varicella in pregnancy?

A
  • severe congenital disabilities if infected in 1st trimester… 0.4 to 2% risk
  • baby can have disseminated disease if before delivery and before maternal antibody response can occur
  • very rare
24
Q

How does Zoster/Shingles occur?

A

reactivation of varicella virus along dermatomes (usually 1 to 3 adjacent)

25
Q

What are the characteristics of Zoster/Shingles?

A
  • can be very painful and lesions can be infectious and cause chickenpox in others
  • herpes zoster opthamalicus: shingles outbreak near eye which can lead to vision loss if left untreated
  • post-herpetic neuralgia: 1/3 of people can develop this which is mild to severe pain after resolution of lesions and can last up to years (more common in people over 60)
  • occurs in more people over 50 due to CTL response for VZV to be waning
26
Q

What are the vaccines for Varicella?

A

Attenuated vaccine:
- for all children to
prevent chickenpox
- 2 shots for complete protection
- contraindicated in immunosuppressed and pregnant people because it is attenuated

Subunit Vaccine Shingrex (enveloped glycoprotein E) with adjuvant:
- approved for shingles for all people over 50 who had chickenpox
- very effective in preventing shingles and post herpetic neuralgia

  • if exposed to chickenpox without having a vaccine before, it can still be taken if within 72 hours to help
  • if contraindicated for live-attenuated: varicella IgI can be given to help prevent infection

Test 4: Virology (17 decks)

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