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RENAL & GENITO-URINARY System > Human Herpesvirus > Flashcards

Human Herpesvirus Flashcards

1
Q

What is the structure of the herpesvirus?

A 
DNA
Caspid
Tegument
Envelope
Glycoprotein spikes
Icosahedral caspid surrounding dsDNA
Virus size 120-200nm
Have 80 genes coding for 100 proteins
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2
Q

How to classify human herpesvirus?

A

alpha herpesviruses: Epidermal/neuronal viruses with a wide host range

  • Type 1 Herpes Simplex - Virus HHV-1
  • Type 2 Herpes Simplex Virus HHV-2
  • Varicella-Zoster Virus (VZV) HHV-3
β-herpesviruses: Slow growth, primarily in T-cells and leukocytes
- Cytomegalovirus (HCMV) HHV-5
- Human Herpesvirus 6 HH
V-6
- Human Herpesvirus 7 HHV-7

γ-herpesviruses: primarily B-lymphocytes:
- Epstein-Barr virus (EBV) - Barr virus (EBV) HHV 4
Human Herpesvirus 8 HHV-8

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3
Q

What does does Herpes Simplex Virus 1&2 cause?

A

Oropharyngeal and genital herpes

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4
Q

What does Varicella-Zoster Virus (HHV-3) cause?

A

Chicken-pox (Varicella) / Shingles (Zoster)

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5
Q

What does Epstein

-Barr Virus (HHV-4) cause?

A

Infectious mononucleosis (glandular fever), Burkitt’s lymphoma, nasopharyngeal carcinoma

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6
Q

What does Cytomegalovirus (HHV-5) cause?

A

Cytomegalic inclusion disease in utero

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7
Q

What does HHV-6 cause?

A

Exanthem subitum, fatigue syndrome

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8
Q

HHV-7 causes what?

A

Pityriasis rosea?

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9
Q

HHV-8 causes what?

A

Kaposi’s sarcoma (in AIDS pts)

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10
Q

What does HSV1 mainly cause?

A

Oral infecs

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11
Q

What does HSV2 mainly cause?

A

Genital infecs

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12
Q

How does HSV 1 cause herpetic gingivostomatitis?

A

Virus enters trigeminal sensory neurones - migrates to trigeminal ganglion
HSV1 becomes latent in trigeminal ganglion but dormant in 50% of cases
Migrates to peripheral nerve endings where active viral particles are shed

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13
Q

What reactivates a herpes simplex infection?

A

UV light
Stress
Illness
Immunosuppression

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14
Q

HSV 2 can cause herpes labialis - features of this?

A

Lesion (on edge of lip) resolves

Virus lays dormant in trigeminal ganglion until reactivated

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15
Q

What causes a primary HSV infection?

A

Source of virus:

  • Skin lesions
  • Saliva
  • Usually HSV1

Passive immunity
From maternal
Antibody in infancy

Source of virus:

  • Genital lesions
  • Genital secretions
  • Usually HSV2
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16
Q

What percentage of the primary HSV infections are symptomatic and asymptomatic?

A 
Asymptomatic = 90-99%
Symptomatic = 1-10%
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17
Q

What occurs when there is establishment of the HSV latent infection?

A

Reactivation of latent virus and 2ndry/recurrent infection

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18
Q

Incidence of herpetic gingivostomatitis?

A

Very common
Mainly affects young children
Sometimes young adults - more severe

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19
Q

Clinical features of herpetic gingivostomatitis?

A 
Incubation period 3-10 days
Duration 5-14 days
Multiple vesicles - rupture to form extensive sloughing ulcers
Gingivitis with erythema and sloughing
Malaise, pyrexia, lymphadenopathy
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20
Q

How to diagnose herpetic gingivostomatitis?

A

Clinical appearance

Main diagnostic difficulty with erythema multiforme

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21
Q

How to investigate herpetic gingivostomatitis?

A

Not normally done
Rising antibody attire/presence of IgM antibodies
Viral culture or PCR

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22
Q

What is the basic method of PCR?

A

Denature DNA to single strands at 95 degrees
Annealing of specific primers to DNA at 55 degrees
Extension by polymerase at 72 degrees
Amplification - Repeat 30-35 times

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23
Q

What occurs by the end of each PCR cycle?

A

Amount of DNA has doubled

24
Q

What occurs by the end of 30 cycles of PCR?

A

1 billion molecules from the one you started with

25
Q

How to manage herpetic gingivostomatitis?

A 
Acyclovir (200mg 5x daily for 5 days) if found early or immunocompromised
Fluids and soft diet
Analgesics/antipyretics (paracetamol)
Local antiseptics (chlorhexidine)
Topical analgesics (difflam)
X-infection control
26
Q

How does acyclovir work?

A

HSV thymidine kinase (TK) phosphorylates guanosine (G) when HSV DNA replicates
ACV is phosphorylated to ACVP
Inhibits virus replication
Is a chain terminator

27
Q

Herpes labialis clinical features?

A

Prodromal irritation
Vesicles at or near mucocutaneous junction of lips
Crusting lesions lasting 7-10 days
Usually re-occurs at same sites
Rarely: may occur, intra-orally, in nose or elsewhere on skin

28
Q

How to manage herpes labialis?

A

Acyclovir cream 5% if used very early

OTC drying and antibacterial agents

29
Q

Prophylactic treatment of herpes simplex virus 2?

A

Rarely justified

Prophylactic acyclovir will prevent lesions in the immunocompromised or those susceptible to erythema multiforme

30
Q

What does acyclovir do in herpes labialis?

A

Prophylactic - oral AVC (600-1000mg/day in 2 doses) is effective
Reduces:
- Duration of pain by 1.4 days
- Time to lesion crusting by 2.1 days
- Occurrence of new lesions by 50%
- Mean number of recurrences over a 4 month observation period
INCREASES mean time to next recurrence from 46 to 118 days

31
Q

What is herpetic whitlow?

A

Herpetic infection of the fingers from handling the oral tissues of someone with active 1 or 2 herpes simplex lesions

32
Q

Features of herpetic whitlow?

A

Very painful
Difficult to treat
Prevention better than cure - wear gloves

33
Q

Features of HSV encephalitis?

A

Mainly affects frontal lobes of the brain
70-80% mortality if untreated
Of survivors, only 3% return to normal
Usually people >50yrs (HSV-1) and neonates (HSV-2) affected

34
Q

Signs and symptoms of HSV encephalitis in adults (HSV-1)?

A

Adults
Headache and behavioural changes over several days
Fever
11% have history of recurrent HSV infecs

35
Q

Signs and symptoms of HSV encephalitis in neonates (HSV-2)?

A 
Adults
Skin rash, lesions and CNS symptoms
Virus present in liver, lung and adrenal glands
Resp distress
Fits and convulsions
Raised intracranial pressure
36
Q

Incidence of HSV encephalitis in neonates?

A

1 per 300,000

37
Q

What do HHV-3 and HSV1 and 2 have in common?

A

Similarities in structure and infection

38
Q

What happens if you get varicella-zoster virus (HHV3)?

A 
Chicken pox/varicella (primary infec)
= Dormant in the dorsal root/trigeminal ganglion
= Remains dormant OR
Reactivation:
Age (70% >50yrs)
Stress
Illness
Immunosuppression

= Herpes Zoster (2ndry infec)
Seldom reoccurs

39
Q

Where does herpes zoster 2ndry infection (shingles) most commonly affect?
What does it look like?

A

Chest and back only on 1 side (opposite to the side infected)
= Blisters, rash

40
Q

Herpes zoster causing oral disease most commonly affects what nerve? What are the 3 phases?

A 
Trigeminal nerve
Phases:
- Preherpetic neuralgia
- Rash
- Post herpetic neuralgia
41
Q

Explain the pre-herpetic neuralgia?

A

Pain in the distribution of the affected division of the trigeminal nerve
Prior to the development of the rash
May mimic dental pain

42
Q

Explain the rash phase of herpes zoster?

A

Unilateral vesicles in the distribution of a branch of the trigeminal nerve:

  • Opthalmic
  • Maxillary
  • Mandibular

Vesicles break down to form:

  • Ulcers
  • Crusting lesions

Lasts 2-3 weeks

43
Q

What eye problems can herpes zoster cause?

A

Glaucoma
Cataract
Double vision
Scarring of the cornea

44
Q

How to manage herpes zoster?

A

Acylovir 800mg 5 x daily for 7 days if seen soon after lesions develop
Analgesics
Ophthalmic referral if eye involved
Avoid contact with children

Alternatives to acyclovir:

  • Valaciclovir 1g 3xdaily for 7 days
  • Famciclovir 250mg 3xdaily for 7 days
45
Q

Explain post herpetic neuralgia of herpes zoster?

A

10% of pts = unpleasant intractable burning pain in the distribution of the affected nerve
More common in elderly
Effective early treatment of zoster may decrease risk of neuralgia
Treat pain with tricyclic antidepressants and neuropathic pain drugs

46
Q

What is HHV-4 (EBV) associated with?

A

Infectious mononucleosis (glandular fever) - acute 1 infec with EBV)
Burkitt’s lymphoma - a B cell malignancy
Nasopharyngeal carcinoma - epi cell malignancy
Oral hairy leukoplakia - seen in AIDS pts and some transplant recipients

47
Q

Where does primary infection EBV replicate and establish latency?

A

Replicates in oropharyngeal epi cells

Establishes latency in B lymphocytes

48
Q

What is EBV latent infection of B lymphocytes necessary for?

A

Virus persistency
Subsequent replication in epi cells
Release of infectious virus into saliva

49
Q

What percentage of the world’s population are infected with EBV?

A

95%

50
Q

Symptoms of infectious mononucleosis EBV?

A

Most are asymptomatic
Sore throat
Swollen cervical lymph nodes
Mild fever

51
Q

EBV in the oral environment - infectious mononucleosis signs?

A

Petechiae on soft palate
Creamy exudates on fauces
Cervical lymphadenopathy

52
Q

What is burkitt’s lymphoma?

A

Malignant, B cell lymphoma of high prevalence in children in tropical Africa at elevations below 1500 metres where malaria is present
Usually affects jaw bone - tumour mass

53
Q

How to treat burkitt’s lymphoma?

A

cyclophosphamide (chemo)

54
Q

What can HHV-5 (Cytomegalovirus) rarely cause in healthy individuals?

A

Glandular fever like illness

Salivary gland swelling

55
Q

What can HHV-5 (Cytomegalovirus) cause in immunocompromised/AIDS pts?

A

Large ragged oral mucosal ulcers
Salivary gland swelling
Retinitis

56
Q

What can HSV-8 cause in AIDS pts?

A

Kaposi’s sarcoma

RENAL & GENITO-URINARY System (4 decks)

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