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BDS4 Oral Medicine > STD2 > Flashcards

STD2 Flashcards

1
Q

What are the features of HSV?

A

Double stranded DNA virus

Part of alpha-herpesviridae family

HSV1- oral vesicular lesions (may be responsible for genital lesions in young adults)

HSV2- genital vesicular lesions

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2
Q

What are the epidemiological features of HSV2?

A

400 million cases globally- 20 mil each year

Africa is most affected

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3
Q

What are the structural components of HSV2?

A

Glycoproteins- surface

Envelope- lipid membrane

DsDNA in core- >80 + genes

Tegument- mesh of viral proteins

Capsid

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4
Q

What are the steps in HSV2 cell cycle?

A
  1. Binding- GC bind to receptors on cell surface
  2. Entry- fusion of membranes, virus is internalised into cytoplasm
  3. Capsid transport- accumulates in nucleus
  4. Transcription
  5. Translation
  6. Replication of viral genome (rolling circle)
  7. Capsid assembly in nucleus of affected cell
  8. Glycosylation- glycoproteins are translated and glycosylated into ER
  9. Glycoprotein export- to cell surface
  10. Glycoprotein containing plasma membrane endocytosis
  11. GC within early endosomes fuse with caspids in cytoplasm
  12. Virus release into ECM
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5
Q

How long does it take for HSV2 to cause cell lysis?

A

24 hours- leads to vesicle and ulcer formation

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6
Q

How does HSV enter sensory nerve axons?

A

Via plexus of free nerve ending in epidermis
-> transpired into neuronal cell bodies in dorsal root ganglia
-> replicates and spreads to other neurone

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7
Q

What occurs in HSV2 latency?

A

Viral genome is maintained within ganglia for life of host as circular genetic elements called episomes in the nucleus
-> closely associated but not integrated into host DNA

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8
Q

What happens upon reactivation of HSV2 in ganglia?

A

Transport toward genital skin or mucosa
-> replication in epidermal cells after passage of virus across axonal epithelial gap
-> discrete shedding

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9
Q

How long does Herpes Genitalis primary infection take to present?

A

4-7 days usually
-> incubation period is 2-12 days

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10
Q

What are the signs and symptoms of HG primary infection?

A

Clusters of erythematous papules/vesicles
-> painful, burning

Fever

Headache

Malaise

Myalgia

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11
Q

What are the features of the prodrome in recurrent lesions of HG?

A

Itching

Tingling

Paraesthesia

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12
Q

What is different about recurrent infections of HG?

A

Fewer lesions

Unilateral

Generally no systemic symptoms

Resolves in 3-5 days

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13
Q

What are the stages in HG lesion development?

A

Vesicle pustule

Wet ulcer

Dry crusts

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14
Q

How long does primary infection of HG take to resolve in absence of antivirals?

A

3 weeks

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15
Q

How long do serum antibodies for HSV2 take to appear?

A

12 weeks

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16
Q

What is a non-primary infection of HG?

A

Infection with HSV1 or 2 in individual that has pre-existing antibodies to other HSV
-> milder presentation due to cross-immunity

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17
Q

How is Herpes Genitalis diagnosed?

A

History

Clinical presentation

Viral diagnostic assays- viral culture, PCR for HSV DNA

Serology- HSV antibodies
-> ELISA, IMMUNOBLOT, POCkit

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18
Q

What are some of the differential diagnoses for HG?

A

Infectious
- Chancroid
- Fungal infection
- Syphilis
- Secondary bacterial infection

Non-infectious
- Aphthous ulcers
- Behcets
- Neoplasm
- Psoriasis
- Sexual trauma

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19
Q

Why is screening for genital herpes not advised for people with no symptoms?

A

False postive results

Doesn’t prompt changes in sexual behaviour

Doesn’t stop the virus from spreading

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20
Q

What is the aim of anti-viral therapy in Herpes Genitalis treatment?

A

Reduce symptoms and likelihood of transmission (no cure)

21
Q

What are the regimes for people with first episodes of HG?

A

Acyclovir- 400mg x 3 per day for 7-10 days

Acyclovir- 200mg x 5 per day for 7-10 days

Valacyclovir- 1g x 2 per day for 7-10 days

Famciclovir- 250mg x 3 per day for 7-10 days

22
Q

What are some of the treatment options for recurrent HG?

A

Acyclovir- 400mg x 3 per day for 5 days OR 800mg x2 per day for 5 days

Famciclovir- 125mg x 2 per day for 5 days

23
Q

What does effective episodic treatment require?

A

Initiation of therapy within 1 day of lesion onset or during prodrome

24
Q

When is suppressive therapy considered for HG?

A

If patient has six outbreaks in a year
-> reduces frequency of recurrence by 70-80%

25
Q

What are the treatment options for suppressive therapy of HSV?

A

Acyclovir- 400mg x 2 per day

Famciclovir- 250mg x2 per day

Valacyclovir- 1g x 2 per day

26
Q

What are the risk factors for HG?

A

Increased number of lifetime sex partners

Oral-genital contact

Presence of other sexual transmitted diseases

Female sex

OCP use

Black/non-hispanic race

27
Q

What is the structure of HPV?

A

Non enveloped doubles stranded DNA virus

28
Q

How is HPV spread?

A

Sexual contact

Microtrauma to skin or mucous membranes

29
Q

How long can HPV infection remain subclinical for?

A

6-10 months

30
Q

What conditions are associated with HPV?

A

Squamous Papilloma

Warts

Condyloma acuminatium

31
Q

How many types of HPV are there?

A

Over 100
-> 40 affect anogenital areas
-> 13 are oncogenic

32
Q

What do the non-oncogenic Low risk types of HPV cause? (6/11)

A

Genital warts

Recurrent respiratory papillomatosis

33
Q

What do the oncogenic high risk types of HPV cause?

A

Cervical, penile, vulvar, vaginal, anal, OPG cancers

34
Q

What allows oncogenic HPV to drive cell division in neoplasia?

A

Ability of E7 protein to bind and degrade pRb proteins

Ability of E6 to degrade P53 and compromise PDZ-domain proteins (regulate cell contact and signalling)

35
Q

What are the top 5 most prevalent types of HPV?

A

HPV16- 3.2%
HPV18- 1.4%
HPV52- 0.9%
HPV31- 0.8%
HPV58- 0.7%

36
Q

How does anogenital warts/condyloma acuminata present?

A

Exophytic lesions
-> Sessile/pendunculated
-> single, multiple, multifocal

Begin as small discrete, soft, pearly papules that coalesce into a plaque over time
-> Can also be verrocous, hyperkeratotic, fungating

37
Q

Where do anogenital warts occur in men?

A

Coronal sulcus

Glans

Scotrum

Penile shaft

Anal/peri-anal region

38
Q

What areas doe anogenital warts typically occur in females?

A

External genitalia

Cervix

Anal/peri-anal area

Rare- urethra, bladder

39
Q

What colour do low risk HPV lesions appear?

A

Variable:
Flesh coloured
Pink
Red
Brown

40
Q

What are the histological features of HPV genital warts?

A

Elongation of dermal papillae

Hyperplasia of stratum spinosum (acanthosis)

Large vacuolated cells (koilocytes) in stratum granulosum

41
Q

What are the oral lesions that HPV can cause?

A

Verruca vulgaris (common wart): exophytic upside down V surface

Condyloma acuminatum: exophytic cauliflower-like surface (sideways C)

Squamous Papilloma: exophytic hairy-like (pedunculated- P shaped) lesions

42
Q

How long does high risk infection of HPV usually last?

A

12- 18 months (then cleared by immune system)

43
Q

What hap[pens if host immune system fails to clear HPV 16/18 infection?

A

Protein E2- which is negative regulator of E6/7 gets abrogated
-> over expression of E6/7 which results in inhibition of tumour suppressor proteins

44
Q

What does inhibition of tumour suppressor genes by E6/7 cause?

A

Inhibition of interferon response

Activation of telomerase

Promotion of cell divisions

Immortalisation and transformation

-> genetic instability, unregulated replication, accumulation of aberrant chromosomal mutations, dysplasia

45
Q

What occurs in a high risk silent infection?

A

Viral genomes persist in basal layer without development of disease or can lead to precancerous squamous intraepithelial neoplasias (cervical, vulval, vaginal, penile, anal)

46
Q

How is HPV diagnoses?

A

Clinical appearance

Hsitology- koliocytes

HPV-DNA on PCR

Serology- not suitable for distinguishing between acute and prior infections (weak immune response)

47
Q

What treatments are available for HPV?

A

Podofilox- wart necrosis
-> BID for 3 days consecutively per week for 4 weeks

Imiquimod 3.75-5% cream

Sinecatechins 10-15% ointment

Surgical excision

Cryotherapy

48
Q

How can HPV be prevented?

A

Vaccine
-> given to all children aged 11-13
-> free up until age 25

BDS4 Oral Medicine (28 decks)

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