Poxviruses Flashcards

1
Q

Poxviruses

A
  • ds DNA enveloped
  • replicate in cytoplasm
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2
Q

Poxviruses that infect humans

A

•Orthopoxviruses

  • Variola major (smallpox major)
  • Variola minor (smallpox minor)
  • Cowpox
  • Vaccinia (hybrid of small pox and cowpox)
  • Monkeypox

•Parapoxviruses

  • Orf
  • Pseudocowpox

•Molluscum contagiosum

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3
Q

Poxviruses Structure

A
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4
Q

Poxviruses Replication

A
  • All events in cytoplasm
  • Rapid adsorption to receptors
  • Endocytosis (cytoplasmic vacuole).
  • First uncoating is removal of outer membrane
  • Second uncoating is partial removal of core membranes and proteins
  • Leads to activation of viral DNA–dependent RNA polymerase
  • Transcripts are translated into virus–coded enzymes which further degrade core proteins and release naked viral DNA
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5
Q

Smallpox

A
  • Orthopoxvirus genus of the Poxviridae family
  • ds DNA enveloped
  • smallpox
  • Variola major (3-20% fatality)
  • Variola minor (1% fatality)
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6
Q

Smallpox Infection

A
  • Infection by inhalation (respiratory tract)
  • Virus first replicates in upper respiratory tract epithelial cells
  • Spread to regional lymph nodes
  • Viremia: target cells are skin, mucous membranes and internal organs
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7
Q

Smallpox Symptoms

A
  • Fever and malaise precede lesions
  • Vesicles appear on face, arms and lower extremities (all at the same time)
  • Considerable variation in outcome: mild to severe fulminant (genetics ?)
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8
Q

Smallpox Complications

A

•keratitis, encephalitis, pneumonia, bacterial superinfections

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9
Q

Smallpox Diagnosis

A

•Clinical picture, serology

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10
Q

Smallpox Prevention

A
  • Vaccinia virus (live vaccine), intradermal, must be 1 year of age
  • Protection is not life long, revaccination at 10 year intervals.
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11
Q

Smallpox Vaccine Adverse Reactions

A
  • Generalized vaccinia: vesicles form over entire body
  • Encephalitis (40% fatality)
  • Progressive vaccinia: immunosuppressed patients, lesions enlarge (50% mortality rate)
  • Pregnancy: death of fetus
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12
Q

Smallpox Treatment

A

•Methisazone (Marboran), reduces severity, must be given early after infection

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13
Q

Monkeypox

A
  • Orthopoxvirus genus of the Poxviridae family
  • ds DNA enveloped
  • similar to smallpox but less severe
  • Primary and secondary transmission possible
  • Majority of the cases due to person-to-person transmission
  • Animals may infect people through bites or people touching animal discharges and rubbing eyes or nose
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14
Q

Orf

A
  • Parapoxvirus of the Poxviridae family
  • ds DNA enveloped
  • natural infection in sheep and goats

–Human infection by contact, usually single lesion which spontaneously regresses

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15
Q

Psedocowpox

A
  • Parapoxvirus of the Poxviridae family
  • Milker‘s nodules (cutaneous lesions similar to Orf, regress spontaneously)
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16
Q

Molluscum Contagiosum

A
  • Molluscipoxvirus genus of the Poxviridae family
  • ds DNA enveloped
  • Infection by contact (can be sexually transmitted)
  • Cutaneous ”pearl– like“ lesions that regress spontaneously