Poxviruses Flashcards
1
Q
Poxviruses
A
- ds DNA enveloped
- replicate in cytoplasm
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
3
Q
Poxviruses Structure
A
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
5
Q
Smallpox
A
- Orthopoxvirus genus of the Poxviridae family
- ds DNA enveloped
- smallpox
- Variola major (3-20% fatality)
- Variola minor (1% fatality)
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
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 ?)
8
Q
Smallpox Complications
A
•keratitis, encephalitis, pneumonia, bacterial superinfections
9
Q
Smallpox Diagnosis
A
•Clinical picture, serology
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.
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
12
Q
Smallpox Treatment
A
•Methisazone (Marboran), reduces severity, must be given early after infection
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
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
15
Q
Psedocowpox
A
- Parapoxvirus of the Poxviridae family
- Milker‘s nodules (cutaneous lesions similar to Orf, regress spontaneously)
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
