Poxviridae Flashcards
Describe the structure and genome of an orthopoxvirus.
Structure: brick-like shape, contains a core and outer membrane, and enveloped.
Genome: double-stranded linear DNA genome
What are the general features of replication cycle of a poxvirus.
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Describe three categories of immunomodulatory proteins encoded by Poxviruses. Give examples.
Virokines:
- resemble host cytokines
- secreted from infected cells to block hosts receptors
Examples: vIL-10, vIL-18
Viroreceptors:
- mimic host cellular receptors
- altered cellular receptors that have lost their transmembrane
sequnces and consequently are secreted from infected cells to sequester ligands
Examples: vINF-Rs, vTNFRs
Intracellular proteins:
- target host signal transduction pathways
- inhibit inner antiviral pathways:
apoptosis β vFLIPβs, serpins
proinflammatory cascades - TNF
List the differences between two strains of variola.
Variola major:
- classic smallpox
- predominant form in Asian epidemics
- higher mortality rate
Variola minor:
- causes milder disease
- less severe prodrome and rash
- low mortality rate
- discovered in 20th century in S. Africa
- was most predominant form in N. America
Describe in detail the clinical features of three stages of disease caused by Variola virus.
Incubation Stage:
- From time of infection to onset of symptoms
- Average 12-14 days (range 7-17)
- Important for epidemiologic investigation
- Considered non-infectious during this stage
- Virus sometimes culturable
Prodromal Stage
- Common symptoms
- High fever, low back myalgias
- Occasional symptoms
- Vomiting, abdominal pain, delirium
- Duration typically 3-5 days
- End of stage heralded by mucosal lesions
- Mucosal lesions onset of infectiousness
Eruptive Stage (Rash)
- Characteristic rash
- Centrifugal (in order of appearance & severity)
- Initially oral mucosaβ borders pre-eruptive stage
- Head, face
- Forearms, hands, palms
- Legs, soles, +/- trunk
