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14 Cards in this Set
- Front
- Back
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What are the class III DNA viruses?
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parvoviruses
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What is the ONLY pathogenic parvovirus in humans?
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Parvovirus B19
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What do some parvoviruses depend on for their replication and what are they viruses known as?
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Some parvoviruses depend on ADENOviruses to provide missing components or else they cannot be replicated
These viruses are called ADENO-ASSOCIATED viruses or DEPENDOVIRUSES |
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Structure of parvovirus?
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*Smallest nucleocapsid of all DNA viruses
Icosahedral, NAKED, 18 - 26 nm LINEAR segment of ssDNA HAIRPIN LOOPS negative OR positve sense DNA |
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Describe parvovirus replication. Temporal control?
What is read to make Viral capsid proteins and what are the viral capsid proteins? What regulates viral replication? How are virions released? |
NOT under temporal control
Parent DNA ---> progeny DNA multiple GENOME-LENGTH REPLICATIVE INTERMEDIATES Progeny DNA ---> construct viral proteins Viral capsid proteins: VP1, VP2, VP3 NS1 and NS2 regulate viral replication Viruses assembled, cell is LYSED to release virions |
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Disease associated with parvovirus?
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Erythema infectiosum (Fifth disease)
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How is erythema infectiosum (5th disease) acquired? Age group affected?
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Respiratory secretions and transplacentally
Age group: 4-10 |
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When does viremia peak in erythema infectiosum? What happens then?
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Viremia peaks 1 WEEK after infection
Sheds viruses in respiratory secretions |
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Where are viruses replicated in erythema infectiosum? What do they do?
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parvovirus replicated in bone marrow
Destroy erythroid precursor cells |
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By day ten of erythema infectiusum there are no erythroblasts in bone marrow and no reticulocytes in blood. How will this affect a normal patient vs. a patient with chronic hemolytic anemia?
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In normal patient: no problem, life span of circulating erythrocytes is 120 days
In patients with chronic hemolytic anemias (sickle cell anemia, thalassemia, or hereditary spherocytosis) average erythrocyte life span is 15-20 days ---> develop APLASTIC CRISIS |
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What happens by days 17-24 in erythema infectiosum (5th disease)?
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IgM peaked, IgG rising, free viruses gone from blood
Rash and arthralgia now appear due to deposition of immune complexes |
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What is the rash in erythema infectiosum known as? Describe the path of the rash. What happens to the rash as time goes on?
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"slapped cheek syndrome"
First 4 days: rash on FOREHEAD and CHEEKS, BEHIND EARS, area around mouth is PALE ---> spreads to LIMBS AND TRUNK Rash fades in center (appear lacy or serpiginous pattern) Fades in 10 days |
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What happens if woman develops transient arthropathy during pregnancy?
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Transplacental transfer of viruses ---> hydrops fetalis (abnormal collection of serous fluid in tissues)
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How is erythema infectiousum diagnosed? Treatment? Prevention?
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Clinical grounds, PCR or EIA
Treatment: NO ANTIVIRAL TREATMENT FOR PARVOB19 Aplastic crisis patients: BLOOD TRANSFUSIONS NO VACCINE |
