adeno,parvo,polyoma virus

Adenovirus, parvovirus, polyomavirus

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Adenovirus

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From Medical Microbiology, 5th ed., Murray, Rosenthal & Pfaller, Mosby Inc., 2005, Fig. 53-1.

Adenovirus Structure

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E1

E2 E4

E3Late genes

Adenovirus Genome

36 kb linear ds DNA

Early genes for host and viral transcription control, viral DNA replication

Late genes for virion structure

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(From Fields Virology, 4th ed, Knipe & Howley, eds, Lippincott Williams & Wilkins, 2001, Fig. 67-5.)

Adenovirus replication cycle

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Adenovirus diseases

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From Medical Microbiology, 5th ed., Murray, Rosenthal & Pfaller, Mosby Inc., 2005,, Fig. 50-4.

Adenovirus pathogenesis

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Summary: adenovirus

• Structure– Medium sized (36 kb) dsDNA genome, naked capsid

• Pathogenesis– respiratory or fecal oral transmission– replication in nucleus; moderately host dependent– local spread; viremia– cellular and humoral immunity important; virus encodes

countermeasures against MHC I expression and apoptosis– direct cell damage from replication; respiratory illness,

conjunctivitis, gastroenteritis, cystitis• Diagnosis

– culture, viral antigen detection• Treatment/prevention

– live military vaccinewww.freelivedoctor.com

Parvovirus

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Parvovirus structure

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Parvovirus Genome

Rep Cap

5 kb ssDNA, inverted terminal repeats (ITR)

Rep gene required for DNA replication

Cap gene encodes capsid proteins

ITR ITR

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Autonomous parvovirus replication

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Helper dependent parvovirus (AAV) replication

AAV DNA integrates into

chromosome 19

Infection without adenovirus

Infection with adenovirus

Superinfect with

adenovirus

Lytic replication

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Parvovirus pathogenesis

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Parvovirus pathogenesis

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Parvovirus• Structure

– Small (5 kb) linear ssDNA genome, naked capsid• Pathogenesis

– respiratory transmission– replication in nucleus, very host dependent, needs S phase

cells or helper virus– viremia– antibody important in immunity– targets erythroid lineage cells; fifth disease (symptoms

immunological); transient aplastic crisis; hydrops fetalis• Diagnosis

– serology, viral nucleic acid• Treatment/prevention

– none

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Polyomavirus

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Polyomavirus genome

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Replication cycle of polyomaviruses. Steps in the replication cycle are indicated by numbers as follows: 1, adsorption of virions to the cell surface; 2, entry by endocytosis; 3, transport to the cell nucleus (route and mechanism not yet known); 4, uncoating; 5, transcription to produce early region mRNAs; 6, translation to produce early proteins (T antigens); 7, viral DNA replication; 8, transcription to produce late region mRNAs; 9, translation to produce late proteins (capsid proteins); 10, assembly of progeny virions in the nucleus; 11, entry of virions into cytoplasmic vesicles (mechanism unknown); 12, release of virions from the cell by fusion of membrane vesicles with the plasma membrane; 13, released virion.

Polyomavirus replication

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Polyomavirus pathogenesis

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Polyomavirus

• Structure– Small (5 kb) circular dsDNA genome, naked capsid

• Pathogenesis– respiratory transmission– replication in nucleus; very host dependent– viremia– persistence in kidneys; reactivation with immune compromise– inapparent infection; hemorrhagic cystitis; PML

• Diagnosis– viral nucleic acid

• Treatment/prevention– cidofovir ?

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