Adenovirus, parvovirus, polyomavirus

Adenovirus

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

Adenovirus Structure

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

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

Adenovirus replication cycle

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

Adenovirus diseases

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

Adenovirus pathogenesis

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 vaccine

Parvovirus

Parvovirus structure

From Medical Microbiology, 4th ed., Murray, Rosenthal, Kobayashi & Pfaller, Mosby Inc., 2002, Fig. 53-1.

Parvovirus Genome

Rep Cap

5 kb ssDNA, inverted terminal repeats (ITR)

Rep gene required for DNA replication

Cap gene encodes capsid proteins

ITR ITR

Autonomous parvovirus replication

Postulated replication of parvovirus (B19) based on information from related viruses (minute virus of mice). The internalized parvovirus delivers its genome to the nucleus, where the single-stranded (plus or minus) DNA is converted to double-stranded DNA by host factors and DNA polymerases present only in growing cells. Transcription, replication, and assembly occur in the nucleus. Virus is released by cell lysis.(From Medical Microbiology, 5th ed., Murray, Rosenthal, Kobayashi & Pfaller, Mosby Inc., 2002, Fig. 56-2.)

Helper dependent parvovirus (AAV) replication

AAV DNA integrates into

chromosome 19

Infection without adenovirus

Infection with adenovirus

Superinfect with

adenovirus

Lytic replication

A "slapped-cheek" appearance is typical of the rash for erythema infectiosum.(From Medical Microbiology, 5th ed., Murray, Rosenthal & Pfaller, Mosby Inc., 2005, Fig. 56-5.)

Parvovirus pathogenesis

From Medical Microbiology, 5th ed., Murray, Rosenthal & Pfaller, Mosby Inc., 2005, Fig. 56-3.

Parvovirus pathogenesis

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

Polyomavirus

Polyomavirus genome

Genome of the SV40 virus. The genome is a prototype of other polyomaviruses and contains early, late, and noncoding regions. The noncoding region contains the start sequence for the early and late genes and for DNA replication (ori). The individual early and late messenger RNAs are processed from the larger nested transcripts.(From Medical Microbiology, 5th ed., Murray, Rosenthal & Pfaller, Mosby Inc., 2005, Fig. 52-7.)

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. (From Fields Virology, 4th ed, Knipe & Howley, eds, Lippincott Williams & Wilkins, 2001, Fig. 63-4.)

Polyomavirus replication

From Medical Microbiology, 5th ed., Murray, Rosenthal & Pfaller, Mosby Inc., 2005, Fig.52-8.

Polyomavirus pathogenesis

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 ?