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15 Cards in this Set
- Front
- Back
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DNA Viruses:
Genome Type Replication Requirements Site of Replication Exceptions Temporal Differences in Gene Transcription (Early vs Late Genes) Geometry |
DNA Viruses:
Genome is DNA with linear or circular configuration Replication requires DNA-dependent DNA polymerase, deoxyribonucleotide triphosphates (esp thymidine) Replicates in nucleus (need to access host enzymes for transcription) POXVIRUS = exception; replicated in cytoplasm Early genes: DNA binding proteins, enzymes Late Genes: structural proteins ALL DNA VIRUSES ARE ICOSAHEDRAL |
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Which DNA viruses encode their own polymerase?
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Larger and more complex DNA viruses!
Herpesvirus Adenovirus Poxviruses |
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Which DNA viruses are enveloped?
Which DNA viruses are non-enveloped? Which are more likely to survive in chlorinated water? |
Herpesviridae
Poxviridae Hepadnaviridae (HBV) Non-Enveloped: Adenoviridae Papovaviridae (papillomas, polyomas) Parvoviridae NONENVELOPED CAN SURVIVE IN POOLS |
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Herpesvirus:
Hallmark Function of Tegument alpha vs beta vs gamma proteins |
Latency within hosts 9 (nonreplicating phase)--mechanism of latency differs for each herpes virus. Can reactivate as shingles when latent in CNV (appear in dermatome)
Tegument contains viral proteins alpha-TIF and viral host shut off protein to steal synthetic machinery alpha proteins = IMMEDIATE early prots: impt for gene transcription and takeover of cell (don't need to synthesize viral prots) Beta = EARLY prots: transcription factors, enzymes, replicate viral DNA (DNA POLYMERASE, thymidine kinase, topoisomerases) Gamma Proteins = LATE proteins: structural prots, capsid prots, glycoprots |
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How does the replication of herpesviridae differ from most other enveloped viruses?
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Doesn't budd
Instead envelope prots accumulate in patches on nuclear membrane Transported to cell surface And attach via glycoprots to adjacent cells FORM MULTINUCLEATED CELLS (SYNCYTIA) Characterizes local spread and progression of lesions in herpes simplex |
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Poxviridae:
Examples (2) Strains exhibiting zoonosis |
Poxviriade = LARGEST and MOST COMPLEX of viruses
Ex: variola (smallpox), molluscum contagiosum Zoonotic: monkeypox, cowpox |
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Variola:
Hosts Reservoirs Latency Morphology Site of Replication |
Variola = Smallpox = subdivision of pox
Humans are the only host No animal reservoirs NO LATENCY (it's a hit-and-run virus). immunity is lifelong THERE ARE NO ASYX INFECTIONS! Morphology: oval/birck-shaped Replicate in cytoplasm (poxviridae) Nite: brings ALL proteins necessary for mRNA and DNA synthesis as well as for prots needed for immune evasion (POXVIRIDAE) |
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What are Guarnieri's bodies?
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Where variola (smallpox) assembles in inclusion bodies; this is where it acquires its outer membrane
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What is the hallmark morphology of poxviriade?
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Virion core has dumbbell shape because of large lateral bodies (double membrane)
Envelope acquired upon exit |
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Describe the infective cycle of smallpox.
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Virus enters and replicates in respiratory tract (asyx)
Infects macs, enter LN's Replicates in LN's Viremia Spreads to spleen, BM, liver, skin (rash) Secondary viremia develops into add'l lzns |
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Advenoviruses:
Latency Structure Affected Organ Systems Method of Transmission Types of Infections (3) in Target Cells |
Latent
Hexagonal Structure with Fibers (allows attachment to host cell receptor!!), Pentons (>100 serotypes, 49 infect humans) Cause respiratory tract infections, ocular infections, UTI, GI's (non-enveloped--can survive secretions), CAN BE VISCERAL (can have secondary viremia bc of replication in lymphatics) Spread mainly respiratory, close contact, fecal-oral, finger to eye Three infection types: 1) Lytic (Ab important to mount, need diff Ab for diff serotypes) 2) Latent 3) Oncogenic Transformation |
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Papovaviridae:
Geometry Genome Type Subtypes Why can it be oncogenic? |
Paovaviridae:
Icosahedral Supercoiled dsDNA Encode proteins that promote cel growth by binding to growth suppressor prots (p53, p105RB)--allow lytic viral replication but may oncogenically transform cells Subfamilies: Papillomaviruses (HPV-1, -100) Polyomaviruses (JC, BK viruses, SV-40) |
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Papillomaviruses:
Genome Type Early Genes Oncoproteins Method of Infection Clinical Manifestations |
Papillomaviruses:
circular genome Early genes: E1-7 enable viral transcription/replication, interact with host genome E6 and E7 allow for immortalization and transformation fns, these are ONCOPROTEINS--manipulate cell cycle regulators, induce chromosomal abnrmlts and block apoptosis E6-->p53 E7-->RB Acquired by direct contact and infect epithelial cells of skin or mucous membrane Virus persists in basal layer and produced in keratinocytes (HPV promotes outgrowth of basal layer to produce thickened cornified layer of dead cells with infectious viral progeny) Can cause benign warts, dysplasia that may become cancerous |
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Which papovavirus results in anogenital warts?
Cervical neoplasia and cancer? |
HPV-6, 11: anogenital
HPV-16,18,31,45: cervical neoplasia, cancer |
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Papovirus:
Subtype causing human disease Requirements for replication Clinical Manifestations |
Papovirus:
Smallest DNA virus B19 causes human dz Requires rapidly dividine cells to replicate (RBC's) B19 causes fifth dz (erythema infetiosum: mild febrile exanthematous dz in children) Goes along with varicella, rubella, roseola, measles |
