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General Characteristics of Viruses

General Characteristics of Viruses. HIV ! Avian Flu ! SARS ! Ebola ! West Nile ! Smallpox ! Hepatitis A, B , C , D , E ! Polio ! HPV !. Viruses infect all living things. Animal kingdom Plant kingdom Microbes. Specificity/selectivity for host.

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General Characteristics of Viruses

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  1. General Characteristics of Viruses

  2. HIV ! Avian Flu ! SARS ! Ebola ! West Nile !Smallpox ! Hepatitis A,B,C,D,E ! Polio !HPV !

  3. Viruses infect all living things • Animal kingdom • Plant kingdom • Microbes • Specificity/selectivity for host

  4. Manifestations of Viral Infections • Asymptomatic • Acute viral syndrome (influenza, rhinovirus, etc) • Persistent viral syndrome (EBV) • Chronic infection • Reactivating (HSV-1/2, VZV (chicken pox/shingles)) • Progressive (HBV, HCV, HIV) • Cancer (EBV, HPV-16, HBV, HCV, KSHV) • Death (HIV, et al) • Acute death (smallpox, Ebola, SARS)

  5. Viral pathogenesis --- disease • Virus replication • Targeted cells • Host response

  6. What is a virus? What are the essential characteristics of a virus? • Physical • Biological

  7. What is a virus? • Physical Characteristics • Genetic Material • Nucleic acid • RNA (ssRNA, dsRNA, segmented) • DNA (ssDNA, dsDNA) • Protein coat (subunit structure) • Nucleoprotein • Capsid • Capsomeres, Geometrical constraints • Envelope (some)

  8. HIV-1, SIV and Other Retroviruses Adenoviruses Rhabdoviruses (rabies)

  9. Size of Viruses

  10. What is a virus? • Genetic material limited • 10^3 to 10^5 bases long • Codes for unique proteins • Polymerases – RNA replication • Kinases • Proteases • Structural proteins • Accessory proteins • Targets for antiviral agents - limited

  11. What is a virus? Biological Charateristics • Viruses as parasites • Parasites • Not capable of independently completing a full replication cycle • Cellular parasites • Subcellular “parasites” • Viruses • Viroids • Prions

  12. What is a virus? • Are viruses alive? • Characteristics of living organisms?

  13. What is a virus? Biological Characteristics • Viral replication strategies • Viral replication cycles • Binding/entry • Uncoating • Genome replication (w/wo integration) • Protein production • Assembly • Budding • Host cell tropism (receptors) • Lytic vs. non-lytic infection

  14. Vaccinia Poliovirus Adenovirus Herpesvirus

  15. Morphological Assays • Electron microscopy • Isolated virus or infected cells • Nonenveloped or enveloped (alternate method to determine if an envelope is present?) • Core structure

  16. Epidemiology • Tracking prevalence of viruses in host populations Blood components and tissue samples • Virus culture • In vitro (tissue culture) • In vivo (susceptible animal model) • Molecular testing • PCR methods • Southern blot • ELISA (enzyme linked immunosorbent assay) • Assay for antigen (viral protein) • Assay for antibody directed against virus

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