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Complexities of Viral Nomenclature

Complexities of Viral Nomenclature. No consistent system for naming viruses – some are named for the: associated diseases (e.g. poliovirus, rabies virus ) specific type of disease they cause (e.g. hepatitis A,B,C, D, E )

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Complexities of Viral Nomenclature

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  1. Complexities of Viral Nomenclature No consistent system for naming viruses – some are named for the: • associated diseases (e.g. poliovirus, rabies virus) • specific type of disease they cause (e.g. hepatitis A,B,C, D, E) • sites in the body that are affected or from which they were first isolated (e. g. rhinovirus and adenovirus) • geographic locations in which they were first isolated (e.g. Sendai virus [Sendai, Japan] and Coxsackievirus[Coxsackie, New york]) • sicentistswho first discovered them (e.g. Epstein-Barr virus) • way in which people imagined they were contracted (e.g. dengue, for “evil spirit” and influenza, for the “influence of bad air) • combinations (e.g. Rous sarcoma virus)

  2. International Committee on Taxonomy of Viruses (ICTV) • member group of the International Union of Microbiological Societies • oversees the ongoing process of devising and maintaining a universal classification scheme for viruses • Assigns viruses to orders, families, subfamilies, genera, and species based on information provided by study groups composed of experts on specific types of viruses.

  3. David Baltimore developed a system to classify viruses based on their genomes…The Baltimore System… dsDNA ssDNA dsRNA ss (+) RNA ss (-) RNA ss (+) RNA with DNA intermediate gapped dsDNA VII

  4. Virus Classification Classical hierarchical system: Kingdom Phylum Class Order - virales Family (-viridae) Genus (-virus) Species (73) (287)

  5. Virus Classification • Order: virales • Family: Filoviridae • Enveloped virions, variably elongated filaments 650–1,400 nm in length and pleomorphic in shape, containing a helical nucleocapsid with single-stranded negative-sense RNA (about 19 kilobases in length) and an endogenous RNA polymerase. • Genera: • Filovirus : contains the Marburg viruses • Ebolavirus:contains the Ebola viruses. • Species (Strain): • Ebolavirus: Ebola-Zaire, Ebola-Sudan, Ebola-Cote d’Ivoire, Ebola-Reston, Ebola-Bundibugyo

  6. DNA Virus Mnemonic "HHAPPPPy", -Hepadna -Herpes -Adeno -Pox -Parvo -Papilloma -Polyoma All DNA viruses except the Parvoviridae are dsDNA Extremely stable, resistant to heat, detergents and chlorination

  7. All RNA viruses except Reoviridae are ssRNA

  8. A27y/o workeratadaycarecenter hasrecentlybeenfeelingtired,hasaslightfever,andhasfeltnauseatedandvomitedseveraltimes.Yesterday,shehadabdominalpainandchills,andtodayshevoideddarkurine.LabtestsforserumenzymesindicatedelevatedASTandALT.Noinfectiousagentcouldbegrowninculture,butPCRtestingdeterminedthatthecausativeagentcontainsapositivesense,Single StrandedRNAgenome.Electronmicroscopyrevealedanakedicosahedralcapsidapproximately28nmindiameter.Thevirusresponsiblefortheinfectionbelongstothefamily: Hepadnaviridae Flaviviridae Picornaviridae Polyomaviridae

  9. A27y/o workeratadaycarecenter hasrecentlybeenfeelingtired,hasaslightfever,andhasfeltnauseatedandvomitedseveraltimes.Yesterday,shehadabdominalpainandchills,andtodayshevoideddarkurine.LabtestsforserumenzymesindicatedelevatedASTandALT.Noinfectiousagentcouldbegrowninculture,butPCRtestingdeterminedthatthecausativeagentcontainsa positive sense, Single Stranded RNA genome.Electronmicroscopyrevealed a naked icosahedral capsid approximately 28 nm indiameter.Thevirusresponsiblefortheinfectionbelongstothefamily: Hepadnaviridae Flaviviridae Picornaviridae Polyomaviridae

  10. Which of the following statements is correct? • Viruses can have an icosahedral capsid or an envelope, but not both. • Helical capsids are always surrounded by an envelope. • Icosahedral capsids are only found among DNA viruses. • Icosahedral capsids are very large.

  11. Which of the following statements about human viruses is correct? • Viruses can have an icosahedral capsid or an envelope, but not both. • Helical capsids are always surrounded by an envelope. • Icosahedral capsids are only found among DNA viruses. • Icosahedral capsids are very large.

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