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]) sicentists who 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) No consistent system for naming viruses – some are named for the associated diseases (e.g. poliovirus, rabies virus, for the specific type of disease they cause (hepatitis A,B,C, D, E) or the sites in the body that are affected or from which they were first isolated (e. g. rhinovirus and adenovirus). Others are named for the geographic locations in which they were first isolated (e.g. Sendai virus (Sendai, japan) and Coxsackievirus (Coxsackie, New york) or for the sicentists who first discovered them (e.g. Epstein Barr virus How viruses should be classified has been hotly debated over the years.

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.

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 1975 Nobel Prize in Physiology and Medicine David Baltimore Renato Dulbecco Howard Martin Temin

Virus Classification Classical hierarchical system: Kingdom Phylum Class Order - virales Family (-viridae) Genus (-virus) Species How viruses should be classified has been hotly debated over the years. As of 2005 the International Committee on the Taxonomy of Viruses, has assigned approximately 40,000 different virus isolated from bacteria, plants and animals to one of 3 orders 73 famillies “-viridae” 287 genera “-virus” Some virologists use a species naming system, but it is not an official designation (73) (287)

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

All DNA viruses except the Parvoviridae are dsDNA 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  Herpesvirus – Herpes simplex, cytomegalovirus, Epstein Barr virus Hepadnaviridae – HBV Papillomaviridae –HPV Polyomaviridae - JC virus – progressive multifocal leukoencephalopathy Adenoviridae – adenoviruses Parvoviridae – Poxviridae

All RNA viruses except Reoviridae are ssRNA Flaviviridae – HCV, Dengue, Yellow Fever Virus Togaviridae – alphaviruses – encephalitis Retroviridae – HIV Coronaviridae – SARS Picronaviridiae – polio Caliciviridae – Norwalk virus Orthomyxoviridae – Inflenza Paramyxoviridae – mumps Rhabdoviridae – rabies Filoviridae – ebola Bunyaviridae – bunyavirus Arenaviridae – lassa virus Reoviridae – rotovirus - gastroenteritis

A 27 y/o worker at a day care center has recently been feeling tired, has a slight fever, and has felt nauseated and vomited several times. Yesterday, she had abdominal pain and chills, and today she voided dark urine. Lab tests for serum enzymes indicated elevated AST and ALT. No infectious agent could be grown in culture, but PCR testing determined that the causative agent contains a positive sense, Single Stranded RNA genome. Electron microscopy revealed a naked icosahedral capsid approximately 28 nm in diameter. The virus responsible for the infection belongs to the family:   Hepadnaviridae Flaviviridae Picornaviridae Polyomaviridae

A 27 y/o worker at a day care center has recently been feeling tired, has a slight fever, and has felt nauseated and vomited several times. Yesterday, she had abdominal pain and chills, and today she voided dark urine. Lab tests for serum enzymes indicated elevated AST and ALT. No infectious agent could be grown in culture, but PCR testing determined that the causative agent contains a positive sense, Single Stranded RNA genome. Electron microscopy revealed a naked icosahedral capsid approximately 28 nm in diameter. The virus responsible for the infection belongs to the family:   Hepadnaviridae Flaviviridae Picornaviridae Polyomaviridae

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.

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.