Transcript virus classification-2

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)
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.
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dsDNA
I.
dsDNA
gapped'dsDNA
II. ssDNA
III. dsRNA
ssDNA
IV. ss (+) RNA
dsRNA'
V. ss (-) RNA
VI. ss (+) RNA with DNA
ss'(+)'RNA
intermediate
VII. gapped dsDNA
ss'(@
)'RNA
VII
Virus Classification
Classical hierarchical system:
Kingdom
Phylum
Class
Order - virales
(73) Family (-viridae)
(287) Genus (-virus)
Species
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 negativesense 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
Extremely stable,
resistant to heat,
detergents and
chlorination
All RNA viruses
except Reoviridae are
ssRNA
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:
1. Hepadnaviridae
2. Flaviviridae
3. Picornaviridae
4. 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:
1. Hepadnaviridae
2. Flaviviridae
3. Picornaviridae
4. Polyomaviridae
Which of the following statements is correct?
1. Viruses can have an icosahedral capsid or an envelope, but
not both.
2. Helical capsids are always surrounded by an envelope.
3. Icosahedral capsids are only found among DNA viruses.
4. Icosahedral capsids are very large.
Which of the following statements about human viruses is
correct?
1. Viruses can have an icosahedral capsid or an envelope, but
not both.
2. Helical capsids are always surrounded by an envelope.
3. Icosahedral capsids are only found among DNA viruses.
4. Icosahedral capsids are very large.