Lecture 2 - Virus Classification Flashcards
What is the most difficult taxomic hierarchy to define for a virus and why?
Virus species are most difficult to classify because they do not breed.
Describe polythetic hierarchical classification
Use of more than one property to describe the virus where no single property is essential.
What are 4 properties used to classify viruses polythetically?
1) nature and sequence of nucleic acid in virion
2) symmetry of capsid
3) presence or absence of envelope
4) dimensions of virion and capsid
Name the 2 virus families with dscDNA genomes
Hepadna
Papova
Name the 3 virus families with dslDNA genomes
Adeno
herpes
pox
Name the virus family with ssDNA genome
Parvo/circo
Name the 4 virus families with +ssRNA genomes
Picorna (calici, astro)
Toga
Flavi
Corona
Name the virus family with a diploid +ssRNA genome
Retro
Name the 4 virus families with -ssRNA genomes
Rhabdo
paramyxo
filo
orthomyxo
Name the virus family with an ambisense -ssRNA genome
Arena
Name the virus family with a dsRNA genome
Reo
Describe the following for Reoviruses:
1) family name derivation
2) virion morphology
3) genome structure
4) noteworthy features
5) species examples
1) respiratory enteric orphan
2) icosahedral, naked, triple-shelled capsids
3) segmented dsRNA
4) capsid structure and incomplete uncoating to subviral particles
5) reovirus, rotavirus
Describe the following for Arenaviruses:
1) family name derivation
2) virion morphology
3) genome structure
4) noteworthy features
5) species examples
1) arenosus = sand (ribosomes inside virion)
2) helical, enveloped
3) -ssRNA in 2 segments
4) ambisense RNA: some genes encoded by genomic RNA others by complementary RNA
5) Lassa fever virus
Describe the following for Orthomyxoviruses:
1) family name derivation
2) virion morphology
3) genome structure
4) noteworthy features
5) species examples
1) myxo = slime
2) helical, enveloped
3) segmented -ssRNA
4) segmented genome, requires nucleus (unusual for RNA viruses)
5) Influenza virus
Describe the following for Filoviruses:
1) family name derivation
2) virion morphology
3) genome structure
4) noteworthy features
5) species examples
1) Filamentous
2) filamentous morphology is unusual, enveloped
3) -ssRNA, 19kb
4) agents of severe hemorrhagic fever in humans
5) ebolavirus
Describe the following for Rhabdoviruses:
1) family name derivation
2) virion morphology
3) genome structure
4) noteworthy features
5) species examples
1) rhabdos = rod
2) helical, enveloped
3) -ssRNA
4) bullet shaped
5) rabies virus
Describe the following for Paramyxoviruses:
1) family name derivation
2) virion morphology
3) genome structure
4) noteworthy features
5) species examples
1) myxo = slime, affinity for mucus
2) helical, enveloped
3) -ssRNA
4) often causes syncytia = cell fusion
5) measles, mumps, RSV
Describe the following for Retroviruses:
1) family name derivation
2) virion morphology
3) genome structure
4) noteworthy features
5) species examples
1) retro = reverse transcribes RNA to DNA
2) enveloped, may or may not be icosahedral
3) diploid +ssRNA
4) diploid genome, reverse transcriptase, RNA tumor viruses
5) HIV
Describe the following for Coronaviruses:
1) family name derivation
2) virion morphology
3) genome structure
4) noteworthy features
5) species examples
1) peplomers (spikes) form halo like sun’s corona
2) helical, enveloped
3) +ssRNA, largest RNA genome
4) large, petal-shaped peplomers, respiratory infections
5) SARS, MERS-CoV
Describe the following for Flaviviruses:
1) family name derivation
2) virion morphology
3) genome structure
4) noteworthy features
5) species examples
1) Flavus = yellow (yellow fever virus)
2) Icosahedral, enveloped
3) +ssRNA
4) often arboviruses, polyprotein processing, often encephalitic or hemorrhagic
5) YFV, Dengue virus, Hepatitis C virus, Zika, West Nile Virus
Describe the following for Togaviruses:
1) family name derivation
2) virion morphology
3) genome structure
4) noteworthy features
5) species examples
1) “wrapped” in envelope
2) Icosahedral, enveloped
3) +ssRNA
4) often arboviruses
5) rubella, semliki forest virus
Describe the following for Picornaviruses (calici, astro):
1) family name derivation
2) virion morphology
3) genome structure
4) noteworthy features
5) species examples
1) pico = small, smallest RNA viruses
2) icosahedral, naked
3) +ssRNA
4) viral protein bound to 5’ end of genome, polyprotein processing
5) polio virus, rhinovirus, hep A virus
Describe the following for Parvo/circoviruses:
1) family name derivation
2) virion morphology
3) genome structure
4) noteworthy features
5) species examples
1) smallest viruses
2) icosahedral, naked, + or - DNA
3) sscDNA, small genome, integrates in host DNA
4) some of the smallest known viruses
5) B19 virus (fifths disease), adeno-associated virus (gene therapy vector)
Describe the following for Poxviruses:
1) family name derivation
2) virion morphology
3) genome structure
4) noteworthy features
5) species examples
1) pocks: vesicular skin lesions
2) complex capsid
3) dslDNA with covalently closed termini (unique)
4) largest animal viruses, replicate in cytoplasm
5) small pox (variola virus), vaccinia virus, molluscum contagiosum virus
Describe the following for Herpesviruses:
1) family name derivation
2) virion morphology
3) genome structure
4) noteworthy features
5) species examples
1) herpein: to creep, nature of lesions
2) icosahedral, enveloped
3) dslDNA
4) latent and recurring infections, human tumors
5) herpes simplex, cytomegalovirus, Epstien-Barr virus, VZV
Describe the following for Adenoviruses:
1) family name derivation
2) virion morphology
3) genome structure
4) noteworthy features
5) species examples
1) latent infection of adenoid tissues
2) icosahedral, naked
3) dslDNA
4) latent infections, cell transformation
5) human adenovirus (common cold)
Describe the following for Papovaviruses:
1) family name derivation
2) virion morphology
3) genome structure
4) noteworthy features
5) species examples
1) Papilloma (warts), polyoma (many tumors), vacuolating (CPE in tissue culture)
2) icosahedral, naked
3) dscccDNA, minichromosome
4) cell transformation, tumor viruses
5) HPV, Merkel cell virus, simian virus 40
Describe the following for Hepadnaviruses:
1) family name derivation
2) virion morphology
3) genome structure
4) noteworthy features
5) species examples
1) hepatitis, DNA
2) icosahedral, enveloped
3) dscDNA, nicked with large ss gap (unique)
4) serum hepatitis, persistent infections, liver cancer
5) hepatitis B virus
Name the 12 enveloped virus families
ACFFHHOPPRRT
Arena, Corona, Filo, Flavi, Hepadna, Herpes, Orthomyxo, Paramyxo, Pox, Rhabdo, Retro, Toga.
Name the 5 non-enveloped virus families
APPPR
Adeno, Papova, Parvo, Picorna, Reo