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Microbiology
11: Intro to Viruses
69
Medical
Graduate
03/06/2010

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Cards

Term
What are 4 tools used in the diagnosis of viruses?
Definition
Tissue cultures
Immunocytochemical staining
Antigen detection
PCR
11-2
Term
What are the two kinds of symmetry that viral capsules exhibit?
Definition
Helical or rod shaped
Spherical with icosahedral symmetry
11-3
Term
T/F. All capsids are composed of capsomeres. What are capsomeres?
Definition
F. They may or may not be composed of capsomeres. Capsomeres are defined as a clustering of capsid proteins discernible by electron microscopy. 11-3
Term
Viral genome + capsid = ???
Definition
nucleocapsid
11-3
Term
The herpes virus has a special layer in between the capsid and the envelope. What is it?
Definition
The tegument. 11-3
Term
The name of an intact infectious viral particle is this.
Definition
What is a virion? 11-3
Term
What happens if an enveloped virus loses its envelope?
Definition
It will no longer be capable of infecting its host.
11-4
Term
Which type of capsid structure requires that the virus have an envelope?
Definition
animal viruses with Helical symmetrical structure 11-4
Term
What are the axes of rotational symmetry in an icosahedral capsid?
Definition
2,3, and 5 fold axes. 11-5
Term
What are the six classes of viruses?
Definition
ssDNA, dsDNA, dsRNA, (-)ssRNA, (+)ssRNA, and retroviruses (also contain (+)ssRNA) 11-5
Term
What are the seven families of DNA viruses?
Definition
Hepadnavirus, herpesvirus, adenovirus, poxvirus, papovavirus, parvovirus, and iridovirus. HHAPPPI "happy' 11-6
Term
What families are ssDNA viruses?
Definition
Parvovirus. 11-6
Term
Which are the only circular DNA virus families?
Definition
Papovavirus, and hepadnavirus.
11-6
Term
Which DNA virus family does not have an icosahedral capsid?
Definition
Poxvirus.
11-6
Term
Which is the only DNA virus that does not replicate in the nucleus?
Definition
Poxvirus.
11-6
Term
Enveloped or naked: Hepadnavirus.
Definition
Enveloped.
11-6
Term
Enveloped or naked Poxvirus.
Definition
Enveloped
11-6
Term
Enveloped or naked: Herpesvirus.
Definition
Enveloped.
11-6
Term
Enveloped or naked: Iridovirus
Definition
Enveloped
11-6
Term
Enveloped or naked: Parvovirus.
Definition
Naked
11-6
Term
Enveloped or naked: Adenovirus.
Definition
Naked
11-6
Term
Enveloped or naked: Papovavirus.
Definition
Naked.
11-6
Term
What are the four classes of RNA viruses?
Definition
(+)ssRNA,(-)ssRNA, segmented (-)ssRNA, and segmented dsRNA. 11-7
Term
What are the 7 steps in the viral life cycle?
Definition

Initiation Phase: Attachment, penetration (entire nucleocapsid enters), uncoating

Replication Phase: gene expression, replication

Release Phase: assembly, and release. 11-8

These main events are common to all viruses, only details vary.

Term
What part of influenza virus binds to what part of host cell?
Definition
Hemagglutinin on influenza virus binds to sialic acid on host cell. 11-8
Term
What does the hemagglutinin on influenza virus bind to on the host?
Definition
Sialic acid.
11-8
Term
What is the requirement for a virus to fuse with the cell plasma membrane?
Definition
It must have an envelope. The envelope fuses with the plasma membrane and allows the nucleocapsid to enter the cell.
11-8
Term
T/F. Only unenveloped viruses enter the cell via receptor-mediated endocytosis.
Definition
F. Both enveloped and unenveloped can enter this way.
11-9
Term
What are the two ways that newly synthesized enveloped viruses can exit the cell?
Definition
Budding through the plasma membrane. Fusion of secretory vesicles containing the virions with the plasma membrane. 11-10
Term
T/F. All enveloped viruses gain their envelop from the plasma membrane of the host.
Definition
T.
Term
What is the only virus that uses host polymerase to replicate their DNA?
Definition
Parvovirus (the only ssDNA family). 11-10
Term
Where in the cell do most DNA viruses replicate their nucleic acid and assemble the nucleocapsid? What is the exception to this?
Definition
The nucleus. Poxviruses replicate in the cytoplasm. They encode all the machinery they need in their genome and do not need nuclear enzymes in the host. 11-10
Term
Where in the cell do most RNA viruses replicate and assemble? What is the exception?
Definition
In the cytoplasm. Influenza (Orthomyxoviridae) viruses are negative sense and make mRNAs in the nucleus. 11-10
Term
Which virus's replication is most error prone?
Definition

RNA viruses utilizing RNA-dependent RNA polymerases. (transcribing RNA to RNA)

11-10

Term
What two forms of viral replication violate the central dogma of biology?
Definition

RNA dependent RNA polymerase

RNA dependent DNA polymerase 11-11

Term
This is an important target for virus therapy (in general).
Definition
Viral polymerase.
11-12
Term
Large viruses like herpesvirus exhibit gene expression that is divided into three classes. What are they?
Definition

Immediate early (alpha), early (beta), and late (gamma)

alpha gene expression required for expression of beta and gamma genes.

beta genes make proteins for viral DNA rep.

gamma genes make proteins for structural proteins.

11-3

(so DNA replication occurs between early and late gene expression)

Term
(-)ssRNA virion particles must bring what with them into the cell in order to complete their infectious cycle?
Definition
RNA polymerase. It must be already present in the virus to turn (-)RNA into (+)RNA that can be transcribed.
11-15
Term
What three components (other than the genome) must be present in the virion of a retrovirus?
Definition
Reverse trancriptase, integrase, and protease. 11-17
Term
What is unique about the hepadnavirus genome?
Definition
Incompletely double stranded DNA. Uses reverse transcriptase for replication. 11-17
Term

Hantavirus is a member of the following family:

 

a. Togaviridae

b. Bunyaviridae

c. Filoviridae

d. Papovaviridae

Definition

b. Bunyaviridae

 

17-3, 11-7

Term
Are viruses motile or nonmotile?
Definition
nonmotile
Term
What are virus envelopes made of?
Definition
lipids (or at least they are lipid-containing). Also have proteins
Term
What is a capsid?
Definition
protein shell surrounding the viral nucleic acid
Term
Are nonenveloped or enveloped viruses easier to destroy?
Definition
enveloped viruses are easier to destroy
Term
WHat are the two types of symmetry exhibited by viral capsids?
Definition
helical and icosahedral
Term
What disase does Poxviridae cause?
Definition
smallpox
Term
What disease does Herpesviridae cause?
Definition
HSV1, HSV2, Epstein Barr Virus (EBV), CMV, VZV, KSHV
Term
What causes HPV?
Definition
Papovaviridae
Term
What's the mnemonic you use to remember the DNA viruses?
Definition
HHIP PA/ P
Term
What's the mnemonic used to remember the RNS viruses?
Definition

Please Call (ss+, nonenveloped)

TCR for (ss+, enveloped)

Friday's Rheal Performance Of BA/R (ss-enveloped/ds nonenveloped).

 

OBAR are all segmented.

Term
Which RNA viruses have segmented genomes?
Definition

Orthomyxoviridae (ss -,enveloped)

Bunyaviridae (ss-,enveloped)

Arenaviridae (ss -, enveloped)

Reoviridae (ds, nonenveloped)

Term
What causes rabies?
Definition
rhabdoviridae (ss -, enveloped RNA virus)
Term
What causes influenza?
Definition
Orthomyxoviridae (ss -, enveloped segmented RNA virus)
Term
What causes Ebola?
Definition
Filoviridae (ss -, enveloped RNA virus)
Term
What family does the Hantavirus belong to?
Definition
Bunyaviridae (ss -, enveloped RNA virus family)
Term
What family does Rotavirus belong to?
Definition
Reoviridae (ds, nonenveloped, segmented RNA viruses)
Term
What family do rhinoviruses belong to?
Definition
Picronaviridae (ss +, nonenveloped RNA viruses)
Term
What family do polio viruses belong to?
Definition
Picornoviridae (ss +, nonenveloped RNA viruses)
Term
What family do noroviruses belong to?
Definition
Caliciviridae (ss +, nonenveloped RNA viruses)
Term
What family of viruses cause SARS?
Definition
Coronaviridae (ss +, enveloped RNA viruses)
Term
What family of viruses cause West Nile and Dengue?
Definition
Flaviviridae (ss +, enveloped RNA viruses)
Term
What family of viruses cause HIV?
Definition
Retroviridae (ss +, enveloped RNA viruses)
Term
What family of viruses cause Hep A?
Definition
Picornaviridae (ss +, nonenveloped RNA viruses)
Term
How do nonenveloped viruses usually exit a host cell?
Definition
usually by lysis
Term
Describe polarity of + and - sense RNA strands.
Definition

+: 5'-3' polarity (is ready to be translated)

-: 3'-5' polarity (must be copied to + sense strand before translation)

Term
What viruses family causes Hep B?
Definition
Hepadnaviridae (ds, enveloped DNA virus)
Term
Describe replication strategy of Retroviruses.
Definition
Syl 11-16
Term
Describe replication strategy of Hepadnaviruses)
Definition
Syl 11-17
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