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162 Cards in this Set
- Front
- Back
What are the DNA viruses in the baltimore classification? |
dsDNA
ssDNA(+) gapped circular dsDNA |
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What are the RNA viruses in the baltimore classification?
|
dsRNA
ssRNA(+) ssRNA(-) ssRNA(+) reverse transcribing viruses |
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Where do most DNA viruses replicate inside the cells?
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nucleus
|
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Where do most RNA viruses replicate inside the cells?
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cytoplasm
|
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What are the steps in virus replication?
|
Virus attachment and entry
Genome replication Virus assembly Virus exit/maturation |
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What are some general cellular structures that viruses attach to?
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Glycoproteins
Carbohydrate residues |
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The type of cell within a host that a virus can infect is referred to as the virus ____________.
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tropism
|
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There are three ways that the virus can cross the outer cell membrane to infect a host cell. What are they?
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Translocation
Endocytosis Membrane fusion (I guess also injection in the case of bacteriophages) |
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The release of the viral nucleic acid from its protective coat is known as ______________.
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uncoating
|
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What are methods of uncoating discussed?
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Uncoating at plasma membrane
Uncoating within endosomes Uncoating at nuclear membrane |
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What part of the virus binds to the host receptor?
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protein capsid or glycoprotein on envelope
|
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Which parts of the virus need to be reproduced to produce the virion?
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genome and capsid
|
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What are some example dsDNA viruses?
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Polymaviridae, Adenoviridae, Herpesviridae, poxviridae
|
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What are some example ssDNA viruses?
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Circoviridae, parvoviridae
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What are some example viruses of the dsRNA genome?
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Reoviridae
|
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What are some example viruses of the ss (-) RNA genome?
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Orthomyxoviridae, paramyxoviridae, Rhabdoviridae
|
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What are some example viruses of the ss (+) RNA genome?
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Retroviridae (uses reverse transcriptase; DNA intermediate)
Coronaviridae, Flaviviridae, Picornaviridae (no DNA intermediate) |
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What are some example viruses of the gapped, circular, dsDNA genome?
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Hepadnaviridae
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T or F:
Viruses with an unsegmented genome tend to translate their proteins from a monocistronic mRNA. |
False!
This describes viruses with a segmented genome. |
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T or F:
Monocistronic describes the translation of a protein into one huge piece that is subsequently broken into smaller proteins. |
False!
This describes polycistronic. |
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What proteins are encoded by the viral genome?
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Structural proteins (gag)
Polymerase proteins (pol) |
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Which protein is critical for negative ssRNA virus replication?
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RNA dependent RNA polymerase
|
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Which protein is critical for positive ssRNA virus replication?
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RNA dependent DNA polymerase
|
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Which viruses assemble in the cytoplasm?
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Picornaviruses, Poxviruses, Reoviruses
|
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Which viruses assemble in the nucleus?
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Adenoviruses, Papovaviruses, Parvoviruses
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Which viruses assemble at the cell membrane?
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Retroviruses
|
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What are the building blocks of the capsid?
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protomers assembled into pentamers (these are the capsid subunits)
|
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What is the stage of the viral cycle when the viron becomes infectious?
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maturation and exit
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How do non-enveloped viruses escape the cell?
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lysis
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How do enveloped viruses escape the cell?
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uses budding to "steal" some of the cell membrane
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What enzyme breaks the viral bond to the cell membrane?
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neuraminidase
|
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What is the interval between viral attachment and the appearance of infectious viral particles?
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Latency
|
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What are Koch's postulates for viruses?
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1. agent must be present in every case of dz.
2. agent must be isolated from host and grown in vitro 3. dz reproduced when pure culture is inoculated into healthy animal 4. same agent must be recovered from infected animal 5. agent must pass through ceramic filter that would retain smallest bacteria |
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What is the range of sizes for viruses?
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20 to 300nm
|
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single-stranded RNA molecules
that lack genes required for their replication are known as... |
...virusoids
|
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An infectious protein is a(n)...
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...prion
|
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What components comprise the virion?
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genome
capsid +/- envelope |
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What is the basic capsid structure of a virus?
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icosahedron
|
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How are viruses classified today?
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Host
Morphology Genome Replication |
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A group of species sharing common characteristics is a(n)...
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genus
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A group of genera sharing close phylogenetic relationship is a(n)...
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family
|
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What are the best type of cells for virus isolation?
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Primary cell cultures
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A cell culture that can exist indefinitely is a(n) ___________________.
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cell line
|
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T or F:
Both primary and secondary cell cultures are explanted from a donor organism. |
True
|
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T or F:
Due to their immortality, cell lines are considered cancer or tumor cells. |
False!
Some are cancer or tumor cells but not all. |
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What are the types of viral infections possible in a host?
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Acute (<2wks)
Persistent Latent |
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What effects on the cell can viral infection incur?
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No effect
Cytopathology Malignant transformation Cell death |
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T or F:
Cytopathic effects cannot be viewed via light microscopy. |
False! They CAN be viewed with light microscopy
|
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What are the cytopathic effects?
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Altered shape
Detachment from substrate Lysis Membrane fusion Syncytia Inclusion body Apoptosis Altered membrane permeability Cytoskeleton change |
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Which viruses cause the CPE syncytia?
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(i) Lentivirus
(ii) Paramyxoviruses (iii) Morbilliviruses (iv) Pneumoviruses (v) Some herpesvirus |
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Where and/or how can some inclusion bodies be found?
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Cytoplasmic/nuclear
single/multiple large/small round/irregular basophilic/acidophilic |
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What are some viruses that cause inclusion body CPEs?
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(i) Poxvirus
(ii) Reovirus (iii) Paramyxoviruses (iv) Rabies virus (v) Herpesvirus (vi) Adenovirus (vii) Parvovirus |
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What are some viruses that cause apopotsis CPEs?
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(a) Adenoviruses
(b) Alphaviruses (c) Chicken anemia virus (d) FIV (e) Herpesvirus |
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What are some viruses that can cause cytoskeletal change CPEs?
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(i) Canine distemper virus
(ii) Vesicular stomatitis viruse (iii) Vaccinia virus (iv) Herpesvirus (v) Enterovirus |
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What are some mechanisms of viral damage to the host cell?
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1) Inhibition of host cell nucleic acid synthesis (DNA and RNA)
2) RNA transcription inhibition. 3) inhibit mRNA processing 4) inhibit protein translation 5) cytopathic effects of viral toxins |
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The incorporation of viral glycoprotein peplomers into the plasma membrane of infected cells where they serve as ligands for RBCs is called...
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...hemadsorption
|
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What are some viruses that exhibit hemadsorption?
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(a) Orthomyxovirus
(b) Paramyxovirus (c) Togavirus (d) calicivirus |
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T or F:
Noncytocidal viruses rarely cause cell death. |
duh...true
|
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What are some examples of virus-induced noncytocidal change?
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behavior change
delayed growth hyperglycemia |
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T or F:
The vast majority of virus infections are sub-clinical, i.e. asymptomatic! |
True
|
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Which viruses have a selective tropism for the skin?
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Papillomaviruses
|
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What are routes of viral infection?
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Skin
Eyes Respiratory mucosa GI (including mouth) Urogenital tract |
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Which viruses commonly enter through the GI tract? Why/how can they do this?
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Enteroviruses
Acid resistant |
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T or F:
Hepatitis A and B both function epidemiologically as an enterovirus. |
False! This describes A not B.
|
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What are some viruses that commonly use the urogenital tract as a port of entry?
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(b) Papillomaviruses
(c) HSV (d) Hepatitis (e) HIV |
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Which viruses use the eye as a common port of entry?
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Adenovirus: “swimming pool conjunctivitis” and “shipyard eye”
Enterovirus: coxsackievirus A24 and enterovirus type 70 Vaccinia and HSV |
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Which viral group is transmitted by an insect vector?
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Arbovirus
|
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Which virus is only transmitted via the bite of a host?
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Rabies virus
|
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How does local virus spread occur?
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cell to cell
|
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Viruses that are released on the apical edge of the cell spread __________ while viruses released on the basal edge spread __________.
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locally; systemically
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Viruses that are released on the _________ edge of the cell spread locally while viruses released on the _________ edge spread systemically.
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apical; basal
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How does systemic virus spread occur?
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afferent lymph drainage to regional lymph nodes then to lymph ducts
via bloodstream via nervous system |
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What are some viruses that spread neurally?
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Polio (piconaviridae)
rabies (rhabdoviridae) bovine herpesvirus 1 and 2 |
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Viruses circulating in the blood plasma or associated with formed blood elements is known as _______.
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viremia
|
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What are the three types of viremia (maybe stages of viremia)?
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Active
Primary Secondary |
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The type of viremia that is not associated with any formed blood elements is __________ viremia.
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plasma
|
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If the virus is within circulating blood cells, it is called _______________ viremia.
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cell-associated
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Where can virus enter the circulation?
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efferent lymphatics
vascular endothelium peripheral monocytic cells |
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Release of the virus by the host into the environment is known as ____________.
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shedding
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What are some viruses shed by oral secretion?
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BHV-1, paramyxo-, corona-, and bovine respiratory syncytial virus
|
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What are some viruses shed via the skin?
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Cowpox, vaccinia, orf, pseudocowpox, molluscum contagiosum viruse, papillomaviruses, herpesvirus, Mareck's dz virus
|
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What are some viruses shed form the urinary tract?
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Rinderpest virus, Flu viruses, Picornaviruses, hepatitiss virus, FMDV, arenaviruses,
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What are some viruses shed via the genital tract?
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(a) Equine arteritis
(b) Herpesvirus (c) Papillomavirus |
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What does “infectious” mean?
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Ability to transmit disease to other organisms
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Why is a virus infectious?
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transmissible
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Which viruses are shed via milk?
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(a) Caprine arthritis-encephalitis virus
(b) Mouse mammary tumor virus (c) Tick-borne flaviviruses |
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Which viruses are shed via blood?
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(a) Equine infectious anemia virus
(b) Bovine leukemia virus |
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Which organs are responsible for viral clearance?
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Liver, lung, spleen, and lymph nodes
|
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What is the role of DNA-dependent RNA polymerase (DRP) in the eukaryotic cell?
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- Transcribes RNA from DNA template
in eukaryotic cells, DRPI direct synthesis of ribosomal RNAs, mRNA, and tRNAs |
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What is the term for the measure of the pathogenicity of the infecting virus?
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Virulence
|
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What does LD50 measure?
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Dose of virus required to cause death in 50% of individuals
|
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What does ID50 measure?
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dose of virus required to cause infection in 50% of individuals
|
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What does TCID50 measure?
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infectious dose that causes cytopathic effect in 50% of individuals
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T or F:
The humoral and cell mediated immune response both kill virus infected cells. |
False.
Only the cell-mediated pathway kills intercellularly. |
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What is bad about a non-neutralizing antibody in viral infection?
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Non-neutralizing antibody only opsonizes the virus but does not inactivate it; allows for viral spread via phagocytes
|
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Are virus-infected cells killed via the CD4/MHCII path or the CD8/MHC1 path?
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CD8/MHC1
|
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What are the 8 types of viral vaccine?
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Live whole virus vaccines
Killed whole virus vaccines Subunit vaccines Recombinant virus vaccines Synthetic peptides Anti-idiotype antibodies DNA vaccines Peptide vaccine |
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When should puppies be vaccinated against rabies?
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@ 16 weeks
|
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When should kittens be vaccinated against rabies?
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12 weeks
|
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When should foals/livestock be vaccinated?
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no earlier than 3-4mos then 4 week intervals
|
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T or F:
Live vaccines should always be used for intraoral or intranasal vaccines. |
True!
|
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Why should you not give a "booster" for a mucosal vaccine?
|
Secondary immune responses are difficult to elicit.
High IgA levels prevent antigen absorption. |
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Which virus typically does the most damage: RNA or DNA virus?
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DNA virus (herpes and pox)
|
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What are the basic evasion mechanisms of viruses?
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Passive (innocuous)
Active (produce proteins that affect immune system) Aggressive (directly target immune system) |
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What are some passive evasion mechanisms of viruses?
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Evasion by noncytocidal infxn
evasion by cell-to-cell spread (masks from immune system) evasion via infxn of nonpermissive cells Restricted viral gene expression |
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What are some active viral evasion mechanisms?
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Evasion of neutralizing Ab (immune decoys)
Interfere w/antigen processing Complement evasion Inhibit interferons |
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What are some aggressive viral evasion mechanisms?
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Immunosuppression by targeting leukocytes
Use virokines |
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A viral product that suppresses or inhibits cytokines is a(n) ___________.
|
virokine
|
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What is the common feature for a virus family?
A. Same host B. Same genome type C. Same morphology D. Same replication strategy E. ABC F. BCD |
F. BCD
|
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What is the suffix for a virus family?
A. Virale B. Viridae C. Virinae D. Virus |
B. Viridae
|
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What is the suffix for a virus subfamily
A. Virale B. Virdae C. Virinae D. Virus |
C. Virinae
|
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How does virus get into cells?
A. Special passport B. Poke a hole C. Endocytosis D. Translocation, fusion E. A, C F. C, D |
F. C, D
|
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What are the essential component that –ssRNA virions must carry before infecting a cell?
A. Passport B. RNA genome C. RNA dependent RNA poly D. B and C E. Envelope |
D. B and C
|
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Name some factors that influence viral susceptibility...
|
1) Genetic constitution
2) Immune response (Overreaction of immune response usually) 3) Cell differentiation 4) Cellular receptor 5) Age 6) Hormonal factors 7) Fever 8) Multiple infection |
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Is the virus stable at room temperature?
|
nope
|
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Is virus stable at pH extremes?
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not generally (I guess enterovirus is)
|
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How much sample is needed for virus diagnosis?
|
~5mL (1-2mL)
|
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What are the methods of virus DETECTION?
|
via electron microscopy
virus isolation in cultured cells virus isolation in animals/chick embryos |
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What are some methods of direct detection and identification of viral nucleic acids?
|
Hybridization (in situ, southern, dot-blots)
PCR (RT, real time, and semi quant) |
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What are some diagnostic methods for identifying a virus?
|
1) Detection and ID of viral antigens
2) Direct detection and ID of viral nucleic acids 3) Virus isolation and identification 4) Detection and quantification of antiviral antibodies |
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What are some tools available for detecting viral antigens?
|
Elisa
Fluorescence antigen microscopy IHC and immunofluorescence immunoelectron microscopy agglutination immunodiffusion |
|
Serology detects the presence of the (choose one) antigen or antibody.
|
Antibody!
|
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What did you see in cells infected w/BAV?
A. Enlarged nuc and nuc inclusion body B. Cell lysis C. Irregular cell morphology D. All of the above |
D. All of the above
|
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What did you see in cells infected w/BVDV
A. Inclusion body in the nuc B. Enlarged nuc C. Inclusion body in the cytoplasm D. Membrane fusion |
C. Inclusion body in the cytoplasm
|
|
How do you isolate viruses from tissue collected from infected animal?
|
Grind tissue
Freeze/thaw Centrifuge; virus will be in supernatant Put on cell line and culture! |
|
How big are circoviruses? What is their capsid morphology?
|
17-22nm
Icosahedral |
|
Describe the genome of circoviruses?
|
Circular, ssDNA genome
ORF1, ORF2, ORF3 – only 3 proteins |
|
PMWS (Porcine Multisystemic Wasting Syndrome) is caused by which virus?
|
Circovirus (Porcine Cicrcovirus type 2)
|
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Which virus causes beak and feather disease?
|
Circovirus
|
|
What is the general pathology of a circovirus infection?
|
young animals
Hemorrhage (subcut and muscle) Pale viscera Fatty bone marrow Thymic atrophy |
|
What happens when RBCs are replaced by fat cells in bone marrow? Which virus is characterized by this pathology?
|
Anemia; circovirus
|
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How does circovirus infection cause immunosuppression?
|
monocyte/macrophage destruction
|
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What is the 2nd smallest DNA virus?
|
Parvovirus
|
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What did you see in cells infected w/BVDV
A. Inclusion body in the nuc B. Enlarged nuc C. Inclusion body in the cytoplasm D. Membrane fusion |
C. Inclusion body in the cytoplasm
|
|
How do you isolate viruses from tissue collected from infected animal?
|
Grind tissue
Freeze/thaw Centrifuge; virus will be in supernatant Put on cell line and culture! |
|
How big are circoviruses? What is their capsid morphology?
|
17-22nm
Icosahedral |
|
Describe the genome of circoviruses?
|
Circular, ssDNA genome
ORF1, ORF2, ORF3 – only 3 proteins |
|
PMWS (Porcine Multisystemic Wasting Syndrome) is caused by which virus?
|
Circovirus (Porcine Cicrcovirus type 2)
|
|
Which virus causes beak and feather disease?
|
Circovirus
|
|
What is the general pathology of a circovirus infection?
|
young animals
Hemorrhage (subcut and muscle) Pale viscera Fatty bone marrow Thymic atrophy |
|
What happens when RBCs are replaced by fat cells in bone marrow? Which virus is characterized by this pathology?
|
Anemia; circovirus
|
|
How does circovirus infection cause immunosuppression?
|
monocyte/macrophage destruction
|
|
What is the 2nd smallest DNA virus?
|
Parvovirus (18-26nm)
|
|
Which of the following is untrue regarding parvoviridae?
A. nonenveloped B. icosohedral C. 3 capsid proteins 4. pH resistant 5. sensitive to temperature extremes |
5. sensitive to temperature extremes
|
|
Describe the genome of parvoviridae.
|
i. Linear, non-seg
ii. 5.2kb ssDNA iii. Palindromic ends |
|
T or F:
FPV (Feline Panleukopenia) is a type of parvovirus. |
True
|
|
Describe the genome of adenoviridae.
|
30-42kb
Linear, ds DNA |
|
What is major capsid protein for parvo?
|
BP2
|
|
Can parvo infect many different tissues in fetus and neonate?
|
yup
|
|
Why do we see cerebellar hypoplasia in newborn (with parvovirus infection)?
|
growing cerebellar cells
|
|
Why does parvovirus infection manifest in diarrhea?
|
kills growing crypt cells
|
|
What are the two main classes of antiviral drugs?
|
Small molecules
Biologicals |
|
What are the subcategories of biological antiviral drugs?
|
Antibodies
Peptides siRNA interferons |
|
Which mechanisms are targeted for antiviral activity? Which is specific to retroviruses?
|
Binding and entry inhibition
Integration inhibitors (retrovirus) Replication inhibitors Egress inhibitors Protease inhibitors |
|
What is the major mechanism of replication inhibition?
|
chain termination during replication
|
|
What are two mechanisms that viral entry inhibitors may use?
|
mimics receptor of virus
mimics host target protein |
|
What type of cell line was used in lab to observe CPE?
|
immortalized rabbit kidney cells (RK-13B)
|
|
T or F:
The virus titer is the approximate number of pathogenic viral particles per mL of serum. |
True!
|
|
What type of CPEs were observed on the BVDV?
|
inclusion bodies in cytoplasm
|
|
What type of CPEs were observed on ERV-1?
|
inclusion bodies in cytoplasm and altered cell morphology
|
|
What type of CPEs were observed in BHV-1 (IBR)?
|
fusion
|
|
What type of CPEs were observed on BAV?
|
intranuclear occlusions; apoptotic bodies
|