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110 Cards in this Set
- Front
- Back
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What is an acute infection?
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rapid production of infectious virus followed by rapid resolution and clearing
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What type of infection is frequently associated with epidemics and common public health problems?
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acute infections
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What does prodromal mean? What is it in measles?
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Beginning of minor symptoms.
Koplik spots. |
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What is a persistent infection?
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infected cells are not effectively cleared by the adaptive immune response and viral gene products continue to be produced for long periods
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What are the 2 types of persistent infections?
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Chronic (infection is eventually cleared) and Latent (infection last the host's lifetime)
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How do you get shingles?
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VZV (chicken pox) infects sensory ganglia and becomes latent
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what are transforming infections?
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a special class of persistant infection where infected cells may exhibit altered growth properties and begin to proliferate faster than uninfected cells
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What's the difference between an invitro mutagen and an in vivo mutagen?
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In vitro will work on DNA at any time in the cell cycle, in vivo will only work while DNA is replicating
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Is mutation rate higher in DNA or RNA?
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RNA because the replicase is not as accurate and their is no proofreading
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What is a wild type mutant?
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an arbitrary determination of the 'original' strain from which all others are considered mutants
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What is a field isolate?
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a strain from one area
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What is a strain?
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a different wild type of the same virus
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What is a type/serotype?
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determined by how the virus interacts with antibodies
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What is a variant?
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a strain different from the wild type for unknown reasons
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What is a mutant?
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a strain that differs from the wild type in a heiritable way
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What is an induced mutation?
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one induced by a mutagen
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What is a plaque morphology mutation?
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mutation results in charge differences of dif. viral replication rate, which causes larger or smaller plaques
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What tool allowed for the yellow fever vaccine?
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plaque morphology
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What is a temperature sensitive mutant?
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one that can only replicate at permissive temperatures, but not at non-permissive (high) temps
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What is a cold-sensitive mutant?
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same as temperature sensitive only a lower temperature is the nonpermissive temperature
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How can one induce deletions?
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growing your virus at a high multiplicity of infection (MOI)
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What is complementation?
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interaction of viral gene products (NOT of the genomes themselves)
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What happens during complementation?
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2 mutant viruses that could not normally replicate can infect the same cell and share gene products resulting in replication and products that are just like the parents
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How can you divide mutations into groups?
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complementation groups
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What is recombination? What are the 2 ways it happens?
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physical interaction of viral genomes. intramolecular recombination and reassortment.
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Which type of recombination occurs when the virus is a simgle piece of nucleic acid? segmented?
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single piece-intramolecular recombination
segmented-reassortment |
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What is intramolecular recombination?
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physically breaking the genome, exchanging information, and reformation. ex.plasmids
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What is reassortment?
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dual infection of a cell and progeny viruses with independently assorted genome segments
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What is the basis for the flu vaccine?
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reassortment (HA and NA from a virulent strain and all other gene segments from an attenuated strain)
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What is genetic reactivation/marker rescue?
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a mutant strain is coinfected with a marked normal gene fragment and the wild type is gotten back. a type of intramolecular recombination
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What is heterozygosity?
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2 copies of genetic information end up in one cell (aberrant packaging)
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What is pleiotropism?
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when a single viral gene has effects on several virus properties
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Why is pleiotropism so important?
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because it allows one to select for an attenuated stain by finding a correlation between virulance and some factor
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What are integrated defective viral genomes the result of?
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virus inserting itself into the host genome
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What are two types of integrated defective viral genomes?
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lysogenic viruses and RNA tumor viruses
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How can lysogenic viruses get host DNA?
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prophage gets some while exiting the genome when it goes into the lytic phase
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How can RNA tumor viruses get host DNA?
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cellular oncogenes get into the viral genome and replace a normal viral gene
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What is a satellite virus?
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a virus with a defective replication unless a helper virus is present
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Do satellite virsus and helper viruses show homology?
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No
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What are psuedovirions?
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A capsid that has no viral genome (either empty or has host genome)
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What is a conditionally defective viral genome?
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only defective under certain conditions (temp, host range, etc.)
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What are defective interfering (DI) particles?
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subgenomic deletion mutants that are missing part of their parental genome, and thus rely on helper viruses to replicate
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Do DI particles and helper viruses show homology?
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Yes, helper virus is the wild type genome of the DI
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What is a common contaminant when working in the lab at a high MOI?
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DI particles
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How can one determine if contaminating DI particles are in a virus pool?
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rate zonal centrifugation and all the tubes have nonrandom alternate bands
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How can you tell if there are DI particles in an assay?
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ragged colonies among dying colonies
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What is the biological role of DI particles?
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lowers lethality of virus in an infected host
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What two things do you need for transfection?
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VLP and plasmid
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What is the only disease to be irradicated worldwide?
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smallpox
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What disease got worse with better sanitation?
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polio
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What immune response do booster vaccines stimulate?
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IgG
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What are interference and secondary spread? (disadvantages with live virus vaccines)
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interfence: cant get the vaccine if you are already sick
secondary spread: ex. smallpox vaccine causes a pustule at vax site that is infectious |
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What are some disadvantages to inactivated virus vaccines?
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no local immunity, boosters needed, potentiation of disease from unbalances immune response
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What are subunit vaccines?
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purified components of a vaccine
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What is a live vector?
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merging a subunit vaccine with a live virus vaccine
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What is a psuedovirion?
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a capsid without nucleic acid
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What are adjuvants?
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immunostimulatory substances added to vaccines
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How are vaccines used as immunotherapy?
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provide immune molecules above the normal amount
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What do some people believe causes autism?
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thimerosal
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What are the 4 adverse event classifications?
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vaccine induced, vaccine potentiated, programmatic error, and cioncidental
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Why must antivirals be very potent?
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otherwise viral mutants will form
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What is bioavailability?
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will the antiviral get to the right place in the body at the right concentration
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What is pharmokinetics?
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will the antiviral persist in the body long enough to be effective
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What do you want to find early in the vaccine making process?
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proof of principle
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What do antivirals target?
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things that are different between host and virus
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What is a parallel track?
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people who do not qualify to be in the clinical trials are allowed to take the unapproved drug
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What types of RNA require viral transcriptase (polymerase) for replication?
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negative sense and ds
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What is VPg?
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viral protein genome, small protein attached to 5' end as a primer used in RNA synthesis
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What protein in picornaviridae is responsible for host range?
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VP1
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What will specific viruses interfere with the attachment of?
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the same type of virus
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Why is picornaviridae translation inefficient?
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because it has only one ORF so it makes the same amount of every protein in its genome
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What are altered particles?
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when VP4 is lost after penetration/uncoating
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How does the viral RNA get released from the capsid inside the host cell?
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a conformational change loosens the capsid (results in empty shells or altered particles)
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What are the 3 possible fates of positive sense RNA?
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1) act as mRNA
2) template for more negative RNA 3) genome for new virion |
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How does the viral capsid 'clamp down' during assemby of picornaviridae?
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VP0 is cleaved
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Where does RNA synthesis occur during picornavirus infection?
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cytoplasm, normal nucleus synthesis is shut down
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How can picornaviridae stop host RNA synthesis?
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cleavage of eIF4G, an initiation factor for capped mRNA
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Are all the hepatitis's related?
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no, they are just all liver inflammations
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What disease will shut down resturants?
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Hep A
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What disease will shut down cruise ships?
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Norwalk virus
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How do you usually get Hep E?
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contaminated water
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What are the 2 genera of Togaviridae?
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alphavirus and rubivirus
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Why might Togaviridae have such a wide host range?
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either use a recepter ubiquitously expressed or use many different receptors
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What glycoprotein in Togaviridae is responsible for host binding?
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E2
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How do conformationally-altered virions rate in infectivity?
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more infectious
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How do togaviridae get into the host cell?
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receptor mediated endocytosis (viropexis)
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What is the strategy of Togavirus replication?
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make 2 transcripts; a full one for genome and shorter one for structural proteins
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Where do Togaviridae assemble and bud in vertebrate cells? Insects?
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Vertebrate: plasma membrane
Insects: Internal vesicles |
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In vertebrate cells what are persistane infetions associated with?
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mutations in nsP2
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What are alphavirus antigenic groups based on?
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sequence similarity of E1 proteins and serology
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Which of the Togaviridae are encephalitic diseases?
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New World Alphaviruses
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What are the three viral structural proteins of flaviviridae?
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envelope, membrane, and capsid
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What binds host cell receptor in Flaviviridae?
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E protein
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By what method can some Flaviviruses bind and enter cells?
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antibody-dependent enhancement
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How do Flaviviridae get into a host cell?
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receptor-mediated endocytosis
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How is replication of Flaviviridae?
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semiconservative and asymmetric
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Where does replication of Flavivirus occur?
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cytoplasm (along ER)
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How do Flaviviruses get their envelope?
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budding in the ER lumen
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What happens immedietly before Flavivirus release?
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cleavage of prM into M mediated by furin
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What genus is mostly arboviruses?
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flavivirus
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What are the 2 cycles of yellow fever?
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urban and sylvan
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How can Hep C be transfered?
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blood
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What do you give people for postexposure management to Hep C?
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IgG, not antivirals
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What is the function of E1, E2, and E3 in coronaviridae?
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E1: matrix protein, for budding
E2: antireceptor E3: hemagglutanin |
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Where does coronavirus bud?
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internal membranes
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What is the first step of + sense RNA replication?
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synthesize RNA dependent RNA polymerase
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What type of subgenomic RNA does coronaviridae have?
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nested
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What do all of the subgenomic RNA peices of coronaviridae have in common?
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polyA tail and leader sequence
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What allows for coronaviridae to have different concentrations of different genes?
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TRS (transcription regulatory sequence)
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What is the main disease in coronaviridae?
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SARS
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