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94 Cards in this Set
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3 assays for virus titration:
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1. plaque assay
2. pock assay (infect embr.egg) 3. transformation assay |
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What is TCID-50?
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inf. dose to infect 50% tissue culture cells
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How are viruses able to inhibit recognition by CMI response? (Name 4 ways)
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1. lack MHC class I antigen so infected cell cannot present (e.g. herpes)
2. induction of mutation - virus change surface (T cell epitope) to avoid detection 3. inhibition of MHC function 4. downreg. of viral protein expression |
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At what age does neonate have highest level of maternal antibody (passive immunity)?
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First couple weeks; then begins to wane
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When is neonate most susceptible to viral infection?
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8-10 weeks; vaccination begins @~12 wks. of age
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What is +ssRNA virus? What type of polymerase might it have?
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Virus that uses single stranded RNA to manuf. RNA or DNA with help of either RNA dependant RNA polymerase or RNA dependant DNA polyermase
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All viruses with this capsid symmetry are enveloped; identify:
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All helical viruses which infect animals are enveloped!
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Generally DNA viruses replicate in ___? Exceptions? (2)
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DNA viruses replicate in NUCLEUS except poxviruses and asfarviruses!
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Which is characteristic of paramyxo/ orthomyxoviruses?
A. RNA dependent RNA polymerase B. DNA dep. RNA polym. C. RNA dep. DNA polym. D. mRNA dep. protein synth. |
A. RNA dependent RNA polymerase
~paramyxov. (CDV)/ orthomyxov. (influ.) have neg. sense RNA fyi: ortho- does its thing in nucleus |
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Which two virus families replicate via reverse transcriptase?
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Retroviridae
Hepadnaviridae |
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What three methods are used for virus cultivation?
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Animal inoculation
Inoculation into embryonated eggs Cell culture |
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What are the different types of cell culture? (3)
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Primary cell culture (high culture medium req.) e.g. kidney cells
Finite or diploid cell lines Continuous cell lines (e.g HeLa cells) |
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What are some methods used for virus titration? (4)
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Plaque assay
Pock assay Transformation assay Quantal assays (TCID50, ID50, LD50) |
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Which of following is NOT method used to detect viral antigens? ELISA, Dot-blot hybridiz., RIA, IFA, Immunoperox. staining, RIP, Western blot, and In-situ hybrid.
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Dot-blot hybridiz. & In-situ hybrid. (both are detecting viral nucleic acid..as anything w/word hybridization in it!)
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What is (RIA)? What is it used for?
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Radioimmunoassay - to detect viral antigen; using labeled anti-viral antibody
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What are these used for?
Dot-blot hybridization In-situ hybridization Southern blot, Northern blot, PCR, sequencing |
Identify, diagnose, or detect virus via it's nucleic acids
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How would you characterize these assays? What are they used for?
Hemagglutination and hemagglutination inhibition Hemadsorption and hemadsorption inhibition Complement fixation |
immunological assays used for virus identification
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what is hemagglutination inhibition?
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inhib. of hemaggl. with Ab specific virus protein; so when Ab present..virus not able to bind RBC's and RBC do not agglutinate
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How are 'quasispecies' of viruses made?
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Errors in replication
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What substances can induce virus mutations? (5)
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Nitrous acid
Hydroxylamine Nitrosoguanidine 5-bromodeoxyuridine Ultraviolet light |
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What are some different types of mutations? (5)
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Plaque morphology mutations
Host range mutations Temperature-sensitive mutations Deletion mutations Point mutations |
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What are some different genetic interactions between viruses?
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Complementation
Recombination (breakage-reunion mechanism, copy-choice mechanism, reassortment) |
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Do viral envelopes contain host cell or viral glycoproteins?
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can have both!
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5 steps in viral replication (invasion of host cell)
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1. attachment
2. penetration 3. uncoating 4. synth of viral components 5. assembly 6. release |
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4 ways viruses penetrate host cell?
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1. translocation (magic!)
2. endocytosis 3. fusion 4. injection (e.g. bacteriophage) |
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3 ways virus releases from host?
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1. lysis of host cell
2. virus budding (taking some of host viral protein/membrane along with it) 3. cell to cell spread |
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early genes
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viral genes that help in viral replication
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late genes
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viral genes that help in assembly of virus (structural, etc)
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Which are more resistant to external environment: enveloped OR nonenveloped?
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non-enveloped
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term refers to disease producing capability of virus compared to other closely related viruses
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virulence
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term for capab. of viruses to infect and repl. in certain tissues or cells
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tropism
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orthomyxoviruses (influenza) are -ssRNA which replicate in nucleus of host cell, describe replication etc:
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In the nucleus of infected cells, the viral (-)RNAs are transcribed into (+)mRNAs (viral transcriptase) and then this new +RNA is replicated by viral RNA–dependent RNA polymerase complex.
note: viral +RNA is used for trx and replication |
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____ results in 1 or more point mutation in viral genome leading to change in virus antigenicity over time
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antigenic drift is slow change in small number of nucleotides; over time
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____ results from sudden reassortment of viral RNA genome
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antigenic SHIFT is major change
Shift = Sudden |
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antigenic shift is more of a problem is what type of viruses?
Example? |
antigenic shift is more problem in segmented virus
e.g. influenza, bird flu..shift can allow to expand host range |
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protease inhibitors are ?
example of virus might be effective against? |
new class of antiviral compounds that inhibit retroviral replication by inhibiting post-translational processing
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why does eclipse phase have 2 parts: replication and transcription?
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Virion basically is 2 parts:
1. viral NA - made via replication (and NS proteins) 2. structural proteins - made via trx!!! note: this is oversimplification but u get the idea |
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What is one way Herpes virus inhibit recogn. by T-cell mediated IR?
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downreg. of viral protein expr. (e.g.herpesviruses, HIV)
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4 Ways virus inhibit recogn. by T-cell mediated IR?
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1. inf. of cell lacking MHC I Ag (neuron) 2.inhib.of MHC function 3. downreg. of viral protein expr.
4. induc. mut.in viral T-cell epitopes |
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T or F: Some viruses able to destroy APC's; if so, provide example.
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True: HIV destroys CD4+ cells (APC)
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What kind of viruses have high rate of spontaneous mutation?
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RNA viruses; RNA dep. RNA polym. does NOT have proofreading ability; so mutations can happen in abs. of mutagen
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2 types of genetic interaction btw. viruses? (have inf. same cell)
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Complementation= incr. eachother's yield w/o exchanging material
Recombination |
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3 types of recombination (1 of examples of genetic interaction btw. viruses)
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Recombination
1. breakage-reunion mechanism 2. copy-choice mechanism 3. reassortment |
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The period from the entry of the virus to the production of the first infectious virus progeny is called as
a. eclipse period b. incubation period c. stationary period d. exponential period e. death period |
A. The eclipse period starts with adsorption and ends with the appearance of the progeny phage in the host cell cytoplasm.
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What are some molecular determinants of viral virulence? (3)
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Envelope glycoproteins and capsid proteins
Viral polymerase and other proteins Noncoding regions of viral genome |
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4 ways viruses evade immune response:
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1. immunosuppression
2. immunotolerance (infect fetus - recognized as self) 3. destruction (inf.) of APC 4. inhibit of recogn. by CMI response |
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Generally RNA viruses replicate in ___? Exceptions? (3)
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RNA -> repl. in CYTOPLASM; except retroviruses, orthomyxoviruses, and reoviruses
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How are host cells generally damaged by viruses? (3)
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*Accumulation of viral structural components
*Form.of virion aggregates within the cell *Shutdown of cellular protein synthesis |
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What are some methods used for virus isolation and identification (looking at it)? (4)
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Light microscopy
Films and smears Biopsy or autopsy Electron microscopy |
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Waht are some non-genetic interactions between viruses? (3)
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Heterozygosis
Interference Phenotypic mixing |
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phases of virus repro. cycle? (4)
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1. eclipse phase (attachment - synthesis) but assembly not complete
2. maturation phase - assembly complete 3. released - get out of cell 4. inactivation - or loss of virus infectivity |
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What difference btw. Hemaggl. inhib. & hemadsorption inhib.?
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w/hemadsorption, cells are used which express viral protein..rbc's adhere to them
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syncytial mutants of viruses like herpes virus, cause ?
this is example of ? |
syncytial mutants of viruses like herpes virus, cause neighboring cells to fuse rather than undergo typical cytolytic changes; example of plaque morphology changes
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T or F: Reassortment in viruses w/segm.genomes has been known to be resp. for periodic pandemics of influenza virus inf.
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True
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Which form of viral interaction occurs when components of replic. apparatus yield increasing prop. of defective or interfering virus (ex: influenza virus) refers to?
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Interference (one of non-genetic Interaction Between Viruses
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What are some limitations of using serology to detect a viral infection?
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*Detects exposure not when exposure occurred
*Paired sera (huh?) *IgM only produced early in infection *CSF (can't do serology on CSF and some viruses are found here?) |
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Chemother. agents inhibit sp. pathways of viral rep; which of following drugs specifically inhibits retroviral rev. trx?
A. Amantadine B. Rimantadine C. Acyclovir D. AZT (Zidovudine) E Ganciclovir |
D. (AZT) - specifically inhibits retroviral rev. trx
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What are some mechanisms of viral virulence? (6)
What can viruses modulate to cause disease in host? |
1. Modulation of host IR
2. Modulation of growth factors and cytokines 3. Modulation of apoptosis 4. Disruption of intracellular Ca homeostasis 5. Prod. of reactive oxygen and nitrogen intermediates 6. Modulation of intracellular deoxynucleoside triph. pool |
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What are some ways that viral infections can persist for a long time? (3)
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1, Ability to infect host cells w/o being cytopathic
2. Integration into host chr. 3. Inhibition of detection and elim. by host IR |
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What factors can reactivate herpesvirus infection? (5)
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1. Immunosupression
2. Stress 3.Hormonal changes 4. Nerve damage 5.UV exposure |
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What are some possible targets for antiviral action in the HIV replication cycle? (5)
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1.Binding 2. Rev. Transcriptase Integration
3. Viral Gene Expression 4.Post-trx processing and assembly 5.Budding or release |
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BONUS: Which of the following statements is true?
a. all the mutations in the viral genome results in an amino acid change. b. eclipse period is same for all viruses c. assembly and maturation events are often inseparable d. mhc class 2 pathway presents antigens to cd8+ t cells e. herpes viruses are generally non enveloped viruses. |
C. assembly and maturation events are often inseparable
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What are some novel approaches to vaccine development? (4 new vaccine types)
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Subunit vaccines (peptides)
Gene deleted vaccines DNA vaccines Virus vectored vaccines |
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What are some different strategies used to develop live wild-type virus vaccines?
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Unnatural route
Unnatural host Unnatural time of year |
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What are some different strategies used to develop live attenuated virus vaccines? (6)
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Naturally occurring variant
Gene reassortment Heat mutated Site-directed mutagenesis Adaptation to natural host (animal passage and cell culture passage) Using vectors |
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What are some different strategies used to develop Inactivated whole virus vaccines? (2)
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Cell culture
Animal tissue |
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What are some different strategies used to develop inactivated virus subunit vaccines? (2)
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Naturally occurring subunits
Detergent-split virus |
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What are some different strategies used to develop inactivated virus peptide vaccines? (1)
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In vitro chemical synthesis
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What type of vaccine created this way?
Recombinant DNA expression in bacteria Recombinant DNA expression in yeast Recombinant DNA expression in mammalian cells Recombinant DNA expression in cell culture or insect cells Recombinant DNA expression in heterologous virus |
some different strategies used to develop inactivated virus protein vaccines? (5)
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What term refers to the fact that protection is conferred on the unvaccinated in a population when a certain threshold number of individuals is vaccinated?
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Herd Immunity
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What is the study of the determinants, dynamics and distribution of disease in populations?
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Epidemiology
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What is the term for a virus that is infecting people worldwide?
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Pandemic (Panzootic)
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What is the measure of disease frequency in a population over a specific period of time?
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Incidence rate (not to be confused w/prevalence rate)
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What are some different types of studies done to investigate causation of an epidemic? (3)
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Cross-section study
Case-control study Cohort study |
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What are all the different modes a virus can be transmitted?
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Horizontal
Direct contact Indirect contact Common vehicle Airborne Arthropod-borne Vertical Iatrogenic (accidental transmission by professionals) Nosocomial (hospital-derived infection) Zoonotic |
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What are some different ways of disease surveillance? (3)
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Notifiable disease reporting
Laboratory-based surveillance Population-based surveillance |
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You have done hemagglutination test. You see red dot. What does this mean?
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RBC's will fall to the bottom of well, forming dot. No virus present, b/c nothing prevent the precipitation.
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You have done hemaggl. inhibition test. You see red dot. What does this mean?
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Positive result. Antibody present (is specific for virus), b/c successfully inhibited agglut. by virus. Inhibition POS wells will have well circumscribed button of unagglutinated RBCs.
~If you see agglutination, virus is present but Ab is not a match. |
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What type of vaccine has most epitopes, promotes CD4+ & CD8+ (endogenous; Th1) IR?
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Modified Live Vaccine - more cross reactivity
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What type of vaccine has limited number of epitopes and only stim. Th2 CD4+ response and is strain specific?
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Killed Vaccines: strain specific, not much cross reactivity e.g. leptospirosis vaccine
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Persistent viral infection usually char. by:
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changes in virus strategy not to kill cell it infects resulting in viral survival accompanied by resist. to host def. mech
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causes infectious mononucleosis
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Epstein barr virus: causes infectious mononucleosis
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infectious mononucleosis (EBV) proliferates how? what mech. does it use for replication?
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* infects host B cells
* initiates replication of EBV genome by host DNA polymerase |
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Example of complimentary viral interaction?
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Adenoassoc. virus: integr. of viral DNA into host chr., coinfection with adenovirus OR herpesvirus required for replication
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provirus?
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virus genome that is integrated into the DNA of a host cell.
e.g.retrovirus genome once has been converted to DNA and intergrated |
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What antiviral drug is a nucleoside analog which inhibits function of reverse transcriptase (retroviruses)?
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Zidovudine (AZT)
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Is subunit vaccine killed or modified live (attenuated)?
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Killed Category I : inactivated (killed) recombinant org. or proteins derived from recomb. org. Proteins are purified and used as protein vaccine (if protein type Cat. I often called subunit vaccine).
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interval between acquisition of infection and transmission to another susceptible host.
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• Generation time
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measure of disease frequency in the population over a specific period of time.
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• Incidence Rate
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Measure of disease frequency at a particular time.
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• Prevalence Rate
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• Nosocomial Transmission
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hospital derived infection
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The intracytoplasmic inclusion bodies of rabies virus are called?
A. Barr bodies B. Bollinger Bodies C. Negri Bodies D. Paschen bodies |
C. Negri Bodies = inclusion bodies seen w/rabies virus infection
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Virus can infect basal layer of skin, replicate only when BL differentiate into kerat.cells:
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Papilloma virus
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Are adeno-assoc.viruses able to integ. into host chr. w/o herpes OR adeno?
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Yes, but need them for replication
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