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59 Cards in this Set
- Front
- Back
Viruses with subgenomic RNA
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Alphaviruses (toga)
Coronaviruses |
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What is different about subgenomic RNA?
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Allows production of viral proteins at DISSIMILAR levels
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Sylvatic cycle
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"Jungle" cycle
Can include monkeys |
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Urban cycle is due to what
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High density living
Humans can participate in transmission cycle significantly |
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How do flaviviruses enter cells?
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Endocytosis
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What do flaviviruses bud through?
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Cell envelope
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What flavivirus is NOT an arbovirus?
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Hepatitis C
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Diseases caused by flaviviruses
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Yellow Fever
Dengue St Louis Encephalitis Japanese B Encephalitis West Nile Encephalitis Hepatitis C Other Encephalitides |
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Why is yellow fever an atypical flavivirus?
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NOT an encephalitis
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Type of vaccine for yellow fever
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Live attenuated
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Symptoms of yellow fever
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Acute febrile illness
Jaundice, hemorrhage, proteinuria |
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How does yellow fever spread within body?
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Hematogenously
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Where does initial growth of yellow fever occur?
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Draining lymph node nearest bite
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How is yellow fever transmitted?
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Mosquito bites
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Where is yellow fever endemic?
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Central America
South America Africa |
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Signs of Dengue Fever (DF)
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Pain for 5-6 days
High, BIPHASIC fever |
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Dengue Hemorrhagic Fever
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DF with:
Hepatomegaly Hemorrhage Shock 10% mortality (due to Ab to other type) |
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Where is Dengue fever widespread?
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India, SE Asia, China
Japan, South America, Africa Middle East |
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Which is more severe?
Jap B or St. Louis encephalitis |
Japanese B
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How many serotypes of Dengue are there?
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4 serotypes
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How long is incubation period for Hep C?
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8 - 10 weeks
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What is the rate of chronic infection in Hep C?
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80%
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How is Hep C transmitted?
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Parenterally
Infected blood, mother-child, sexually |
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Togavirus that is NOT an arbovirus
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Rubella (rubivirus)
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What are "spikes" on togaviruses made of?
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Surface glycoproteins E1 and E2
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Which is larger?
Togaviruses, or Flaviviruses |
Togaviruses
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Structural genes are at what end of the togavirus RNA?
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3' end
This is reverse of picorna, flavi, etc. Requires SUBGENOMIC EXPRESSION |
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How are togaviruses taken up by cells?
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Endocytosis
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What do togaviruses bud through?
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Host cell plasma membrane
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Distinctive characteristics of togaviruses and coronaviruses
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SUBGENOMIC RNAs
Viral gene order is reversed (structural @ 3') Temporal gene expression |
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Only alphavirus that is NOT cytolytic
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Rubella
(Exhibits limited CPE) |
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Rubella key points
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Acute febrile illness w/ rash and lymphadenopathy
Respiratory transmission Incubation ("prodrome") of 2-3 weeks Ab appears at time of rash (lifelong immunity) Live attenuated vaccine |
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Common manifestations of Congenital Rubella Syndrome
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Congenital Heart Disease
Blindness/Cataracts Enlarged liver/spleen Retardation |
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Diagnostic sign for CRS
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Rubella virus-specific IgM in infant
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Timing breakdown for CRS pathogenesis
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50% of abnormalities, infected during 1st month
20% during 2nd month 4% during third month SO, timing is very important w/ regards to abnormalities developing |
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What virus family entails the encephalitides (WEE, VEE, EEE)?
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Togaviridae
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EEE/WEE/VEE
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Range from mild flu-like illness to encephalitis/coma/death
Neurologic sequelae in 30% Fatality in 35% WEE and EEE are maintined in wild birds Killed vaccines available |
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Chikungunya
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Febrile illness found in Asia & Africa
Caused by togaviridae Vector is same as YF and Dengue |
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What is the largest RNA virus genome?
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That of Coronaviruses
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Coronavirus membrane contains what three proteins?
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E1, E2
Hemagglutinin |
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In terms of RNA, what differentiates coronoviruses from picorna?
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Sub-genomic expression
RNA is capped @ 5' end |
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Where do coronaviruses bud into?
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Golgi
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How are coronaviruses released from cells?
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Exocytosis
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What are the two group names of coronaviruses?
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229E
OC43 |
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Most likely source of coronavirus transmission
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Respiratory droplets
BUT, blood and fecal/oral has been shown |
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Receptors for 229E coronaviruses
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Aminopeptidase N
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Receptors for OC43 coronaviruses
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Sialic Acid
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What types of cells in particular do coronaviruses destruct?
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Ciliated epithelial cells
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Characteristic shared between coronaviruses and rhinoviruses
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Poor growth in cell culture
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Seasonality of coronavirus colds
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Winter months
Highest incidence when rhinovirus colds are lowest |
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Abs to coronavirus are directed against what?
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E2
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What are the incubation and symptom periods of coronavirus colds?
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Incubation -- 2-3 days
Symptoms -- 5-7 days |
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Animal reservoir for SARS
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Palm civet
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Where does coronavirus replication occur?
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All throughout the body
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Incubation period for SARS
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5 - 15 days
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Diagnostic criteria for SARS
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Mild -- Asymptomatic
Moderate -- >100.4 F w/ cough, or SOB, or hypoxia Severe -- above symptoms PLUS radiographic evidence |
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Current treatment for SARS
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Mostly supportive
Correct hypoxia Treat for community acquired pneumonia |
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Virus family of Norwalk virus (from Clin Corr)
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Caliciviridae
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Characteristic of coronas in common with NEG. strand viruses?
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Genome is coated with N protein
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