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59 Cards in this Set

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Viruses with subgenomic RNA
Alphaviruses (toga)
Coronaviruses
What is different about subgenomic RNA?
Allows production of viral proteins at DISSIMILAR levels
Sylvatic cycle
"Jungle" cycle
Can include monkeys
Urban cycle is due to what
High density living
Humans can participate in transmission cycle significantly
How do flaviviruses enter cells?
Endocytosis
What do flaviviruses bud through?
Cell envelope
What flavivirus is NOT an arbovirus?
Hepatitis C
Diseases caused by flaviviruses
Yellow Fever
Dengue
St Louis Encephalitis
Japanese B Encephalitis
West Nile Encephalitis
Hepatitis C
Other Encephalitides
Why is yellow fever an atypical flavivirus?
NOT an encephalitis
Type of vaccine for yellow fever
Live attenuated
Symptoms of yellow fever
Acute febrile illness
Jaundice, hemorrhage, proteinuria
How does yellow fever spread within body?
Hematogenously
Where does initial growth of yellow fever occur?
Draining lymph node nearest bite
How is yellow fever transmitted?
Mosquito bites
Where is yellow fever endemic?
Central America
South America
Africa
Signs of Dengue Fever (DF)
Pain for 5-6 days
High, BIPHASIC fever
Dengue Hemorrhagic Fever
DF with:
Hepatomegaly
Hemorrhage
Shock

10% mortality (due to Ab to other type)
Where is Dengue fever widespread?
India, SE Asia, China
Japan, South America, Africa
Middle East
Which is more severe?

Jap B or St. Louis encephalitis
Japanese B
How many serotypes of Dengue are there?
4 serotypes
How long is incubation period for Hep C?
8 - 10 weeks
What is the rate of chronic infection in Hep C?
80%
How is Hep C transmitted?
Parenterally
Infected blood, mother-child, sexually
Togavirus that is NOT an arbovirus
Rubella (rubivirus)
What are "spikes" on togaviruses made of?
Surface glycoproteins E1 and E2
Which is larger?

Togaviruses, or Flaviviruses
Togaviruses
Structural genes are at what end of the togavirus RNA?
3' end

This is reverse of picorna, flavi, etc.
Requires SUBGENOMIC EXPRESSION
How are togaviruses taken up by cells?
Endocytosis
What do togaviruses bud through?
Host cell plasma membrane
Distinctive characteristics of togaviruses and coronaviruses
SUBGENOMIC RNAs
Viral gene order is reversed (structural @ 3')
Temporal gene expression
Only alphavirus that is NOT cytolytic
Rubella
(Exhibits limited CPE)
Rubella key points
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
Common manifestations of Congenital Rubella Syndrome
Congenital Heart Disease
Blindness/Cataracts
Enlarged liver/spleen
Retardation
Diagnostic sign for CRS
Rubella virus-specific IgM in infant
Timing breakdown for CRS pathogenesis
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
What virus family entails the encephalitides (WEE, VEE, EEE)?
Togaviridae
EEE/WEE/VEE
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
Chikungunya
Febrile illness found in Asia & Africa

Caused by togaviridae

Vector is same as YF and Dengue
What is the largest RNA virus genome?
That of Coronaviruses
Coronavirus membrane contains what three proteins?
E1, E2
Hemagglutinin
In terms of RNA, what differentiates coronoviruses from picorna?
Sub-genomic expression
RNA is capped @ 5' end
Where do coronaviruses bud into?
Golgi
How are coronaviruses released from cells?
Exocytosis
What are the two group names of coronaviruses?
229E
OC43
Most likely source of coronavirus transmission
Respiratory droplets

BUT, blood and fecal/oral has been shown
Receptors for 229E coronaviruses
Aminopeptidase N
Receptors for OC43 coronaviruses
Sialic Acid
What types of cells in particular do coronaviruses destruct?
Ciliated epithelial cells
Characteristic shared between coronaviruses and rhinoviruses
Poor growth in cell culture
Seasonality of coronavirus colds
Winter months

Highest incidence when rhinovirus colds are lowest
Abs to coronavirus are directed against what?
E2
What are the incubation and symptom periods of coronavirus colds?
Incubation -- 2-3 days
Symptoms -- 5-7 days
Animal reservoir for SARS
Palm civet
Where does coronavirus replication occur?
All throughout the body
Incubation period for SARS
5 - 15 days
Diagnostic criteria for SARS
Mild -- Asymptomatic
Moderate -- >100.4 F w/ cough, or SOB, or hypoxia
Severe -- above symptoms PLUS radiographic evidence
Current treatment for SARS
Mostly supportive
Correct hypoxia
Treat for community acquired pneumonia
Virus family of Norwalk virus (from Clin Corr)
Caliciviridae
Characteristic of coronas in common with NEG. strand viruses?
Genome is coated with N protein