RNA Viruses Flashcards
(140 cards)
1
Q
Where do RNA viruses replicate?
A
in the cytoplasm
2
Q
What enzyme do RNA viruses require?
A
RNA-dependent-RNA polymerase
3
Q
What does + and - genomes mean?
A
+ means they’re able to serve as mRNA
- means they’re a complement of mRNA. They require transcriptase protein packaged in virion
4
Q
Naked viruses (and genome)
A
Picornaviridae (ssRNA)
Caliciviridae (ssRNA)
Astroviridae (ssRNA)
Reoviridae (dsRNA)
5
Q
Enveloped viruses
A
Togaviridae Flaviviridae Bunyaviridae Arenaviridae Rhabdoviridae Paramyxoviridae Myxoviridae Coronaviridae Filoviridae Retroviridae
6
Q
Picornaviruses
A
Enterovirus Rhinovirus Hepatovirus Parechovirus Kobuvirus
7
Q
Medically important Enteroviruses
A
Poliovirus (3 serotypes) Coxsackie A (types 1-22, 24) Coxsackie B (types 1-6) Echovirus (types 1-9, 11-27, 29-34) Enterovirus (types 68-71) Rhinovirus (A, B, C, 100+ serotypes)
8
Q
Medically important Hepatovirus
A
Hepatitis A virus
9
Q
Picornavirus genome
A
small, icosahedral, naked
ssRNA+
10
Q
Picornavirus capsid?
A
formed from 60 copies of non-glycosylated proteins
11
Q
Picornavirus life-cycle?
A
attachment entry via receptor-mediated endocytosis uncoating genome acts as mRNA replication in cytoplasm (6-7 hours) release of visions by cell lysis
12
Q
Picornavirus attachment receptors
A
members of the immunoglobulin superfamily
canyon structure at the vertices of virus is point of attachment
13
Q
What receptor does Polio use?
A
PVR/CD155
14
Q
What receptor do rhinoviruses and several coxsackieviruses use?
A
ICAM-1
15
Q
Picornavirus replication
A
proteins translated as one polyprotein
translation initiated at internal ribosome entry site and polyprotein cleaved by viral protease
16
Q
Picornavirus transmission
A
fecal-oral respiratory secretions (saliva, sputum, nasal mucus)
17
Q
Rhinovirus types 1-100 characteristics
A
labile at acidic pH
optimum growth at 33C
18
Q
Enterovirus, Hep A characteristics
A
resistant to pH between 3-9, detergents, heat, mild sewage treatment
19
Q
Where do enteroviruses replicate?
A
in the mucosa of the lymphoid tissue of the tonsils and pharynx, then M cells and lymphocytes of the Peyer patches and enterocytes of intestinal mucosa
20
Q
What occurs after the primary replication of enteroviruses?
A
Primary viremia spreads virus to target tissues with the viral receptor and a second phase of viral replication occurs, resulting in secondary viremia and symptoms
21
Q
How was epidemic poliomyelitis transmitted?
A
fecal contamination of drinking water routine
22
Q
What virus caused “infantile paralysis”?
A
Polio
23
Q
What are the different degrees of paralysis caused by polio?
A
spinal cord: anterior horn cells and motor cortex – paralysis of limbs or complete flaccid paralysis
bulbar: cranial nerves and respiratory center in the medulla – paralysis of neck and respiratory muscles
24
Q
Poliovirus symptoms and disease
A
most are asymptomatic because replication is restricted to the GI tract
range from mild fever with diarrhea to flaccid paralysis
can progress to meninges and brain
25
Poliovirus vaccines
3 serotypes of polio are in the vaccine
Inactivated (IPV) - Salk
Oral (OPV) - Sabin
We only use the IPV in the USA to prevent vaccine-associated disease
26
What are the four non-polio enteroviruses?
Coxsackie A and B
Echovirus
Other enteroviruses 68-71
27
What general disease do non-polio enteroviruses cause?
vesicular disease and aseptic meningitis (asymptomatic or mild)
28
What disease does Coxsackie A cause?
herpangina and hand, foot, and mouth disease
aseptic meningitis
conjunctivitis
29
What disease does Coxsackie B cause?
myocardial and pericardial infections
pleurodynia
aseptic meningitis
30
What disease does echovirus cause?
aseptic meningitis outbreaks (every summer)
31
What disease do enteroviruses 68-71 cause?
respiratory and conjunctivitis among other diseases
32
What are the other picornaviruses?
Parechovirus
| Kobuvirus
33
What disease does parechovirus cause?
respiratory and GI diseases
rare encephalitis
myocarditis
34
What disease does Kobuvirus cause?
GI diseases
35
What is Enterovirus Vesicular Disease and what are the symptoms?
hand, foot, and mouth disease
common viral illness
fever, blister-like sores in the mouth, and a skin rash
36
What are the most common causes of Enterovirus Vesicular Disease?
Coxsackie A16 and Enterovirus 71
37
What population most commonly gets Enterovirus Vesicular Disease?
infants and children
38
Enterovirus Vesicular Disease diagnosis and treatment
diagnosed typically clinical
| no specific treatment, just relieve symptoms
39
When is Enterovirus Meningitis most common?
during the summer and early fall months
40
Most common cause of viral meningitis?
| What are the other viral infections that can cause meningitis?
Enteroviruses
```
Mumps
Herpesviruses
Measles
Influenza
Arboviruses
LCMV
```
41
What are the common symptoms of viral meningitis in infants?
In adults?
fever, irritability, poor eating, hard to awaken
high fever, severe headache, stiff neck, sensitivity to bright light, sleepiness or trouble waking up, nausea, vomiting, lack of appetite
42
What disease does Enterovirus 68 cause? Where is the virus found?
How is it spread?
Respiratory disease
Respiratory secretions
Cough, sneezes, or contaminated surfaces
43
What is the principal agent of the common cold?
Rhinovirus
44
Rhinovirus characteristics
binds to ICAM-1
major cause of URI in all age groups (restricted to upper respiratory tract)
more than 100 independent serotypes
45
Rhinovirus incubation and symptoms
1-2 day incubation
| symptoms last 3-7 days
46
Hepatitis A characteristics
```
+ssRNA
Picornavirus family
27 nm particle
icosahedral
non-enveloped
1 serotype
```
47
Hepatitis A transmission
fecal-oral
initial replication in the enteric mucosa
virus excreted in feces before symptoms
viremia spread to liver
48
Hepatitis A incubation
3 weeks (15-45 days)
49
Hepatitis A symptoms
Fever, nausea, anorexia, RUQ pain, dark urine, clay-colored stool
50
What is the icteric phase of Hepatitis A?
jaundice, yellow eyes, skin, mucous membranes
pruritis
enlarged and tender liver
51
diagnosis of Hepatitis A
positive IgM anti-HAV
52
Where does viral replication of Hepatitis A occur? What are the steps?
```
LIVER
lymphoid cell infiltration
necrosis of parenchymal cells
proliferation of Kupffer cells
biliary stasis
CTL damage to hepatocytes
infection clears and liver damage is reversed
chronic infections are extremely rare
```
53
Hepatitis A disease
Infection:disease ratio
asymptomatic or mildly ill
children: 20:1
adults: 1:1
54
Hepatitis A risk factors
```
Personal contact
poor hygiene
overcrowding
daycare, nursing homes
contaminated food -- shellfish, vegetables, milk, water
illicit drug use
international travel
men who have sex with men
```
55
Who is Hepatitis A vaccine recommended for?
international travelers
men who have sex with men
injection and non-injection drug users
56
prevention of Hepatitis A
inactivated whole-virus vaccine
| -adapted virus inactivated with formalin
57
viruses that cause gastroenteritis
Caliciviruses (community-wide, Norovirus)
Astrovirus (mild, self-limiting, children)
Rotavirus (reovirus family, infants)
Adenoviruses (DNA)
58
What are the factors that contribute to transmission risk of viruses that cause gastroenteritis?
large quantities of virus in stool
| virus resistant to environment
59
Calicivirus characteristics
naked, icosahedral
+ssRNA
single capsid protein
viral surface has 32 cup-shaped depressions
60
Species of calicivirus that is primary agent for acute diarrheal disease? Where is it most commonly found?
Norovirus
Ubiquitous
cruise ships and daycare diarrhea
61
Most predominant Norovirus genogroup? The others are?
GII.4
GI, GII, GIII, GIV, GV
62
Norovirus transmission?
fecal-oral via contaminated food, surfaces, aerosol transmission from vomiting
infection can occur with as few as 10 virus particles
63
Norovirus pathogenesis
infection of epithelial cells in stomach/intestine causes malabsorption of carb --> accumulation in the intestinal lumen
inhibition of water reabsorption
64
Norovirus diagnosis
RT-PCR with sequencing for genotype determination
65
Astrovirus characteristics
```
similar to caliciviruses
star-shaped
acid-stable
heat-resistant
cannot be grown in cell culture
```
66
Astrovirus disease
infection occurs world-wide and accounts for 2-8% of cases of diarrhea in infants
67
Two types of reoviruses?
Rotavirus
| Colorado Tick Fever
68
Reovirus genome characteristics
```
dsRNA
segmented genome
icosahedral capsid
naked
mRNA made form negative strand of ds-RNA genome
```
69
What is the leading cause of severe acute gastroenteritis among children worldwide?
Rotavirus
70
Rotavirus transmission
fecal-oral (super contagious)
very stable and remains viable for weeks to months
late fall, winter, early spring
71
Rotavirus replication
occurs in villous epithelium of small intestine
| 1-3 day incubation followed by abrupt disease onset
72
Rotavirus infection and symptoms
localized -- decreased absorption of glucose, sodium, and water
vomiting, abdominal cramps, low-grade fever, watery stools
73
Rotavirus treatment? diagnosis?
supportive! rehydration
detection of virus particles or viral antigen in stool
74
Rotavirus prevention? reinfection?
two oral, live vaccines for infants
may develop disease more than once because don't form full immunity since there are so many different types, but second infection is less severe than the first rotavirus infection
75
Safety concern with rotavirus vaccine?
intussusception after vaccination
76
Colorado Tick Fever characteristics
12 double stranded RNA genomic segments
77
Colorado Tick Fever disease
acute disease with fever, headache, severe myalgia
78
Where is Colorado Tick Fever most commonly found?
western and northwestern US, western Canada
79
What is the host for Colorado Tick Fever? natural hosts?
Dermacentor andersoni wood tick
mammals (squirrel, rabbits, deer)
80
Hepatitis E virus genome characteristics
+ssRNA 7.2 kB
similar to calicivirus and rubella
32 nm non-enveloped, icosahedral
4 genotypes, 1 serotype
81
Hepatitis E incubation period
average is 40 days
| range is 15-60 days
82
Hepatitis E transmission
fecal-oral
83
Hepatitis E hosts
humans are natural host, but viruses have been detected in primates and other animal species
84
Where is Hepatitis E most commonly found?
developing countries with poor sanitation
85
Hepatitis E disease
```
only acute
symptoms most common among adolescents and young adults and pregnant women
MAY fulminate (acute liver failure, death)
```
86
Risk factors for Hepatitis E
poor sanitation and HEV shedding in feces
87
Hepatitis E prevention
don't drink water of unknown purity
don't eat uncooked shellfish
don't eat uncooked fruit/veggies not peeled or prepared by traveler
88
Hepatitis E diagnosis and treatment
IgG detection
supportive care
89
Enveloped RNA virus characteristics
very diverse
| + and - stranded families
90
most prevalent and significant enveloped RNA viruses?
influenza, paramyxo, retrovirus
91
What kind of diseases do enveloped viruses cause?
CNS disease and hemorrhagic fevers
92
Enveloped viruses?
Togaviruses
Flaviviruses
Bunyaviruses
Arenaviruses
93
What diseases do Togaviruses cause?
```
Equine encephalitis viruses (EEE)
VEE
WEE
Chikungunya fever
Rubella
```
94
What diseases do Flaviviruses cause?
```
Yellow fever
Dengue fever
St. Louis Encephalitis
West Nile Fever
Powassan virus
Hepatitis C
```
95
What diseases do Bunyaviruses cause?
California Encephalitis
LaCrosse Encephalitis
Rift Valley Fever
Hantavirus
96
What diseases do Arenaviruses cause?
Lymphocytic choriomeningitis virus (LCMV)
Lassa Fever Virus
Junin
Machupo
97
Togavirus characteristics and cell entry?
+ssRNA
enveloped
icosahedral
entry via receptor-mediated endocytosis
98
Two members of the Togavirus family?
Alphavirus
| Rubivirus
99
Alphavirus host and transmission?
Host: mammal or bird
Transmission: mosquito bite (only female)
Humans are primary host for Chikungunya during epidemics
100
Alphavirus replication and disease
viral replication in gut of vector
systemic phase with viremia and fever
active infection of target tissue (CNS, skin, blood vessels, viscera, muscles)
101
Where is Alphavirus Encephalitis found?
in horses and humans as a dead-end host
102
Type of Alphaviral Encephalitis?
Eastern Equine Encephalitis (EEE)
Western Equine Encephalitis (WEE)
Venezuelan Equine Encephalitis (VEE)
103
Arbovirus diagnosis
```
clinical features (travel, activities)
serum or CSF for virus-specific IgM and neutralizing antibodies
```
104
Eastern Equine Encephalitis (EEE)
most severe - 33% mortality
severe neurological sequelae
Atlantic and Southern coastal states
reservoir in birds
105
Western Equine Encephalitis (WEE)
```
not severe, most recover completely
most frequently symptomatic in children
symptoms range from flu-like to encephalitis
2-3% mortality
bird-mosquito-bird cycle
western and midwestern states
```
106
Venezuelan Equine Encephalitis (VEE)
very low mortality (0.5%)
devastating for horses
reservoir in rodents rather than birds
chiefly South America and Southern US
107
Chickungunya Fever Virus outbreaks
Asia, Thailand, Malaysia, India
| Recent in Americas and US
108
Chickungunya Fever Virus symptoms
may be asymptomatic OR
debilitating illness with high fever, petechial or maculopapular rash, headache, fever, fatigue, nausea, vomiting, muscle pain, joint pain (severe arthralgia)
109
Chickungunya Fever Virus replication
in fibroblasts, skeletal muscle, progenitor cells, myofibers
110
Chickungunya Fever Virus diagnosis and treatment
serology for IgM/IgG four days after illness
no vaccine or treatment
111
Chickungunya Fever Virus vectors
aedes aegypti
| aedes albopictus
112
Flavivirus characteristics
```
+ssRNA
enveloped
icosahedral
serologically related with some cross-reactivity
similar to Togaviruses
```
113
Flavivirus cause _____ and ______. Subtypes of each?
Encephalitis and hemorrhagic fevers
```
Encephalitis:
West Nile (US)
St Louis (US, Canada)
Powassan (North America)
Japanese B (Asia, pigs and birds)
Murray Valley (Australia)
```
Hemorrhagic fevers:
Yellow Fever
Dengue Fever
114
Yellow Fever Transmission
Sylvatic cycle and urban cycle (mosquito)
sporadic
forested areas, rainy seasons
115
Yellow Fever hosts
monkeys, man
116
Yellow Fever symptoms
```
mostly asymptomatic, but can cause
sudden onset flu-like symptoms
chills, fever, myalgia, vomiting
15% can progress to visceral infection of liver and/or kidneys -- jaundice, GI hemorrhage
characteristic black vomit
shock, multisystem organ failure
10% mortality
```
117
Yellow Fever prevention, diagnosis, and treatment
prevention: avoid mosquitos, live attenuated 17D vaccine
diagnosis: clinical presentation, serology, viral detection
treatment: supportive care
118
Dengue Fever statistics
most widespread arbovirus in the world
estimated 100 million cases/year
now in the US
4 serotypes, so multiple infections possible
119
Dengue Fever transmission
aedes aegypti mosquito feeds on person during 5-day period when large amounts of virus are in the blood
120
Dengue Fever symptoms?
4-7 days after mosquito bite, last 3-10 days
severe headache and pain in muscle and joints
rapidly fading maculopapular rash, hematuria, leukopenia, thrombocytopenia
121
What disease is also known as breakbone fever?
Dengue Fever
122
What is Dengue Hemorrhagic fever?
Shock syndrome, occurs upon re-infection with another serotype
it's an immune-mediated disease
circulatory shock and hemorrhage
high mortality
123
Three requirements for Dengue epidemics:
large numbers of vector
large numbers of people with no immunity to Dengue
opportunity for contact between the two
124
Dengue Fever treatment
treat the symptoms!
blood transfusion
IV fluids and electrolytes
oxygen therapy
125
What is Powassan Virus?
North American tick borne flavivirus
126
Reservoir for Powassan Virus
small mammals (squirrels, groundhogs)
127
Hosts, reservoirs, and vectors for St. Louis Encephalitis
Host: humans
Reservoir: bird
Vector: mosquito
128
What caused the unexplained viral encephalitis in NY metro area in 1999 when there were dead birds at Bronx Zoo?
West Nile Virus
129
Two types of West Nile Virus infections? Clinical description of each?
Non-neuroinvasive and neuroinvasive
Non-neuroinvasive: acute systemic febrile illness
headache, myalgia, arthralgia, rash, GI symptoms
Neuroinvasive: aseptic meningitis, encephalitis, acute flaccid paralysis
fever, stiff neck, altered mental status, seizures, limb weakness, CSF pleocytosis, abnormal neuroimaging
130
How can West Nile Virus be transmitted?
mosquitos
| human-to-human (blood transfusion, transplanted organs, breast milk, transplacental)
131
West Nile Virus diagnosis?
serum or CSF test for WNV-specific IgM antibodies
132
West Nile Virus treatment and prevention
treatment: supportive care
prevention: no vaccine! control vector and avoid exposure
133
Two members of the Bunyavirus family?
Lacrosse Encephalitis virus
| Rift valley fever
134
Lacrosse Encephalitis virus locations and most common infection time
upper midwestern, mid-Atlantic, southeastern states
| peaks in summer months
135
Lacrosse Encephalitis virus vector and environments?
aedes triseriatus (mosquito!)
suburban and rural environments
136
Lacrosse Encephalitis virus reservoir
chipmunk, squirrels
137
Rift Valley Fever location and transmission
Africa
| mosquitos and sandflies
138
Heartland Virus
Bunyavirus family
transmitted by ticks
8 cases in Missouri and Tennessee
fever, fatigue, anorexia, nausea, diarrhea, leukopenia, thrombocytopenia
139
Bourbon Virus
Thogotovirus associated with febrile illness and death
1 patient in Kansas
transmitted by ticks
fever, fatigue, anorexia, nauea, diarrhea, leukopenia, thrombocytopenia
140
What is an arbovirus?
virus transmitted by arthropod vectors
