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USMLE Step I Microbiology > RNA viruses > Flashcards

RNA viruses Flashcards

1
Q

Reoviruses–envelope?

A

NO

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2
Q

Reoviruses–RNA structure

A
  • DS linear
    • 10-12 segments
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3
Q

Reoviruses–capsid symmetry

A
  • icosahedral
    • double
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4
Q

reoviruses–medical importance

A
  • coltivirus–Colorado tick fever
  • Rotavirus–#1 cause of fatal diarrhea in children
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5
Q

Picornaviruses–envelope

A

NO

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6
Q

Picornaviruses–RNA structure

A
  • SS + linear
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7
Q

Picornaviruses–capsid symmetry

A
  • icosahedral
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8
Q

Picornaviruses–medical importance

A
  • Poliovirus–polio Salk/Sabin vaccines–IPV/OPV
  • Echovirus–aseptic meningitis
  • Rhinovirus–“common cold”
  • Coxsackievirus
    • aseptic meningitis
    • herpangina–mouth blisters, fever
    • hand, foot, and mouth disease
  • HAV
    • “PERCH”
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9
Q

Hepevirus–envelope

A

NO

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10
Q

Hepevirus–RNA structure

A
  • SS + linear
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11
Q

Hepevirus–capsid symmetry

A
  • icosahedral
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12
Q

Hepevirus–medical importance

A
  • HEV
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13
Q

Caliciviruses–envelope

A

NO

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14
Q

Caliciviruses–RNA structure

A
  • SS + linear
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15
Q

Caliciviruses–capsid symmetry

A
  • icosahedral
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16
Q

Caliciviruses–medical importance

A
  • norovirus–viral gastroenteritis
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17
Q

Flaviviruses–envelope

A

YES

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18
Q

Flaviviruses–RNA structure

A
  • SS + linear
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19
Q

Flaviviruses–capsid symmetry

A
  • icosahedral
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20
Q

Flaviviruses–medical importance

A
  • HCV
  • Yellow fever
    • arbovirus, arthropod borne (mosquitoes, ticks)
  • Dengue
    • arbovirus, arthropod borne (mosquitoes, ticks)
  • St. Louis encephalitis
    • arbovirus, arthropod borne (mosquitoes, ticks)
  • West Nile virus
    • arbovirus, arthropod borne (mosquitoes, ticks)
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21
Q

Togaviruses–envelope

A

YES

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22
Q

Togaviruses–RNA structure

A
  • SS + linear
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23
Q

Togaviruses–capsid symmetry

A
  • Icosahedral
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24
Q

Togaviruses–medical importance

A
  • Rubella
  • Eastern equine encephalitis
    • arbovirus, arthropod borne (mosquitoes, ticks)
  • Western equine encephalitis
    • arbovirus, arthropod borne (mosquitoes, ticks)
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25
Retroviruses--envelope
YES
26
Retroviruses--RNA structure
* SS + linear * 2 copies
27
Retroviruses--capsid symmetry
* icosahedral * HTLV * complex and conical * HIV
28
Retroviruses--medical importance
* have reverse transcriptase * HTLV--T cell leukemia * HIV--AIDS
29
Coronaviruses--envelope
YES
30
Coronaviruses--RNA structure
* SS + linear
31
Coronaviruses--capsid symmetry
* helical
32
coronaviruses--medical importance
* "common cold" * SARS * MERS
33
Orthomyxoviruses--envelope
YES
34
Orthomyxoviruses--RNA structure
* SS - linear * 8 segments
35
Orthomyxoviruses--capsid symmetry
* helical
36
Orthomyxoviruses--medical importance
* influenza virus
37
Paramyxoviruses--envelope
YES
38
Paramyxoviruses--RNA structure
* SS - linear * nonsegmented
39
Paramyxoviruses--capsid symmetry
* helical
40
Paramyxoviruses--medical importance
* **P**a**R**a**M**yxovirus: * **P**arainfluenza--croup * **R**SV--bronchiolitis in babies * **R**x--**R**ibovirin * **M**easles, **M**umps
41
Rhabdoviruses--envelope
YES
42
Rhabdoviruses--RNA structure
* SS - linear
43
Rhabdoviruses--capsid symmetry
* helical
44
Rhabdoviruses--medical importance
* Rabies
45
Filoviruses--envelope
YES
46
Filoviruses--RNA structure
* SS - linear
47
Filoviruses--capsid symmetry
* helical
48
Filoviruses--medical importance
* Ebola/Marburg hemorrhagic fever--often fatal!!
49
Arenaviruses--envelope
YES
50
Arenaviruses--RNA structure
* SS + or - circular * 2 segments
51
Arenaviruses--capsid symmetry
* helical
52
Arenaviruses-medical importance
* LCMV--lymphocytic choriomeningitis virus * Lassa fever encephalitis--spread by rodents
53
Bunyaviruses--envelope
YES
54
Bunyaviruses--RNA structure
* SS - circular * 3 segments
55
Bunyaviruses--capsid symmetry
* helical
56
Bunyaviruses--medical importance
* California encephalitis * **arbo**virus, **ar**thropod **bo**rne (mosquitoes, ticks) * Sandfly/Rift Valley fevers * **arbo**virus, **ar**thropod **bo**rne (mosquitoes, ticks) * Crimean Congo hemorrhagic fever * **arbo**virus, **ar**thropod **bo**rne (mosquitoes, ticks) * Hantavirus--hemorrhagic fever, pneumonia
57
Delta virus--envelope
YES
58
Delta virus--RNA structure
* SS - circular
59
Delta virus--capsid symmetry
* uncertain
60
Delta virus--medical importance
* HDV is a "defective" virus that requires the presence of HBV to replicate
61
Negative stranded viruses--properties and name the 6 viruses
* most transcribe - strand to + * virion brings its own RNA dependent RNA polymerase * includes: * **A**renaviruses * **B**unyaviruses * **P**aramyxoviruses * **O**rthomyxoviruses * **F**iloviruses * **R**habdoviruses * "**A**lways **B**ring **P**olymerase **O**r **F**ail **R**eplication"
62
name the 4 segmented viruses
* all are RNA viruses * **B**onyaviruses * **O**rthomyxoviruses (influenza viruses) * **A**renaviruses * **R**eoviruses * **"BOAR"**
63
name the 5 Picronaviruses
* **P**oliovirus * **E**chovirus * **R**hinovirus * **C**oxsackievirus * **H**AV * "Pico**RNA**virus = small **RNA** virus" * "**PERCH** on a '**peak**'" (**pic**o)
64
properties of Picornaviruses
* RNA is translated into 1 large polypeptide that is cleaved by proteases into functional viral proteins * all are enteroviruses (fecal-oral spread) except rhinovirus
65
what can Picornavirus cause?
* aseptic (viral) meningitis (except rhinovirus and HAV)
66
properties of Rhinovirus
* a picornavirus * nonenveloped RNA virus * \>100 serologc types * acid labile--destroyed by stomach acid; therefore, does not infect the GI tract (unlike other picronaviruses)
67
what does rhinovirus cause?
* common cold * "**Rhino** has a runny **nose**"
68
properties of Yellow Fever virus
* flavivirus (also an arbovirus) transmitted by *Aedes* mosquito * virus has a monkey or human reservoir * may see Councilman bodies (eosinophilic apoptotic globules) on liver biopsy
69
Yellow fever virus--symptoms
* high fever * black vomitus * jaundice * "flavi" = yellow, jaundice
70
properties of rotavirus
* segmented dsRNA virus (a reovirus) * villous destruction with atrophy leads to dec absorption of Na+ and loss of K+
71
what is rotavirus the most important global cause of?
* infantile gastroenteritis
72
what does rotavirus cause? when is it common, and where?
* major cause of acute diarrhea in the US * "**ROTA**virus = **R**ight **O**ut **T**he **A**nus" * during winter * especially in day care centers, kindergartens
73
what is recommended for infants regarding rotavirus?
* CDC recommends routine vaccination of all infants
74
properties of influenza viruses
* orthomyxoviruses * enveloped * - ssRNA viruses with 8 segment genome * contain hemagglutinin (promotes viral entry) and neuraminidase (promotes progeny virion release) antigens
75
what are patients with orthomyxovirus at risk of?
* patients at risk for fatal bacterial superinfection * most commonly *S. aureus, S. pneumoniae, H. influenzae*
76
reformulated vaccine for influenza virus
* reformulated vaccine ("the flu shot") contains viral strains most likely to appear during flu season, due to the virus' rapid genetic change
77
what type of vaccine is most often used for the flu shot?
* killed viral vaccine
78
live attenuated virus for influenza virus
* contains temperature sensitive mutant that replicates in the nose but not in the lung * administered intranasally
79
genetic shift/antigenic shift
* causes pandemics * reassortment of viral genome segments, such as when segments of human flu A virus reassort with swine flu A virus
80
genetic drift/antigenic drift
* causes epidemics * minor (antigenic drift) changes based on random mutation in hemagglutinin or neuroaminidase genes
81
genetic drift vs. shift
* **S**uddent **S**hift is more deadly than gra**d**ual **D**rift
82
rubella virus
* togavirus * causes rubella, once known as German (3 day) measles
83
rubella virus--symptoms
* fever * postauricular and other lymphadenopathy * arthralgias * fine, confluent rash that starts on face and spreads centrifugally to involve trunk and extremities
84
rubella virus--congenital
* causes mild disease in children but serious congenital disease (a ToRCHeS infection) * congenital rubella findings include "blueberry muffin" appearance due to dermal extramedullary hematopoiesis
85
what does Paramyxoviruses cause?
* cause disease in children * include those that cause * parainflueza: croup--seal like barking cough * mumps * measles * RSV: causes respiratory tract infection--bronchiolitis, pneumonia * in infants
86
properties of Paramyxoviruses
* all contin surface F (fusion) protein, which causes respiratory epithelial cells to fuse and form multinucleated cells
87
what prevents pneumonia caused by RSV infection in premature infants?
* Palivizumab * monoclonal antibody against F protein
88
Croup (acute laryngotracheobronchitis)
* caused by parainfluenza viruses (paramyxovirus) * results in: * "seal like" barking cough * inspiratory stridor * narrowing of upper trachea and subglottis leads to characteristic steeple sign on x-ray
89
what can cause severe croup cause?
* severe croup can result in pulsus paradoxus secondary to upper airway obstruction
90
Measles (rubeola) virus--presentation
* a paramyxovirus that causes measles * presentation: * prodromal fever with cough * coryza * conjunctivitis * "3 **C**'s of measles: **C**ough, **C**oryza, **C**onjunctivitis" * Koplik spots--bright red spots with blue white centers on buccal mucosa (A) * followed 1-2 days later by a maculopapular rash (B) that starts at the head/neck and spreads downward * Lymphadenitis with Warthin-Finkeldey giant cells (fused lymphocytes) in a background of paracortical hyperplasia
91
Measles virus--possible sequelae
* SSPE--subacute sclerosing panencephalitis, occurring years later * encephalitis (1:2000) * giant cell pneumonia--rarely, in immunocompromised
92
Measles virus and Vitamin A
* vitamin A supplementation can reduce morbidity and mortality from measles, particularly in malnourished children
93
mumps virus
* paramyxovirus that causes mumps * symptoms: * **P**arotitis (A) * **O**rchitis (inflammation of testes) * aseptic **M**eningitis * **P**ancreatitis * "Mumps make your parotid glands and testes as big as **POM-P**oms"
94
why is mumps uncommon?
* due to effectiveness of MMR vaccine
95
what can mumps cause especially after puberty?
* can cause sterility
96
properties of Rabies virus
* bullet shaped virus (A) * negri bodies--cytoplasmic inclusions (B) * commonly found in Purkinje cells of cerebellum and hippocampal neurons * travels to CNS by migrating in a retrograde fashion up nerve axons after binging to ACh receptors
97
Rabies--incubation and prophylaxis
* rabies has long incubation period (weeks to months) before symptoms onset * postexposure prophylaxis is wound cleaning plus immunization with killed vaccine and rabies immunoglobulin * example of passive-active immunity
98
Rabies--progression
* fever * malaise --\> agitation * photophobia * hydrophobia * hypersalivation --\> paralysis * coma --\> death
99
Rabies--transmission
* more commonly from bat, raccoon, and skunk bites that from dog bites in the US * aerosol transmission (ie. bat caves) also possible
100
properties of Ebola virus
* filovirus * targets endothelial cells, phagocytes, hepatocytes
101
Ebola virus--incubation and presentation
* presents following an incubation period of up to 21 days * presentation: * abrupt onset of flu like symptoms * diarrhea/vomiting * high fever * myalgia
102
Ebola virus--what can it progress to?
* can progress to: * DIC * diffuse hemorrhage * shock
103
Ebola virus--diagnosis
* diagnosed with RT-PCR within 48 hours of symptoms onset * high mortality rate
104
Ebola virus--transmission
* requires direct contact with: * bodiy fluids * fomites (including dead bodies) * infected bats or primates (apes/monkeys) * high incidence of nosocomial infection
105
Ebola virus--treatment and prevention of transmission
* supportive care * no definitive treatment * strict isolation of infected individuals and barrier practices for health care workers are key to preventing transmission

USMLE Step I Microbiology (44 decks)

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