RNA viruses Flashcards by Annie Chow

reoviruses

rotavirus
coltivirus

non-enveloped, icosahedral, dsRNA virus

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Reovirus- Rotavirus

non-enveloped, icosahedral, dsRNA reovirus

primary cause of fatal diarrhea in children worldwide (6% of child deaths under age 5)

deadly due to severe diarrhea, vomiting, dehydration, electrolyte abnormalities

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Reo-virus Coltivirus

non-enveloped, icosahedral, dsRNA reovirus

Colorado tick fever
found in mountainous regions of western US and Canada

spread by woodtick to hikers, hunters, and the like

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Picornavirus- enterovirus

non-enveloped, ss+ linear, icosahedral

enteroviruses include poliovirus, coxsackivirus, and echovirus

primary spread via feco-oral route, alternatively resp secretions

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polio

this is a picornavirus, icosahedral, non-enveloped, ss+linear RNA

it affects the anterior horns of the spinal horn, and motor neurons of the pons and medulla leading to paralysis

salk vaccine- killed and injected
sabin vaccine- live and eaten

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Echovirus

picornavirus, enterovirus
ss+linear RNA
non-enveloped
icosahedral

summer outbreaks of
viral meningitis
URI
myocarditis

detection is possible via PCR of CSF, which enables outpatient care and conservation of healthcare resources (not much treatment needed for viral meningitis)

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Coxsackivirus

picornavirus, enterovirus, ss+ linear RNA, icosahedral, non-enveloped

hand-foot-mouth disease
viral myocarditis, pericarditis
aseptic meningitis
herpangina
febrile pharyngitis

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HAV

picornavirus, ss+linear RNA, icosahedral, non-enveloped

feco-oral spread

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Rhinovirus

picornavirus, ss+linear RNA, icosahedral, non-enveloped. common cold. >100 serologic types.
Acid labile, destroyed by stomach acid, and does not infect the GI tract (unlike other picornaviruses)

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Calicivirus- Norwalk virus

nonenveloped, icosahedral, ss+linear
viral gastroenteritis
vomiting, diarrhea, point- source outbreaks

cruise ship
nursing home

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Flavivirus

Enveloped, SS+linear, icosahedral
includes arboviruses (arthropod-borne)
includes yellow fever and hep C, which turn the skin yellow

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Flavivirus- Arbovirus- Yellow fever virus

a flavivirus
enveloped
ss+linear
icosahedral

yellow fever-
Aedes mosquito
reservoir- humans and monkeys
Sub-Saharan Africa and South America

hemorrhagic disease (epistaxis, petecheal, purpuric gum lesions, black vomitus, Councilman bodies on liver biopsy)
high fever
jaundice

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Flavivirus- Arbovirus- Dengue virus

ss+RNA linear, enveloped, icosahedral

most common mosquito-born disease worldwide

classic breakbone fever-
retroorbital pain
joint pain
HA

complication- dengue hemmorhagic fever= thrombocytopenia and increased capillary wall fragility

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Flavivirus- arbovirus- WNV

ss+linear, enveloped, icosahedral

endemic in USA since 1999
flu-like sx are common: HA, malaise, back pain, myalgia, anorexia 3-6 days

severe sx in 1/150: meningitis/encephalitis, flaccid paralysis (anterior horn involvement), alterations in consciousness, death

Dx with serology for WNV IgM abs, serum or CSF

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Arboviruses that cause encephalitis

St. Louis encephalitis virus
Eastern equine encephalitis virus
Western equine encephalitis virus
California encephalitis virus

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flavivirus- arbovirus-st. louis encephalitis

ss+RNA linear, enveloped, icosahedral

arbovirus (mosquito- born)

can cause encephalitis

Togavirus- Rubella

ss+linear RNA, enveloped, icosahedral

congenital disease leads to 
cataracts
deafness
heart defects
-PDA
-pulmonic stenosis

blueberry muffin

Coronavirus

enveloped, ss+linear, helical

“common cold” and SARS

common cold

rhinovirus

coronavirus

Retrovirus- Human T cell leukemia virus

enveloped, SS+linear RNA, 2 copies, icosahedral

uses reverse transcriptase

infects motor neurons of the anterior horn

poliovirus

WNV

Orthomyxovirus- influenza

enveloped, helical, ss (-)RNA
hemagglutinin promotes viral attachment to host cell

neuraminidase promotes release of progeny virions

rapid genetic change
-reassortment= shift, which leads to pandemics
rearrangement= drift, which leads to seasonal epidemics

patients are susceptible to viral PNA and serious bacterial infections with s. aureus, s. pneumoniae while they are infected with influenza

mechanism of action for zanamivir, oseltamavir

inhibit neuraminidase
virion not released from host cell
use only in severe influenza, must be administered within 24 hrs of symptom onset

Paramyxovirus- parainfluenza

ss-RNA linear, nonsegmented
enveloped
helical

parainfluenza virus- croup
seal- like barking cough, inspiratory stridor that mimics asthma
steeple sign on xray
pulsus paradoxus secondary to upper airway obstruction

paramyxovirus- respiratory syncytial virus

ss-RNA linear, nonsegmental, enveloped, helical bronchiolitis +/- PNA in the small bronchioli of babies winter brassy cough, wheezing, respiratory distress passive immunization with palivizumab (monoclonal RSV immunoglobulin), monthly during the winter months in premature infants, or infants who have chronic lung disease treatment: supportive NOT ribavirin

winter viruses

influenza rotavirus RSV

summer viruses

enteroviruses -poliovirus, echovirus, coxsackivirus arbovirus- WNV

Ribavirin

guanosine analog approved for RSV, hepatitis C no longer recommended for RSV side effects: teratogenicity, hemolytic anemia

Rubeola- paramyxovirus

ss-RNA linear, nonsegmental, enveloped, helical cough coryza (runny nose) conjunctivitis maculopapular rash descending from head to toe Koplik spots early on (blue grey spots on buccal mucosa, surrounded by a base of red complications- years later there may be subacute sclerosing panencephalitis (SSPE), or giant cell PNA (immunocompromised host)

Mumps- paramyxovirus

ss(-)RNA linear, nonsegmented, enveloped, helical parotitis, orchitis (possible future sterility), meningitis

Viral meningitis

coxsackievirus echovirus enterovirus mumps virus

Rhabdovirus- rabies

ss(-) linear RNA, enveloped, helical transmission from bat, raccoon, skunk, dog to human infection is retrigrade vie neurons and ACHR to hippocampus and purkinke cells of cerebellum Negri bodies are eosinophilic cytoplasmic inclusions symptoms manifest months to years later fever/malaise/n/v progresses to hydrophobia, photophobia, agitation, hypersalivation progresses to coma and death

Bunyavirus- hantavirus

ss(-) 3 segments of RNA, enveloped, helical ``` hemorrhagic fever pulmonary syndrome -fever -progressive pulmonary edema -respiratory failure ``` spread by aerosolized deer mouse urine

segmented viruses

Bunyaviruses Orthomyxoviruses Arenaviruses Reoviruses

mouse urine

lassa virus (Arenavirus) LCMV (arenavirus) hantavirus

Filoviruses

ss-RNA, linear, enveloped, helical Ebola and Marburg viruses Ebola spread through fluids fever, HA, myalgia leading to vomiting, diarrhea, fluid loss, electrolyte imbalance, multiorgan failure, shock, death treatment: supportive prevention is key (contact and droplet isolation to prevent transmission of someone has been exposed)

characteristic "barking seal" cough

croup

childhood diarrhea in winter months

rotavirus

asthma- sounding infection in infants (esp preemies)

paramyxovirus | RSV