RNA viruses

Question 1

reoviruses

Answer 1

rotavirus
coltivirus

non-enveloped, icosahedral, dsRNA virus

Question 2

Reovirus- Rotavirus

Answer 2

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

Question 3

Reo-virus Coltivirus

Answer 3

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

Question 4

Picornavirus- enterovirus

Answer 4

non-enveloped, ss+ linear, icosahedral

enteroviruses include poliovirus, coxsackivirus, and echovirus

primary spread via feco-oral route, alternatively resp secretions

Question 5

polio

Answer 5

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

1. salk vaccine- killed and injected
2. sabin vaccine- live and eaten

Question 6

Echovirus

Answer 6

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)

Question 7

Coxsackivirus

Answer 7

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

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

Question 8

HAV

Answer 8

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

feco-oral spread

Question 9

Rhinovirus

Answer 9

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)

Question 10

Calicivirus- Norwalk virus

Answer 10

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

cruise ship
nursing home

Question 11

Flavivirus

Answer 11

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

Question 12

Flavivirus- Arbovirus- Yellow fever virus

Answer 12

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

Question 13

Flavivirus- Arbovirus- Dengue virus

Answer 13

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

Question 14

Flavivirus- arbovirus- WNV

Answer 14

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

Question 15

Arboviruses that cause encephalitis

Answer 15

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

Question 16

flavivirus- arbovirus-st. louis encephalitis

Answer 16

ss+RNA linear, enveloped, icosahedral

arbovirus (mosquito- born)

can cause encephalitis

Question 17

Togavirus- Rubella

Answer 17

ss+linear RNA, enveloped, icosahedral

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

blueberry muffin

Question 18

Coronavirus

Answer 18

enveloped, ss+linear, helical

“common cold” and SARS

Question 19

common cold

Answer 19

rhinovirus

coronavirus

Question 20

Retrovirus- Human T cell leukemia virus

Answer 20

enveloped, SS+linear RNA, 2 copies, icosahedral

uses reverse transcriptase

Question 21

infects motor neurons of the anterior horn

Answer 21

poliovirus

WNV

Question 22

Orthomyxovirus- influenza

Answer 22

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

Question 23

mechanism of action for zanamivir, oseltamavir

Answer 23

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

Question 24

Paramyxovirus- parainfluenza

Answer 24

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

Question 25

paramyxovirus- respiratory syncytial virus

Answer 25

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

Question 26

winter viruses

Answer 26

influenza
rotavirus
RSV

Question 27

summer viruses

Answer 27

enteroviruses
-poliovirus, echovirus, coxsackivirus

arbovirus- WNV

Question 28

Ribavirin

Answer 28

guanosine analog
approved for RSV, hepatitis C

no longer recommended for RSV

side effects:
teratogenicity, hemolytic anemia

Question 29

Rubeola- paramyxovirus

Answer 29

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)

Question 30

Mumps- paramyxovirus

Answer 30

ss(-)RNA linear, nonsegmented, enveloped, helical

parotitis, orchitis (possible future sterility), meningitis

Question 31

Viral meningitis

Answer 31

coxsackievirus
echovirus
enterovirus
mumps virus

Question 32

Rhabdovirus- rabies

Answer 32

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

Question 33

Bunyavirus- hantavirus

Answer 33

ss(-) 3 segments of RNA, enveloped, helical

hemorrhagic fever
pulmonary syndrome
-fever
-progressive pulmonary edema
-respiratory failure

spread by aerosolized deer mouse urine

Question 34

segmented viruses

Answer 34

Bunyaviruses
Orthomyxoviruses
Arenaviruses
Reoviruses

Question 35

mouse urine

Answer 35

lassa virus (Arenavirus)
LCMV (arenavirus)
hantavirus

Question 36

Filoviruses

Answer 36

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)

Question 37

characteristic “barking seal” cough

Answer 37

croup

Question 38

childhood diarrhea in winter months

Answer 38

rotavirus

Question 39

asthma- sounding infection in infants (esp preemies)

Answer 39

paramyxovirus

RSV