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Micro > 07a: Picornaviruses > Flashcards

07a: Picornaviruses Flashcards

1
Q

Picornavirus: (enveloped/non-enveloped) with (ss/ds) (RNA/DNA). Also (helical/icosahedral/complex) capsid.

A

Non-enveloped;
ssRNA (pos-sense strand)

Icosahedral (and v. stable)

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2
Q

Picornavirus family contains which medically significant genera?

A
  1. Enterovirus
  2. Rhinovirus
  3. Heparnavirus (not important for this class)
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3
Q

T/F: Entero- and rhino-viruses are both resistant to inactivation by heat and low pH.

A

False - both resistant to heat inactivation, but only enterovirus resistant to low pH

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4
Q

T/F: Entero- and rhino-viruses are both resistant to inactivation by detergent.

A

True

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5
Q

T/F: Enteroviruses are stable in presence of proteases and bile.

A

True

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6
Q

Binding site of (X) virus is a canyon-like structure at the vertices of the (capsid/envelope). This prevents (Y) from accessing the binding site.

A

X = picornavirus
Capsid (icosahedron)
Y = Ab (too big)

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7
Q

(X) virus family enters host via viropexis. What occurs immediately after entry into cell?

A

X = picornavirus

Genome uncoated and plus-sense RNA translated immediately

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8
Q

Following translation of picornavirus mRNA in (nucleus/cytoplasm), (X) event takes place. The (host/viral) (Y) Polymerase then synthesizes (plus/neg)-sense RNA template.

A

Cytoplasm;
X = polyprotein cleavage (by viral proteases)

Viral; X = RNA-dep-RNA
Neg-sense

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9
Q

T/F: Replication and assembly of picornaviruses take place in cytoplasm.

A

True

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10
Q

T/F: Picornavirus virions released either by budding or lysis.

A

False - lysis

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11
Q

Enteroviruses usually transmitted via (X) route. Outbreaks typically occur in which settings/seasons?

A

X = fecal-oral

Crowded conditions (schools/daycares) and in the summer

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12
Q

Enterovirus infection is often presented with (X) symptoms.

A

X = no

But viral shedding can occur for up to a month

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13
Q

T/F: Enteroviruses are human pathogens that typically cause enteric (GI) disease.

A

False

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14
Q

Poliovirus, part of the (X) virus genera, infection in (early/late) life causes more severe disease.

A

X = enterovirus (in picornavirus family)

Late

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15
Q

Coxsackievirus, part of the (X) virus genera, infection in (early/late) life causes more severe disease.

A

X = enterovirus (in picornavirus family)

Late

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16
Q

(Newborns/adults/elderly) are at the highest risk of serious enterovirus infection.

A

Newborns and neonates

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17
Q

Poliovirus has (broad/narrow) tissue tropism. This is because it:

A

Narrow;

Recognizes receptor found on only few/certain cell types

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18
Q

T/F: All enteroviruses has narrow tissue tropism.

A

False - poliovirus does; others are relatively broad

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19
Q

Enterovirus: primary replication occurs in (X). Later, replication occurs in (Y) of intestinal tract.

A

X = lymphoid tissues/mucosa of pharynx/tonsils

Y = lymphoid tissue of Peyer’s patches

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20
Q

T/F: Enterovirus infection pathogenesis, if symptoms present, typically due to immunopathogenesis (not viral cytopathic effects).

A

False

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21
Q

Enterovirus infection: viral shedding may occur for (X) days. This (can/can’t) be reduced if viral-specific Ab are present.

A

X = 30

Can’t (shedding occurs despite Ab presence)

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22
Q

T/F: Enterovirus infection provides life-long immunity.

A

True - but type-specific

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23
Q

Enterovirus: (X) protective response plays major role in preventing initial establishment of
infection in the oropharynx and GI tract.

A

X = Intestinal IgA

24
Q

Enterovirus: (X) protective response plays major role in preventing viremic spread.

A

X = Serum IgG

25
Q

T/F: Poliovirus causes asymptomatic illness 90% of the time in unvaccinated people.

A

True!

26
Q

Most severe outcome of poliovirus infection is:

A

Paralytic poliomyelitis (0.2% in unvacc people)

27
Q

Aside from asymptomatic illness, list the three illnesses that can be caused by poliovirus in unvaccinated people.

A
  1. Abortive poliomyelitis (5%)
  2. Nonparalytic poliomyelitis (aseptic meningitis; 2%)
  3. Paralytic poliomyelitis (0.2%)
28
Q

Poliovirus transmitted via (X) route. There are (Y) number of serotypes and vaccines to how many of those?

A 
X = fecal-oral
Y = 3

2 vaccines that contain all 3 serotypes

29
Q

Paralytic poliomyelitis: generally characterized by an (symmetrical/asymmetrical) (X) with (ipsi/bi/contra)-lateral sensory loss.

A

Asymmetrical
X = flaccid paralysis

NO sensory loss

30
Q

Which critical cells are dying in paralytic polio to produce the characteristic symptoms?

A

Anterior horn neurons in SC

31
Q

T/F: Paralytic polio always results in death within the next few weeks.

A

False - paralysis progression can be followed by complete recovery, residual paralysis, or death

32
Q

Bulbar polio results when the virus affects (X), resulting in which symptom?

A

X = brain stem

Respiratory paralysis

33
Q

T/F: When CNS invasion occurs in polio, the virus can be found in stool.

A

True

34
Q

When prodrome/minor illness is taking place in poliovirus infection, can the organism be detected in stool?

A

No, not yet

35
Q

Treatment for polio primarily involves (X).

A

X = symptomatic relief, resp support, physiotherapy

36
Q

T/F: There’s no standard antiviral therapy for polio.

A

True - but pleconaril available on limited basis

37
Q

Sabin vaccine for (X) infection is (live/dead). List some advantages.

A

X = poliovirus
Live, attenuated

  1. Replicates in GI (IgA produced)
  2. Easy to administer (oral)
  3. Longer immunity
38
Q

Sabin vaccine: list some disadvantages.

A
  1. Can revert to virulent strain (cause polio)
  2. Other enteroviruses interfere with replication
  3. Must keep cold
39
Q

Salk vaccine for (X) infection is (live/dead). How many doses are given?

A

X = poliovirus
Dead

4 doses (in early life, done by age 6 or so)

40
Q

T/F: Salk vaccine is preferred over Sabin vaccine. It’s the only one available in the US.

A

True

41
Q

T/F: One advantage of Salk vaccine is secondary protection by spread to others.

A

False - true of Sabin vaccine

42
Q

T/F: Neonates should be vaccinated for polio a day or two after birth since they are most susceptible to infection.

A

False - first dose at 2 months; maternal Ab protect for about 6 mo.

43
Q

T/F: In case of polio outbreak, quarantine would help control/prevent spread.

A

False - proven ineffective

44
Q

Most common diseases caused by Groups A and B Coxsackievirus:

A
  1. Aseptic meningitis!!
  2. Non-specific URT disease (flu-like)
  3. Rashes
  4. Polio-like paralytic disease (transient)
45
Q

Most common route of transmission of Coxsackievirus is (X). Can also be transmitted via (Y).

A 
X = fecal-oral route
Y = aerosolized droplets
46
Q

Group A Coxsackievirus targets (X) body sites. List the two group-specific diseases it causes.

A

X = skin/mucous membranes

  1. Herpangina
  2. Hand-foot-and-mouth disease
47
Q

T/F: Both group-specific diseases caused by Group A Coxsackievirus are self-limiting.

A

True

48
Q

Herpangina symptoms:

A

Fever, sore throat, tender vesicles in oropharnyx, anorexia, vomiting

(Due to group A Coxsackievirus infection)

49
Q

(X) disease caused by (Y) microorganism: small, tender cutaneous vesicles on palms/soles
and buttocks; ulcers in oral mucosa, mild fever.

A 
X = Hand-foot-and-mouth disease
Y = group A Coxsackievirus
50
Q

List the two group-specific diseases caused by group B Coxsackievirus

A
  1. Pleurodynia

2. Pericarditis/myocarditis

51
Q

T/F: Both group-specific diseases caused by Group B Coxsackievirus are self-limiting.

A

False - can lead to more serious heart damage/failure

52
Q

Most frequent cause of common cold is (X). Infection occurs via which routes/mechanisms?

A

X = rhinovirus

Direct: resp droplets
Indirect: contaminated fomites

53
Q

T/F: Child is more likely to suffer from common cold than adult.

A

True

54
Q

T/F: Rhinovirus replicates best at body T (37oC) in LRT than in cooler T in URT.

A

False - vice versa

55
Q

T/F: Rhinovirus not extremely infectious (requires about 500 virions to initiate serious infection).

A

False! Just 1 virion to initiate infection!

56
Q

T/F: Cell-mediated immunity plays largest role in battling rhinovirus infection

A

False - plays no role..

57
Q

T/F: Nasal IgA and serum IgG are induced by rhinovirus infection.

A

True - but transient and relatively ineffective

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