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ID Unit 3 > Picorno > Flashcards

Picorno Flashcards

1
Q

What is special about the different species in the Enterovirus genus group?

A

Can get genetic recombination (in same species) can occur quite regularly
- Can also get cross species genetic recombination but not as bueno

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2
Q

Serotypes

A

Host: has neutralizing antibodies
Virus: has antigenic epitopes of capsid proteins

Epitopes on capsid proteins recognized by antibodies that neutralize infectivity.

Immunity against 1 serotype is not protective against other serotypes

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3
Q

Most common respiratory virus causing infxn in hospitalized pts with Acute Respiratory Illness of all ages

A

Picornaviruses
(enterovirus & rhinoviruses)

~25 of all pts

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4
Q

When are seasonal epidemics of enterovirus disease in US?

A

June-Nov
(Peak late summer-Early fall)

*other virus in summer: WNV

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5
Q

Most common cause of meningitis in: newborns (0-6 mo)

A

GBS

E. coli

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6
Q

Most common cause of meningitis in: children (6mo-6yrs)

A
  1. S. pneumo
  2. Neisseria meningitidis
  3. H influ B
  4. Enterovirus
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7
Q

Most common cause of meningitis in:

6-60 yrs

A
  1. Enterovirus!
  2. S. pneumo
  3. N. Meningitidis
  4. HSV
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8
Q

Do picornavirus have replication proteins in virus particles? Are they naked or encapsulated? What does that mean?

A

Nope - they are mRNA organisms that replicate via RNA intermediates in the cytoplasm of your cells,
(but they do bring with them RNA pol)

They are a naked virus - very stable and resistace to inactivation in environment

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9
Q

ECHO

A 
Enteric
Cytopathic 
Human
Orphan virus 
(can detect in healthy babies - most of time doesnt cause disease)
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10
Q

Neutralizing IgG antibodies in the blood will block viremia and disease, what can it not block?

A

Infection

not at mucosal surfaces, das where IgA works

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11
Q

How often is poliovirus assymptomatic?

A

90-95%

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12
Q

How does poliovirus infect the CNS?

A

day 7-14 after igestion of fecal material

Can cross BBB or retrograde axonal infxn
(up motor neurons innervating skeletal muscle)
- Motor neurons kills –> acute flaccid paralysis (AFP)

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13
Q

Which polio vaccine is used in US? IPV or OPV?

A

IPV

  • Inactivated poliovirus vaccine
  • Killed + injected
  • Protective systemic immunity IgG

IPV failes to block infxn + person to person transmission

*more expensive than OPV
10x more

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14
Q

Which vaccine has better mucosal immunity, IPV or OPV?

- TIme required for the attenuating mutations to revert in children

A

OPV

  • Oral poliovirus vaccine
  • more used in world (not US)
  • 48 hrs - time req for attenuating mutations to revert in children
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15
Q

Who getting OPV can end up with Vaccine associated paralytic poliomyelitis (VAPP)?

A

Infants, first dose
- they have much higher risk

Contacts of OPV recipients (non-immune, first exposure)

Immunocompromised

*OPV is unstable

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16
Q

Which serotype of OPV can revert?

A 
All 3 (1,2,3)
but Poliovirus 1 reverts less readily

*2 and 3 have been eradicated

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17
Q

Only hu pathogen purposely eradicated to date

- what factors contributed?

A

smallpox
Rinderpest

*but still exists in lab freezers

*smallpox was easy to detect, bc people present with symptoms 100% of the time
- polio is harder to find
Virus replicated only in hu
Efficacious vaccine

18
Q

Who still receives smallpox vaccinations?

A

US military personnel

19
Q

Where is polio eradication most impacted (inhibited)?

A 
Pakistan
Afghaistan
Israel
Syria
- Type I poliovirus

*Areas of disrupted public health relations

20
Q

What is set to become the second hu disease in hx after smallpox to be eradicated?

A

Guinea worm disease (Dracunculus medinisis)

  • W/o any vaccine or medical tx
21
Q

Resevoir for poliovirus

A

only infects hu
(no non hu)
- can only survive for days-weeks outside hu host
- if we vaccinate enough people, poliovirus will disappear from the environment due to the absence of susceptible hosts

22
Q

What do we use to find poliovirus?

A

acute flaccid paralysis (AFP) surveillance

Get sick –> go to sleep –> wake up with AFP –> get two fecal samples 24-48 hours apart within 14 days onset of paralysis

*only 1 of ~100 infected indiv develop paralysis

23
Q

BIvalent OPV induces protection against what?

A

Serotype 1 & 3 more frequently than trivalent OPV
- esp against type 1 poliovirus
- remember type 1 had more attenuating mutations than 2 + 3.
(Poliovirus types compete with eachother for the cells they infect)

24
Q

Does bivalet or trivalent OPV work better?

A

Bivalent (1,3)
- instead of replicating and trying to outcompete the other types of poliovirus for infecting cells, it can focus on “activating” and induce an antigenic response

(in trivalent vaccine, poliovirus 1,2,3 are constantly trying to outcompete eachother)

less immunity to type 2

25
Q

Why is Acute flaccid paralysis going up but polio cases going down?

A

better surveillance of polio via fecal samples

- most are now caused by non-polio viruses

26
Q

Without neutralizing abs against poliovirus nucleocapsid in immunodeficient indiv, what to worry about?

A

OPV can persistently shed in feces

27
Q

What serotypes of OPV revert to produe cVDPVs

A

all of themmm

*all of them can cause outbreaks of AFP as well

28
Q

How many years did the PV vaccine strain circulate from person to person if the sequencing revealed that the VDPV had 3% nucleotide variation from its corresponding OPV strain

A

3 years

1% per year

29
Q

Currently the best way to eliminate ongoing circulation of cVDPV2 in a community is vaccination with

A

Trivalent OPV

trivalent IPV cannot give you mucosal immunity

30
Q

Difference between viral and bacterial meningitis?

A

Viral meningitis is not life threatening and recover w/o therapeutic interventions

31
Q

How many cases of acute myocarditis is due to enteroviruses?

A

1/3 of all cases

*10% of cases progress to chronic dilated cardiomyopathy

32
Q

Most frequent cause of common colds

A

rhinovirus

33
Q

(+) strand RNA viruses can be (3):

A
  1. Packaged into nucleocapsids –> virion particles
  2. Become mRNA molecules to amplify the infxn w/in the cytoplasm
  3. Serve as template RNAs for more (-) strand RNA synthesis
34
Q

(+) strand RNA virion particles do not contain replicase proteins, but their genomic RNA fxns as ____ upon release into the cytoplasm. Significance?

A

mRNA
–> codes for viral replicase which is composed of:
RNA dependent RNA pol, other enzymatic proteins (RNA helicase, capping enzymes, proteases)

35
Q

Why are picornavirus infxns often innocuous?

A

The patient’s acquired immune response typically produces serotype-specific neutralizing antibodies b4 the virus spreads from mucosal portals of entry to critical target organs.

36
Q

Poliovirus

  • Neutralizing ab binds:
  • Does life long immunity occur following infxn?
  • What doesnt humoral immunity protect against?
A

Nucleocapsid

Yes

GI infxn (ie no sterilizing immunity)

37
Q

IPV

  • Killed or live
  • Advantages (3)
  • Disadvantages (3)
A

Killed virus vaccine

Adv:
- induces protective systemic IgM/IgG
- Absence of live virus prevents reversion of virus in the vaccine
- Acceptable for immunocompromised
(no VAPP)

Disadv:

  • Cost
  • Requires injxn
  • Poor mucosal immunity
38
Q

OPV

  • Killed or live
  • Advantages (3)
  • Disadvantages (3)
A

Live attenuated given orally

Adv:

  • Inexpensive
  • EZ admin (oral)
  • Induces mucosal immunity (IgA) and systemic IgM/IgG

Disadv:
- Attenuated vaccine virus commonly reverts to neurovirulent forms during replication in vaccines
(VAPP in vaccinees)
- Revertant virus is passed in the stool of vaccinees and frequently infects contacts
(VAPP in susceptible contacts of vacinnees)

39
Q

CDC recommendation for poliovirus vaccination in infants in 1997

A

Two doses of IPV followed by two doses of OPV

First dose (IPV): 
6-12 weeks of age
Second dose (IPV): 
6-8 weeks after 1st dose

Third and fourth dose (OPV)
Age 2 and 4

*note that in 2000, CDC wants IPV only in US

40
Q

Goal of ceasing OPV poliovirus vaccination

A

After a period of 2/m years of surveillance in which no wildtype poliovirus is found, completely cease OPV poliovirus vaccination simultaneously around the world.
- Goal: 2019

41
Q

When should stool samples be taken in cases of AFP when polio is suspected?

A

w/in first two weeks after onset of paralysis

- highest [ ] of poliovirus in stools

ID Unit 3 (12 decks)

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