Picorno Flashcards
What is special about the different species in the Enterovirus genus group?
Can get genetic recombination (in same species) can occur quite regularly
- Can also get cross species genetic recombination but not as bueno
Serotypes
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
Most common respiratory virus causing infxn in hospitalized pts with Acute Respiratory Illness of all ages
Picornaviruses
(enterovirus & rhinoviruses)
~25 of all pts
When are seasonal epidemics of enterovirus disease in US?
June-Nov
(Peak late summer-Early fall)
*other virus in summer: WNV
Most common cause of meningitis in: newborns (0-6 mo)
GBS
E. coli
Most common cause of meningitis in: children (6mo-6yrs)
- S. pneumo
- Neisseria meningitidis
- H influ B
- Enterovirus
Most common cause of meningitis in:
6-60 yrs
- Enterovirus!
- S. pneumo
- N. Meningitidis
- HSV
Do picornavirus have replication proteins in virus particles? Are they naked or encapsulated? What does that mean?
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
ECHO
Enteric Cytopathic Human Orphan virus (can detect in healthy babies - most of time doesnt cause disease)
Neutralizing IgG antibodies in the blood will block viremia and disease, what can it not block?
Infection
not at mucosal surfaces, das where IgA works
How often is poliovirus assymptomatic?
90-95%
How does poliovirus infect the CNS?
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)
Which polio vaccine is used in US? IPV or OPV?
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
Which vaccine has better mucosal immunity, IPV or OPV?
- TIme required for the attenuating mutations to revert in children
OPV
- Oral poliovirus vaccine
- more used in world (not US)
- 48 hrs - time req for attenuating mutations to revert in children
Who getting OPV can end up with Vaccine associated paralytic poliomyelitis (VAPP)?
Infants, first dose
- they have much higher risk
Contacts of OPV recipients (non-immune, first exposure)
Immunocompromised
*OPV is unstable
Which serotype of OPV can revert?
All 3 (1,2,3) but Poliovirus 1 reverts less readily
*2 and 3 have been eradicated
Only hu pathogen purposely eradicated to date
- what factors contributed?
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
Who still receives smallpox vaccinations?
US military personnel
Where is polio eradication most impacted (inhibited)?
Pakistan Afghaistan Israel Syria - Type I poliovirus
*Areas of disrupted public health relations
What is set to become the second hu disease in hx after smallpox to be eradicated?
Guinea worm disease (Dracunculus medinisis)
- W/o any vaccine or medical tx
Resevoir for poliovirus
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
What do we use to find poliovirus?
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
BIvalent OPV induces protection against what?
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)
Does bivalet or trivalent OPV work better?
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
