Human Polioviruses Flashcards
1
Q
Classification
A
Family: Picornaviridae
Genus: Enterovirus
Species: polio virus
2
Q
Characteristics
A
Naked nucleocapsid
+ssRNA
No virion polymerase
Acid stable
Cytoplasmic replication
!!! Three serotypes: type 1, 2 and 3 !!!
3
Q
Transmission
A
Fecal-oral route
4
Q
Pathogenesis
A
Virus replicates:
- pharynx
- Payer patches of GIT (2 - 3 weeks)
> spread to local lymph nodes
then spreads through the bloodstream to the CNS
- most infections are asymptomatic or very mild
- aseptic meningitis is more frequent than paralytic polymyelitis
> paralysis is the result of death of motor neurons (mainly anterior horn of spinal cord) - pathogenesis of postpolio syndrome is unknown
5
Q
Diseases
A
> Paralytic poliomyelitis
- poliomyelitis has been eradicated in Western Hemisphere and many other countries
- asymmetric paralysis that can lead to respiratory insufficiency
> Aseptic meningitis: affects mainly children!
- CSF glucose is normal
- CSF has elevated protein content
6
Q
Microbiological diagnosis
A
- isolation of the virus from spinal fluid indicates infection of the CNS
- isolation of virus from stool indicates infection but not necessarily disease
(Found in GIT of asymptomatic carriers [acid stable virus]) - detected in cell culture by CPE
- serological year: neutralisation
- a significant rise in antibody titer in convalescent-phase serum is also diagnostic
7
Q
Treatment and prevention
A
Treatment: no antiviral therapy
Prevention:
- killed (Salk) vaccine —> IV»_space;> only forms IgG
- live, attenuated (Sabin) vaccinе»_space;> oral form —> gives rise to IgA and IgG
Current US recommendation is to use killed vaccine , as the live vaccine can be passed in faeces and potential infection
