Poliovirus

Question 1

Micro details of Poliovirus

Answer 1

Nonenveloped icosahedral capsid

• positive ss RNA genome
• 3 serotypes

Question 2

Poliovirus reservoir and transmission

Answer 2

humans are only reservoir

• fecal-oral spread
• MC in summer months

Question 3

Incubation period of poliovirus and how does it attack the body

Answer 3

• 7-14 days
• initial replication in lymphoid tissues of pharynx and gut
• secondary spread is viremic and spreads to CNS
• motor neurons are destroyed by virus replication

Question 4

What are the types of diseases of poliovirus

Answer 4

1. Abortive poliomyelitis
2. Aseptic meningitis (nonparalytic)
3. Paralytic poliomyelitis - risk of paralysis increases w/ age, any paralysis after 6 months is permanent

Question 5

What is post-polio syndrome?

Answer 5

increased weakening of muscles later in life

Question 6

How to dx polio?

Answer 6

1. Specimen collection sites - stool, rectal swabs, throat swabs, CSF
2. Neutralization assays
3. Vaccine strains can be distinguised from wild virus using specific antibodies

Question 7

Control of polio

Answer 7

1. inactivated w/ formaldehyde or chlorine
2. resistant to detergents and ethanol
3. both inactivated and live vaccines exist
4. US - use inactivated only

Question 8

SALK IPV - adv and disadv

Answer 8

Adv - formalin inactivation prevents reversion to virulence

Disadv - 4 subQ injections, protects against paralysis but not spread of wild virus

Question 9

Who can’t use SALK IPV

Answer 9

those allergic to neomycin, streptomycin, or polymyxin B

Question 10

Sabin Live OPV - adv and disadv

Answer 10

Adv - cheap, oral admin, protects against paralysis AND spread of wild virus
Disadv- can revert to virulence during preparation or during shedding by recipients