CNS Viruses -- Poliovirus

Question 1

Structure?

Answer 1

Nonenveloped, icosahedral capsid, 7.5kb ssRNA (+)-sense genome

Question 2

Type of paralysis?

Answer 2

Flaccid

Question 3

How is it spread? When?

Answer 3

Fecal-oral; summer months

Question 4

Reservoir?

Answer 4

Humans

Question 5

Site of initial replication?

Answer 5

Lymphoid tissue of pharynx and gut

Question 6

How does secondary spread occur? Target?

Answer 6

Viremia; motor neurons

Question 7

If infection exceeds subclinical manifestation, what three types occur?

Answer 7

Abortive (no CNS, MC), Aseptic meningitis (nonparalytic), Paralytic

Question 8

What age group do most infections occur in?

Answer 8

<5 y/o

Question 9

What age group is most predisposed to paralysis?

Answer 9

Adults

Question 10

How is poliovirus best inactivated? What is it resistant to?

Answer 10

Formaldehyde or cholrine; detergents and ethanol

Question 11

Can the IPV revert to virulence? What’s its disadvantage?

Answer 11

No; can’t prevent spread of wild virus

Question 12

What’s the benefit of the OPV? Disadvantage?

Answer 12

Protects against paralysis and spread of all 3 serotypes; can revert