Polio

Question 1

Polio - the basics

Answer 1

• 20C pandemic
• 1905, epidemics identified in Sweden (Otto Ivar Wickman)
  – Delayed infection as a consequence of improved hygiene probably causing disease
  emergence.
• Epidemics

Question 2

Polio - the specifics

Answer 2

– 1909: Virus first identified
– 1948: Enders, Weller & Robbins grew the virus
– 1953: large-scale outbreak in the USA
– 1955: Salk vaccine
– 1961: Sabin vaccine
– 1988: World Health Assembly targeted eradication

Question 3

Polio: long-term impact

Answer 3

• high child morbidity & mortality
• severe sequalae among survivors, lasting entire lives
• impacted public health policies; esp. vaccination
• changing attitudes to medical research; pressure groups, fundraising

Question 4

Polio virus

Answer 4

• Picorna virus
• 3 serotypes, each of which use the same receptor
• humans only known natural host
• simple molecular machine

Question 5

Picorna virus

Answer 5

• +ve strand RNA
• species C Enterovirus

Question 6

Polio genome

Answer 6

• ~7,500nt (TINY)
• 3 regions (P1, P2, P3)
• 4 structural proteins:
• 7 nonstructural proteins

Question 7

Polio structural proteins

Answer 7

• VP1, VP2, VP3, VP4
• make the capsid

Question 8

Polio non-structural proteins

Answer 8

• P1: replication, protein processing, and cell biology of viral infection

Question 9

Polio virion

Answer 9

60 copies of each capsid protein

Question 10

Polio serotypes

Answer 10

• CD155; PVR gene
• found in Old World Monkeys & higher primates

Question 11

Genetic structure of the polio virus

Answer 11

• VPg protein covalently linked to the 5’ end of the RNA strand.
• 5’: contains RNA UTR IRES.
• single ORF; cleaved to form the separate proteins.
• obligate parasite of human ribosomes

Question 12

Polio IRES

Answer 12

• highly structured
• 750nt nc region
• internal ribosome entry site