Case Study Comparison Chart: Polio

Question 1

what is the full name for polio?

Answer 1

poliomyelitis

Question 2

what is the causative agent of poliomyelitis

Answer 2

polio virus

Question 3

describe the structure of polio virus (4)

Answer 3

• icosahedral
• ss+RNA (does not package replicase)
• nkd (resists degradation and can withstand stomach acid)
• enterovirus (oral-fecal route)

Question 4

describe the different stages of a polio infection (4)

Answer 4

1. digestive tract
2. lymphatic stage
3. viremia stage (blood), crosses blood-brain barrier to
4. neural stage (CNS)

Question 5

describe the general distribution (%) of polio symptoms

Answer 5

99% of people are asymptomatic or mild symptoms

1% get paralytic polio

Question 6

can asymptomatic people transmit polio? if so, how and for how long?

Answer 6

yes. in feces, for 4-6 weeks.

Question 7

how to detect virus in fecal sample?

Answer 7

direct ELISA test

Question 8

describe some symptoms of paralytic polio (4 groups)

Answer 8

• muscle weakness (atrophy)
• flaccid paralysis in limbs and chest
• headache, fever, stiffness in neck (inflammation)
• GI symptoms

Question 9

what happens to an infected motor neuron? why is that significant?

Answer 9

it dies, cutting off the signals to muscles

Question 10

why is polio hard to study?

Answer 10

• hardy: resistant to degradation
• dangerous. Cutter incident, humans are the only host.

Question 11

what is one example of why polio is ~dangerous~ to study?

Answer 11

the Cutter incident

Question 12

what happened in the Cutter incident?

Answer 12

Cutter was a lab that produced vaccines. Some batches of Salk’s polio vaccine contained live virus which led to tons of people being infected upon vaccination and 5 children died.

Question 13

what happens in post polio syndrome?

Answer 13

motor neurons compensate for the motor neurons that were killed when the body was infected with polio

Question 14

what eventually happens to the motor neurons that don’t die upon infection?

Answer 14

they die later because they’ve spent their lifetimes compensating for the missing neighboring motor neurons that died

Question 15

who is most susceptible to polio infection?

Answer 15

children under 5

Question 16

who is most susceptible to paralysis?

Answer 16

older children/teens and young adults

Question 17

what puts people at risk for contracting polio? (2)

Answer 17

• poor water sanitation
• decreased vaccine rates

Question 18

how to prevent polio? (one word)

Answer 18

vaccines

Question 19

what vaccines are available for polio?

Answer 19

OPV and IPV

Question 20

who developed the OPV? what does it stand for?

Answer 20

Sabin. Oral polio vaccine.

Question 21

which antibodies respond when the OPV is administered?

Answer 21

IgG and IgA

Question 22

why does OPV prevent the spread of polio?

Answer 22

IgA replicates in mucous membranes, neutralizes the virus in the mucous membranes so not only does it not spread through feces, but the vaccine spreads through feces instead

Question 23

how many doses are required for OPV?

Answer 23

one

Question 24

how many doses are required for IPV?

Answer 24

multiple

Question 25

OPV: attenuated or inactivated?

Answer 25

attenuated

Question 26

cons of OPV?

Answer 26

attenuated vaccine, meaning a strain can mutate to virulent form (very uncommon, 1/24 mil.)

Question 27

who developed the IPV? what does it stand for?

Answer 27

Salk. Inactivated polio vaccine

Question 28

which antibodies respond when the IPV is administered?

Answer 28

IgG

Question 29

IPV: attenuated or inactivated?

Answer 29

inactivated

Question 30

did the Cutter incident occur with the OPV or IPV?

Answer 30

Salk: IPV

Question 31

List the 6 stages of a polio infection/life cycle:

Answer 31

1. endocytosis 2. release + protein synthesis 3. replicase made 4. replication of RNA 5. translation packaging 6. cell lysis to release viral particles

Question 32

which surface protein does polio virus bind to?

Answer 32

host cell receptor CD155