Lec 16 - Viral Vaccines 1

Question 1

first origins of vaccination

Answer 1

variolation
2000yrs ago, inhalation of powdered small pox scabs

Question 2

how did variolation develop in the 1700s

Answer 2

scab crust from mild smallpox cases inoculated into the skin
= a form of live attenuated vaccine

Question 3

Edward Jenner

Answer 3

first successful vaccination
cowpox material to prevent smallpox
formed the basis of the modern smallpox vaccine

Question 4

why was the initial vaccine by eddy jenner not the best

Answer 4

unstable
lost potency over time

so they freeze dried it = could be more widely distributed

Question 5

what was first inactivated vaccine

Answer 5

by Pasteur and Roux
against rabies
based on dried spine material of infected rabbits

Question 6

how has the rabies vaccine developed

Answer 6

now use human cell lines to generate the material
- purified via a filter
- inactivated by beta-propriolactone

Question 7

5 types of vaccines

Answer 7

• whole inactivated virus
• attenuated live virus
• purified subunits
• DNA (not approved in humans yet)
• RNA

Question 8

which vaccine gives lifelong immunity

Answer 8

attenuated live virus

Question 9

ways to get an attenuated live virus

Answer 9

• using related virus from another animal
  -administration of pathogenic/attenuated virus through unnatural route
• passage of virus through unnatural host
• passage of virus at sub optimal temp.

Question 10

problems with live attenuated

Answer 10

• under attenuation
• reversion of the mutations
• instability
• heat labile
  (hard to distribute)
• contamination of viral cell culture

Question 11

example of virus produced via the use of unnatural host cells and sub optimal temperatures

Answer 11

measles vaccine

Question 12

common chemicals used to inactivate viruses

Answer 12

formalin
beta-propiolactone

Question 13

what do inactivated vaccines require to stay effficient

Answer 13

boosters

Question 14

general dose needed for live vs attenuated

Answer 14

live = low
inactivated = high

Question 15

what is adjuvant

Answer 15

a substance that enhances the body’s immune response to an antigen

Question 16

antibody response from live vs attenuated

Answer 16

live = good = IgG from bloodstream, IgA from mucosal membranes
and cell mediated response

attenuated = IgG only, no cell mediated response

Question 17

why doesnt live vaccine need boosters

Answer 17

strong enough immune response on its own
also
replicates itself (unlike inactive) = amplifies the immune response itself

Question 18

what is the current polio vaccine given

Answer 18

Inactivated Polio vaccines IPV

Question 19

what kind of immunity does IPV give

Answer 19

IgG mediated immunity in blood
so can still injest polio and it replicates in gut
but prevents progression to CNS via blood

= need 3 doses for 99% immunity

Question 20

OPV

Answer 20

trivalent oral polio vaccine
the live attenuated version which targeted all 3 serotypes

Question 21

primary attenuating mutation of OPV

Answer 21

One of the mutations was the virus had reduced ability to translate its RNA template in the host cell

Question 22

how is OPV effiecient in protecting non-vaccinated individuals

Answer 22

live virus shedding in stools of vaccinated people
so non vaccinated people gaining immunity

Question 23

what serotypes of polio still around

Answer 23

3 serotypes
2 have been eradicated
only Type 1 still circulating

Question 24

how many cases of paralytic polio occured with OPV

Answer 24

1 in 750,000

but in areas where chance of getting gpolio was 1 in 100, was deemed acceptable risk

then was replaced by IPV

Question 25

why the big move to make subunit vaccines

Answer 25

other ones are hard to produce, expensive, need to culture lots of virus
and lots of surveillance needed

this ones cheaper
and
on a full virus one, the other viral proteins can dampen the response to protective antigens

Question 26

1st subunit vaccine made

Answer 26

hep B vaccine
the excess coat proteins made in the blood of a HepB patient can be purified
but very risky

Question 27

1st subunit vaccine made

Answer 27

hep B vaccine
the excess coat proteins made in the blood of a HepB patient can be purified
but very risky

Question 28

what is used now to make the hep B vaccine

Answer 28

the gene encoding the antigen is cloned into plasmid