Contraceptive Vaccines

Question 1

what is the principle of contraceptive vaccines?

Answer 1

To use the immune system to limit fertility

Question 2

what is a contraceptive vaccine?

Answer 2

A vaccine that induces an autoimmune response to components of the reproductive system, leading to infertility / sub fertility.

Question 3

what’s the function of the immune system?

Answer 3

• detects invading agents
• destinguishes them from organisms cells
• responds to/ clears the invading agent

Question 4

why do we need new contraceptives?

Answer 4

current contraceptive options have limitations

Question 5

list the antibodies and their function;

Answer 5

IgM = agglutination, first antibody of immune response

IgG = most abundant in internal fluids

IgA = must abundant in secretions

IgE = antiparasite action, allergies

IgD = mainly on lymphocyte surface

Question 6

Describe the constituents of a vaccine

Answer 6

Antigen

Adjuvant (non-specific activates immune system)

Question 7

What antibodies cross the placenta?

Answer 7

IgG

Question 8

Why do we need new contraceptives?

Answer 8

No new ones in 50 years

Limited ones available and most of them dont reach third world countries or are too expensive

Question 9

Whats a current vaccine that is effective on wild life?

Answer 9

GonaCon

Question 10

Describe Gonacon structure?

Answer 10

• It is GnRH conjugated via two amino acids to KLH (limpet haemocyanin)

(KLH is very soluble and many GnRH may bind)
- Emulsified in mycobacterial and oil adjuvent (contains m.avium-produces memory immune response)

Question 11

What is the purpose of the KLH conjugated to GonaCON?

Answer 11

KLH is foreign and stimulates the immune system, as it is conjugated to GnRH the immune system then starts to attack GnRH thus being effective at making animals infertile.

Question 12

What is KLH replaced by nowadays?

Answer 12

Blue protein

Question 13

What is GonaCon effective against?

Answer 13

White tailed dear
Elk
Wild Horses
Swine
Bison
Domestic Cats
Rats

Question 14

What are things to consider when designing contraceptive drugs in humans?

Answer 14

Human considerations;

• Is it a contraceptive or abortifacient effect (ethics, morals of religious groups/ people etc)
• Reliability
• Reversibility!
• Delivery system (mode, frequency, dont want daily injections!!)

Question 15

What are things to consider when designing contraceptive drugs in animals?

Answer 15

Animal considerations

• Wild/Feral or domestic
• Reliability (can herd immunity be attained?.)
• Reversibility
• Delivery system (mode, frequency)
• Interspecies cross reactivity (will making possum infertile lead to cows also becoming infertile?)

Question 16

What could be potential targets of contraceptive vaccines?

Answer 16

Reproductive Hormones
Gametes
Trophectoderm
Placenta
Milk Proteins

Question 17

Describe reproductive hormones that could be targeted?

Answer 17

GnRH
LH and FSH
Progesterone and Estrogen

Highly Conserved
- Can manipulate these to create subfertility

Considerations;
- Systemic Side effects?

Question 18

Describe how contraceptive vaccines could target ovum?

Answer 18

Ovum

• Could target ZP3 as all ovum have this (highly conserved across species)
• Loss of ZP3 would disrupt ovarian function
• Preventing sperm/oocyte binding

Question 19

Describe how contraceptive vaccines could target sperm

Answer 19

Sperm

• Males or in female reproductive tracts
• Could use systemic or mucousal immunity
• Problem ; high numbers of sperm to target

Question 20

Describe how contraceptive vaccines could target trophectoderm?

Answer 20

• Trophoblast surrounds the pre-implantation blastocyst
• Could prevent implantation
• Antigens are only expressed on preimplantation

Question 21

Describe placental targets for contraceptive vaccines

Answer 21

• Abortifaction

- Ethical issues about using it in humans or animals

Question 22

Describe how milk production could be targeted;

Answer 22

Mainly useful for marsupials

• Short gestation then long lactation in pouch phase
• Lack of lactation = death

Question 23

Of the potential immune system targets, what branches of the immune system to they activate?

Answer 23

Hormones
- Systemic humoral IgG
Gametes
- Mucosal immunity
- Cell-mediated immunity
- Complement activation
Placenta
- Cell-mediated immunity
Milk Proteins
- Mucosal IgA

Most ensure correct targets

Question 24

What are some methods of delivery and who would they be used on?

Answer 24

Injection
- Humans and domestic animals
Baits
- Wild/feral animals
Recombinant vectors
- Wild/feral animals

Question 25

Describe how the bait system works;

Answer 25

Oral ingestion activates mucosal immunity

Question 26

Describe how the recombinant vector works

Answer 26

• Interspecies specificity of the vector (virus, parasite)

- Interspecies specificity of the antigen

Question 27

What is a current vaccine under trail that may prevent women from becoming pregnant?

Answer 27

Immunisation against hCG using beta chain

• Produced large quantities of hCG Ab
• No pregnancy in nearly all women

Question 28

What is a $50 million prize being offered for

Answer 28

A development of a vaccine that targets both cats and dogs

• targets both sexes
• cheap
• single administration

Question 29

What vaccine did larrys students design?

Answer 29

SPRASA

• Discovered as the antigen or antisperm antibodies in infertile men
• Expressed only in sperm/testis/ovaries

Question 30

What were the results of the SPARSA study?

Answer 30

10 mice immunised with SPARSA

• 7 mice infertile after 5 attempts at mating
• 3 pregnant after 2 time tries.

Question 31

What were the conclusions of SPARSA

Answer 31

Little effect on ovarian follicles-mating behaviour unaffected