Immunisation: what are the 2 types of immunisation
- Passive immunisation
- Transfer of antibodies, temporary immunity
- Active immunisation:
- Administration of an antigen > development of immune response
- Immunity is not immediate
- Immunity is long-lasting and can be re-stimulated
vaccine
Active immunisation: 2 types of vaccines
- Infectious
- Infecting animal without producing disease
- Single dose is effective
- Live virulent, recombinant marker
- Non-infectious
- Requires up to 3 doses
Killed whole, subunit, naked DNA
- Requires up to 3 doses
Active immunisation: list some properties of ideal vaccine:
- Inexpensive
- Consistent formulation
- Stable
- Long shelf life
- Induce appropriate immune response
- Induce long lived immune response
No adverse effects
Live virulent vaccines: what is this?
- Injection of live and virulent infectious agent
Quite uncommon - injecting animal with the virus- risk of spreading to animal, contamination etc.
Live attenuated vaccines:
- Most common
Intact and viable organism but with reduce virulent
Means of attenuation of live vaccines:
‘weakened’ form of germ that causes disease. What are 4 ways this can be achieved?
- Multiple passages through cell culture in which they are not adapted
- Heating
- Use of antigenically related organisms (use of CAV-2 to protect against Cav1)
Deletion of modification of virulence using molecular techniques
List few disadvantages of infectious vaccines (live)
- Reversion of virulence
- Wrong route of administration
- Less stable
- Specialised storage conditions
Contamination with another unrelated organism
Recombinant organism vaccines:
- Non virulent virus –> viral gene –> recombinant virus with inserted target virus gene –> carrier virus expressing product of inserted gene
Marker vaccines; what do they detect? How do we know if its due to an infection or secondary to vaccination (can we even tell?)?
If detect serum antibodies in an animal, are they due to an actual infection or secondary to vaccination?
- Can test for natural expression of the vaccine strain
Are the antibodies different? NO, BUT, we can use certain antibodies with removed proteins to see whether it is naturally occurring virus (will express the protein) and which is just from vaccination (won’t express the protein).
Non infectious vaccines: what are these?what is the process for these (3 steps)
- Killed whole organism vaccines - dead virus but still have antigenic structure to stimulate response.
Process:
* Virus is treated with chemicals (formalin, alcohol)
* Killing (but antigenicity is preserved)
* No replication and no pathology, but still antigenic structure that can stimulate immune response in animal
Problems?
Need multiple doses over time as immune response at T0, won’t have long lasting immunity if not replication
What are adjuvants in non infectious vaccines
- Need something to boost the immune response - adjuvants required*
- Added to vaccine to boost response
Usually cause more side effects.
- Added to vaccine to boost response
What are the differences between live attenuated vaccine and killed vaccines**
Think about storage, immunity, risks, adjuvants, cost, risk of spreading disease etc.
- Live attenuated vaccine:
- More effected immunity, don’t need multiple doses and can be given by natural route
- Killed vaccine:
- More stability on storage
- Easy to store
- Lower cost
BUT require adjuvants and higher doses as don’t multiply
Non infectious vaccines: subunit vaccines
- Not containing the entire organism, but only the immunogenic structural protein
Adjuvants: what are these?
- Substances added to the vaccine in order to maximise its effective
- Effects:
- Increased speed or magnitude of immune response
- Reduction of amount of antigen or # doses
- Establishment of long-term memory of response
- Side effects:
May cause tissue irritation/lesion
Feline injection site sarcoma: example of adjuvant side effects
- Rare side effect of vaccine injection, occurs most commonly with killed vaccines containing adjuvants
- Increased risk with multiple injections
- Induces chronic inflammation, which may be linked to carcinogenesis of FISS
Meloxicam, cisplatin, long-acting penicillin etc can also induce sarcomas
3 adjuvant types are:
1) Depot adjuvants
1. Aluminium salts (insoluble) mixed with Ag
2. Infection > formation of granuloma > slow leakage of Ag into body > prolonged antigenic stimulation
2) Particulate adjuvants
1. Phagocytose particles incorporating with Ag > more effective delivery
3) Immunostimulatory adjuvants
Enhanced cytokine production and selective stimulation of Th1 or Th2 cells
4 adverse consequences of vaccines are:
1) Transient pyrexia and lethargy (few days post vaccination)
2) Type 1 hypersensitivity response (pruritus, oedema)
3) Type II or III hypersensitivity reaction
4) Feline injection site sarcoma: especially with FeLV and rabies vaccines; poor prognosis
Dog has just been vaccinated but is now developing this disease/has clinical signs for this disease. Why?
List 3 of each the following:
- Vaccine factors
Host factors
- Viruses may have different strains/mutation of the virus so the immune response will not recognise the new strain
- Animal was already infected - so vaccination would not have worked.
- Puppies: maternal antibodies - need to have correct window where you can vaccinate puppies effectively.
O didn’t wait long enough for vaccine to be effective to take the dog out etc. (e.g. Kennel cough) - Vaccine factors: improper storage, administration and expiry date
- host factors: maternal antibody interference, immunsuppressed dog, animal incubating disease at time of vaccination
