Vaccine production Flashcards
What is vaccination stimulating
Deliberately administer antigens to stimulate an animal to produce its own immunity
B cells an antibody production
T cells
Why vaccinate for the immune system
Repeated exposure stimulates a secondary immune response
Takes time to develop an immune response
Long lasting
How was the first vaccine made
The first vaccination was performed by Jenner in 1796
Inoculated a healthy child with cowpox
Exposed him to smallpox
No disease
At one stage smallpox killed 400,000 people a year in Europe
Now eradicated thanks to vaccination
Risk with vaccination
Unwanted reactions
Lack of efficiency/misplaced reliance on vaccination
Cost
Risk to no vaccination
Disease (assuming vaccine is effective)
When are vaccinations helpful
Disease is common, difficult or expensive to successfully treat
Often epidemic, severe, viral diseases
Disease that pose a human health risk (zoonotic)
Vaccine is efficacious
Vaccine has low risks to use
Want to stimulate adaptive immunity with minimal inflammation
Traditional killed vaccines are
Also known as -inactivated vaccines
Live bacteria or virus is cultured and then killed
Formaldehyde
Acetone
Alcohols
Alkylating agents
Alternatively, toxin is cultured and inactivated
Killed vaccines may contain
Antigens specific to the organism
Antigens that stimulate pattern recognition receptors
Often combined with an adjuvant
Down sides to a killed vaccine
Tend to be less immunogenic
Weaker, less complete, shorter period of immunity
Very limited or no interferon production
Advantages with killed vaccines
Less risk of inducing disease
Attenuation is
modification of a pathogen so that it is less virulent
Less likely to cause disease
Modified live vaccines are
Attenuated
Still infects animal, still capable of replicating within the host’s cells
Replicates and produces immunity
Advantages of MLV
Whole organism is used so they tend to stimulate a strong immunity
Immunity tends to be long lasting
Immunity tends to be rapid (sometimes days)
Less likely to cause allergic reaction (no adjuvant)
Why does MLV produce a strong immunity
Whole organism is used so they tend to stimulate a strong immunity
Contain variety of antigens
Broad immunity
May only require one dose for initial vaccination
Often contain antigens that non-specifically stimulate immune system
Activate pattern recognition receptors
No need for adjuvants
Immunity is like that produced by natural infection
Disadvantages of MLV
Possibility of spread of vaccine virus to other animals
Possibility of reversion to a virulent form
More of a concern with older MLV
If vannine is contaminated, contaminating agent will not be activated
Bovine Leukosis in Australia spread by a babesiosis vaccine (made with bovine blood)
May interfere with diagnostic tests
Often have an antigen deleted to help differentiate vaccination from disease
Why is spread by a MLV an issue
Good (increased herd immunity)
Bad – Spread of MLV IBR vaccine from calf to pregnant cow (may cause disease issues in immunocompromised/pregnant animals)
Can cause abortion
How are MLV made traditonally
Long term culture on an unusual medium
Growth of the virus in a species or tissue culture that it does not normally infect
Rinderpest (a pathogen in cattle) was grown in rabbits until it was no longer pathogenic to cattle
Distemper virus grown in kidney cells
How are MLV made through genetic manipulation
Delete virulence factor/rep;ication factor
Alter the genetic code in some way that makes them less likely to cause severe disease
Sub-unit vaccines are
Gene cloning- type 1
Single/small group of antigens amplified by gene cloning
Take known major antigen
Isolate responsible gene
Insert into bacteria (E.coli), yeast or another organism
Antigen produced by the organism and excreted into medium (broth)
It is then harvested and purified
Advantages of sub unit vaccines
Minimal risk of developing disease
Disadvantages of a sub unit vaccine
Antibody response may be weak
Protein (antigen) may not be appropriately modified or folded
No stimulation of pattern recognition receptors (unless an adjuvant is added)
Incorrect presentation of antigen to host
Some animals may NOT response to the antigen
Genetically Attenuated Organisms - Type 2 is and attenuated for
Like traditional MLV vaccines but modified (attenuated) by genetic engineering
Attenuation:
Targeted
Multiple steps making reversion difficult – irreversible?
Rapid
Can knock out minor antigens, use as a marker for vaccination
Commonly used method of making MLV vaccines
Live recombinant organism are
This is a successful method of making commercial vaccines
Insert part of the genome of a pathogen into a harmless vector that replicates within the host
Canarypox or vaccinia often used as a vector
Adenovirus for COVID
Plant cells as a vector – allow for some vaccines to be given orally
Canarypox is an ideal vector beacuse
Canarypox only partially replicates in mammals
No new competent virus particles produced (usually)
Large stable genome – includes code for ‘virus factories’
Easy to insert viral pathogen DNA
Infected cells can express high levels of antigen
Canarypox is
Recumbent organsim
No immune response to the canarypox vector
Can be used as a “booster”
What happens once a recumbent organism is created
Thy may be killed and incorporated into a vaccine
The live organism may be used to produce a vaccine
Antigens belonging to pathogen are then expressed in host
What vaccines are recombinant
Vaccinia was originally developed for the control of smallpox
Disease eradicated by vaccination
Now, vaccinia is modified to control other diseases
Oral rabies vaccine for wildlife (Boehringer Ingelheim)
Over 100 million doses sold
Polynucleotide Vaccines (COVID) – Type 4 is produced by
Sequence viral DNA/RNA
Identify genes that code for viral antigens on the surface of infected cells
Mass produce a messenger RNA copy of this gene
Package it in a lipid nanoparticle
Protects the delicate mRNA
Inject the mRNA into the susceptible individual
Lipid nanoparticles fuse with human cell membranes
mRNA directs human cell to produce viral antigen
Displayed on cell surface
Stimulates immune response
Advantages of polynucleotide vaccines
Very rapid development of vaccine
RNA so cannot change genetic code of vaccinated person
Disadvantages of polynucleotide vaccine
Must know sequence
Has to be stored at very cold temperature
Only one or small group of antigens
Adjuvants are
Included in killed vaccines or those with highly purified antigen
Slow release
What are the functions of adjuvanats
Slow down release of antigen (gives the immune system time to react)
Increase the strength or magnitude of the immune response
May decrease the amount of antigen or number of doses required
May select for a specific immune response – for example stimulate CMI, Th1 vs. Th2
Why are adjuvants slow release
Aluminium salts
Freunds Incomplete Adjuvant
Immunostimulant Adjuvants are and work for
Various bacteria/bacterial parts
Anerobic corynebacteria
Lipopolyssaccharide
Sugar polymers, detergents
Stimulate specific pattern recognition receptors and activate dendritic cells and macrophages→ helper T cells
Particulate Adjuvants are used for
not yet widely incorporated into vet med
Liposomes, ISCOMS, Microparticles
Deliver antigen to antigen presenting cells in a form that is easy to process (phagocytose)
What is freuds complete adjuvant
Combined adjuvant
Oil-water emulsion and killed mycobacterium
Problematic in cattle- can cause a positive tuberculin test
Highly toxic to dogs and cats
Killed Vaccines advantage and disadvantage?
Least risk of virulence
Often shorter period of immunity and mora vaccine reaction problems
MLV advantage and disadvantage?
Strong, long lasting immunity with smaller risk of reaction
Risk of disease if improperly attenuated or given off label
Passive immunization is
The administration of preformed antibody(antisera) from an immune to a susceptible individual
Like colostrum
Performed when immediate protection is needed against a serious disease
Provides temporary immunit
How to preform passive immunization
Donor animals are vaccinated for a specific antigen
Plasma or serum is collected from the donor animals and the antibodies are harvested
Equine antisera is
Typically used for clostridial organisms especially tetanus
Disease often rapidly fatal
Signs caused by toxins
Toxoids are denatured (inactivated) toxins, used to repeatedly vaccinate horses, serum is harvested
(Equine) immune globulin preparation called:
Antiserum
antitoxin
Often combine antitoxin with active immunization for long lasting immunity
What to do to avoid tetanus in equine wounds
If not vaccinated/not current for tetanus
Passive protection
Tetanus antitoxin
Simultaneously induce/boost active immunity
Tetanus toxoid vaccination
Routine vaccination provides the best protection
Passive Immunity Using Hybridomas is
Monoclonal antibody against E. coli, rota and coronavirus
Raised in a mouse hybridoma
Mouse immunoglobulin
Given orally to calves to protect against scours
Problems of passive immunization
Antibody os often from a different species
Immune reaction shortens life of antibodies
Risk of anaphylaxis
Type III hypersensitivity reaction
May interfere with active immunity (vaccination)
Only involve antibody, not cell mediated immunity
Storage of vaccines
Vaccines are biological products
Always consult the package insert or manufacturer.
Generally, as a rule:
Keep refrigerated
What to do for the vaccine fridge
About 50% full
Date multi use containers at time of first use
Place vaccine in breathable plastic mesh baskets and clearly label baskets by type of vaccine
Keep baskets 5-8 cm from walls and other baskets
Keep vaccine in their original boxes until you are ready to use them
Keep vaccines with shorter expiration dates to the front of the shelf/basket
Place temperature probe/vial in middle of refrigeration unit
Keep temperature between 2 – 8°C (aim for 5°C)
Check and log temp daily
What not to do with the vaccine fridge
Store food or drink in refrigerator- only vaccine in the vaccine storage unit
Place vaccine in solid plastic trays or containers
Store vials out of their original individual packaging
Place vaccine in veggie bins, drawers, door shelves or on floor of refrigerator
Open door more than necessary
What to do when moving vaccines
Ice chest and freezer bags
Portable electric coolers
Active immunization is activated by
Vaccination
Animal makes its own antibody
passive immunization is activated by
Colostrum, antitoxins, antiserum
Antibody is performed and given to animal
Correct vaccine storage temp
Store between 2-8*C
