Vaccines Flashcards
What are the 3 main criteria to consider when to vaccinate
Disease is commune and difficult to treat (endemic, severe, viral)
Vaccine is effective
Vaccine has low risks (compared to risk of not vaccinating)
What are the 4 main risks of vaccinating
Unwanted reactions
Not effective
Misplaced dependence on the vaccine (not 100% effective)
Cost
What is active immunization vs passive immunization
Passive is what is seen with colostrum antibody transfer from damn to neonate
Active immunization is deliberately administering antigens to stimulate the animal to produce its own immunity
Describe the traditional killed vaccine type
The live bacteria/virus is cultured and then killed (using formaldehyde, alcohol or alkylating agents) or a toxin is coloured and inactivated
May contain antigens specific to the organism and/or antigens that stimulate pattern recognition receptors
Describe the effectiveness of traditional killer vaccines, and the advantages or Disadvantages
Tend to be less immunogenic (weaker, less complete -doesn’t contain the whole virus, shorter periods of immunity since the virus is not replicating)
No or very litter interferon production
Often contains an adjuvant to increase effectiveness of the vaccine
Increased risk of adverse reactions to the adjuvants
Describe modified live vaccines
Developed in 2 ways:
1) long term culturing on an unusual medium to change it slightly
2) genetic manipulation (deletes virulence factors, makes bacteria antibiotic dependent, alters genetic code)
Live pathogen is Modified greatly to reduce risk of causing disease
Still infects the animal and replicates to stimulate immunity
What are the advantages of modified live vaccines
The whole pathogen is involved to stimulate strong immunity
Broad immunity (may only require 1 dose for initial vaccination, and contain antigens that non-specifically stimulate the immune system)
Active pattern recognition receptors
Long lasting immunity
Rapid onset of immunity
Less likely to cause adverse reactions (no adjuvant)
What are the disadvantages of modified live vaccines
Possibility of spreading pathogen (vaccinating pregnant dams and it spreads disease to neonate)
Possibility of reversion to a virulent form (mainly older MLV)
May interfere with diagnostic tests (often have an antigen deleted to help differentiate vaccination from the disease -test for deleted antigen)
Describe subunit vaccines
Single/small group of antigens amplified by gene cloning (using known major antigen, isolate responsible gene, insert into E.Coli,plant or organism, antigen is excreted into a medium and harvested and purified)
What are the advantages of sub unit vaccines
Minimal risk of disease or developing an infection
What are the disadvantages of sun unit vaccines
Antibody response may be weak (protein not appropriately modified, no stimulation of pattern recognition receptors, incorrect presentation to the host, some animals may not respond to it)
Less effective, doesn’t have whole virus
Describe genetically attenuated organisms
Like traditional attenuated vaccines (MLV) but not modified by genetic engineering
Attenuation: Targeted: removes damaging parts of the pathogen.
Multiple steps making reversion difficult Rapid, can knock out major antigens (used as a marker for testing)
Commonly used method for MLV
Describe recombinant vaccines
Inserting a part of a pathogen genome into a harmless vector that replicates in the host but does not cause disease (not meant for that species/mammals)
Used the same as a live vaccine, antigens belonging to a pathogen then expressed in the host
Alternatively: can be grown in culture, killed and used as a vaccine
What the two common viruses used as vector for recombinant vaccines, describe why they are chosen
Canarypox
Canarypox only partially replicates in mammals (meant for avian cells)
No new competent virus particles produced, large stable genome including code for “virus factories”, easy to insert viral pathogen DNA into, infected cells can express high levels of antigen
No immune response to the Canarypox itself
Vaccinia
Originally developed for control of smallpox, now it is modified to control other diseases (Rabies)
Give two examples of common vectored vaccines
West Nile virus:
1) Canarypox vector
2) yellow fever vector
Both give better immunity than killer vaccines and need 2 doses for initial series
FeLV:
1) canarypox vector (not as effective as killer adjuvant)
What are polynucleotide vaccines
Widely used in Covid 19 vaccines
Very quick development:
Sequence of DNA/RNA of pathogen/gene that codes for antigens is identified and used to mass produce mRNA to copy this gene.
This gene is packaged in a lipid nanoparticle (protects) and is injected into the animal susceptible to the disease. The lipid nanoparticles fuse with cell membranes and the mRNA message directs cells to produce the viral antigens and displays them on cell surfaces. This stimulate an immune response
What are the advantages of polynucleotide vaccines
Very rapid development
Uses RNA so it cannot change the genetic code of the individual vaccinated (only gives mRNA message to start the mechanism of replication in cells)
What are the disadvantages of polynucleotide vaccines
Has to be stored at very cold temperatures
Only has one or small group of antigens
The DNA/RNA sequence for the gene must be known
Why may an adjuvant be added to a vaccine
To slow down the release of the antigen (gives the immune system time to find it and create a response)
To increase the strength of the immune response
To improve the delivery of the vaccine
Describe depot adjuvants
Creates a slow release
Aluminum salts
Freunds incomplete adjuvant: most common of the two types
Describe immunostimulant adjuvants
Various killed bacteria/bacterial parts (anaerobic corynebacteria, BCG, lipopolysaccharide)
Sugar polymers, detergents
All stimulate pattern recognition receptors and activate immune cells
Describe delivery system adjuvants
Liposomes, ISCOMS, microparticles
Small particles containing antigen, easy to phagocytose and present to the immune system
Describe combined adjuvants
Freunds complete adjuvant: water-oil emulsion +inactivated mycobacterium
describe passive immunization
Administration of preformed antibody
Performed when the need for antibody is immediate against a serious disease
Less reactions, and much faster response
What are the two types of passive immunization used (besides collateral antibody)
Equine antisera
Hybridoma genetic manipulation
Describe equine antisera
Typically used for color riding organisms especially tetanus (rapidly fatal and caused by toxins)
Toxoids are denatured (inactivated) toxins used to repeatedly vaccinate horses and the serum is harvested
Equine immunoglobulin preparation is called an antiserum or antitoxin
Often used in conjunction with traditional vaccination for long lasting immunity
Describe the necessary vaccination for tetanus in horses
Antitoxin is used of the horse was not vaccination or vaccinated over a year ago (this provides immediate passive protection and boosts active immunity)
Routine vaccination is the best protection
Describe passive immunity using Hybridomas
Culture of hybrid cells that results from the fusion of B cells and myeloma cells
Monoclonal antibody against E.Coli, rota or coronavirus
Raised in a mouse hybridoma
Mouse immunoglobulin given orally to calves to protect against scours
What are the problems with passive immunity
Antibody often from a different species (immune reaction shortens life and there is a risk of anaphylaxis)
May interfere with active immunity
Only involves antibodyC not cell mediated immunity
As a general re, how do you know how to store vaccines
Read the label
What are some tips on what you should do for a vaccine fridge
Date multi use containers
Only keep 50% full to allow good airflow
Use breathable plastic mesh baskets (label), keep baskets away from other baskets and away from walls
Keep vaccines in original box until they are used
Keep vaccines with shorter expiration dates to the front of the fridge
Place the temperature probe in the middle of the fridge
Keep temperature between 2-8 degrees (5 is ideal)
Check and log temperature daily
What are some things to avoid with a vaccine fridge
Never store food or drinks in the fridge
Don’t Place vaccine in solid plastic trays
Don’t store vials out of their original packaging
don’t put anything in the veggie bins, drawers or on the floor of the fridge
Don’t open door unnecessarily
Never over pack
What are some options for travelling with vaccines
Ice boxes
Freezer bags
Portable electric coolers
Describe vaccines for immunocastration
Vaccine for pigs against gonadotropin releasing hormone (GnRH) IMPROVAC
Contains GnRH linked to a carrier to stimulate an immune reaction
Antibodies bind to animals GnRH, block its activity so the anterior pituitary does not produce FSH/LH to stimulate the testes
Two doses starting at 12 weeks of age
No risk on accidental injection to self on first occasion
What deems a vaccine as “core”
Regarded as essential or highly recommended
For severe and common diseases
Effective
Risk of adverse reaction is small
Benefits of vaccination is likely to exceed the risks
What deems a vaccine as “non-core” or optional
Depends on location or spikes in disease prevalence
What are the two methods of systemic administration of vaccines? What are the disadvantages and advantages? What are some precautions
IM or SQ
Advantages: reliable administration, systemic immunity (IgG)
Disadvantages: difficult technique, no or little IgA
Ensure there is a clean bottle and new needle and syringe
What are the two methods of mucosal administration? What are the disadvantages and advantages?
PO or IN
advantages: both local and systemic immunity (IgA and IgG), do not require a needle, but may need alternate device
Disadvantages: requires effective restraint, potential for variable vaccine administration (may cough, sneeze or foam at mount and loose some of the dose), requires a MLV (killed is not as effective in the route)
True or false
Combo vaccines are not as effective as single vaccines
FALSE
there is no issue with combo vaccines
Many Killed vaccines consist of an initial priming vaccination followed by a secondary vaccination typically ___ days later. Maximal immunity develops about ___ weeks later. Booster vaccination is done ___ years later.
21-28 days later
2-3 weeks later
1-3 years later
What happens after the initial priming vaccine
There is NO antibody initially
Antigen has to be phagocytosed by dendritic cells and taken to lymphocytes to create memory cells, B cells and then antibodies
What is the first antibody typically made
IgM followed by IgG, IgA and IgE
Describe how maternal immunity interacts with vaccination
Passive immunity from maternal antibody in colostrum prevents successful vaccination, the circulating antibodies kill off the antigens in the vaccine and does not allow for the body to make any antibody
How are puppies and kittens vaccinated in terms of maternal antibody
Typically given multiple vaccinations in the beginning
8, 12 and 16 weeks, followed by 1 year and then every 1 or 3 years after that
Or vaccination can be delayed until after colostrum antibody is gone (usually about 12 weeks in kittens and puppies and up to 6 months in foals and calves)
Why may an individual not respond to vaccination
Incorrect storage or administration of the vaccine
Inability to respond: colostrum antibody, genetic differences, immune suppression
High antibody levels following vaccination are associated with
Strongly antigenic vaccines (some are more antigenic than others)
Small dogs
First vaccination as a younger adult (3-4 years old)
Certain breeds respond better
About ___% of dogs experience adverse reactions.
0.4%
When Most vaccine reactions occur?
The day of vaccination
When are adverse vaccine reactions most often seen
Small dogs
When Multiple vaccines given as once
Repeated vaccines
Neutered dogs
What are the most common adverse reactions seen
Lethargy, fever and inflammation at the injection site
Describe why discomfort at the time of vaccination is common
Struggling during administration increases destruction of tissue, pain and inflammation
May lead to biting or severe discomfort
Can be reduced by proper restraint, appropriate environment, rewards and distraction
Describe inflammation seen with vaccinations
Typically occurs after 1-7 days
Warmth, swelling and edema at the injection site and a possible fever
Usually subsides on its own (can use NSAIDs)
May develop into an abscess and severe reactions can cause abortions
Describe hypersensitivity type 1 reactions seen with vaccinations
Rare by is a serious problem
Associated with repeated vaccination (mainly with killed vaccines)
Type 1 (anaphylaxis) occurs within minutes (may have a history) IgE mediated
Describe hypersensitivity type 3 reactions seen with vaccination
Occurs when antigen-antibody complexes deposit in the tissues
Occurs 2-3 weeks following infection/vaccination
Signs: intense local information, purpura, blue eye, ischemic dermatitis and alopecia
Describe hypersensitivity type 4 reactions seen with vaccination
The cellular infiltrate is T cells and macrophages. These produce a granuloma at the injection site which may abscess (more common with depot (oil) vaccines)
Describe vaccine induced autoimmune diseases
Rare
Tend to occur with vaccines grown in cell lines of the same species and when the vaccine contains an adjuvant
The adjuvant may stimulate immunity to vaccine cell line antigens and the antibodies then cross react with host antigens
Describe vaccine induced hypertrophic osteodystrophy
Rare
Thickening of the long bones following vaccination
Mainly reported in Weimaraners vaccinated with MLVs
Starts within 10 days of vaccination
Treated with corticosteroids
Some believe there is a pre-existing immunodeficiency in this breed and will used killed vaccines instead
Describe injection site sarcomas
Invasive tumour, will Metastasize and must be removed with very large margins
Rare problem in cats (1 in 5000)
associated with vaccination with multiple vaccines given at a time or vaccines with strong adjuvants
Problems affects young adult cats and are difficult and expensive to treat
What is a common error seen with vaccine manufacturing
Poor attenuation of the vaccine (contaminated vaccines)
True or false
Some vaccines are mildly immunosuppressive
True
May be transient
How can you prevent adverse reactions
Always obtain a full history (previous reactions)
Pretreat with antihistamines
Close monitoring for 20 mins after vaccination to detect anaphylaxis
Don’t over vaccinate
How do you treat adverse vaccine reactions
Anaphylaxis: epinephrine and/or antihistamines, corticosteroids, and IV fluids
Fever and soreness treated with NSAIDs
Describe vaccine approval
All vaccines must be licensed by the CFIA
they must be manufactured in appropriate facilities following safety and cleanliness standards
Describe the 80:80 challenge studies when approving vaccines
Standard:
80% protection in those vaccinated
80% disease prevalence in unvaccinated population
Not always followed and may only need to show an antibody response
