Difference between revisions of "Vaccines"

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[[Image:Syringe.jpg|right|thumb|200px|<p>'''Syringe'''</p>Source: Wikimedia Commons; Author: ZaldyImg (2008)]]
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<big><center>[[Immunology - WikiBlood|'''BACK TO IMMUNOLOGY''']]</center></big>
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==Introduction==
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<big><center>[[Host invasion by microorganisms - WikiBlood|'''BACK TO HOST INVASION BY MICROORGANISMS''']]</center></big>
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Why do we vaccinate animals?
+
 
 +
 
 +
==Why Vaccinate?==
 +
 
 
*To protect against infectious diseases
 
*To protect against infectious diseases
−
*Where there is no effective treatment once infected e.g. FeLV, FIV
 
−
*Where disease is life-threatening e.g. Canine Parvovirus
 
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*To prevent the spread of disease by virus excretion e.g. Rabies, FMDV
 
  
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The goal is to vaccinate 90% of the population to reduce the amount of '''endemic''' virus until no new infections occur. Once the disease risk is low, vaccination can be replaced by an eradication or quarantine programme.
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*Where there is no effective treatment once infected
 +
**E.g. FeLV, FIV
 +
 
 +
*Where disease is life-threatening
 +
**E.g. Canine Parvovirus
  
−
==How do vaccines work?==
+
*To prevent the spread of disease
−
Vaccination induces an immunological memory of the infectious organism. High levels of [[T cell differentiation#Cytotoxic T-Cells|cytotoxic T cells]] and neutralising [[Immunoglobulins - Overview|antibody]] are activated 24 - 48 hours post vaccination as a [[B cell differentiation#Secondary T Cell Dependent Response|secondary response]] (instead of 4-10 days later as a [[B cell differentiation#T-Cell Dependent Response|primary response]]). Neutralising [[Immunoglobulins|antibody]] then blocks the attachment of the infectious organism to host cell receptors.
+
**E.g. Rabies, FMDV
  
−
'''Endogenous vaccines''' cause antigens to be made as new proteins by the cell, bacterium or virus and involves [[Major Histocompatability Complexes#MHC I|MHC class I]] processing live virus, recombinant virus or DNA vaccines.
+
==How do we vaccinate?==
  
−
'''Exogenous vaccines''' are when the antigen is processed from the outside by endocytosis without any new proteins being made by the host cell. This involves [[Major Histocompatability Complexes#MHC II|MHC class II]] processing inactivated and subunit vaccines.
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*Usually by subcutaneous injection for '''systemic''' protection ([[Immunoglobulin G - WikiBlood|IgG]])
  
−
==Route of Administration==
+
*For '''mucosal''' immune reponse, intranasal administration is best ([[Immunoglobulin A - WikiBlood|IgA]])
−
*Usually by subcutaneous injection for '''systemic''' protection. Some vaccines such as the [[Vaccinations_for_Rabbits#Myxomatosis_Vaccination|myxomatosis]] vaccine NobivacTM Myxo (Intervet UK Ltd) require an intradermal injection as part of the administration procedure.
 
−
*For a localised '''mucosal''' immune response, intranasal administration is required ([[Immunoglobulin A|IgA]]) e.g. kennel cough vaccine.
 
  
−
==Vaccination Options==
+
==What do we vaccinate with?==
−
[[Image:Passive Immunisation.jpg|thumb|right|200px|Passive Immunisation - Copyright nabrown RVC]]
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[[Image:Passive Immunisation.jpg|thumb|right|150px|Passive Immunisation - Copyright nabrown RVC]]
−
===Passive immunisation===
+
'''Passive immunisation'''
 +
*Administer antibodies
 +
**Maternally-derived antibodies in colostrum
 +
**Antiserum (artificial)
  
−
'''Advantages'''
 
 
*Immediate protection
 
*Immediate protection
  
−
'''Disadvantages:'''
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*Short duration of action
−
*Short duration of action; temporary protection is obtained by the administration of preformed [[Immunoglobulins - Overview|antibody]] from another individual of the same or of a different species. The acquired antibodies are used in combination with [[Adaptive Immune System - Overview#Antigen Recognition|antigen]], and catabolised by the body, meaning protection is gradually lost over time
+
[[Image:Active Immunisation.jpg|thumb|right|150px|Active Immunisation - Copyright nabrown RVC]]
−
*Injection of antiserum may cause an [[Adverse Drug Reactions|allergic response]]
+
'''Active immunisation'''
−
*Antiserum contains many antibodies, not just the specific [[Immunoglobulins|antibodies]] needed
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*Administer antigen so the patient's own antibodies protect against disease
 +
**Living organisms
 +
**Dead organisms
 +
**Toxoids
 +
**Subunit antigens
 +
**DNA
  
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'''Types of antibodies administered:'''
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*Delay in protection
−
*Maternally-derived antibodies in [[Materno-Fetal Immunity - Introduction#Passive transfer via colostrum|colostrum]] when there is a [[Failure of Passive Transfer|failure of passive transfer]] of [[Immunoglobulin G]]
 
−
*Antiserum
 
−
**The antibodies are used in combination with [[Adaptive Immune System - Overview#Antigen Recognition|antigen]] (and often an adjuvant) which is injected into a host animal
 
−
**The immune system of that animal synthesises antibodies
 
−
**Repeated injections at intervals increases total [[Immunoglobulins - Overview|antibody]]  production
 
−
**The immunised animal is bled and the serum collected which contains the newly made antibodies. The serum is called '''antiserum'''.
 
−
**The serum can then be injected into a different animal to confer passive immunisation
 
  
 +
*Often needs two or more doses
  
−
Examples of passive immunisation:
+
*Long duration of action
−
{| style="width:60%; height:200px" border="1" align=left
 
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!INFECTION
 
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!HUMAN SOURCE OF ANTIBODY
 
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!EQUINE SOURCE OF ANTIBODY
 
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!USE
 
−
|-
 
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| '''Tetanus Diptheria'''
 
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| Used
 
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| Used
 
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| Prophylaxis treatment
 
−
|-
 
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| '''Botulism'''
 
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| Not used
 
−
| Used
 
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| Treatment
 
−
|-
 
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| '''Venomous bite'''
 
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| Not used
 
−
| Used
 
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| Treatment
 
−
|-
 
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| '''Rabies'''
 
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| Used
 
−
| Not used
 
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| Post-exposure to virus
 
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|}
 
−
<Br clear="left">
 
−
<br>
 
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[[Image:Active Immunisation.jpg|thumb|right|200px|Active Immunisation - Copyright nabrown RVC]]
 
  
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===Active immunisation===
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==What antigen(s) do we use in the vaccine?==
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Active immunisation requires the administration of antigen so the patient develops their own antibodies to protect against disease. Suitable antigens include:
 
−
*Living organisms
 
−
*Dead organisms
 
−
*Toxoids
 
−
*Subunit antigens
 
−
*DNA
 
  
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'''Advantages'''
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===Whole Organsim===
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*Long duration of action; once antibody is produced against the antigen, [[B cell differentiation#Memory cells|memory cells]] are formed which continue circulating in the body
 
  
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'''Disadvantages'''
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*Live attenuated organism
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*The host's immune system needs to evoke an immune response against the antigen which can take a few days
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**Virulent organisms cannot be used as vaccines as they would cause disease
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*Can require two or more doses to be effective; the first dose initiates the '''priming''' reaction where antibody production ceases after a few weeks, but the second and subsequent doses create memory cells which remain in the circulation for a much longer period of time.
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**Virulence is reduced by growing the organism in altered conditions so that it is less able to replicate when introduced to the host and therefore less likely to cause disease
  
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==Vaccine Antigens==
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*Killed inactivated organism or toxin (toxoid)
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Potential antigenic substances include:
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**Virulent and toxic organisms cannot be used as vaccines as they would cause disease
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===Whole Organism===
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**Organisms can be killed using radiation or chemicals so that they still posess the antigens to stimulate an immune response, but the organisms are unable to replicate inside the host
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'''Live Attenuated (LA) vaccines''' include the organism but in an altered form - virulent organisms cannot be used as vaccines as they have the potential to cause disease. Virulence is reduced by growing the organism in altered conditions (e.g. in cells or eggs), so that it is less able to replicate when introduced into the host, and is therefore less likely to cause disease. Virulence can also be reduced by genetic engineering, or by using naturally occurring avirulent strains.
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**Toxins are inactivated to produce a toxoid which will still have the antigens needed to produce an immune reponse but will not be harmful to the host
 +
**Needs two doses
  
 +
===Subunit Vaccine (part of the organism)===
  
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LA vaccines produce a superior response to disease than using killed organisms as the dose of antigen is larger and more sustained, and the response takes place at the site of natural infection, producing a greater local response than with killed organism vaccines. Examples include:
+
*Purified protein
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*The current vaccine for tuberculosis (called BCG) contains an attenuated form of a mycobacteria
+
**From lysed organisms
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*Vaccines for leishmaniasis
 
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*Vaccines for parainfluenza virus 3 of calves is developed to be temperature-sensitive so that it grows at 34 C in the upper respiratory tract but not at 38 C in the lungs
 
  
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'''Killed inactivated organism or toxin (toxoid)''' are useful where virulent and toxic organisms cannot be used as vaccines as they would cause disease. Organisms can be killed using radiation or chemicals so that they still possess the antigens to stimulate an immune response, but the organisms are unable to replicate inside the host. Alternatively, toxins are inactivated to produce a toxoid which will still have the antigens needed to produce an immune response but will not be harmful to the host. Two doses are required to [[B_cell_differentiation#Primary_T_Cell_Dependent_Response|'''prime''']] the immune system initially, and then induce an immunoligical [[B_cell_differentiation#Secondary_T_Cell_Dependent_Response|'''memory''']] of the disease causing organism.
+
*Recombinant or synthetic protein
 +
**The gene for the antigen required is inserted into a virus vector or cloned into bacteria
 +
**Small antigens, such as peptides can be synthetically produced
  
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1:4000 formaldehyde is used in the preparation of killed vaccines; inactivants containing azuridines and beta propiolactone are being developed which do not leave a persistent infectious viral fraction (like formaldehyde).
+
*DNA coding for proteins (antigens)
 +
**Can be vaccinated directly into the host
  
−
===Subunits (part of the organism)===
+
===Adjuvants===
−
These can be purified proteins such as a single envelope protein separated from a purified virus by detergent and then centrifuged (traditional method) - genetic engineering can now make single protein vaccines quickly and accurately.
 
  
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Recombinant or synthetic proteins can also be used as a subunit - the gene for the antigen required is inserted into a virus vector or cloned into bacteria allowing endogenous expression of the antigen. Small antigens, such as peptides, can be produced synthetically where necessary e.g. with Influenza viruses that are constantly mutating, and Canary pox vaccines encoding rabies or FeLV spike proteins (canary pox is safe as it undergoes incomplete replication in mammalian skin cells).
+
*Used with vaccines containing inactivated organisms which alone only stimulate a weak immune response
  
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Subunit antigens can also be isolated using the DNA coding for antigenic proteins; circular DNA plasmids are expanded in disabled E.coli strains and then purified - the plasmids expressing the foreign gene can be vaccinated directly into the host.
+
*Some create a depot of antigen at the injection site allowing a steady flow of antigen into the afferent lymph
  
−
==Adjuvants==
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*Some stimulate the immune system to amplify the adaptive immune reponse to antigens
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Adjuvants are used with vaccines containing inactivated organisms which alone would only stimulate a weak immune response. Some adjuvants create a depot of antigen at the injection site allowing a steady flow of antigen into the afferent lymph, while others stimulate the immune system to amplify the adaptive immune response to antigens e.g. pathogen-associated molecular patterns (PAMPs). PAMP-like adjuvants assist naive [[T cells|T cell]] priming.
+
**E.g. Pathogen-associated molecular patterns (PAMPs)  
 +
**E.g. PAMP-like adjuvants which assist naive T cell priming
  
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Different subtypes of [[T cell differentiation|T helper cells]] are stimulated by different adjuvants, for example:
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*Different subtypes of T helper cells are stimulated by different adjuvants
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*Aluminium salts generate bias [[T cell differentiation#TH2 Cells|T helper II]] responses for antibody-mediated immunity
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**E.g. Aluminium salts generate bias T helper II reponses for '''antibody'''-mediated immunity
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*Killed mycobacteria generate IL-12 producing good '''cell'''-mediated immunity
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**E.g. Killed mycobacteria generate IL-12 producing good '''cell'''-mediated immunity
  
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Adjuvants decrease the number of injections needed and the amount of antigen that needs to be administered, but they have been associated with vaccine reactions.
+
==Which type of vaccine is used for each disease?==
  
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==Marker Vaccines==
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*The life-cycle of the organisms needs to be understood to ascertain the best type of immune reponse for fighting the particular infection
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Marker vaccines distinguish infected from vaccinated animals in disease control programmes.
 
−
They contain a deleted protein or gene; vaccinated animals cannot make antibody to the missing protein whereas infected animals can and this helps immunosurveillance for animals infected by an organism in countries that vaccinate against that disease.
 
  
−
==Tailoring Vaccines for Specific Diseases==
+
*A vaccine can be created to provide specific immunity which is best suited for fighting the specific infection
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*The life-cycle of infectious organisms needs to be understood to ascertain the best type of immune response for fighting that particular infection
 
−
*A vaccine can be created to provide the specific immunity best suited for fighting the associated infection
 
  
−
===Immunity to Viral Infection===
+
===Immunity to Virus Infection===
−
[[Image:Virus Life Cycle.jpg|thumb|right|200px|Virus Life Cycle - Copyright Dr Brian Catchpole BVetMed PhD MRCVS]]
 
−
The virus life cycle consists of an extracellular phase, a replicative intracellular phase and another extracellular phase spreading viral particles to other cells to begin the life cycle again
 
  
−
Immunity for the extracellular phase requires neutralising [[Immunoglobulins - Overview|'''antibody''']]:
+
*The virus life cycle consists of an extracellular phase, a replicative intracellular phase and another extracellular phase spreading virual particles to other cells to begin the life cycle again
−
*[[B cells]] needed
 
−
*[[T cell differentiation#TH2 Cells|T helper type II cells]] needed (for the [[Major Histocompatability Complexes#MHC II|MHC class II pathway]])
 
−
*Live, killed and subunit vaccines can be used
 
  
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Immunity for the intracellular phase requires [[T_cells#Cytotoxic_CD8.2B|CD8+ cytotoxic T lymphocytes (CTL)]] and uses the [[Major Histocompatability Complexes#MHC I|MHC class I pathway]].
+
*Immunity for the extracellular phase requires neutralising '''antibody'''
−
*Only live vaccine can be used to get into cells (entering via the endogenous pathway)
+
**B cells needed
 +
**T helper type II cells needed (for the MHC class II pathway)
 +
**Live vaccine can be used
 +
**Killed vaccine can be used
 +
**Subunit vaccine can be used
 +
 
 +
*Immunity for the intracellular phase requires '''CD8+ cytotoxic T cells'''
 +
**MHC class I pathway
 +
**Only live vaccine can be used to get into cells (entering via the endogenous pathway)
  
 
===Immunity to Bacterial Infection===
 
===Immunity to Bacterial Infection===
  
−
*Extracellular bacterial infection needs antibody production for [[Complement#Opsonisation|opsonisation]] and to activate the [[Complement|complement pathways]]
+
*Extracellular bacterial infection need '''antibody''' production for opsonisation and to activate the complement pathways
−
*[[B cells]] are needed
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**B cells needed
−
*[[T cell differentiation#TH2 Cells|T helper type II cells]] are needed
+
**T helper type II cells needed
  
−
Vesicular infections can only be cured by organisms being destroyed inside [[Macrophages|'''macrophages''']]
+
*Vesicular infections can only be cured by organisms being destroyed inside '''macrophages'''
−
*[[T cell differentiation#TH1 Cells|T helper type I cells]] are needed
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**T helper type I cells needed
  
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==When do we vaccinate?==
+
==When do we Vaccinate?==
−
[[Image:Colostrum Intake.jpg|right|thumb|200px|Colostrum Intake - Copyright Prof Dirk Werling DrMedVet PhD MRCVS]]
 
−
[[Image:Vaccinating puppies with Parvo.jpg|right|thumb|200px|Response to vaccination against canine parvovirus depending on antibody titre of puppies - Copyright Prof Dirk Werling DrMedVet PhD MRCVS]]
 
−
*Breeding females can be vaccinated so that immunity is passively transferred to their offspring via the [[Materno-Fetal Immunity - Introduction#Passive transfer via colostrum|colostrum]] - this protects neonates for the first 8-12 weeks of life.
 
  
−
*Vaccination of young animals should be when the natural passive immunity decreases below the threshold for providing protection. Active immunity should then be stimulated so that the animal has sustained protection. If vaccination is given too early, the natural immunity can interfere with immunisation by binding and neutralising the vaccine antigens.
+
*Usually when animals are young
  
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*Two vaccines are usually given to allow for differences between individual animals in the time taken for any natural immunity to decrease.
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*Breeding females so immunity is passed to offspring via the colostrum
 +
**Protects neonates for the first 8-12 weeks of life
  
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===Dog Vaccinations===
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*Vaccination of young animals should be when the natural passive immunity decreases below the threshold for providing protection. Active immunity should then be stimulated so that the animal has constant protection. The vaccination should not be given too early, as the natural immunity can interfere with immunisation by binding and neutralising the vaccine antigens.
−
Diseases routinely covered by vaccination include:
 
  
−
*[[Canine Parvovirus]]
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*2 vaccines are usually given to allow for differences between neonates as the point where natural immunity decreases and active immunity needs to be stimulated, will differ between littermates and between different animals
  
−
*[[Canine Distemper Virus|Canine Distemper]]
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===Dog Vaccinations===
  
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*[[Infectious Canine Hepatitis]]
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'''Diseases covered by Vaccination'''
  
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*[[Leptospirosis - Cats and Dogs|Leptospirosis]]
+
*Canine Parvovirus
  
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*[[Canine Parainfluenza - 2|Canine Parainfluenza virus]]
+
*Canine Distemper
  
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*[[Canine Infectious Tracheobronchitis|Kennel Cough]]
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*Canine Infectious Hepatitis
  
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*[[Rabies]]
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*Leptospirosis
  
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'''When to Vaccinate'''
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*Canine Parainfluenza virus
  
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Puppies are usually first vaccinated between 6 to 8 weeks of age; a second vaccination is given 3-4 weeks later. Younger puppies (less than 16 weeks old) may require the third booster 3-4 weeks later, making the vaccination schedule to end between 14 to 16 weeks old. Adult dogs need booster vaccination regularly (depending on the specific vaccination and the recommendations of the vaccine manufacturer).
+
*Kennel Cough (optional)
  
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===Cat Vaccinations===
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*Rabies (optional)
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[[Image:Sebby cat.jpg|thumb|right|175px|Cat - Copyright nabrown RVC]]
 
−
'''Diseases covered by Vaccination'''
 
  
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*Feline Infectious Enteritis ([[Feline Panleucopenia]])
+
'''When to Vaccinate'''
  
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*'Cat Flu', including Feline [[Feline Herpesvirus 1|Herpesvirus]] and [[Feline Calicivirus]]
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*Puppies are usually vaccinated between 6 to 8 weeks of age
 +
**A second vaccination is needed 2 weeks later
  
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*[[Feline Leukaemia Virus]] (FeLV)
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*Adult dogs need booster vaccination regularly (depending on the specific vaccination)
  
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*[[Feline Immunodeficiency Virus]]
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===Cat Vaccinations===
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* [[Chlamydiosis, Feline|Feline chlamydiosis]] (Chlamydophila felis)
 
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'''When to Vaccinate'''
 
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Kittens are usually vaccinated around 9 weeks old and a second vaccination is given 3 weeks later. Adult cats need booster vaccination regularly (depending on the specific vaccination and the vaccine manufacturers recommendations).
 
  
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===Rabbit Vaccinations===
 
−
[[Image:Buzz bunny.jpg|thumb|right|200px|Rabbit - Copywright L. Drew RVC]]
 
 
'''Diseases covered by Vaccination'''
 
'''Diseases covered by Vaccination'''
  
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*[[Vaccinations_for_Rabbits#VHD_Vaccination|Viral Haemorrhagic Disease]]
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*Feline Infectious Enteritis
  
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*[[Vaccinations_for_Rabbits#Myxomatosis_Vaccination|Myxomatosis]]
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*Feline Infectious Respiratory Disease 'Cat Flu'
 +
**Feline Herpesvirus
 +
**Feline Calicivirus
  
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'''When to Vaccinate'''
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*Feline Leukaemia virus
−
Rabbits can be vaccinated against [[Myxomatosis|myxomatosis]] from 6 weeks of age and VHD from 2½ to 3 months of age. Booster vaccinations are given every 12 months. In areas at high risk of myxomatosis, it is recommended to give myxomatosis boosters at six-monthly intervals. Some myxomatosis vaccines need to given [[Vaccinations_for_Rabbits#Myxomatosis_Vaccination|partially intradermally]].
 
  
−
==Vaccine Failure==
+
*Feline Infectious Viraemia virus
−
Failures do occur and should be reported on the VMD [http://www.vmd.gov.uk/ 'yellow form' MLA252A] if the events occur in the United Kingdom. Vaccine failures in other European Union (EU) Member States, Norway, Iceland and Liechtenstein should be reported to the relevant competent authority where the event occurred using the [http://www.ema.europa.eu/ema/index.jsp?curl=pages/regulation/document_listing/document_listing_000176.jsp&mid=WC0b01ac058002ddcb/ EU reporting forms for veterinarians] which are available in each EU language on the [http://www.ema.europa.eu/ European Medicines Agency] website. Circumstances leading to vaccine failures include:
 
−
*Recipient is already infected with the virus or is immunosuppressed and unable to mount an immune response.
 
  
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*Break down of the '''cold-chain''' during transport (incorrect storage of vaccines requiring refrigeration)
+
*Feline Chlamydophilosis (optional)
  
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*Improper administration (e.g.myxomatosis vaccine)
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'''When to Vaccinate'''
  
−
*Accidental mixing of inactivated and live vaccines in the same syringe
+
*Kittens are usually vaccinated around 9 weeks old
 +
**A second vaccination is needed 3 weeks later
  
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*Recipient has maternal antibody to the vaccine
+
*Adult cats need booster vaccination regularly (depending on the specific vaccination)
  
−
*Immunity waning due to missed booster vaccination
+
===Rabbit Vaccinations===
  
−
*Vaccine is damaged during manufacture
+
'''Diseases covered by Vaccination'''
  
−
{{Learning
+
*Viral Haemorrhagic Disease
−
|flashcards = [[Vaccination Flashcards|Vaccination Flashcards]]
 
−
|full text =[http://www.cabi.org/cabdirect/FullTextPDF/2009/20093258316.pdf '''Factors influencing vaccine efficacy - a general review.''' Rashid, A.; Rasheed, K.; Akhtar, M.; Pakistan Agricultural Scientists Forum, Lahore, Pakistan, JAPS, Journal of Animal and Plant Sciences, 2009, 19, 1, pp 22-25, 18 ref.]
 
  
−
[http://www.cabi.org/cabdirect/FullTextPDF/2009/20093115229.pdf ''' Establishing vaccine protocols - focus on client communication.''' Datz, C.; The North American Veterinary Conference, Gainesville, USA, Small animal and exotics. Proceedings of the North American Veterinary Conference, Orlando, Florida, USA, 17-21 January, 2009, 2009, pp 608-611]
+
*Myxomatosis
  
−
[http://www.cabi.org/cabdirect/FullTextPDF/2009/20093115232.pdf '''Feline lifestyle vaccination protocols.''' Lappin, M. R.; The North American Veterinary Conference, Gainesville, USA, Small animal and exotics. Proceedings of the North American Veterinary Conference, Orlando, Florida, USA, 17-21 January, 2009, 2009, pp 621-624, 18 ref.]
+
'''When to Vaccinate'''
  
−
[http://www.cabi.org/cabdirect/FullTextPDF/2007/20073166574.pdf '''Immunological basis of vaccination.''' Lunn, D. P.; The North American Veterinary Conference, Gainesville, USA, Large animal. Proceedings of the North American Veterinary Conference, Volume 21, Orlando, Florida, USA, 2007, 2007, pp 135-137]
+
*Rabbits can be vaccinated against Myxomatosis from 6 weeks of age
  
−
[http://www.cabi.org/cabdirect/FullTextPDF/2007/20073166575.pdf '''Equine vaccines: what works, what doesn't?''' Lunn, D. P.; The North American Veterinary Conference, Gainesville, USA, Large animal. Proceedings of the North American Veterinary Conference, Volume 21, Orlando, Florida, USA, 2007, 2007, pp 138-140]
+
*HVD from 2½ to 3 months of age 
  
−
|Vetstream = [https://www.vetstream.com/canis/Content/Freeform/fre00859.asp Vaccination Protocol]
+
*Booster vaccinations are given every 12 months
−
}}
 
  
 
==Links==
 
==Links==
−
:[[:Category:Viral Organisms|Viruses A to Z]]
 
−
:[[:Category:Bacterial Organisms|Bacteria A to Z]]
 
  
−
==References==
+
*[[Clinical Case 3|Myxomatosis Clinical Case]]
 +
 
 +
*[[Viruses|Viruses A to Z]]
  
−
'''Textbooks'''
+
==Creators==
−
*Ivan Roitt: '''Essential Immunology,''' Ninth edition
 
  
−
'''Lecture Notes'''
+
[[Natalie Brown]]
−
*Dr Brian Catchpole BVetMed PhD MRCVS
 
−
*Dr Peter H Russell BVSc MSc PhD MRCVS FRCPath
 
  
−
<br><br>
+
<big><center>[[Immunology - WikiBlood|'''BACK TO IMMUNOLOGY''']]</center></big>
−
{{Jim Bee 2007}}
+
<big><center>[[Host invasion by microorganisms - WikiBlood|'''BACK TO HOST INVASION BY MICROORGANISMS''']]</center></big>
−
[[Category:Immunology]]
 

Revision as of 17:21, 25 August 2008

BACK TO IMMUNOLOGY
BACK TO HOST INVASION BY MICROORGANISMS


Why Vaccinate?

  • To protect against infectious diseases
  • Where there is no effective treatment once infected
    • E.g. FeLV, FIV
  • Where disease is life-threatening
    • E.g. Canine Parvovirus
  • To prevent the spread of disease
    • E.g. Rabies, FMDV

How do we vaccinate?

  • Usually by subcutaneous injection for systemic protection (IgG)
  • For mucosal immune reponse, intranasal administration is best (IgA)

What do we vaccinate with?

Passive Immunisation - Copyright nabrown RVC

Passive immunisation

  • Administer antibodies
    • Maternally-derived antibodies in colostrum
    • Antiserum (artificial)
  • Immediate protection
  • Short duration of action
Active Immunisation - Copyright nabrown RVC

Active immunisation

  • Administer antigen so the patient's own antibodies protect against disease
    • Living organisms
    • Dead organisms
    • Toxoids
    • Subunit antigens
    • DNA
  • Delay in protection
  • Often needs two or more doses
  • Long duration of action

What antigen(s) do we use in the vaccine?

Whole Organsim

  • Live attenuated organism
    • Virulent organisms cannot be used as vaccines as they would cause disease
    • Virulence is reduced by growing the organism in altered conditions so that it is less able to replicate when introduced to the host and therefore less likely to cause disease
  • Killed inactivated organism or toxin (toxoid)
    • Virulent and toxic organisms cannot be used as vaccines as they would cause disease
    • Organisms can be killed using radiation or chemicals so that they still posess the antigens to stimulate an immune response, but the organisms are unable to replicate inside the host
    • Toxins are inactivated to produce a toxoid which will still have the antigens needed to produce an immune reponse but will not be harmful to the host
    • Needs two doses

Subunit Vaccine (part of the organism)

  • Purified protein
    • From lysed organisms
  • Recombinant or synthetic protein
    • The gene for the antigen required is inserted into a virus vector or cloned into bacteria
    • Small antigens, such as peptides can be synthetically produced
  • DNA coding for proteins (antigens)
    • Can be vaccinated directly into the host

Adjuvants

  • Used with vaccines containing inactivated organisms which alone only stimulate a weak immune response
  • Some create a depot of antigen at the injection site allowing a steady flow of antigen into the afferent lymph
  • Some stimulate the immune system to amplify the adaptive immune reponse to antigens
    • E.g. Pathogen-associated molecular patterns (PAMPs)
    • E.g. PAMP-like adjuvants which assist naive T cell priming
  • Different subtypes of T helper cells are stimulated by different adjuvants
    • E.g. Aluminium salts generate bias T helper II reponses for antibody-mediated immunity
    • E.g. Killed mycobacteria generate IL-12 producing good cell-mediated immunity

Which type of vaccine is used for each disease?

  • The life-cycle of the organisms needs to be understood to ascertain the best type of immune reponse for fighting the particular infection
  • A vaccine can be created to provide specific immunity which is best suited for fighting the specific infection

Immunity to Virus Infection

  • The virus life cycle consists of an extracellular phase, a replicative intracellular phase and another extracellular phase spreading virual particles to other cells to begin the life cycle again
  • Immunity for the extracellular phase requires neutralising antibody
    • B cells needed
    • T helper type II cells needed (for the MHC class II pathway)
    • Live vaccine can be used
    • Killed vaccine can be used
    • Subunit vaccine can be used
  • Immunity for the intracellular phase requires CD8+ cytotoxic T cells
    • MHC class I pathway
    • Only live vaccine can be used to get into cells (entering via the endogenous pathway)

Immunity to Bacterial Infection

  • Extracellular bacterial infection need antibody production for opsonisation and to activate the complement pathways
    • B cells needed
    • T helper type II cells needed
  • Vesicular infections can only be cured by organisms being destroyed inside macrophages
    • T helper type I cells needed

When do we Vaccinate?

  • Usually when animals are young
  • Breeding females so immunity is passed to offspring via the colostrum
    • Protects neonates for the first 8-12 weeks of life
  • Vaccination of young animals should be when the natural passive immunity decreases below the threshold for providing protection. Active immunity should then be stimulated so that the animal has constant protection. The vaccination should not be given too early, as the natural immunity can interfere with immunisation by binding and neutralising the vaccine antigens.
  • 2 vaccines are usually given to allow for differences between neonates as the point where natural immunity decreases and active immunity needs to be stimulated, will differ between littermates and between different animals

Dog Vaccinations

Diseases covered by Vaccination

  • Canine Parvovirus
  • Canine Distemper
  • Canine Infectious Hepatitis
  • Leptospirosis
  • Canine Parainfluenza virus
  • Kennel Cough (optional)
  • Rabies (optional)

When to Vaccinate

  • Puppies are usually vaccinated between 6 to 8 weeks of age
    • A second vaccination is needed 2 weeks later
  • Adult dogs need booster vaccination regularly (depending on the specific vaccination)

Cat Vaccinations

Diseases covered by Vaccination

  • Feline Infectious Enteritis
  • Feline Infectious Respiratory Disease 'Cat Flu'
    • Feline Herpesvirus
    • Feline Calicivirus
  • Feline Leukaemia virus
  • Feline Infectious Viraemia virus
  • Feline Chlamydophilosis (optional)

When to Vaccinate

  • Kittens are usually vaccinated around 9 weeks old
    • A second vaccination is needed 3 weeks later
  • Adult cats need booster vaccination regularly (depending on the specific vaccination)

Rabbit Vaccinations

Diseases covered by Vaccination

  • Viral Haemorrhagic Disease
  • Myxomatosis

When to Vaccinate

  • Rabbits can be vaccinated against Myxomatosis from 6 weeks of age
  • HVD from 2½ to 3 months of age
  • Booster vaccinations are given every 12 months

Links

Creators

Natalie Brown

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