What is a Vaccine?o A vaccine is a non-pathogenic antigen that mimics aparticular pathogen in order to elicit an immune response as ifthat actual pathogen were in the body.o The overall goal of a vaccine is to establish immunityagainst that particular pathogen.
TYPES OF VACCINES Vaccine ExamplesImmunoglobulin (IG) Varicella Zoster IG Human Normal IG Hep B IG, Tetanus IGAnti-toxins Diphtheria anti-toxin Botulinum anti-toxinInactivated/subunit Diphtheria/tetanus/acellular pertussis /inactivatedvaccine polio/Haemophilus influenzae b (DTaP/IPV/Hib) Meningococcal C (MenC), Pneumcoccal (PPV & PCV) Human papillomavirus vaccine (HPV) Hepatitis A vaccine (HAV) Hepatitis B vaccine (HBV),Live attenuated Measles, mumps and rubella (MMR), Yellow fever
VACCINE COMPOSITIONComponent Purpose ExampleAdjuvants enhance the immune response to a aluminium salts vaccinePreservatives prevent bacterial or fungal contamination thiomersal of vaccineAdditives stabilise vaccines from adverse gelatine conditions such as freeze-drying or heat, thereby maintaining a vaccine’s potencyResiduals from Inactivating agents formaldehydemanufacturingprocess Antibiotics - prevent bacterial neomycin, streptomycin, contamination during manufacturing polymyxin B process Egg proteins- some vaccine viruses are grown in chick embryo cells influenza, yellow fever Yeast proteins Hep.B vaccine
ACTIVE VACCINEStimulates Humoral Immune Response,Cellular Immune Response or Both, with the aim of protecting against or eliminating a pathogen PASSIVE VACCINEPreparation of Abs, Protect against a pathogen ordisease and is administered before, at or around the time of known or potential exposure
comparison of different vaccine types LIVE VACCINES (ATTENUATED) (MMR, Oral Polio)Advantages: One or few doses required Long lasting protection Both humoral and cellular responsesDisadvantages: Controlled attenuation normally required Poorly defined composition Risk of reversion to pathogenicity Certain risk of transmission
comparison of different vaccine types KILLED VACCINES (Polio and Influenza)Advantages: No risk of reversion to pathogenicity No risk of transmissionDisadvantages: Multiple dose typically required Poorly defined composition Antigen produced by cultivation of a pathogen Mainly humoral responses Adjuvants normally needed
Attenuated vaccines Killed(Inactivated) vaccinesProduction Virulent pathogen is grown under Virulent pathogen is inactivated by abnormal culture conditions for chemicals or irradiations. attenuationBooster Generally requires only a single Requires multiple boostersrequireme booster.ntRelative Less stable More stable on storageStabilityType of Humoral and cell mediated Mainly humoralimmunityinducedReversion May revert to virulent form and Cannot revert to virulent formtendency cause disease.Adjuvents Unnecessary Required for most vaccinesInflammat Less chances More chances of mounting anory allegic reactionresponseCost Reletively cheap Relatively costly
comparison of different vaccine types TOXOIDES (Tetanus and Diphtheria)Advantages: Product is devoid of live organism Implies greater safetyDisadvantages: Multiple dose typically required Relatively expensive to manufacture Cultivation of a pathogen for toxin production
SUBUNIT VACCINESSUBUNIT VACCINES ARE DEFINED AS THOSE CONTAINING ONE OR MORE PURE OR SEMI-PURE ANTIGENS
comparison of different vaccine types SUBUNIT VACCINES (NON-RECOMBINANT)Constituent proteins of bacteria or virus are isolated and purifiedAdvantages: Defined Composition Various delivery systems availableDisadvantages: Antigens must be produced and purified by cultivation of apathogen Multiple doses typically required Adjuvant needed
RECOMBINANT SUBUNIT VACCINES•Identify and isolate a specific gene fromvirulent bacteria or virus (gene that codesimmuno protective protein).•Gene is inserted into plasmid DNA and ligated with ligase.•New (engineered) plasmid inserted into Target gene another bacterium (transform).•Allowed to grow and actually produce the antigenic protein.•The vaccine is comprised of purifiedproteins recovered from the expression vector.
comparison of different vaccine types RECOMBINANT SUBUNIT VACCINESAdvantages: No risk of pathogenicity Defined composition Various delivery systems Simplified large scale production Further engineering possibleDisadvantages: Multiple doses typically require Adjuvants needed
comparison of different vaccine types RECOMBINANT VECTOR VACCINES Based on microorganisms such as viruses or bacteria that do notcause disease in target animals or humans. The viruses or bacteria are used as vectors, or carriers, to deliverharmless genes into the cells of the body. The body produces proteins from the genes and these proteinsstimulate an immune response against the specific protein.
comparison of different vaccine types RECOMBINANT GENE DELETED VACCINES Involves isolation and removal of viral gene(s) that code for “non- required” proteins This process is intended to decrease the virulence of the virus making it suitable for administration in vaccineAdvantages: The absence of specific antigens from the virus can be used todifferentiate between vaccine virus and natural (“wild-type”) virus.Disadvantages: Potential exists for virus to revert to its original, virulent state. Degree of protection could be limited since immune response is
comparison of different vaccine types RECOMBINANT VIRAL VECTOR VACCINES• Isolate an immunoprotective protein gene from a virulent virus.• Clone the gene to a vector of a non virulent virus.• These live vectored vaccines are being used to not only controlinfectious diseases of domestic animals, but of wildlife as well.• This approach has resulted in a dramatic reduction intransmission of RABIES from wildlife to domestic animals andhumans. This would not have been possible by conventionalmethods.
comparison of different vaccine types RECOMBINANT VIRAL VECTOR VACCINESAdvantages:• Risk of reversion to virulence is eliminated if virus vector is notcapable of intracellular replication.• Both CMI and Humoral Immunity is good if the vector is capableof intracellular replication.Disadvantages:• Weak CMI response if vector is incapable of intracellularreplication.• The vaccine utilizes very specific protective proteins. The immuneresponse may be reduced in some animals.
DNA VACCINEUses only the DNA from infectious organisms.Avoid the risk of using actual infectious organism.Provide both Humoral & Cell mediated immunityRefrigeration is not required
TRANSITIONAL VACCINEUses weakened or killed form of infectious organism.Create possible risk of the vaccine being fatal.Provide primarily Humoral immunityUsually requires Refrigeration.
CONTRAINDICATIONS & PRECAUTIONS Vaccine Contraindication PrecautionsAll vaccines •A confirmed anaphylactic reaction to •If individual acutely unwell on day of a previous dose of the vaccine or to a vaccination, postpone until recovered(live and component of the vaccineinactivated) •PregnancyDTP •As above •If evidence of evolving neurological abnormality or current neurological deterioration, including poorly controlled epilepsy, immunisation should be deferred until condition stabilisedInfluenza •As above and additionally: •Where possible, thiomersal free influenza vaccines recommended for pregnant •Individuals with confirmed women and infants anaphylactic hypersensitivity to egg productsLive vaccines •As above and additionally: •If ITP following previous MMR vaccine,(MMR, varicella) perform antibody test •Immunocompromising treatment or condition •If confirmed anaphylactic reaction to egg, seek further advice with view to •Pregnancy immunisation under controlled conditions
VACCINE FAILURE• Primary failure – an individual fails to make an adequate immune response to the initial vaccination (e.g. in about 10% of measles and mumps vaccine recipients) The primary cause of vaccine failure is an interfering level of maternal antibody.• Secondary failure – an individual makes an adequate immune response initially but then immunity wanes over time (a feature of most inactivated vaccines, hence the need for boosters)
Veterinary Advice: Vaccination Failure • vaccination 1) The clinical disease is failure or failure of being caused by the immunization occurs vaccine itself (live vaccines only) because of one of two OR reasons: 2) The clinical disease is being caused by a wild- type, infectious disease organism that has infected the animal from its local environment
CAUSES OF VACCINE FAILURE• USE OF EXPIRED VACCINE • COLD AND HIGH DENSITY STRESS• GENETIC RESISTENCE • POOR NUTRITION• IMPROPER STORAGE OF VACCINES • PRESENCE OF AMMONIA IN HOUSES• HEALTH STATUS OF THE FLOCK • ADMINISTRATION ERRORS QUALITY OF WATER• IMMUNO SUPPRESSION DUE TO DRUGS • MATERNAL ANTIBODIES• MYCOTOXINS • PRESENCE OF VARIANT IN FIELD• WATER DEPRIVATION AND HEAT STRESS • POOR ANTIGENICITY OF VACCINES• GEONETICS • INTERFERENCE• VACCINATION REATIONS
USE OF EXPIRED VACCINE GENETIC RESISTENCE• Vaccines are expired by many • The major histocompatibility ways, among the most common complex varies from bird to are the expired in storage due bird and its structure dictates if to sale, expired in storage due a bird will respond to an to sale, expired due to less shelf antigen at all. Due to some life ( it must be year plus when structural lacks in MHC it is reached in Pakistan ) expired possibility that the birds are supply by the manufacturer recognize the one of the only with few months in hand. antigens. Therefore that strain of birds might be more susceptible to pathogen.
IMPROPER STORAGE OF VACCINES HEALTH STATUS OF THE FLOCK• This is the most common cause • The infectious agents such as of vaccine failure in routine Chicken Anemia Agent (Circo uses of vaccines. This might be virus), Gumboro Disease Virus due to transportation from (Birna virus), Marek’s Disease market to farm or from Virus (Herpes Virus ), REO manufacturer to distributor to Virus, Salmonella and market, failure of electricity, Mycoplasma etc. may cause failure of refrigerators, storage varying degree negative in deep freezers, exposure of immunomodulation which sunlight. consequently may lead to Ignoring the use of ice box, vaccinal failure or adverse coolers or thermos and using reaction in the face of these the translucent thin membrane disease shoppers permitting the sunlight exposure.
IMMUNO SUPPRESSION DUE TO DRUGS MYCOTOXINS • Presence of mycotoxin in the• Continuous administration of feed affect the vaccinal Immuno-suppressive drugs response very badly. Mycotoxin such as chloramphenicol, reduce host immunity directly furazolidone may cause cause by reducing the Macrophage poor immunity development. engulfing tendency and production of toxin, lymphocytes which give poor out put in immunity development. Mycotoxin indirectly affect the bird by producing steroids from the adrenal glands which decrease the lymphocytes and increase the neutrophils by the virtue of increased nutrophil the bird become Immune compromised.
WATER DEPRIVATION AND HEAT STRESS GEONETICS• Due to water deprivation the • Means simply the geographical bird is exposed to heat stress. influence on the geonetics of Due to heat stress lot of steroid local poultry population. The production do occur which geonetical influence may affect decrease the lymphocytes the ultimate response of birds produce the antibodies. This is to vaccine under indigenous common observation that the environments and may result in dehydrated and heat exposed vaccine failure. The difference birds commonly infected with pay more if they are present in coli septicemia and other MHC. diseases
COLD & HIGH DENSITY STRESS VACCINATION REACTIONS• These are social stress as well • Adverse vaccine reaction, as stress like heat stress and however do not serve a useful decrease the immunity by purpose and should be decreasing the number of prevented if at all possible. lymphocyte, which is the Several factors can affect the factory of antibodies. severity of the reaction that occur. These include: • Chick quality • Level of maternal antibodies • Vaccine strain • Doses of vaccine used • Route of application • Timing of vaccination • Immuno suppression • House sanitation • Down time • Water,litter and air quality
PRESENCE OF AMMONIA IN HOUSES POOR NUTRITION• Hypoproteinemia especially • On the port of entry from where the protein hurt the immune pathogens are entered the body to response as antibodies are produce infection there are some host defense mechanism which made up of amino acids. Poor prevent the entry of pathogens. nutrition causes problem with Hairs cilia moist membranes are metabolism, protein synthesis among the preventive cushions. and immunity. The moist membranes of or the mucous membranes among the gut , trachea, nostrils and bronchi produce Immunoglobulin .a through the lymphocytes present on the surface of these organs. This is called secretory immune mechanism and it is watch dog on the port of entry.
ADMINISTRATION ERRORS_QUALITY OF WATERWater quality is poor in most of the areas ofPakistan, particularly in salinity affectedareas such as Faisalabad, Sheikhupura andMultan Division, where the salt level is half ofthe sea water and EC even in Islamabad is600-2000. Poor water quality and high saltconcentration produce ill effect on thevaccine diluted in such kind of water.
PRESENCE OF VARIANTS IN FIELD MATERNAL ANTIBODIES• High maternal antibodies inhibit • It has been observed that with the chicken immune response. It the emergence of new variants has negative feed back effect on B the classical vaccines are no lymphocytes. Moreover high levels more effective to control the of maternal antibodies against infectious agent such as Gumboro, disease. Classical vaccine of also play a role in neutralizing the gumboro is missing the VP-2 vaccinal antigen thus making the protien therefore it is not vaccine less effective and effective against field variant or designing the vaccine program strain. The hot intermediate more difficult. Due to high and intermediate plus do have maternal antibodies not only the the VP-2 protein and can vaccinal antigen is destroyed but penetrate up to the site of also the maternal antibodies are proliferation. In the same also destroyed leaving the bird exposed to field challenge if earlier manner classical IB is no more vaccination in high titer is done. effective against IB variants.
POOR ANTIGENICITY OF VACCINES INTERFERENCE• Live vaccines must be applied at a • Do not give live respiratory level at or above the minimum vaccines (IB,ND,ILT) within 3 infective dose. After the live virus to 4 days if not combined by the has been applied the bird serves as manufacturer in licensed a virus production site. The bird is combination. Reaction may be media in which the initial dose of vaccine can multiply to a level too great or response to the which will stimulate a proper later vaccine may be immune response. For potency compromised due to testing of vaccines, always contact interference. This is also true in well facilitated Lab. Inactivated case of ND and AI vaccine. Do vaccines should contain sufficient ND vaccine earlier than amount of antigen to stimulate an proceed for AI vaccine. immune response when applied the bird as there is no multiplication of the virus of bacteria in the bird.