Wafaa Abd El-GhanyPoultry Dis. Dept.,

Fac. Vet. Med., Cairo Univ.

It is immunization of the birds with immunogenic strain of a particular micro-organism (s) to stimulate the

bird’s immune response against this (ese) particular microorganism (s).

I. To prevent:1. Clinical disease and mortality (ND &

IBD).2. Loss of body weight (Reo &

mycoplasmosis).3. Leg problems (Reo &

mycoplasmosis).4. Fall in egg production (ND,IB & EDS).5. Fall in hatchability (Salmonellosis &

mycoplasmosis).6. Egg transmission of disease agents

(AE,CA, Salmonellosis & mycoplasmosis).

7. Immunosuppression (IBD,CA & MD).

II. To control:An outbreak (emergency) to stop mortality and prevent spread of infection. (in early stages) as ND,ILT,FP.

III.To provide: Maternal immunity to

progeny as ND, IB, IBD, Reo, CA, AE…

Active immunity: It developed due to infection or

vaccination with immunogenic agent (suitable dose & molecular weight).

Acquired active immunity consists of both a cellular arm & humoral one which are closely intertwined.

The key effectors cells for both of these arms are the lymphocyte T and B, respectively.

Passive immunity: It resulted from the transfer of

maternal antibodies to the offspring via the yolk or injection of hyper immune sera to the birds at any age (antisera is obtained from immunized hens) (IB, IBD, AE & DVH).

The degree of protection conferred depends on the amount and specificity of the transferred antibodies.

It lasts only as long as antibodies remain reactive in the blood after which the bird losses any resistance to that specific infection (generally 3-6 weeks).

Local (mucosal) immunity: It depends on the induction of

interferon, IgA and blocking receptors. Interferon acts by inhibiting the viral

protein synthesis by blocking of ribosoms of cells infected by the virus and consequently inhibits the multiplication cycle of the virus to be completed.

It represents the immune organs in eyes (harderian gland), upper respiratory tract (lymph nods, thymus glands) & digestive tract (pyre's patches along the intestinal tract).

Primary Secondary

Spleen

Other lymphoid tissues

Bursa of Fabricius

Thymus

The bursa of Fabricius is a unique primary lymphoid organ in avian species where B lymphocytes mature and differentiate.

The bursal follicles consist of B lymphocytes (85-95%), T cells (<4%) and other non-lymphoid cells including macrophages.

The bursa reaches its greatest size about 2 weeks after hatching and then undergoes gradual involution at 11 till 16 weeks of life .

The bursal B cells proliferate rapidly, with more than 5% of bursal lymphocytes dividing per hour.

However, 90-95% of these B cells die rapidly through Apoptosis.

The bursa can trap some antigens and undertake some antibody synthesis.

Several hormones have been extracted from bursa, the most important is bursin, which activates B cells but not T cells.

It is an immunogenic micro-organism or part of it even its product (toxin) that given to the host to stimulate its immune response against this organism and this immune response must be measured in vitro and in vivo.

1. Live vaccines:A. Lentogenic strain

vaccines: It is a naturally weak strains or mild pathogenic. Eg: ND vaccines (HB1, F strain & La

Sota). Under certain conditions they may

cause symptoms and 0-5% mortalities.

1. Live vaccines:A. Apathogenic strain

vaccines: Depending on un-susceptible

(Heterologus) host. Eg: HTV is used for vaccination

of chickens against MDV. Eg: PPV is used for vaccination

of chickens and turkeys against pox virus.

1. Live vaccines:B. Pathogenic (hot) strain

vaccines: Depending on un-susceptible age

(age resistant phenomenon). Some hot strains are used for

vaccination of adult (not susceptible) to produce specific antibodies that used for vaccination of young offspring (susceptible age).

Eg: DVH, IBD, AE & IB.

1. Live vaccines:B. Pathogenic (hot) strain vaccines: Another method of vaccination by

such hot strain is to exposure of the bird to the virus by an un-natural route that stimulate immune response rather than the disease.

This technique is effective only with certain types of viruses in certain species of birds.

Eg: Introducing ILTV to chickens by the cloacal route instead of tracheal one.

2. Live attenuated vaccines: Strains of known pathogenicity

are attenuated by heating or passage through a heterologus host (ECEs, TC, host, etc….).

During the process of attenuation the organism lost its virulence, but remained enough antigenic to induce immune response.

Eg: IBV vaccine is prepared by egg passage of known pathogenic strain for either 52 (H52) or for 120 (H120) times.

2. Live attenuated vaccines: By increasing the passage times,

the virulence of the organism will decrease (weak).

H120 vaccinal strain is used as a first dose (priming) for synthetisation of immune response followed by (booster) by H52.

Eg: NDV vaccine (Kumarove) is prepared from mesogenic strain.

Eg: IBDV vaccine (D78). Eg: AE, ILT, etc………………

3. Inactivated (killed) vaccines:

Consists of concentrated antigen (over one million particle/ml) either bacteria (bacterin) or virus (vaccine) that combined with oil emulsion (Freund’s) or water as aluminum hydroxide as adjuvant.

The organism is inactivated by formalin, heat, irradiation, B propiolactan, etc…..

4. Recombinant (synthetic) (subunit) vaccines:

Separate the specific portion of the virus that is responsible for inducing an immunogenic response and concentrate this portion of the virus in the vaccine.

This vaccine has no DNA or RNA that are necessary for viral replication.

Mechanism of recombinant vaccine :

1. Insert the immunogenic portion (gene) from known pathogenic organism into a vector (non pathogenic bacteria, virus or yeast).

2. inoculate this vector containing the gene into the bird.

3.The vector inside the bird will replicate containing the inserted gene.

4.The immune response will be stimulated against the vector and consequently the inserted gene.

Eg: F gene of NDV and TRT are inserted into the vector (HVT or FPV) in one vaccine.

1) Rapid & strong immune response.2) Depends mainly on local immunity

(IgA).3) Short negative phase (24-72 hours).Eg: Immune response against living

NDV vaccines depends mainly interferon production, production of IgA (eyes, the upper respiratory and upper digestive tracts) and blockage phenomenon (blocking cell receptors against field virulent viruses).

4) Used for diseases control (emergency vaccination).

Eg: ND, ILT & PP.Eg: NDV outbreaks (vaccinate

healthy birds on condition of morbidity and mortality rates not exceed 50%).

5) Need minimal amount of antigen (multiplication in the target organs).

6) Cheap.

7) Continuous immune response due to (multiplication in the target organs), either in the upper respiratory tract (NDV & IBV) or upper digestive tract (IBDV & AEV).

8) Easily to be used or handled.9) No handling of individual birds

(no stress).10)Used for massive vaccination (in

the drinking water or spray).

Eg: all living vaccines are used as mass vaccines, except komarove, MDVV, Pox VV & DVHVV that are used by injection.

11) Easily to be transported (lyophilized) in small packages.

1) Some virus vaccines give post vaccinal reaction in the form of symptoms, mortalities or even drop in egg production.

Eg: Moderate and hot strains of IBDVV.2) May produce carrier status due to

lateral spread of the virus (re-cycling or rolling).

3) Spreading of infection after virus shedding into older un-vaccinated birds in lay as the vaccine itself may produce the disease.

Eg: AEVV & IBVV.

4) The attenuated virus can transformed to virulent strain through adverse or continuous passages in susceptible host (bird-bird).

5) Short period of immune response (short stationary phase from 2-3 weeks)

6) Need continuous boostring (short stationary phase)

7) Maternal antibodies can inactivate the virus vaccine as it is living one.

7) May transmit some diseases especially vertical one (AE, ALC, salmonellosis & mycoplasmosis) due to preparation of vaccine in non SPF eggs or in commercial ones.

8) Risk of impurities and contamination with other infectious agents.

9) Improper handling can inactivate the virus vaccine (chemicals in tape water, etc…..).

10) It is usually mono-valent vaccine (contains only one organism).

1) Give high and prolonged level of immune response (solid immunity) especially when primed with living vaccine.

2) Long stationery phase (6 weeks - 6 months) due to presence of adjuvant.

3) Safe to the host (no lateral spread of the virus).

4) No virus shedding.5) No possibility of vertical diseases

transmission.

6) Stable.7) Not interfere with the maternal

antibodies.8) No post-vaccinal reaction.9) May be used for diseases

eradication in a long run.10)Poly valent (ND+IBD+EDS).

1) Must be administrated individually to each bird (stress factor).

2) Consumed time.3) Laborious.4) Expensive.5) Difficult to be transported (large in

size).6) Administered only by injection, so it

may transmit some diseases through contaminated needle from bird to another or induce abscess formation at the injectable site (carcass rejection).

7) Used mainly for layers and breeders.8) May stimulate latent infection or

even death of the birds due to stress of injection.

9) Long negative phase (2-3 weeks) that delay the appearance of immune response, but it could be overcomed by priming with living vaccine at a suitable interval according to the blood level of antibodies.

10) Poor immunogenicity as it requires concentrated antigen with adjuvant.

1. Highly stable.2. Highly safe like inactivated vaccines as

no viral replication, no shedding and no disease production.

3. Pure (free from extraneous proteins or other contamination).

4. Poly valent.5. Highly effective like live vaccine but not

converted into virulent virus.(Significant protection with no adverse

reaction).6. Still under investigation.7. Highly cost

Must be valid (not expired). Of low price. Suitable for species and age of the

birds. Suitable for the type of production (not

use oil adjuvant for broilers to avoid abscess and carcass rejection).

Of suitable dose (not low or high). Applied on recommended technique. Should be stored at suitable

temperature (4-8 C). It should be titrated (no. of vaccinal

particles or units / vaccinal dose).

i. Individual vaccination:a. Eye drop (intra-occular).b. Nasal drop (intra-nasal).c. Injection (I/M, S/C or I/dermal).d. Peek dipping.

ii. Massive vaccination:a. Drinking water.b. Spray (coarse or fine or aerosol).

Advantages: Simple. Quick. Un-expensive. Easily applied. Massive vaccination. Could be used in case of emergency

vaccination of respiratory tract infected flocks.

It used with all living vaccines (ND, IB, ILT, IBD, etc…..)

Disadvantages: Un-homogeneous immunity.

Precautions : 1. Stop administration of antibiotics 24 hrs

before & after vaccination.

2. Start vaccination in the early morning to avoid the heat and direct sun light.

3. The birds should be deprived of water (remove drinkers) for 2-4 hours before vaccination.

4. Increase the number of drinkers (plastic ones) by 50% at the vaccination time.

5. Wash plastic drinker only with water, not use any detergent or disinfectant that inactivated the virus vaccine.

6. The vaccine should be opened under the water surface.

Precautions : 7. The vaccine should be reconstituted in clean,

cool and chlorine, nitrate, carbonate and disinfectant free water to prevent the virus inactivation.

8. In case of using tape water, the water must be boiled let to stand over night to get rid of chlorine.

9. Dried skimmed milk powder must be dissolved in water before the vaccine at a rate of (2gm/L) and should be mixed with water 20-30 min. before vaccine addition to give time for stabilization, protection and neutralization from any damaging and deleterious components in the water as organic matter, chlorine and solids.

Precautions : 10. Amount of water acc. to the bird’s

age: 15 day 15L/ 1000 bird. 3 weeks 20L/1000 bird. Older than 40 days 40L/ 1000

bird.11. The vaccine should be used as soon

as possible after re-constitution and certainly within 2 hours.

12. Walk along the side of the birds to stimulate the birds movement.

Advantages: Simple. Quick. Un-expensive. Easily applied. Massive vaccination. It used with all living vaccines (ND, IB, IBD, etc….)

Disadvantages: Un-homogeneous immunity. Contraindicated in birds suffering from

respiratory diseases especially ILT or mycoplasmosis as the infection could be activated after latency as well as severe post- vaccinal reaction.

Precautions : 1. It is more efficient in controlled (closed)

environment than open one.

2. Stop fans and dim light in case of closed system.

3. Close the inlet and outlet in case of open system.

4. Spray over the bird’s heads by a distance 40-60 cm. for 10 min.

5. Collect the birds in small area (third of the floor area) to minimize the interspaced area.

6. Allow the birds to settle quietly before spraying process.

Precautions : 7. Wear a mask to protect yourself and also the

attendant do.

8. The vaccine should be reconstituted in distilled water to prevent the virus inactivation and closure of sprayer or atomizer nozzle from impurities that present in tape water.

9. The amount of water is 200ml (young) – 400ml (adult) / 1000 bird.

Coarse spray (10µm) Young up to 1 month

Fine (aerosol) (5 µm) Older. Penetrate respiratory tract.

10. The birds shout be kept 20 min. after vaccination, then ventilate the house.

Advantages: The most effective method. Ensure each bird take the proper

dose. It used in case of living vaccines as

ILT, IB, ND, etc……

Disadvantages: Time consuming. Laborious. Cost. Stress on birds.

Precautions:1. The vaccine should be reconstituted in

distilled water.2. Volume of distilled water is 50 ml / 1000

doses.3. The bird is hold in a horizontal position and

dropping one drop using standardized dropper in one eye or one nasal opening, the drop descend through the naso-lacrimal duct to the pharynx or the buccal cavity.

4. You must observe the bird as it must swallow the vaccinal drop by opening and closing its mouth.

5. Some companies add coloured substances as crystal violet to ensure that each bird is vaccinated.

All living vaccines are given by drinking water or spray method as mass vaccination except:

Marek’s disease virus vaccine that given S/C.

Avian pox and duck virus hepatitis that given intradermal.

Newcastle disease virus vaccine (komarove) is given I/M.

The injection route is only used for inactivated vaccines either I/M or S/C route.

An automatic syringe is used to adjust vaccinal dosage.

Precautions : 1) Periodical shaking of the bottle (to avoid

injection of adjuvant).2) Regular checking on the dose and regular

changing of the needles to minimize the spread of contamination (about every 200 bird).

3) Avoid injection during egg production.4) Injection may be S/C at the back of the

neck or I/M into the breast or thigh muscles.

5) Accuracy is important as incorrect needle placement can result in head swelling, granuloma, liver damage or lameness depending on the injection site.

It is the principle method for administration of FPVV in chickens using forked needle.

The inoculation site of the wing web should be examined 7-14 days post vaccination to detect the vaccinal take (post vaccination reaction), which appeared in 95 – 100% of vaccinated birds as slightly raised and swollen area or granulomas or nodular scabs at the site of injection (good immune response).

In case of absence of this take, it should be re-vaccinate birds.

Also, this method could be used in AEVV and in FC(CU) strain.

vaccine takes on the chickens wing web. A take is a swelling of the skin or scab in the site where the vaccine was applied and is evidence of a successful vaccination.

Foot web: It is used in case of DVHVV & FC. In ova: This system is now being used in

some countries for administration of

NDVV and MDVV. Fertile chicken eggs are inoculated

at 18 days old on transfer into the

hatcheries.

I. Factors related to the vaccine or error on the part of manufactures:

1. Insufficient antigen titer (inadequate antigen content).

2. Poor immunogenicity.3. Defective packing.4. Contamination.

II. Factors related to the veterinarian (dose and vaccination method):

1. False storage and transportation.

2. Using the vaccine after the expiry date.

3. False technique of vaccination.(using of un-sterile equipments, insufficient drinkers, etc…)

III. Factors related to the host:1. Presence of maternal antibodies

(neutralization).2. Immune-suppressed host (IBD,

CIA, Tumors, mycotoxicosis, antibiotics, etc……..).

3. Improper bird’s age.4. Genetic variability between

birds in vaccinal response.

IV. Other factors:1. Error in vaccination timing.(the period between two successive vaccinations depends on the viral neutralizing antibody titer, usually not less than 3-4 weeks).2. Miss diagnosis.3. Stressors (malnutrition, heat, etc….).4. If the target virus is already infecting

the bird at the vaccination time.

Sterility test: Inoculate the locally prepared or imported vaccine into different media specific for bacterial growth

(MaConkey, Frey’s, etc….) to ensure it is free from bacterial and mycoplasma

contamination. Also, inoculate on selective media for

fungi (Sabaroud dextrose) to ensure it is free from fungal contamination.

Safety test: A group of birds are vaccinated

with 10 fold doses/bird and are subjected for observation for 2 weeks to ensure that the vaccinal strain is safe not induced any signs or lesions or deaths.

Potency test: The vaccine is titrated. Living vaccines are inoculated

into ECE or TC. Inactivated vaccines are

inoculated in a group of birds, after 2-3 weeks serum samples are collected for detection of antibody titer using serological tests (AGPT, ELISA, SNT & HI).

Challenge test: A group of birds are vaccinated by

the tested vaccine, after 2-3 weeks the birds are challenged by infective dose of the virulent field strain of the virus that used in the vaccine and then the birds are observed for signs, mortalities and lesions.

The protection rate of any vaccine should be not less than 80%.

Extraneous virus free test:

The vaccine should be free from any contaminating viruses especially ALC.

In Vivo:1.Vaccinal take.2.Challenge test. In vitro:1.Serological tests (AGPT, ELISA, SNT & HI).

2.Egg (embryo) susceptibility test.

It is used in case of AE (vertically transmitting disease).

It is used for determination if the breeders get previously infected with AEV or vaccinated against it through the detection of antibodies that transferred from dams to offspring.

Take 30-40 ECEs at 6 days old from the tested flock, then inoculated them with egg adapted virus followed by observation period about 1 week.

Detect the embryos with specific virus lesions (leg paralysis & muscular dystrophy) and others with no lesions.

Absence of lesions indicated presence of antibodies in these embryos that prevented and neutralized the lesions.

High immune response with history of vaccination. Previous infection if no history of vaccination.