Immunity and Vaccination

By

Prof.Dr.M.M.AMER Prof. of Poultry Diseases,

Fac. of Vet. Med., Cairo University.

Professor of Poultry Diseases, Faculty of

Veterinary Medicine, Cairo University.

Mobile &WhatsApp +201011828228

profdramer123@gmail.com

Avian immune system

Spleen

Mucosal associated lymphoid

tissues (MALT):

Bronchial associated

lymphoid tissue (BALT)

Gut associated lymphoid

tissue (GALT).

Head associated lymphoid

tissues (HALT): contain the

Harderian gland, lacrimal

gland.

Germinal centers.

Diffuse lymphoid tissues.

Secondary

Bursa of Fabricius

Thymus

Bone marrow

Primary

Avian immune system

The primary function of the immune system

is to provide the bird with the ability to resist

the invasion by any injurious disease agent.

A crucial aspect of the immune system is that

it has an immunologic memory. This allows

the bird to respond to the second challenge of

a particular disease agent with a more rapid

and effective immune response.

Avian immune response

Main component of immune response:

Antigen-

presenting

cell (APCs) B-cells T-cells

Macrophages,

dendertic cells

and B cells

Antibodies (Ab)

Different types

of T cells & NK

Interferons &

cytokins.

Avian immune system

Bursa of Fabricius

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 .

Avian immune system

Bursa of Fabricius

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.

Vaccination

Aim of vaccination

1. To prevent:

– Clinical disease and mortality (ND, IBD).

– Loss of body weight (Reo, Mycoplasma).

– Leg problems (Reo, Mycoplasma).

– Fall in egg production (ND,IB,EDS).

– Fall in hatchability (Salm., Mycoplasma).

– Egg transmission of disease agents

(AE,CA,Salm.,Mycoplasma).

– Immunosuppression (IBD,CA,MD).

Vaccination.

Types of vaccines.

Iive vaccines Dead vaccines

2. To control:

An outbreak (emergency) to stop mortality and

prevent spread of infection. (in early stages) as

ND,ILT,FP.

3. To provide:

– Maternal immunity to progeny as ND,

IB,IBD,Reo,CA,AE…

Vaccination

Aim of vaccination

Vaccination.

Types of vaccines.

Live vaccines.

– Naturally weak as lentogenic strain of ND.

– Attenuated by some suitable means e.g. H120 of IB.

– Apathogenic strain of the disease organism e.g. serotype 2 of

MD.

– Pathogenic strain of the disease organism as AE in adult birds.

Dead vaccines.

– Concentrated antigen combined with oil emulsion

or Al OH adjuvant.

No -Interferon production

-Stimulated if boostered by live

vaccines.

-local immunity stimulated.

-Impossible. -Vaccine virus excretion possible.

Risky (Pox,IBD,ILT) & Beneficial (AE)

-Higher titers. -Produce lower antibody titers.

-Long duration. -Short duration of immunity.

-Late immune response. -Early onset of immunity.

-Encourage persistent immune response. -Adjuvant not possible.

-Must be injected. -Route of administration variable

-Large quantity of antigen -Small quantity of antigen

Inactivated vaccines Live vaccines

-Costly.

-Easier but costly.

-Lower cost for production.

-Storage and transportation require strict

measures

-Not effective. -Highly effective during epizootics.

-High and frequently homogenous. -Vertical transmission of immunity.- low

& irregular

-Higher risk (mineral oil). -Risk to vaccinator (zoonotic dis.)

More common. -Limited multiple vaccines.

-No unless abscess formation or

hematoma at site of injection.

-May provoke tissue reactions requiring

corrective medication.

-No danger of vaccine contamination. -Danger of vaccine contamination.

-Usually effective, duration of response

prolonged.

-Booster vaccination frequently

ineffective or effect short lived.

-Delayed. -Protection soon.

-Less susceptible to MDAb. -Very susceptible to neutralization by

maternally derived antibody.

Inactivated vaccines Live vaccines

Live Inactivated Vectored

Storage and

constitution

frozen, freeze-

dried; chilled, liquid

chilled,

suspension,

emulsion

frozen, cryo-frozen (liquid nitrogen)

Adjuvants no yes no

Administration

route

mass (spray, aerosol,

drinking water) or

individual (eye drop,

injection)

injection

in ovo, individual (eye drop, injection-

subcutaneous or wing-web) or mass(spray,

aerosol) depending on the vector

Duration of

immunity short long long

Response to the

vaccine Systemic and local systemic systemic and local

Antibody immune

response IgY, IgM, IgA IgY, IgM

IgY, IgM, IgA (depending on

vector and route of administration)

Cell-mediated

immune response Strong weak strong, for NDV-vectored

Affected by

maternal

antibodies

yes

depending on the level of

antibodies

yes,

depending on

the level of

antibodies

Yes

depending on vector ( can be overcome by

inoculation route &vaccine dose) affected

by antibodies against FPV &HVTvector

Item Live Inactivated Vectored

Affected by

antibodies from

previous

vaccinations

yes,

if induced by live vaccines

Yes

depending on

the level of

antibodies

yes,

if induced by live vaccines; HVT-vectored

vaccine significantly affected by pre-existing

anti-HVT antibodies

Protection onset 2–3 weeks 6–8 weeks 4–5 weeks

Clinical signs after

vaccination

possible mild respiratory

signs depending on many

factors (age, immunity,

etc.)

no NDV-vectored – not studied;

NDV-inserted – no

Cost less expensive More

expensive Variable

Genotype Vaccine

strain

I class II ((i.e. I2, V4, PHY-

LMV42- Ulster) Any Any ND Genotype

(rFPV and rHVT)

II (LaSota, B1, Clone30)

Vaccination methods

Drinking Water.

– Live vaccines are often administered via drinking water.

– Advantages: Massive vaccination . Easily applied.

– Disadvantages: Unhomogeneous immunity.

– Precautions:

The vaccine reconstituted in clean, cool, chlorine free water.

Water must contain skimmed milk (2gm/L) which act as stabilizer and protect the live virus from deleterious subs. As organic matter, solids or chlorine, which may be in water.

Drinking Water.

– Precautions:

The birds should be deprived of water for 2-4

hours.

Vaccine is diluted acc. to age:

– 15 day 15L/ 1000 bird.

– 3 weeks 20L/1000 bird.

– Older than 40 days 40L/ 1000 bird.

Vaccination methods

Spray. – Coarse spray (10µm) Young up to 1 month

– Fine (aerosol)(5 µm) Older.

– Penetrate respiratory tract.

– Advantages: Massive vaccination .Easily applied.

– Disadvantages: some resp. affections as Mycoplasma & severe post-vacc. reaction (ILT).

Vaccination methods

Spray. – Precautions:

Vaccine should be reconstituted in dist. Water.

200ml (young) – 400ml (adult) / 1000 bird.

Time of exposure is 5 – 10 seconds & walking slowly

It is more effective in controlled environment than open sided houses.

In closed houses, fans should be turned off, inlets and outlets closed, lights dimmed and the birds allowed to settle quietly, before spraying commences.

Vaccination

methods

Eye drop:

– As ILT.

– Advantages: The most effective. The proper dose.

– Disadvantages: Time consuming, labors’ cost & stress

on birds.

– Precautions:

The vaccine should be reconstituted in dist. Water.

Volume of dist. Water is 50 ml / 1000 doses.

Vaccination methods

Intramuscular (into breast or leg) or

subcutaneous (in the back of the neck) injection.

– Live vaccines as Marek’s Dis. & Viral arthritis.

– Killed vaccines.

– Advantages: The most effective. The proper dose.

Emulsion slow release of antigen prolonged immunity.

– Disadvantages: Time consuming, labors’ cost & stress

on birds. Risk on the vaccinator (allergy).

Vaccination methods

Intramuscular (into breast or leg) or

subcutaneous (in the back of the neck) injection.

–Precautions:

Periodical shaking of the bottle.

Regular checking on the dose and

regular changing of the needles to

minimize contamination.

Avoid injection during egg production.

Vaccination

methods

Automatic S.C

Wing web.

– Fowl pox vaccines or cholera..

– Vaccinal takes in 95 – 100% of vaccinated birds

at 7 – 14 days post vaccination. ( slightly raised and

swollen area or granulomas or nodular scabs at the site

of injection.

Vaccination methods

In Ovo vaccination.

– At 17 – 19 days of embryonation.

– MD vaccine using Egg injection system.

Vaccination methods

Vaccinal Failure

Vaccine Bird

•Storage (vaccine delivery)

•Dose & diluents

•Highly attenuated X vv dis.

•Lacking of some serotypes.

•Reconstitution as MD vaccine.

•Inappropriate administration.

•Mishandling of live vaccines.

•Age (time of vacc.

•Maternal immunity.

•Other vaccines (ND , IB).

•General health condition

•Management.

•Immunosuppressives.

To assess efficacy of vaccine, field challenge, new pathogen,

MDAbs. and Revaccination by detection of Serologic

profiles above or below the BASELINE.

It is useful if analyzed adequate samples over time to a

program, in a location, in a specific bird, using specific

and consistent techniques, with samples run consistently

“To ESTABLISH A NORMAL by a specific laboratory.

BASELINE”

a. In broiler:

Regular sampling and testing of blood at slaughter.

b. In layer and breeder:

Before placing in layer building.

Periodic monitoring during production cycle.

4. Serologic Monitoring

•It is impossible to differentiate between antibodies from

vaccination and field infection. In field challenge it may be higher.

„„A valid interpretation of results requires a complete knowledge of

vaccination history‟‟

• Poultry takes 1-3 weeks to produce detectable levels of antibodies.

• Blood during the middle of a disease outbreak (not be able to detect

any antibodies to the disease agent) and 2 weeks later (antibody

levels will be high).

• For diagnosis of field challenge serum samples must be taken at

acute (Abs –ve) and shortly after recovery „„convalescent‟‟ (Abs

+ve). Definitive diagnosis obtained when interpreted serological

results in conjunction with the clinical signs and lesions.

• Single positive serologic test only indicates that the flock was

exposed to that disease agent during its life.

• Titer reported from different laboratories may be confusing, as

laboratories used different reagents or techniques.

Interpretation of Serologic Data

Thank you