immunity and vaccination - cu
TRANSCRIPT
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
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