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Developing Immunity

Understand the avian immune system, antibody production, vaccine efficacy, and factors affecting immunity to protect poultry from diseases.

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Developing Immunity

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  1. Developing Immunity Immunity: Power to resist infection and destroy their activity Acquire ability in the body that differentiate F. S. Phagocytosis of the organism,secretion, obstructed Immune System: Foreign substances that used as antigen Which causes the production of antibodies It is a highly specialized defense system called the Immune System. Resisting disease caused by infectious agents.

  2. Immune System • Two types: • T- system (Thymus system): Immature lymphocytes originating in the yolk sac & bone marrow pass through the thymus called T- Lymphocytes. • Mature, grow & accumulate in the lymphoid organs • T- cell do not produce antibodies • Power to develop lymphokines- destroy foreign cells in the presence of AB, called cellular immunity

  3. Immune System • B- System (Bursal system): T- cells & other lymphocytes pass through the bursa of Fabricius in the young chicks & maturation takes place • Plasma cells develop in the B- system, including the bursa, spleen, & cecal tonsils & produce AB. • B- system produce > 700 times AB than T- system. • Diseases that affect thymus or bursa of young chick disrupts the development of B or T- system Anamnestic response: Development of lymphocytes that act as a memory cells, referred to as anamnestic response.

  4. Suppression of Immune System Certain diseases & conditions affect immune systems: • Suppression of the T- system: 1. Marek’s disease; 2. Heat & cold; 3. Genetic origin; 4. Incomplete vaccine reaction; 5. Aflatoxicosis • Suppression of the B- system: 1. IBD; 2. Heat & cold ; 3. Lymphoid leucosis; 4. Nutritional deficiency; 5. Toxins; 6. Inclusion body hepatitis; 7. Aflatoxins; 8. Mycoplasmosis; 9. Coccidiosis; 10. Reo infection. 11. Low antibody production.

  5. Antibodies and Immunity • Physiology of Antibodies • If foreign substance enters the chicken, the body acts to eliminate it. • Bacteria are proteins, that are foreign to the birds. • Foreign protein produce a toxic reaction – disease. • Body system generates a chemical called antibody inactivates them. • Antibody Behavior • Independent antibody for each disease

  6. Antibodies and Immunity • Length of time for AB production that varies on: • No. of organisms involved at invasion time • Virility or virulency of the organism • Condition of the bird (freedom from stress) • Type of organism • Immunity long-lasting from vaccine to vaccine • Antibodies may not destroy all organisms. e.g. the atrophied ova have no blood supply, so Salmonella pullorum harbored & continue to live on & multiply

  7. Variability in AB Production • Higher the titer, the greater the number of antibodies • Titer determines resistance: 1. If AB titer become low severe reinfection may occur; 2. Severity of the 2nd. Invasion will be determined by the no. of AB in the bird at that time. • Age of the bird and AB: • Young chicks seem more susceptible than older birds.

  8. Parental or Passive Immunity • Decrease of AB is much more rapid in chicks than adult • AB no. in chicks correlated with no. in chicks • Chicks with no parental immunity are easily invaded • Passing live organisms through the eggs. Parental Immunity Not Effective with Some Disease: ILT, Mycoplasma, Fowl pox.

  9. Vaccine and Vaccination • Vaccine: A suspension of living living or inactivated organisms used as an antigen in order to confer active immunity. • Vaccination: A method of producing active immunity against a specific infection by means of inoculation with a vaccine.

  10. How Vaccines Work • Used to produce a mild infection • Antigen part produce AB in some specific organ • Protect by the invasion of that specific organism • Vaccination efficacy depends on administration procedure & virulency, quality & quantity of antigen

  11. Routes of Vaccine administration • Intramuscular 10. Feather follicle • Subcutaneous 11. Spray • Ocular • Nasal • Oral • Drinking water • Dust- into RT through nostrils • Cloacal • Wing web

  12. Types of Vaccines Vaccines may be classified into three groups according to their efficacy or method of manufacture: • Live virus vaccine: Live virus, completely capable of producing disease & transmitting to any susceptible birds. • Attenuated vaccine: Organisms become weakened (attenuated) by various methods & produce milder form of disease(No evidence of disease). • Killed vaccine: Killed organisms, have the capacity to produce AB (delay & long lasting immunity).

  13. Parental Immunity & Vaccination • Killed vaccination after live vaccination become hyper immunization in parents body • MDA transferred to progeny, sometimes retained up to 2- 3 wks. • Some live vaccines not response in presence of MDA

  14. Stress and Vaccination • Vaccines produce a mild effect on the healthy bird • Stress can accentuate the effect • During which birds should not be vaccinated: • When the birds are “ off feed” • Periods of extremely hot weather • S.C. & clinical form of Coccidiosis & Mycoplasmosis • Vaccination reaction of other diseases • When birds are being medicated or are diseased • Following beak trimming • First few weeks of an induced molt.

  15. Vaccination Failure • Vaccine problem: • Cool chain 9. Strain not specific • Less tight bottle cork 10. Accurate dosing • Light stimulation 11. Antigen quantity • Diluent acidity or alkalinity • Mutation of live vaccine virus • Classic or standard strain not act on variant strain • Antigen virulency not suitable for field virus • If live vaccine virus killed or loss antigenic property

  16. Vaccination Failure (Cont.) • Technical or using problem: • Improper vaccination place & procedure • Not use specific vaccine in specific time • Long time vaccination after dilution • Use improper vaccination equipments

  17. Vaccination Failure (Cont.) • Birds own problem: • Vaccinate diseased birds • Deficiency of protein, vitamins & minerals • Vaccinate stressed birds • Vaccinate against disease that is present S.C. form • If bird is infested with worm or coccidia • Bird affected with immunosuppressive disease like- IBD, Reo, Marek’s, Mycotoxicosis etc.

  18. Vaccination Failure (Cont.) • Parent farm and/ or hatchery problem: • Not remove Salmonella carrier parents, Salmonella present in hatchery, DOC carry Salmonella and if vaccinate these DOC • Minimum or no MDA in omphalitis affected chicks • If parent not vaccinated two times one at 19-21wks. & 40-45 wks. With killed vaccine in vvIBD affected area • DOC from different parent flock and age

  19. Vaccination Failure (Cont.) • Feed problem: • Deficiency occur due to less quality feed • Mold & Mycotoxin and other organism in feed • Minimum knowledge of poultry farmers • Use of unwanted drug • Farm established not in scientific way, not maintain bio-security properly • Not done area basis combined vaccination program Vaccine titer and Antibody titer.

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