VETERINARY IMMUNOLOGY

IMMUNOLOGY• the scientific study of all aspects of immunityIMMUNITY • non- susceptibility to the invasive or

pathogenic effects of microorganisms• Is an enhanced state of responsiveness to a

specific substance, induced by prior contact with that substance

• State of resistance to an infection

Historical Highlights in Veterinary Immunology

Date Event

12th century “Variolation” or “Inoculation” -Chinese rubbed infected pox materials on cuts of skin

1754 Rinderpest or “cattle plague” outbreak started inoculation of healthy animals with piece of string soaked in the nasal discharge of infected animal as preventive measure to control rinderpest

1798 Edward Jenner used cowpox to vaccinate humans against small pox. Vaccination term was coined from “vacca” latin for cow

1879 Louis Pasteur established the general principle of vaccination using Pasteurella multocida model in chickens.

1879 Louis Pasteur•Founder of the Science of Immunology•Father of Immunology•First to produce Bacillus antracis vaccine•Developed the first Rabies vaccine using dry spinal cord of rabies infected rabbits

1890-1904 Daniel Salmon and Theobald Smith used heat killed culture of Salmonella enterica cholerasuis to protect pigeonsVon Behring and Shibasaburo Kitasato sucessfully tested vaccines for diptheria and tetanusVon Behring named and discovered antibodies

1905 Robert Koch discovered the tuberculin reaction and won the Nobel Prize

1955- 1960 Jonas Salk and Alfred Sabin discovered the different forms of the poliomyelitis vaccine which was used to control the disease worldwide.

1984 George Kohler and Cesar Milstein won Nobel Prize for production of monoclonal antibodies

• Defense of the body or protection of the body is a function of multiple defense systems that can control or destroy most of invaders

• An effective immune system is essential to life

TYPES OF IMMUNITY

NATURAL OR INNATE IMMUNITY• Nonspecific• Present from birth• Consists of

a. Barriers to antigens: e.g. skin, mucous membranes, b. chemical and cellular defense mechanisms , e.g.

Inflammation- a focused defense response where local changes in tissues brought about by microbial invasion or tissue damage result in increased blood flow and local accumulation of cells that can attack and destroy the invaders.Complement System

TYPES OF IMMUNITY

ACQUIRED IMMUNITY (Specific/ Adaptive)– Expressed after exposure to a given substance or

antigen and is specific– An adaptive response wherein the system can learn to

recognize invaders when it encounters them again and that can respond even more rapidly and effectively. The acquired immune system can recognize foreign invaders, destroy them and retain the memory of the encounter.

– Consist of: Humoral Immunity Cell Mediated Immunity

A comparison of Innate and Acquired Immunity

INNATE IMMUNITYAlways “on “

ACQUIRED IMMUNITYTurned on by antigens

Cells involved

Onset

Specificity

Potency

Memory

Effectiveness

Macrophages, dendritic cells, neutrophils

Rapid ( min- hrs)

Common microbial structures

Maybe overwhelmed

None

Does not improve

T and B cells

Slow (days –weeks)

Unique antigens

Rarely overwhelmed

Significant memory

Improves with exposure

THE BODY’S DEFENSES Invading Microorganisms

Physical Barriers Examples:

Innate Immunity Examples:

Specific Immunity Examples:

BODY DEFENSE

Acquired Immunity

Humoral Immunity

Antibodies

Cell mediated Immunity

Lymphocytes

Innate Immunity

TYPES OF IMMUNE RESPONSE

A. Humoral Immune Response (Antibody mediated Immunity)- acquired immunity response to exogenous antigens that are extracellular

Antibodies or Immunoglobulins- protective factors synthesized by the body against an antigen or upon exposure to an antigen.

Ex. Tetanus antitoxin when injected to a horse prevents tetanus infection.

HUMORAL IMMUNE RESPONSE

A. Primary Immune Response- response that occurs following a first exposure to an antigen, antibodies produced are relatively small, no antibodies are detected for a week ( lag period) after injection. Antibodies peak at 10-14 days before declining.

B. Secondary Immune Response- a response that occurs following a second or subsequent exposure to antigen, the response is immediate and antibody rises rapidly at a higher level than the primary response. The features of the secondary immune response indicate that the immune system is able to remember previous exposure to an antigen also known as ANAMNESTIC RESPONSE.

TYPES OF IMMUNE RESPONSE

B. Cell Mediated Immune Response (CMI)– Mediated by lymphocytes and phagocytes E.g. Graft rejection demonstrates the existence of

a mechanism wherein foreign cells differing slightly from an animals own normal cells are rapidly recognized and eliminated.

– CMI and Humoral Immune Response not entirely separate but they act together.

TOLERANCE

• The immune system must recognize its own cells as not foreign and not mount an immune response. Tolerance breakdown results to autoimmune disease.

• Examples. Systemic Lupus Erythromatosus (SLE), Hemolytic anemia and myasthenia gravis

MECHANISM OF IMMUNE RESPONSE

1. Method of trapping and processing antigens (Ag)

2. Mechanism of reacting specifically to an Ag3. Produce antibodies (Ab) or participate in CMI4. Cells retain memory of event and able to

react to the same Ag in the future.

Mechanism of Acquired Immune ResponseForeign Material

Extracellular Intracellular(Exogenous) (Endogenous)e.g. parasite, protozoa, bacteria, fungi e.g. viruses, intracellular protozoa , cancer

cells

Antigen Processing Cells ( APC)

Antigen sensitive CellsB cell T cell

Memory cells Ab producing cells Effector cell Memory cell

Ab production Cell mediated Immunity

Antigen elimination

Stop