Immunology for getting through to your clients (Proceedings)
Infectious conditions like respiratory diseases, reproductive diseases and neonatal diarrheas continue to "plague" animal owners! To combat these "plagues," there are three management options: 1) increase the resistance to the disease of the animal/herd (vaccination and nutrition), 2) prevent the access of the disease to the herd (biosecurity), and 3) treatment. This discussion will emphasize immunization in an approach that has been beneficial in keeping client:veterinarian:vaccination relationships viable and active.
The basis of immunologic resistance is the recognition and disposal of an invading "infectious organism" by the "immune system" to prevent the establishment of infection and the development of disease. Vaccines have been developed to maximize the natural mechanism(s) of animals to resist and combat infectious disease.
The mammalian immune system has two major components; 1) natural resistance and 2) acquired immunity. Immunization depends on the acquired immune system's ability to identify and dispose of foreign invaders through production of neutralizing chemicals—antibodies—or stimulation of specialized cells—T-cells. Natural resistances are those innate characteristics of mammals that prohibit access of an infectious agent to the host animal.Natural resistance includes physical and physiological barriers and is a key factor in the survival of all animals. Physical barriers include intact skin and mucous membranes and motility of the intestinal tract and the mucocillary apparatus of the respiratory tract. Natural physiological barriers involve the pH and secretions of the various systems. Species resistance to various microorganisms is due to genetically defined receptors on the surface of the cells, i.e., IBR will not infect swine because the necessary cellular receptor is both host animal and virus specific.
Acquired immunity (immunization) involves complex molecular and cellular mechanisms which 1) recognize an invading foreign substance (ANTIGEN) and develop specific immune responses (ANTIBODIES and IMMUNE CELLS) to dispose of the invader and 2) develop specific memory (ANAMNESTIC RESPONSE) for each invading substance. Acquired immunity consists of several components.
• Antigen recognition: the interaction of the invading foreign antigen (protein) with specific cells and the subsequent stimulation of the appropriate component of the immune system.
• Immunity is the production of specific proteins (antibodies) that appear in the blood. Lymphocytic stem cells differentiate into the "B cell" series that produce specialized chemicals called immunoglobulins or antibodies. Antibodies are able to bind to the specific antigen and "neutralize" its activity.
o The major serum protective immunoglobulins are IgG, and IgM. IgM is the first immunoglobulin to develop in response (5-7days) to the antigen and is "broadly active" (less specific)." IgG develops within 7-14 days and is very specific to the antigen that simulated its production.
• Local immunity is the development of secretory IgA antibodies on the surface of the respiratory, urogenital and GI tracts. In this response, surface lymphocytes of the tracts process and produce IgA; specific epithelial cells in the tracts attach a "secretory protein" to the IgA molecule that makes the immonogloubulin resistant to extreme pH and various enzymes present in tract secretions.
• Cell mediated immunity is the production of specific cells that remove or kill infected cells. CMI results with stimulated stem cells produce "T cells," which recognize certain types of antigen within cells and destroy the "infected" cells before the microorganism, especially viruses, is released from the cell and infects other cells.
• Immunologic memory, or the anamnestic response, permits the humoral and cell-mediated immune systems to "remember previous encounters" and respond more rapidly and specifically when re-exposed to the invading agent--the premise for vaccination. Local immunity has little or no "memory" and must constantly be "reminded" by re-exposure or revaccination. The anamnestic response also recognized magnitudes lesser amounts of an antigen than was required to stimulate the primary response additionally, the memory response routinely results in more antibody production or more "T" cell production. Vaccination does not mean immunization! Vaccination and immunization programs require regular repetitive revisiting of immunization programs and immunology.
o Cell mediated immunity is the production of specific cells that remove or kill infected cells. CMI results with stimulated stem cells produce "T cells," which recognize certain types of antigen within cells and destroy the "infected" cells before the microorganism, especially viruses, is released from the cell and infects other cells.