Practical Applications of Immunology. Chapter 18

Transcription

1 Practical Applications of Immunology Chapter 18

2 I. Vaccines A. Definition A suspension of organisms or fractions of organisms that is used to induce immunity (immunologic memory). The mechanism of memory is mediated by memory T and B cells that provides a quick and effective secondary response to pathogenic antigens (e.g. Hepatitis B, tetanus toxin). In general, polysaccharide antigens found in bacteria do not stimulate production of effective antibodies as well as protein antigens found in viruses.

3 II. Principles and Effects of Vaccination A. Herd Immunity Immunity that results when most of the population is immune. Outbreaks are reduced to sporadic cases because there are not many susceptible individuals.

4 II. Principles and Effects of Vaccination B. Principle Vaccines used in US to Prevent Bacterial Diseases

5 II. Principles and Effects of Vaccination C. Principle Vaccines Used in US to Prevent Viral Diseases

6 II. Principles and Effects of Vaccination D. Schedule of Childhood Immunizations

7 III. Types of Vaccines and Their Characteristics A. Attenuated Whole-Agent Vaccines B. C. Consist of live attenuated (weakened) microorganisms that mimic an actual infection. Attenuated virus vaccines generally provide life-long immunity (Sabin polio and MMR). Inactivated Whole-Agent Vaccines Consist of killed bacteria or viruses (Salk polio, influenza, and pneumococcal). Toxoids Inactivated toxins directed to make antibodies that inactivate toxins produced by pathogens. Usually need booster immunization every 10 years or so (tetanus and diphtheria toxoids). Examples: tetanus and diphtheria toxoids.

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9 III. Types of Vaccines and Their Characteristics D. E. Subunit Vaccines Consist of only antigenic fragments of a microorganism that induce the best immune response. Includes recombinant vaccines (hep B fragments produced by yeast) and acellular products that retain desired antigenic fractions. Newer pertussis vaccines are acellular. Safer because they cannot reproduce in recipient. Conjugated Vaccines Combine the desired capsular polysaccharide antigen (weak immunizer in young children) with a protein that boosts the immune response in children under 2 years old. Example: Hemophilus influenza (Hib) capsular antigen with diphtheria protein toxoid.

10 r-hbvax r-hbvax is a non-infectious, inactivated recombinant subunit viral vaccine derived from HBsAg Produced in yeast cells using recombinant DNA technology developed by Korea Green Cross Corporation. It is a whitish turbid liquid which is produced by culture of genetically engineered yeast cells which carry the relevant gene of HBsAg, purified and inactivated by several physico-chemical steps such as ultra centrifugation, column chromatography and formaldehyde treatment. Pentacel, Diphtheria and Tetanus Toxoids and Acellular Pertussis Adsorbed, Inactivated Poliovirus and Haemophilus b Conjugate (Tetanus Toxoid Conjugate) Vaccine. Pentacel vaccine is indicated or active immunization against diphtheria, tetanus, pertussis, poliomyelitis, and invasive disease due to Haemophilus influenzae type b (Hib). Pentacel vaccine will help simplify the immunization schedule by reducing the number of injections infants and young children will receive in their first two years of life, said Wayne Pisano, President and Chief Executive Officer, sanofi pasteur.

11 III. Types of Vaccines and Their Characteristics F. Nucleic Acid Vaccines or DNA Vaccines Under development. Foreign DNA injected and foreign protein made by host cell until the DNA is degraded. With DNA vaccines the individual is not injected with the viral antigen, but with DNA encoding the antigen. DNA vaccines are injected into patients either as naked DNA or DNA carried by a non-pathogenic virus vector. In either case, the DNA gains access to cells where the antigen protein is synthesized by normal cell mechanisms and presented to the immune system to stimulate the immune response to it. Immunomic Therapeutics, Inc. Immunomic Therapeutics, Inc.

12 III. Types of Vaccines and Their Characteristics G. Safety of Vaccines No vaccine is perfectly safe or effective, but still remains the most safe and effective means of preventing infectious disease in children. Most parents never see a case of polio or measles and are remote abstractions to them. Reports or rumors of harmful effects are rarely accurate, but lead parents to avoid vaccination for themselves or children.

13 Opposition to vaccination, from a wide array of vaccine critics, has existed since the earliest vaccination campaigns. The Cow-Pock or the Wonderful Effects of the New Inoculation! (1802)