Vaccine Immunity

9 Key excerpts on "Vaccine Immunity"

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  eBook - ePub

  The Covid-19 Vaccine Guide

  The Quest for Implementation of Safe and Effective Vaccinations

  • Kathryn M. Edwards, Walter A. Orenstein, David S. Stephens(Authors)
  • 2021(Publication Date)
  • Skyhorse

    (Publisher)

  Chapter 2 Introduction to Vaccines and Vaccinology

  V accines are the most cost-effective intervention for preventing human disease. What is a vaccine? How does it work? How do vaccines protect?

  A vaccine is a substance, such as an inactivated protein from an infectious organism, that when given to a person induces an active immune response to prevent or mitigate a disease. Your immune system acts as an army. The immune system ideally detects the foreign invading germ (i.e., virus, bacterium, fungus), generally called a “pathogen,” and destroys it or contains it so that it cannot cause disease. What a vaccine does is give the immune system practice so that when it encounters the real pathogen, it is ready. Without practice from the vaccine, the pathogen can overwhelm an unprepared immune system, causing serious illness.

  The immune system can protect against infection and disease in two different ways. First, it can secrete immune proteins, called antibodies, into blood or tissues that bind to the invading pathogen and prevent it from multiplying or invading cells of the human body and enhancing the uptake of the pathogens into special cells (“phagocytes”) which destroy the pathogen. This aspect of the immune system is often called the humoral immune system. Critical players in this response are B cells and specialized B cells called plasma cells. The plasma cells produce the antibodies that circulate in the blood and other body fluids and tissues, which when encountering the pathogen neutralize it or bind to it, facilitating destruction of the pathogen by other cells of the immune system.

  Second, the immune system consists of specialized cells, called T cells, which destroy infected human cells and prevent the pathogen from spreading and causing serious disease. This aspect of the immune system is called the cellular immune system.

  A number of vaccines include substances called adjuvants or immune system helpers. These adjuvants enhance the immune response to the vaccine. In the United States, the most common adjuvants are aluminum-based compounds. But an increasing number of vaccines have other new adjuvants that stimulate immunity, particularly in the elderly or those with less-robust immune responses (see https://www.cdc.gov/vaccinesafety/concerns/adjuvants.html

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  Pharmaceutical Biotechnology

  Fundamentals and Applications, Third Edition

  • Daan J. A. Crommelin, Robert D. Sindelar, Bernd Meibohm, Daan J. A. Crommelin, Robert D. Sindelar, Bernd Meibohm(Authors)
  • 2016(Publication Date)
  • CRC Press

    (Publisher)

  This is effectuated by administration of antigenic components that (1) consist of, (2) are derived from, or (3) are related to the pathogen. The success of vaccination relies on the induction of a long-lasting immunological memory. Vaccination is also referred to as active immunization, because the host’s immune system is activated to respond to the “infection” through humoral and cellular immune responses, resulting in adaptive immunity against the particular pathogen. The immune response is generally highly specific: it discriminates not only between pathogen species, but often also between different strains within one species (e.g., strains of meningococci, poliovirus, influenza virus). Albeit sometimes a hurdle for vaccine developers, this high specificity of the immune system allows an almost perfect balance between response to foreign antigens and tolerance with respect to self-antigens. Apart from active immunization, administration of specific antibodies can be utilized for short-lived immunological protec-tion of the host. This is termed passive immunization (Fig. 2). Traditionally, active immunization has mainly served to prevent infectious diseases, whereas passive immunization has been applied for both prevention and therapy of infectious diseases.

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  eBook - ePub

  The Vaccine Book

  • Barry R. Bloom, Barry R. Bloom, Paul-Henri Lambert(Authors)
  • 2002(Publication Date)
  • Academic Press

    (Publisher)

  Despite the enormous success of current vaccines, there are no uniformly effective vaccines for infections such as HIV, malaria, and Mycobacterium tuberculosis, which today account for a substantial proportion of the deaths worldwide from infection. Moreover, the substantial morbidity and mortality associated with Ebola virus infection and the potential threat of bioterrorism have made vaccine biology a major priority of scientific and medical investigation. Although the goal of vaccination is to provide protection against disease caused by a microorganism, it is also important to develop a thorough understanding of the immune mechanism by which protection is achieved. This facilitates a more systematic approach to vaccine development that allows for the improvement of existing vaccines and the rational design of future vaccines. Thus, vaccine studies seek to define “immune correlates” of protection that can provide a useful guide in determining the type of immune response a vaccine should elicit. In this regard, immune responses can be divided into humoral (antibody) and cellular (T cell) immunity. The majority of licensed human vaccines work by inducing protective antibodies. Therefore, the immune correlates for most current vaccines are derived by measurement of the level of antibody elicited after immunization. It is also important to point out that, whereas antibodies are necessary and possibly sufficient for protection against certain infections, protective immunity against many infectious diseases involves a complex interplay of both the humoral and cellular immune responses. Indeed, a major impediment to the development of successful vaccines against HIV, M. tuberculosis, and malaria has been a lack of understanding of how to induce long-term protective cellular immune responses. This part of Chapter 2 will first review the basic immunology relevant to the goals of inducing and maintaining humoral and cellular immune responses

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  Encyclopedia of Epidemiology

  • Sarah Boslaugh, Sarah E. Boslaugh(Authors)
  • 2007(Publication Date)
  • SAGE Publications, Inc

    (Publisher)

  More specifically, when a person is vaccinated, he or she is exposed to a version of a pathogen that has been altered so that it does not produce disease, but so that it still contains antigens, or the parts of the pathogen that stimulate the immune system to respond. The B lymphocytes in an indivi-dual’s blood then detect these antigens in the vaccine and react as if the real infectious organism was invad-ing the body. During this process, the B lymphocytes clone themselves producing two types of cells: plasma cells and memory B cells. The plasma cells produce antibodies that attach to and inactivate the pathogen. This response is known as the primary immune response; it can take up to 14 days for this process to reach maximum efficiency. Over time, the antibodies gradually disappear, but the memory B cells remain. If an individual is exposed to the disease-causing pathogen again, these dormant memory cells are able to trigger a secondary immune response. This occurs as memory B cells multiply quickly and develop into plasma cells, producing anti-bodies that in turn attach to and inactivate the invading pathogen. Unlike the primary response, this secondary response usually takes only hours to reach maximum efficiency. It is through this process that vaccination is able to protect individuals from disease. Vaccination is also beneficial at the population level. When a sufficient number of individuals in a population are immune to a disease, as would occur if a large proportion of a population was vaccinated, herd immunity is achieved. This means that if there is 1069 random mixing of individuals within the population then the pathogen cannot be spread through the population. Herd immunity acts by breaking the trans-mission of infection or lessening the chances of susceptible individuals coming in contact with a per-son who is infectious.

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  Human Biology

  • Cecie Starr, Beverly McMillan(Authors)
  • 2015(Publication Date)
  • Cengage Learning EMEA

    (Publisher)

  passive immunity Immunity conferred by injected antibodies to a pathogen. It does not stimulate the recipient’s immune system to produce antibodies. vaccine Prepared sub-stance that contains an antigen. Most vaccines are made using dead or weak-ened antigens. Immunology in Everyday Life may be helped by injections of antibodies that confer passive immunity . A patient receives antibodies that have been purified from another source, preferably someone whose adaptive immune system already has produced a large amount of the antibody. The result is “passive” immunity because the recipient’s own B cells are not n Modern science has developed powerful weapons that can enhance the immune system’s functioning or harness it in new ways to prevent or treat disease. Vaccination stimulates immunity Vaccination (“immunization”) is a way to increase your immunity against a specific disease. A vaccine is a prepared substance that contains an antigen. A vaccine is injected into the body or taken orally, some-times according to a schedule (Table 9.3). The first injection elicits a pri-mary immune response that confers active immunity . A later booster shot elicits a secondary response, in which more effector cells and memory cells form. The booster can provide long-lasting protection. Many vaccines are made from killed or extremely weakened patho-gens. For example, weakened polio-virus particles are used for the Sabin polio vaccine. Worldwide vaccina-tions with a weakened relative of the smallpox virus allowed a suc-cessful global effort to eradicate the disease (Figure 9.15). Other vaccines are made using inactivated forms of natural toxins, such as the bacterial toxin that causes tetanus. Today many vaccines are made with genetically engineered viruses (Chapter 21). These harmless “transgenic” viruses incor-porate genes from three or more different viruses in their genetic material.

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  New Vaccine Technologies

  • Ronald W. Ellis(Author)
  • 2001(Publication Date)
  • CRC Press

    (Publisher)

  C hapter 1 New Technologies for Making Vaccines Ronald W. Ellis Introduction T he past two decades have witnessed an explosion in the number of technological and immunological approaches for making new vaccines. These developments have flowed from advances in a broad range of scientific fields. Some of the earliest applications of the newer technologies were to improving previously existing vaccines. However, most recent applications have been directed toward the development of new vaccines for diseases not previously approachable. The protective immunity elicited by a vaccine ideally would be life­ long and robust after one or a few doses with minimal side effects (reactogenicity). Available vaccines and those under development fall short o f this ideal, thus stimulating new research in the field. There are two broad categories of vaccines, active and passive. An active vaccine stimulates the host’s immune system to produce specific antibodies or cellular immune responses or both, which would protect against or eliminate a disease. A passive vaccine is a preparation o f anti­ bodies that neutralizes a pathogen and is administered before or around the time of known or potential exposure. Most references to the term vaccine are to active vaccines, which are the object of the vast majority of research and development activities in the field as well as the subject of this chapter. Although it is desirable or essential to administer a passive vaccine in specific instances (particularly if no active vaccine is available or sometimes for immuno­ compromised individuals), establishing lasting immunity through the administration of an active vaccine is a very important means of preventive medicine. This chapter summarizes the major technologies, key issues and immunological objectives for making different kinds of active vaccines.

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  Immunology for Pharmacy Students

  • Wei-Chiang Shen, Stan G. Louie(Authors)
  • 2019(Publication Date)
  • Routledge

    (Publisher)

  Vaccines Newborns have little immunity against pathogens found in the environment. Other than maternal immunoglobulins, newborns have no immune defense mechanism and are at the mercy of infectious organisms present in the environment. Passive immunity could be conferred by the oral administration of maternal milk containing protective immunoglobulins. However, active immunity can only be conferred by direct antigenic exposure that will initiate immune priming, thus producing memory against the pathogen. When an infectious organism is administered to an individual, this can be considered as a deliberate active immunization or vaccination. Following Jenner’s initial findings, little was done to further describe the protective nature of deliberate immunization. Not until Louis Pasteur’s discovery that sheep inoculated with heat treated anthrax bacilli could confer protection against virulent bacilli was there any advancement in vaccine technology. The heating process was able to weaken or attenuate the anthrax such that the immunological response was conferred without developing full-blown clinical disease. The weakened anthrax was immunogenic enough to prime the immune system, yet unable to produce physiological signs of infection. This discovery suggested that clinical disease was not necessary for immune priming. Instead, antigen exposure was all that was necessary to prime the immune system. Vaccination has the capacity to protect the immunized patient by priming the immunological defense against a secondary exposure. Vaccines are immunogens capable of stimulating the host immune system, where deliberate exposure to the antigen results in the production of memory B- and T-lymphocytes against the specific target. A patient is adequately immunized when a second exposure enables the individual to more rapidly respond to the antigen with both humoral and cellular components. This accelerated immune VACCINES 139

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  Perspectives in Medical Virology, vol. 1

  Perspectives in Medical Virology, vol. 1

  • Brian Evans(Author)
  • 2003(Publication Date)
  • Elsevier

    (Publisher)

  As is often the case in human endeavour most work on a topic does not lead to most succeSs (e.g. we know more about influenza than any other virus, but it is the least successfully con- trolled) and conversely single brilliant steps of a moment by one or two persons can lead to tremendous advances (e.g. smallpox and polio vaccines). In this same chapter we would also like to introduce the reader to mathematical-modelling ideas which are designed to help epidemiologists to co-ordinate and design immunization campaigns in a logical way. General principles of viral immunopathology, epide- miology, immune response and virus neutralization will also be discussed. Finally, we should not forget techniques and principles of vaccine production and standard- ization, and studies of side reactions and efficacy of vaccines in the field. The inter- relationship of all these factors is important for the planned demise of any virus disease of man. 2.2. Simple immunological concepts relevant to viral vaccines Following infection with a virus, two different types of immunological reaction may occur to a varying degree. Firstly, synthesis and release of free antibodies into the blood and other body fluids (humoral immune response) which would neutralize 38 virus particles themselves or mediate an immune response to a virus infected cell. Secondly, production of sensitized lymphocytes may occur which are responsible for cell mediated immunity (CMI). This latter cell mediated immunity may also be effective against viruses replicating intracellularly because cytotoxic T cells, for example, can lyse virus infected cells, which have virus antigens on the cell surface (reviewed by Mims, 1982).

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  Microbiology

  Principles and Explorations

  • Jacquelyn G. Black, Laura J. Black(Authors)
  • 2018(Publication Date)
  • Wiley

    (Publisher)

  Finally, much greater effort is needed to make immunizations available in underdeveloped countries. Active Immunization To develop active immunity, as noted earlier, the immune system must be induced to recognize and destroy infec- tious agents whenever they are encountered. Active im- munization is the process of inducing active immunity. It can be conferred by administering vaccines or toxoids. A vaccine is a substance that contains an antigen to which the immune system responds. Antigens can be derived from living but attenuated (weakened) organisms, dead organisms, or parts of organisms. A toxoid is an inactivated toxin that is no longer harmful, but retains its antigenic properties. 1. What are monoclonal antibodies, and how are they produced? What are their uses? 2. Distinguish among the various kinds of T cells and their functions. 3. What are NK cells? How do they function? IMMUNIZATION Throughout the world each year a great number of chil- dren, most of them under 5 years old, die of three infectious diseases for which im- munization is available. About 140,000 die of measles, 58,000 die of tetanus, and 51,000 die of whooping cough. Another 4 million die of various kinds of diar- rhea, against which some immunization is possible. Most of these deaths occur in underdeveloped countries. About 80% of the world’s children are immunized against measles, diphtheria, pertussis, tetanus, tuberculosis, and polio. Where Can a Bacterium Hide from the Immune System? Why is it so difficult to make vaccines against some bacte- ria? Some bacteria have really good hiding places—inside of phagocytes! Antibodies and complement proteins can’t get at them there. But wait, aren’t phagocytes supposed to be part of your immune system, programmed to kill the bacteria they ingest? How can some bacteria safely hide inside phago- cytes? These intracellular bacteria have many very different evasion mechanisms, which differ from one species to another.

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