Serology

8 Key excerpts on "Serology"

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  eBook - ePub

  Day's Veterinary Immunology

  Principles and Practice

  • Brian Catchpole, Harm HogenEsch(Authors)
  • 2023(Publication Date)
  • CRC Press

    (Publisher)

  CHAPTER 10

  IMMUNODIAGNOSTICS

  Serology, Immunoassays and Measurement of Cell-Mediated Immunity

  DOI: 10.1201/9781003310969-10

  OBJECTIVES

  At the end of this chapter, you should be able to:

  • Define ‘Serology’ and understand the role of serological testing in clinical veterinary medicine.
  • Describe the production of an antiserum.
  • Briefly describe the different types of immunoassays employed for diagnostic purposes.
  • Understand why it would be useful to test the function of lymphoid or phagocytic cells in a clinical situation.
  • Describe the principle of the lymphocyte stimulation test.
  • Describe the principle of evaluation of lymphocyte or NK cell cytotoxic function.
  • Describe how the function of phagocytic cells may be evaluated.

  10.1 Introduction

  Serology is the in vitro study/analysis of antibodies in serum, plasma or other biological fluids and is commonly undertaken in clinical medicine. Practising veterinarians will regularly employ serological testing as part of their diagnostic approach to animals suspected of suffering from infectious or immune-mediated disease or sometimes to determine whether an animal has responded appropriately to vaccination (or requires a booster vaccine). Other immunoassays use specific antibodies for analysis of clinical samples to detect the presence of antigens associated with infection by a specific pathogen or to measure a biomarker (e.g. hormone or cytokine).

  When dealing with an infectious disease, it is important to appreciate the stage of infection, which will dictate whether the best diagnostic approach is to look for antigen at the site of infection or to look for antibodies in the blood (Figure 10.1 ). More refined serological tests may be used to quantify the amount of antibody present and by repeat blood sampling of a patient (acute and convalescent serum), one can determine whether the amount of antibody might be increasing (as is the case in an active infection). Some serological tests are designed to detect either IgM or IgG antibody and the relative proportions of these may indicate the stage of the infection

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  eBook - PDF

  Viral and Rickettsial Infections of Animals

  • A. O. Betts, C. J. York, A. O. Betts, C. J. York(Authors)
  • 2013(Publication Date)
  • Academic Press

    (Publisher)

  To consider Serology simply a laboratory adjunct, however, would be to miss important leads it may afford to a more thorough understanding of the characteristics of a given viral agent itself and of the disease it produces. Serology, as a branch of immunology, looks backward to the pathological changes produced by the virus, their location, and the extent 269 270 Christine E. Rice and the cellular reaction of the host; it reveals the residual or present antibody response to an earlier or continuing stimulus. The major problems for the viral serologist are related to the fact that both of the primary reagents, antigen as well as antibody, are produced in living cells with all their inherent variability. The in vitro aspects of viral Serology involve the many complex physico-chemical reactions of antigens with antibodies which constitute the special field of the immunochemist. During the past four decades, methods of quantitation of considerable precision have been developed which have widened our understanding of these processes. We have come to consider antibodies as somewhat heterogeneous populations of globulin molecules rather than uniform entities. Recognition of the potential differences in these populations has led to more intensive investigation of antibody produc-tion in different species of animals, of their reaction to different antigens, of the importance of time relationships, and of genetic and other factors. The serologist depends on the pathologist to elucidate the symptomatology and tissue changes in each virus disease, on the immunophysiologist to unravel the mysteries of antibody production, on the immunochemist and immunophysicist for an understanding of the mechanism of the antigen-antibody reaction itself, and on the statistician for advice as to the best methods of handling the inherently variable data.

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  Veterinary Epidemiology

  • Michael Thrusfield(Author)
  • 2013(Publication Date)
  • Butterworth-Heinemann

    (Publisher)

  16 Serological epidemiology Serological epidemiology is the investigation of disease and infection in populations by the measure-ment of variables present in serum. A range of constituents of serum can be measured, including minerals, trace elements, enzymes and hormones. One of the main constituents of serum that is frequently measured is the specific antibody activity of globulins. Alternative terms for antibody measurement are 'titration' and 'assay'. Antibodies provide evidence of current and previous exposure to infectious agents; their assay is commonly employed in veterinary medicine as a relatively efficient and cheap means of detecting this expo-sure. This chapter describes methods of measuring antibodies and comparing their levels in groups of animals, and discusses the interpretation of results. Finally, serum banks are described. The analytical methods are equally applicable to other diagnostic tests, such as those that detect enzymes and minerals, in which case, however, results can be compared with normal reference levels. Although values for the latter are available in published tables (e.g. Kaneko, 1980), each laboratory should estab-lish its own norms. If the values are Normally distributed, or can be transformed to Normality, then a one-sample f-test can be applied to compare a population's values with those of a reference population. The serological diagnosis of disease based on the detection of circulating antibodies is one of the techniques available for the identification of current and previous exposure to infectious agents. This and other methods are listed in Table 16.1. A range of tests to detect antigen/antibody reactions has been developed over the last 100 years and more are being added to the range.

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  eBook - PDF

  Handbook of Human Immunology

  • Maurice R.G. O'Gorman, Albert D. Donnenberg, Maurice R.G. O'Gorman, Albert D. Donnenberg(Authors)
  • 2008(Publication Date)
  • CRC Press

    (Publisher)

  437 422 Handbook of Human Immunology, Second Edition 14.1 INTRODUCTION The goal of this chapter is to familiarize the reader with the methods and ratio- nale employed for serologic testing for infectious diseases. Serologic testing entails the detection and quantification of antibodies to infectious agents, the agents them- selves, or a component of the agent. Serology is used when the definitive approach to laboratory diagnosis of infection, isolation, or recently, molecular detection, is not possible, appropriate, or necessary. In addition to diagnostic applications, serologic tests are used to assess immune status, immune competence, and for patient man- agement. Serologic methods can be highly sensitive, specific, and rapid; however, the appropriate application and interpretation of a serologic test requires an appre- ciation of the biology of the humoral immune response, including host factors that influence the response, performance characteristics of the specific method used, and characteristics of the infectious agent being tested for. The results of serologic tests, interpreted in the light of these considerations, provide important information for the diagnosis and management of patients with bacterial, viral, fungal, and parasitic diseases. 14.1.1 T HE ANTIBODY RESPONSE Details of the cellular and molecular aspects of the humoral immune response will not be reviewed here; the reader is referred to other chapters in this edition as well as texts that provide excellent discussions of this topic [1]. It is relevant to note, how- ever, that the characteristics of an antibody response to a pathogenic microorganism in any given individual vary due to the influence of several factors.

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  eBook - ePub

  Veterinary Epidemiology

  • Michael Thrusfield, Robert Christley, Michael Thrusfield(Authors)
  • 2018(Publication Date)
  • Wiley-Blackwell

    (Publisher)

  20 Diagnostic testing

  The range of diagnostic techniques that are currently available for the diagnosis of infectious and non‐infectious diseases is wide, and includes clinical and pathological examination; microbiological, biochemical and immunological investigation; and diagnostic imaging (e.g., radiography and ultrasound). These techniques may be used either to diagnose disease in the individual animal, or to investigate disease in populations. This chapter focusses primarily on the assessment and performance of diagnostic tests when applied to populations1 . Diagnosis of infectious diseases using serological methods is addressed first. This is followed by a more general discussion of diagnostic testing.

  Serological epidemiology

  Serological epidemiology is the investigation of disease and infection in populations by the measurement of variables present in serum. A range of constituents of serum can be measured, including minerals, trace elements, enzymes and hormones. One of the main constituents that is frequently measured is the specific antibody activity of immunoglobulins, and it is investigation of antibodies that is commonly understood to comprise Serology. Alternative terms for antibody measurement are ‘titration’ and ‘assay’. Antibodies provide evidence of current and previous exposure to infectious agents; their assay is commonly employed in veterinary medicine as a relatively efficient and cheap means of detecting this exposure in both individual animals and populations.

  The statistical methods employed to analyse antibody levels are equally applicable to other serological tests, such as those that detect enzymes and minerals, in which case, however, results can be compared with normal reference ranges. These commonly include: (1) the mean ± two standard deviations for Normally‐distributed data, selected from a normal (i.e., reference) population; and (2) the middle 95% of values (i.e., from the 2.5th to 97.5th percentile: see Chapter 12 ) from a reference population for data that are not Normally distributed (Farver, 2008). Although values for reference levels are available in published tables (e.g., Kaneko et al., 2008), each laboratory should establish its own norms. If the values are Normally distributed, or can be transformed to Normality, then a one‐sample t‐test (see Table 14.1 ) can be applied to compare a sample’s values with those of a reference population; otherwise one‐sample non‐parametric methods may be appropriate (see Table 14.2

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  eBook - ePub

  Medical Microbiology Illustrated

  • S. H. Gillespie(Author)
  • 2014(Publication Date)
  • Butterworth-Heinemann

    (Publisher)

  Serology can provide rapid diagnosis, long before the results of cultural methods are available. This can be achieved by detecting the presence of antigens specific to the pathogen sought (e.g. meningococcal group C polysaccharide in the CSF) or detecting the presence of pathogen-specific IgM (e.g. the diagnosis of neonatal toxoplasmosis).

  Non-cultivatible pathogens

  When organisms are difficult or dangerous to cultivate, Serology may be the only means available for the resources of a routine diagnostic laboratory. Treponema pallidum may be maintained in whole animal culture (rabbit testes) but this facility is only available at the national reference laboratory or in commercial companies who manufacture antigen.

  In some infections diagnosis by culture is available, but clinicians need to confirm the diagnosis as soon as possible so that appropriate treatment can be initiated. Typhoid fever and brucellosis exemplify a number of these points. Both organisms are easily cultivatible but are relatively slow to grow. Clinicians may wish to confirm or exclude these diagnoses as part of their overall differential diagnosis and thus a serological technique which gives the answer in a few hours can speed the diagnostic process.

  Serology has much to offer when organisms are difficult to detect by direct examination or slow to grow in culture, e.g. Mycobacterium tuberculosis . No serological method has ever established itself to fill this niche, but the large number of different techniques which have been investigated are evidence of the need.

  Evaluation of immunization

  Serological techniques are used in establishing immunity to infectious diseases, e.g. rubella. Response to vaccination can also be evaluated by serological means, and the concentration of antibody achieved may be determined. For some vaccines there is an agreed antibody concentration which should be achieved after vaccination to result in immunity. In hepatitis B, subjects should have >10 IU anti-hepatitis B surface antigen antibody to be considered immune.

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  eBook - ePub

  Forensic Science

  A Beginner's Guide

  • Jay Siegel(Author)
  • 2012(Publication Date)
  • Oneworld Publications

    (Publisher)

  7

  Forensic biology: the analysis of blood and other body fluids

  As we saw in Chapter 6, four major areas of forensic biology are pathology, anthropology, entomology, and odontology. The other major area is the examination of biological fluids for the presence of evidentiary materials. These substances can be analyzed to associate them with a suspect or victim of a crime. One particular biological substance, DNA, is often considered to be a separate area of forensic biology, but DNA is an evidentiary material in biological fluids and could be considered a part of Serology. In this chapter, we will use conventional nomenclature and consider DNA separately. Also included in this chapter is blood spatter, the spatial analysis of bloodstains to determine how the patterns they form can be used to determine how the blood got there and what type of spatter it is.

  Forensic Serology: past and present

  Forensic Serology has traditionally been used for several purposes, the first and foremost of which is to determine if a stain or other material is a body fluid and, if it is, to identify the type of fluid. In addition, certain body fluids, such as blood, contain substances which differ within the human population, making them useful in differentiating among possible suspects or victims. With the exception of cellular DNA, none of these factors is rare enough to be used to individualize a stain to one person.

  Almost all body fluid associations of this type have been made using blood, which is the body fluid most often encountered at crime scenes. Blood is a suspension of solid materials in an aqueous solution. The liquid portion of blood, plasma, comprises about 55% of the total volume of blood. Substances dissolved in the plasma include proteins, carbohydrates, fats, salts and minerals, and antibodies, plus materials that are responsible for the clotting of blood. The suspended materials in blood make up the other 45% and include red blood cells, white blood cells, and platelets. Red blood cells (erythrocytes) are formed in bone marrow and are primarily responsible for the transport of oxygen to cells and carbon dioxide away from them. They have no nucleus (and no nuclear DNA). White blood cells (leukocytes) are normally formed in the lymph nodes and are primarily involved in the body’s immune system. Platelets (thrombocytes) are instrumental in blood clotting. Through a series of blood vessels, starting with the major arteries and veins and going down to the smallest of capillaries, blood is carried to every cell in the body.

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  eBook - ePub

  Medical Immunology, 7th Edition

  • Gabriel Virella(Author)
  • 2019(Publication Date)
  • CRC Press

    (Publisher)

  15 Diagnostic applications of immunology Ajay Grover, Virginia Litwin, and Gabriel Virella

  Introduction Serological assays Classical assays Tests based on immunofluorescence Monoclonal antibody-based assays Flow cytometry Cell isolation Immunohistochemistry Highly sensitive immunoassays Enzyme immunoassay Evaluation of cellular immune responses

  Laboratory tests for assessment of lymphocyte function ex vivo

  Laboratory tests for assessment of lymphocyte function in vivo

  Laboratory tests for assessment of phagocytic cell function Bibliography

  Introduction

  Scientists have made use of the exquisite sensitivity and specificity of antibody recognition for use in assays for both diagnostic and basic research applications. Technological advances in methods to generate antibodies and to detect antibody-antigen binding have transformed laboratory medicine and basic research in many fields. A variety of platforms make use of a variety of tags (fluorescence, electro-chemiluminescence, heavy metals) to detect antibody-antigen interactions. These technologies are sensitive, specific, quantitative, and relatively rapid. Immunoassays and flow cytometry have replaced more laborious, less-sensitive methods that relied on the detection of antibody-antigen aggregates in gel-based systems (immunodiffusion). Applications of these serologic and molecular methods are quite broad. They have been applied to the diagnosis of infectious diseases, the detection of previous infection, the monitoring of neoplasms and vaccine efficacy, the assay of hormones and drugs, and pregnancy diagnosis. In some cases, the antigen being measured is itself an antibody. Measurement of specific antibodies has found wide application in the diagnosis of infectious, allergic, autoimmune, and immunodeficiency diseases.

  Serological assays

  Immunoserologic assays can be developed for antigen or antibody detection or quantitative assay. For antibody detection or measurement, a purified preparation of antigen must be available. For example, when human serum is tested for antibody to diphtheria toxoid, a purified preparation of the toxoid must be available. Next, a method for detecting the specific antigen-antibody reaction must be developed. Conversely, to detect antigens in biological fluids, specific antibodies must be available. In both types of assays, positive and negative controls are mandatory for proper interpretation of the results.

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