Veterinary Immunology and Serology are fundamental to understanding host–pathogen interactions, disease resistance, diagnostic methods, vaccination and immune protection. This book has been developed as a practice and revision resource for aspirants preparing for ICAR-JRF, SRF, ARS, UPSC and State PSC examinations. Its objective questions cover essential concepts as well as recent developments in innate and adaptive immunity, antigen–antibody reactions, hypersensitivity, immunodiagnostics, vaccines and serological assays. The questions encourage conceptual learning, self-assessment and analytical thinking. The book will support veterinary students, teachers, researchers and competitive-examination aspirants in identifying knowledge gaps, strengthening understanding and improving examination readiness.

This chapter introduces the historical development and fundamental concepts of immunology. It highlights the contributions of Edward Jenner, Louis Pasteur, Elie Metchnikoff, Paul Ehrlich, Emil von Behring and other pioneering scientists. Important discoveries related to vaccination, phagocytosis, antibody formation, cellular immunity, ELISA, radioimmunoassay and hybridoma technology are addressed. The chapter also explains antigens, immunogens, epitopes, haptens, adjuvants and the desirable characteristics of an effective immunogen. Questions concerning smallpox and rinderpest eradication, vaccine development and primary and secondary immune responses help readers understand the scientific milestones that established immunology as an essential discipline within veterinary and biomedical sciences.

This chapter examines the major forms and mechanisms of immunity. It distinguishes innate immunity from adaptive immunity and explains specificity, diversity, immunological memory and self–non-self recognition. Natural and artificial forms of active and passive immunity are discussed through examples involving infection, vaccination, maternal antibodies and antiserum administration. The chapter introduces pattern-recognition receptors, pathogen-associated molecular patterns and Toll-like receptors involved in microbial recognition. It also covers inflammation, its cardinal signs, acute-phase proteins and the roles of neutrophils and other innate defence components. These objective questions provide a clear foundation for understanding how animals resist infections and develop long-lasting protective immune responses.

This chapter describes the cells, tissues and organs responsible for immune defence. It examines lymphocytes, macrophages, dendritic cells, neutrophils, mast cells, natural killer cells and plasma cells, emphasizing their respective functions. Primary and secondary lymphoid organs—including bone marrow, thymus, bursa of Fabricius, spleen, lymph nodes and mucosa-associated lymphoid tissue—are discussed. The chapter also covers lymphocyte maturation, antigen presentation, phagocytosis, immune-cell surface markers and the organization of lymph-node regions. Positive and negative selection of T lymphocytes and the formation of memory cells are included. Together, these topics explain how immune components develop, communicate and coordinate effective responses against infectious agents.

This chapter focuses on the structure, classes, properties and biological functions of immunoglobulins. It introduces the basic antibody molecule, including heavy and light chains, variable and constant regions, antigen-binding sites and Fc fragments. The characteristics of IgG, IgM, IgA, IgE and IgD are examined in relation to their distribution and immune functions. Questions cover primary and secondary immune responses, placental transfer, mucosal protection, allergic reactions, complement activation and agglutination. The chapter also addresses antibody affinity, avidity, isotypes, allotypes, idiotypes, class switching and Bence-Jones proteins. It provides essential knowledge of how antibodies recognize antigens and contribute to immune protection and diagnosis.

This chapter explains how B-cell receptors, T-cell receptors and major histocompatibility complex molecules participate in antigen recognition. It differentiates MHC class I and class II pathways and describes the processing of endogenous and exogenous antigens. The roles of dendritic cells, macrophages and B lymphocytes as professional antigen-presenting cells are examined. Topics include MHC restriction, antigenic peptides, proteasomal degradation, ubiquitination and recognition by CD4-positive and CD8-positive T lymphocytes. The chapter also discusses superantigens, opsonization, phagocytosis, T-independent antigens and species-specific MHC systems such as BoLA and the avian B complex. These concepts explain the initiation of adaptive immune responses.

This chapter introduces the complement system as an important component of innate and adaptive immunity. It explains the classical, alternative and lectin pathways of complement activation and identifies the molecules involved in each pathway. The formation and functions of C3 convertase, C5 convertase and the membrane attack complex are discussed. Questions address complement-mediated cell lysis, inflammation, chemotaxis and opsonization. The roles of C3b, C3a, C4a, C5a, properdin, factor H and other regulatory proteins are also examined. By covering the activation and regulation of complement, the chapter explains how this system enhances antibody activity and helps eliminate invading microorganisms

This chapter examines cytokines as essential signalling molecules that regulate immune and inflammatory responses. It introduces interleukins, interferons, chemokines, tumour necrosis factors and colony-stimulating factors. Their sources, target cells and biological actions are considered in relation to immune-cell activation, differentiation, migration and communication. The chapter explains important properties such as pleiotropy, redundancy, synergy and antagonism. It also covers antiviral activity, chemotaxis, inflammation, fever and the regulation of humoral and cell-mediated immunity. Special attention is given to excessive cytokine production, cytokine storms and septic shock. These questions help readers understand how cytokines coordinate protective immunity and contribute to immune-mediated disease.

This chapter explores the four types of hypersensitivity reactions described under the Gell and Coombs classification. Type I immediate hypersensitivity, Type II cytotoxic reactions, Type III immune-complex disease and Type IV delayed hypersensitivity are examined in detail. The roles of IgE, mast cells, basophils, antibodies, complement and T lymphocytes are highlighted. Clinical examples include anaphylaxis, milk allergy, haemolytic disease, transfusion reactions, serum sickness, glomerulonephritis, farmer’s lung and the blue-eye condition associated with canine hepatitis. Diagnostic applications, including the tuberculin and Coombs tests, are also addressed. The chapter explains how exaggerated or inappropriate immune responses can damage tissues and produce disease.

This chapter examines immune-system failure arising from reactions against self-antigens or inadequate immune responses. It introduces immunological tolerance, central and peripheral tolerance, clonal deletion and clonal anergy. Important autoimmune diseases—including myasthenia gravis, Graves’ disease, systemic lupus erythematosus, multiple sclerosis, rheumatoid arthritis and Sjögren’s syndrome—are considered. The chapter also discusses molecular mimicry and the production of autoantibodies. Primary, secondary and severe combined immunodeficiency disorders are differentiated, with examples such as Chédiak–Higashi syndrome. Immune-privileged sites and immunological paralysis are also covered. These topics explain the mechanisms that normally prevent self-reactivity and the consequences that arise when immune regulation becomes defective.

This chapter introduces hybridoma technology and its application in producing monoclonal antibodies. It explains the fusion of antibody-producing B lymphocytes with immortal myeloma cells, selection in HAT medium and the roles of HGPRT and polyethylene glycol. The survival and cloning of hybrid cells and the advantages of monoclonal antibodies are considered. The chapter also discusses tissue and organ transplantation, including autografts, isografts, allografts and xenografts. The immunological mechanisms of acute graft rejection, donor histocompatibility antigens and the involvement of T lymphocytes are addressed. These questions connect laboratory antibody production with transplantation immunology and its diagnostic, therapeutic and research applications.

This chapter deals with the principles and applications of serological tests used to detect antigens and antibodies. It distinguishes primary, secondary and tertiary binding tests and explains antibody titre, affinity, avidity, sensitivity and specificity. Important techniques include precipitation, agglutination, complement fixation, neutralization, immunofluorescence, ELISA, radioimmunoassay, Western blotting and the radioallergosorbent test. The chapter also addresses serum decomplementation and the interpretation of positive and negative reactions. These methods are central to the laboratory diagnosis, surveillance and control of infectious diseases. The objective questions enable readers to compare diagnostic techniques and select appropriate tests according to their principles, applications and analytical performance.

This chapter examines the principles, preparation and application of vaccines and biological products. It compares live attenuated, inactivated, toxoid, subunit, recombinant, vector, DNA and mRNA vaccines. Vaccine development phases, immunogenicity, safety, efficacy and post-marketing surveillance are introduced. The chapter discusses adjuvants, including alum, Freund’s adjuvants, liposomes, ISCOMs and delivery systems. Important veterinary vaccines for brucellosis, foot-and-mouth disease, anthrax, Newcastle disease, infectious bronchitis, goat pox, sheep pox and peste des petits ruminants are covered. Questions also address bacterins, toxoids, attenuation, booster requirements and reversion to virulence, providing practical knowledge of immunoprophylaxis in animal-health management.