Immunogen

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An immunogen is any substance that generates B-cell (humoral/antibody) and/or T-cell (cellular) adaptive immune responses upon exposure to a host organism. [1] [2] Immunogens that generate antibodies are called antigens ("antibody-generating"). [2] Immunogens that generate antibodies are directly bound by host antibodies and lead to the selective expansion of antigen-specific B-cells. Immunogens that generate T-cells are indirectly bound by host T-cells after processing and presentation by host antigen-presenting cells. [3]

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An immunogen can be defined as a complete antigen which is composed of the macromolecular carrier and epitopes (determinants) that can induce immune response. [4]

An explicit example is a hapten. Haptens are low-molecular-weight compounds that may be bound by antibodies, but cannot elicit an immune response. Consequently, the haptens themselves are nonimmunogenic and they cannot evoke an immune response until they bind with a larger carrier immunogenic molecule. The hapten-carrier complex, unlike free hapten, can act as an immunogen and can induce an immune response. [5]

Until 1959, the terms immunogen and antigen were not distinguished. [6]

Used carrier proteins

It is copper-containing respiratory protein, isolated from keyhole limpets (Megathura crenulata). Because of its evolutionary distance from mammals, high molecular weight and complex structure it is usually immunogenic in vertebrate animals. [7]
(also blue carrier immunogenic orotein) It is alternative to KLH isolated from Concholepas concholepas. It has the similar immunogenic properties as KLH but better solubility and therefore better flexibility. [8]
It is from the blood sera of cows and has similarly immunogenic properties as KLH or CCH. The cationized form of BSA (cBSA) is highly positively charged protein with significantly increased immunogenicity. This change possesses a greater number of possible conjugated antigens to the protein. [9]
Also known as egg albumin, OVA is the main protein (60-75%) found in hen egg white. OVA is soluble in dimethyl sulfoxide (DMSO), which enables the conjugation of haptens that are not soluble in aqueous buffers. The immune response can be enhanced using an adjuvant injected together with the immunogen. [10]

Immunological adjuvants

An adjuvant (from Latin adiuvare – to help) is any substance, distinct from antigen, which enhances immune response by various mechanisms: recruiting of professional antigen-presenting cells (APCs) to the site of antigen exposure; increasing the delivery of antigens by delayed/slow release (depot generation); immunomodulation by cytokine production (selection of Th1 or Th2 response); inducing T-cell response (prolonged exposure of peptide-MHC complexes [signal 1] and stimulation of expression of T-cell-activating co-stimulators [signal 2] on the APCs' surface) and targeting (e. g. carbohydrate adjuvants which target lectin receptors on APCs). Adjuvants have been used as additives to improve vaccine efficiency since the 1920s. Generally, administration of adjuvants is used both in experimental immunology and in clinical settings to ensure a high quality/quantity memory-enhanced antibody response, where antigens must be prepared and delivered in a fashion that maximizes production of a specific immune response. Among commonly used adjuvants are complete and incomplete Freund's adjuvant and solutions of aluminum hydroxide or aluminum phosphate. [11] [12]

Related Research Articles

<span class="mw-page-title-main">Antigen</span> Molecule triggering an immune response (antibody production) in the host

In immunology, an antigen (Ag) is a molecule, moiety, foreign particulate matter, or an allergen, such as pollen, that can bind to a specific antibody or T-cell receptor. The presence of antigens in the body may trigger an immune response.

<span class="mw-page-title-main">DNA vaccine</span> Vaccine containing DNA

A DNA vaccine is a type of vaccine that transfects a specific antigen-coding DNA sequence into the cells of an organism as a mechanism to induce an immune response.

<span class="mw-page-title-main">T helper cell</span> Type of immune cell

The T helper cells (Th cells), also known as CD4+ cells or CD4-positive cells, are a type of T cell that play an important role in the adaptive immune system. They aid the activity of other immune cells by releasing cytokines. They are considered essential in B cell antibody class switching, breaking cross-tolerance in dendritic cells, in the activation and growth of cytotoxic T cells, and in maximizing bactericidal activity of phagocytes such as macrophages and neutrophils. CD4+ cells are mature Th cells that express the surface protein CD4. Genetic variation in regulatory elements expressed by CD4+ cells determines susceptibility to a broad class of autoimmune diseases.

Haptens are small molecules that elicit an immune response only when attached to a large carrier such as a protein; the carrier may be one that also does not elicit an immune response by itself. The mechanisms of absence of immune response may vary and involve complex immunological interactions, but can include absent or insufficient co-stimulatory signals from antigen-presenting cells.

Polyclonal antibodies (pAbs) are antibodies that are secreted by different B cell lineages within the body. They are a collection of immunoglobulin molecules that react against a specific antigen, each identifying a different epitope.

<span class="mw-page-title-main">Conjugate vaccine</span> Type of vaccine

A conjugate vaccine is a type of subunit vaccine which combines a weak antigen with a strong antigen as a carrier so that the immune system has a stronger response to the weak antigen.

<span class="mw-page-title-main">Adaptive immune system</span> Subsystem of the immune system

The adaptive immune system, also known as the acquired immune system, or specific immune system is a subsystem of the immune system that is composed of specialized, systemic cells and processes that eliminate pathogens or prevent their growth. The acquired immune system is one of the two main immunity strategies found in vertebrates.

<span class="mw-page-title-main">Antigen-presenting cell</span> Cell that displays antigen bound by MHC proteins on its surface

An antigen-presenting cell (APC) or accessory cell is a cell that displays an antigen bound by major histocompatibility complex (MHC) proteins on its surface; this process is known as antigen presentation. T cells may recognize these complexes using their T cell receptors (TCRs). APCs process antigens and present them to T cells.

Immunogenicity is the ability of a foreign substance, such as an antigen, to provoke an immune response in the body of a human or other animal. It may be wanted or unwanted:

In immunology, an adjuvant is a substance that increases or modulates the immune response to a vaccine. The word "adjuvant" comes from the Latin word adiuvare, meaning to help or aid. "An immunologic adjuvant is defined as any substance that acts to accelerate, prolong, or enhance antigen-specific immune responses when used in combination with specific vaccine antigens."

Malaria vaccines are vaccines that prevent malaria, a mosquito-borne infectious disease which affected an estimated 249 million people globally in 85 malaria endemic countries and areas and caused 608,000 deaths in 2022. The first approved vaccine for malaria is RTS,S, known by the brand name Mosquirix. As of April 2023, the vaccine has been given to 1.5 million children living in areas with moderate-to-high malaria transmission. It requires at least three doses in infants by age 2, and a fourth dose extends the protection for another 1–2 years. The vaccine reduces hospital admissions from severe malaria by around 30%.

<span class="mw-page-title-main">Keyhole limpet hemocyanin</span>

Keyhole limpet hemocyanin (KLH) is a large, multisubunit, oxygen-carrying, metalloprotein that is found in the hemolymph of the giant keyhole limpet, Megathura crenulata, a species of keyhole limpet that lives off the coast of California, from Monterey Bay to Isla Asuncion off Baja California.

Immune stimulating complexes (ISCOMs) are spherical open cage-like structures (typically 40 nm in diameter) that are spontaneously formed when mixing together cholesterol, phospholipids and Quillaja saponins under a specific stoichiometry. The complex displays immune stimulating properties and is thus mainly used as a vaccine adjuvant in order to induce a stronger immune response and longer protection. A specific adjuvant based on ISCOM technology is Matrix-M.

A subunit vaccine is a vaccine that contains purified parts of the pathogen that are antigenic, or necessary to elicit a protective immune response. Subunit vaccine can be made from dissembled viral particles in cell culture or recombinant DNA expression, in which case it is a recombinant subunit vaccine.

<i>Megathura crenulata</i> Species of mollusc

Megathura crenulata is a northeastern Pacific Ocean species of limpet in the family Fissurellidae known commonly as the great keyhole limpet or giant keyhole limpet. Megathura is a monotypic genus; in other words, this is the only species in that genus. This species occurs along the rocky coast of western North America, its distribution extending from Southern California to the Baja California peninsula in Mexico. It is found in the intertidal zone and in the sea up to a depth of 33 meters.

Peptide-based synthetic vaccines are subunit vaccines made from peptides. The peptides mimic the epitopes of the antigen that triggers direct or potent immune responses. Peptide vaccines can not only induce protection against infectious pathogens and non-infectious diseases but also be utilized as therapeutic cancer vaccines, where peptides from tumor-associated antigens are used to induce an effective anti-tumor T-cell response.

Immunogenic cell death is any type of cell death eliciting an immune response. Both accidental cell death and regulated cell death can result in immune response. Immunogenic cell death contrasts to forms of cell death that do not elicit any response or even mediate immune tolerance.

Immunology is the study of the immune system during health and disease. Below is a list of immunology-related articles.

The p-i concept refers to the pharmacological interaction of drugs with immune receptors. It explains a form of drug hypersensitivity, namely T cell stimulation, which can lead to various acute inflammatory manifestations such as exanthems, eosinophilia and systemic symptoms, Stevens–Johnson syndrome, toxic epidermal nercrolysis, and complications upon withdrawing the drug.

Nicotine vaccine is a novel immunological strategy for treating nicotine addiction. Nicotine vaccine uses active immunization as the methodology to create polyclonal antibodies to the antigens, which is then used to treat drug abuse. The immune system is then able to identify nicotine as a foreign substance and initiate an immune reaction targeting the drug. As a result, the quantity of nicotine that enters the brain would decrease after receiving the vaccine. In preclinical studies, nicotine vaccines have demonstrated the ability to combat the negative effects of nicotine abuse, but none of the developed vaccines has been authorized for use in clinical trials as a smoking cessation strategy. Theoretically, the decrease of nicotine's rewarding effects should result in smoking cessation. Some companies have tested candidate vaccines in clinical trials, but evidence failed to show the adequate antibody responses or exhibit superior efficacy to factors concerning placebo.

References

  1. ↑ "im·mu·no·gen", Merriam-Webster Collegiate Dictionary (11th ed.), Springfield, Massachusetts, USA: Merriam-Webster, Inc., 2003, a substance that produces an immune response
  2. 1 2 "Immunogen". immunopaedia.org.za. 4 March 2015. Archived from the original on 2021-10-21. Retrieved 2021-10-21. A substance capable of eliciting a immune response. All immunogens are antigens, but some antigen are not immunogens (e.g. haptens)
  3. ↑ "Antigen - an overview | ScienceDirect Topics". www.sciencedirect.com. Retrieved 2024-09-24.
  4. ↑ "Immunogen - an overview | ScienceDirect Topics". www.sciencedirect.com. Retrieved 2024-09-11.
  5. ↑ Abbas A.K.; Lichtman A.H.; Pillai S. (2012). Cellular and Molecular Immunology. 7th edition. Elsevier, Ed. Gruliow R. pp. 101–103, 483.
  6. ↑ Medical Dictionary, Merriam-Webster. "Immunogen". Archived from the original on 2014-01-01. Retrieved 2013-12-31.
  7. ↑ Harris J.R.; Markl J. (1999). "Keyhole limpet hemocyanin (KHL): a biomedical review". Micron. 30 (6): 597–623. doi:10.1016/s0968-4328(99)00036-0. PMID   10544506.
  8. ↑ Arancibia S.; Del Campo M.; Nova E.; Salazar F.; Becker M.I. (2012). "Enhanced structural stability of Concholepashemocyanin increases its immunogenicity and maintains its non-specific immunostimulatory effects". Eur J Immunol. 42 (3): 688–99. doi:10.1002/eji.201142011. hdl: 10533/126832 . PMID   22144228. S2CID   205788372.
  9. ↑ Chen J.S.; Chen A.; Chang L.Ch.; Chang W.S.W.; Lee H.S.; Lin S.H.; Lin Y.F. (2004). "Mouse model of membranous nephopathy induced by cationic bovine serum albumin: antigen dose response relation and strain differences". Nephrol Dial Transplant. 19 (11): 2721–2728. doi: 10.1093/ndt/gfh419 . PMID   15385633.
  10. ↑ De Silva B.S.; Egodage K.L.; Wilson G.S. (1999). "Purified protein derivate (PPD) as an immunogen carrier elicits high antigen specificity to haptens". Bioconjug Chem. 10 (3): 496–501. doi:10.1021/bc9800724. PMID   10346883.
  11. ↑ Abbas A.K.; Lichtman A.H.; Pillai S. (2012). Cellular and Molecular Immunology. Elsevier. p. 85.
  12. ↑ Cox J.C.; Coulter A.R. (1997). "Adjuvants –a classification and review of their modes of action". Vaccine. 15 (3): 248–256. doi:10.1016/s0264-410x(96)00183-1. PMID   9139482.
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