Immunogen

Last updated

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.

Contents

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

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. [3]

Until 1959, the terms immunogen and antigen were not distinguished. [4]

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. [5]
(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. [6]
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. [7]
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. [8]

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. [9] [10]

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 any molecule, molecular structure, foreign particulate matter, or pollen grain that can bind to a specific antibody or T-cell receptor. The presence of antigens in the body may trigger an immune response. Antigens can be proteins, peptides, polysaccharides, lipids, or nucleic acids.

<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">Hemocyanin</span> Proteins that transport oxygen throughout the bodies of some invertebrate animals

Hemocyanins (also spelled haemocyanins and abbreviated Hc) are proteins that transport oxygen throughout the bodies of some invertebrate animals. These metalloproteins contain two copper atoms that reversibly bind a single oxygen molecule (O2). They are second only to hemoglobin in frequency of use as an oxygen transport molecule. Unlike the hemoglobin in red blood cells found in vertebrates, hemocyanins are not confined in blood cells but are instead suspended directly in the hemolymph. Oxygenation causes a color change between the colorless Cu(I) deoxygenated form and the blue Cu(II) oxygenated form.

An immune response is a reaction which occurs within an organism for the purpose of defending against foreign invaders. These invaders include a wide variety of different microorganisms including viruses, bacteria, parasites, and fungi which could cause serious problems to the health of the host organism if not cleared from the body. There are two distinct aspects of the immune response, the innate and the adaptive, which work together to protect against pathogens. The innate branch—the body's first reaction to an invader—is known to be a non-specific and quick response to any sort of pathogen. Components of the innate immune response include physical barriers like the skin and mucous membranes, immune cells such as neutrophils, macrophages, and monocytes, and soluble factors including cytokines and complement. On the other hand, the adaptive branch is the body's immune response which is catered against specific antigens and thus, it takes longer to activate the components involved. The adaptive branch include cells such as dendritic cells, T cell, and B cells as well as antibodies—also known as immunoglobulins—which directly interact with antigen and are a very important component for a strong response against an invader.

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 that is composed of specialized, systemic cells and processes

The adaptive immune system, also known as the acquired 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 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."

<span class="mw-page-title-main">Malaria vaccine</span> Vaccine that is used to prevent malaria

A malaria vaccine is a vaccine that is used to prevent malaria. The only approved malaria vaccine is RTS,S, known by the brand name Mosquirix. As of April 2022, the vaccine has been given to 1 million children living in areas with moderate-to-high malaria transmission. It requires at least three doses in infants by age 2, with a fourth dose extending 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.

A subunit vaccine is a vaccine that contains purified parts of the pathogen that are antigenic, or necessary to elicit a protective immune response. A "subunit" vaccine doesn't contain the whole pathogen, unlike live attenuated or inactivated vaccine, but contains only the antigenic parts such as proteins, polysaccharides or peptides. Because the vaccine doesn't contain "live" components of the pathogen, there is no risk of introducing the disease, and is safer and more stable than vaccine containing whole pathogens. Other advantages include being well-established technology and being suitable for immunocompromised individuals. Disadvantages include being relatively complex to manufacture compared to some vaccines, possibly requiring adjuvants and booster shots, and requiring time to examine which antigenic combinations may work best.

<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, also called epitope 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.

<span class="mw-page-title-main">Recombinant subunit vaccine</span>

Recombinant subunit vaccines are biological preparations that are composed of microbial subunits produced using recombinant DNA technology. They act to provide active acquired immunity to infectious diseases. The first recombinant subunit vaccine was produced in the mid-1980s to protect people from Hepatitis B. Notable recombinant subunit vaccines licensed include ENGERIX-B, GARDASIL-9, FLUBLOK(influenza), SHINGRIX and NUVAXOVID.

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. ↑ Abbas A.K.; Lichtman A.H.; Pillai S. (2012). Cellular and Molecular Immunology. 7th edition. Elsevier, Ed. Gruliow R. pp. 101–103, 483.
  4. ↑ Medical Dictionary, Merriam-Webster. "Immunogen".
  5. ↑ 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.
  6. ↑ 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.
  7. ↑ 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.
  8. ↑ 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.
  9. ↑ Abbas A.K.; Lichtman A.H.; Pillai S. (2012). Cellular and Molecular Immunology. Elsevier. p. 85.
  10. ↑ 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.
This page is based on this Wikipedia article
Text is available under the CC BY-SA 4.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.