Background
Mesut Karahan in Synthetic Peptide Vaccine Models, 2021
In general, the adaptive immune system is divided into two different categories, cellular and humoral (Skwarczynski and Toth 2016). Also, cells of this adaptive immune system respond to specific regions of infectious agents known as epitopes (peptides and peptide vaccines are most commonly used in the adaptive immune system). One or more epitopes are located in various regions of infectious agents, a larger molecule known as an antigen, and these antigens are highly related to stimulating the immune system. Humoral immune responses are very important and basically these responses are dependent on the action of glycoproteins, antibodies secreted from B cells by binding to specific epitopes by B cell-specific receptors on the cell surface, and upon the binding of the B cell receptor to a matching epitope; B cells can mature into plasma. B cells formed in this way provide an important protection by starting to secrete epitope-specific antibodies that will protect an individual from infectious diseases (Siegrist 2013). Cellular immune responses are based on the action of T immune cells. All these cells contain histocompatibility complex class I (MHC-I) molecules in their nuclear activities. When an intracellular infectious agent is formed near the cell membrane, cells may be present on surface linear epitopes of these infectious agents complexed with MHC-I because this molecule is responsible for stimulating the immune system against infectious (Moser and Leo 2010) (Figure 1.1).
Modulating Cytolytic Responses to Infectious Pathogens
Thomas F. Kresina in Immune Modulating Agents, 2020
Other viral mechanisms of immune system evasion exist, including viral latency; down-regulation of MHC class 1, or adhesion molecules; and replication in “immune-privileged” sites [1]. Our focus in this review is on alteration of viral epitopes to induce stronger, more effective CTL responses while retaining activity toward the original virus-encoded peptide. In some cases, the coevolution of mammals with viruses and intracellular bacteria has resulted in pathogen genomes lacking strong immunodominant epitopes. The mammalian host is consequently hindered in its ability to mount a strong, specific, effective, and protective response quickly. A method to improve on these moderate to weak epitopes in viruses, intracellular bacteria, and tumors is imperative in order to generate epitopes which can induce enhanced CTL activity. Epitope improvement can lead to more direct and efficient immune responses in vaccine development and bypasses the higher costs, side effects, and lower immunogenicity associated with some attenuated or heat-killed virus-based vaccines.
Definition of an Allergen (Immunobiology)
Richard F. Lockey, Dennis K. Ledford in Allergens and Allergen Immunotherapy, 2014
Most people, both atopic and nonallergic, mount a vigorous response to antigens, utilizing all subclasses of immunoglobulins except IgE [1]. Atopic individuals mount the same response as nonatopic individuals but with the addition of an IgE response. The major difference in immune antibody response to antigen and allergen is consequently quite narrowly localized. The additional production of high-affinity IgE is directed to the dominant epitopes of the antigen. The epitopes seem to be the same as those recognized by other antibody classes. Unusual patterns of response by other subclasses of antibodies has been frequently mentioned, especially an enhanced IgG4 response. This may appear in individual circumstances as studies of large populations of immune-response profiles to allergens have not revealed any systematic differences.
The use of biologics in the treatment of autoimmune liver disease
Published in Expert Opinion on Investigational Drugs, 2020
Christopher Chang, Atsushi Tanaka, Christopher Bowlus, M. Eric Gershwin
There are, however, four mechanisms that have been proposed that can play a role in disruption of tolerance. These include molecular mimicry [3], bystander activation [4], epitope spreading, and viral persistence. Molecular mimicry occurs when there are similarities between self and foreign proteins. This leads to autoreactive T and B cells erroneously recognizing the self-protein as dangerous and mounting an immunological response to it. Bystander activation is a process by which T cells can be activated in the absence of normal T cell receptor stimulation, thus bypassing the normal immunoregulatory checkpoints. Epitopes are sites on the surface of an antigen to which antibody binds. Epitope spreading involves the ability of the immune system to respond to epitopes that are distinct from and non-cross reactive with the dominant epitope. It is generally the secondary cryptic epitopes that lead to the development of autoimmunity. These phenomena are not mutually exclusive and any of them or combination of them can lead to autoimmunity. Biological modifiers are usually in the form of a monoclonal antibody or fusion protein which is designed to target some of the pathways involved in the pathogenesis of autoimmunity.
Recent trends in next generation immunoinformatics harnessed for universal coronavirus vaccine design
Published in Pathogens and Global Health, 2023
Chin Peng Lim, Boon Hui Kok, Hui Ting Lim, Candy Chuah, Badarulhisam Abdul Rahman, Abu Bakar Abdul Majeed, Michelle Wykes, Chiuan Herng Leow, Chiuan Yee Leow
An epitope is the part of an antigen that is recognized by the adaptive immune system. It binds to specific receptors including antibodies, MHC molecules and T-cell receptors [28]. The binding portion of an antibody is termed a paratope. Epitopes can be either continuous or discontinuous. A continuous or linear epitope is a relatively short (usually 5–6) amino acid sequences recognized by the paratope of a corresponding antibody. In contrast, a discontinuous epitope consists of non-adjacent segments of amino acids, not necessarily from one chain, which form a specific 3D structure, which can also be recognized by antibodies. Since discontinuous epitope arises from a specific 3D fold, it is also known as conformational epitope. Notably, epitopes recognized by B-cell epitopes may contain lipids, nucleic acids or carbohydrates, giving resultant antibodies a vast repertoire while T-cell epitopes are usually peptide fragments. The investigation, identification and development of epitopes are crucial in promoting the advancement of diagnostics and therapeutics [110].
Applying lessons from human papillomavirus vaccines to the development of vaccines against Chlamydia trachomatis
Published in Expert Review of Vaccines, 2018
Kathryn M. Frietze, Rebeccah Lijek, Bryce Chackerian
Vaccines that mediate protection only through antibodies generate responses that can be tailored to a specific antigen, and even to a specific epitope of that antigen. This provides a unique opportunity to elicit almost monoclonal-like responses to an epitope of interest. This is useful when targeting a so-called ‘cryptic epitope,’ which is not normally immunogenic but could be protective if antibodies are produced by vaccination. This strategy has been employed in efforts to generate a ‘Pan-HPV’ vaccine by targeting the highly conserved HPV L2 epitope described above [48]. Displaying a short, conserved epitope of L2 on the surface of a VLP vaccine platform generates an immunogen capable of eliciting specific antibody responses that protect against a broad range of HPV types [48]. Highly specific targeting of epitopes could also be useful if the protein antigen contains epitopes that act as ‘immunological decoys.’ Avoiding targeting these epitopes could increase vaccine potency.
Related Knowledge Centers
- Antibody
- B Cell
- Conformational Epitope
- Paratope
- Protein
- Protein Tertiary Structure
- Immune System
- Antigen
- T Cell
- Linear Epitope