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  • Lymphocytes
  • class II a's major histocompatibility antigens found only on immunocompetent cells, primarily B lymphocytes and macrophages. (thefreedictionary.com)
  • In this way MHC molecules chaperone which type of lymphocytes may bind to the given antigen with high affinity, since different lymphocytes express different T-Cell Receptor (TCR) co-receptors. (wikipedia.org)
  • Antigen presentation: MHC molecules bind to both T cell receptor and CD4/CD8 co-receptors on T lymphocytes, and the antigen epitope held in the peptide-binding groove of the MHC molecule interacts with the variable Ig-Like domain of the TCR to trigger T-cell activation Autoimmune reaction: Having some MHC molecules increases the risk of autoimmune diseases more than having others. (wikipedia.org)
  • Viruses that establish lifelong latent infections must ensure that the viral genome is maintained within the latently infected cell throughout the life of the host, yet at the same time must also be capable of avoiding elimination by the immune surveillance system especially must avoid being detected by host CD8+ cytotoxic T lymphocytes (CTLs). (wikipedia.org)
  • TLR9 is expressed by numerous cells of the immune system such as B lymphocytes, monocytes, natural killer (NK) cells, keratinocytes, melanocytes, and plasmacytoid dendritic cells. (wikipedia.org)
  • viruses
  • The C-terminal portion of the STag protein is distinct from LTag but shares an additional ~100 residues with middle tumor antigen in those viruses that express it, such as murine polyomavirus. (wikipedia.org)
  • The 19 and 58-kDa mutant viruses were found to transform BRK cells with 11 and 25% of the efficiency of wild type virus, respectively. (uu.nl)
  • Viruses lacking a viral envelope often have complex mechanisms for entry into the host cell. (wikipedia.org)
  • Unlike many viruses that enter the cell through endocytosis, polyomaviruses penetrate the cell membrane and enter the cytosol from the late endoplasmic reticulum rather than from endosomes, although conformational changes in response to low pH in endolysosomes have been hypothesized as critical steps in the process. (wikipedia.org)
  • This infection causes a host cell to become malignant and can be either cytocidal (usually in the case of RNA viruses) or persistent (usually in the case of DNA viruses). (wikipedia.org)
  • Lastly, biologic effects include the viruses' ability to affect the activity of antigens and immunologlobulins in the host cell. (wikipedia.org)
  • Chronic infections have similar cellular effects as acute cytocidal infections but there is a limited number of progeny and viruses involved in transformation. (wikipedia.org)
  • Most MCV viruses found in MCC tumors, however, have at least two mutations that render the virus nontransmissible: 1) The virus is integrated into the host genome in a monoclonal fashion and 2) The viral T antigen has truncation mutations that leave the T antigen unable to initiate DNA replication needed to propagate the virus. (wikipedia.org)
  • Gammaherpesviruses are of primary interest due to the two human viruses, EBV and KSHV and the diseases they cause.The gammaherpesviruses replicate and persist in lymphoid cells but some are capable of undergoing lytic replication in epithelial or fibroblast cells. (wikipedia.org)
  • However, in general virus-cell interactions are mediated by commonly occurring molecules on the cell surface, and therefore are likely not a major contributor to individual viruses' observed cell-type tropism. (wikipedia.org)
  • After binding to molecules on the cell surface, the virion is endocytosed and enters the endoplasmic reticulum - a behavior unique among known non-enveloped viruses - where the viral capsid structure is likely to be disrupted by action of host cell disulfide isomerase enzymes. (wikipedia.org)
  • Viruses offer an efficient means of delivering genes into cells, which they evolved to do, and are thus of great use as experimental tools. (wikipedia.org)
  • This danger can be avoided by the use of viruses which lack key genes, and which are thus unable to replicate after entering a cell. (wikipedia.org)
  • Many viruses take advantage of this relationship by inducing certain TLR9 expression patterns to first infect the cell (down-regulate) then trigger the onset of cancer (up-regulate). (wikipedia.org)
  • gene
  • A somewhat more common tumor antigen variant, an overprinted gene encoding a protein called ALTO, may be evolutionarily related to MTag. (wikipedia.org)
  • MTag plays a role in viral DNA replication and in the transition from early to late gene expression, and its absence can cause defects in viral capsid assembly. (wikipedia.org)
  • The STag protein is expressed from a gene that overlaps the large tumor antigen (LTag) such that the two proteins share an N-terminal DnaJ-like domain but have distinct C-terminal regions. (wikipedia.org)
  • initiation codon, transformed primary baby rat kidney (BRK) cells with an efficiency of about half of that of a wild type Ad5 El plasmid, whereas a plasmid with a mutation in the gene for the 58-kDa Elb protein transformed the same primary cells with only one-third of the wild type efficiency. (uu.nl)
  • Unlike T cells, NK cell receptors are germline encoded, and therefore do not require somatic gene rearrangements. (wikipedia.org)
  • The T antigen is a spliced gene that forms multiple different proteins depending on the splicing pattern. (wikipedia.org)
  • Env is a viral gene that encodes the protein forming the viral envelope. (wikipedia.org)
  • The expression of the env gene enables retroviruses to target and attach to specific cell types, and to infiltrate the target cell membrane. (wikipedia.org)
  • The mature product of the env gene is the viral spike protein, which has two main parts: the surface protein (SU) and the transmembrane protein (TM). (wikipedia.org)
  • The env gene codes for the gp160 protein which forms a homotrimer, and is cleaved into gp120 and gp41 by the host cell protease, Furin. (wikipedia.org)
  • This gene is preferentially expressed in immune cell rich tissues, such as spleen, lymph node, bone marrow and peripheral blood leukocytes. (wikipedia.org)
  • virally
  • KIR receptors can distinguish between major histocompatibility (MHC) class I allelic variants, which allows them to detect virally infected cells or transformed cells. (wikipedia.org)
  • According to the missing-self hypothesis, inhibitory KIR receptors recognize the downregulation of MHC class I molecules in virally-infected or transformed self cells, leading these receptors to stop sending the inhibition signal, which then leads to the lysis of these unhealthy cells. (wikipedia.org)
  • Because natural killer cells target virally infected host cells and tumor cells, inhibitory KIR receptors are important in facilitating self-tolerance. (wikipedia.org)
  • Cells that have been virally transformed can be differentiated from untransformed cells through a variety of growth, surface, and intracellular observations. (wikipedia.org)
  • adenovirus
  • HEK 293 cells were generated in 1973 by transformation of cultures of normal human embryonic kidney cells with sheared adenovirus 5 DNA in Alex van der Eb's laboratory in Leiden, the Netherlands. (wikipedia.org)
  • the transformation by adenovirus was performed by Frank Graham, a post-doc in van der Eb's lab. (wikipedia.org)
  • However, the original adenovirus transformation was inefficient, suggesting that the cell that finally produced the HEK 293 line may have been unusual in some fashion. (wikipedia.org)
  • Graham and coworkers provided evidence that HEK 293 cells and other human cell lines generated by adenovirus transformation of human embryonic kidney cells have many properties of immature neurons, suggesting that the adenovirus preferentially transformed a neuronal lineage cell in the original kidney culture. (wikipedia.org)
  • Given the location of the adrenal gland (adrenal means "next to the kidney"), a few adrenal cells could plausibly have appeared in an embryonic kidney derived culture, and could be preferentially transformed by adenovirus. (wikipedia.org)
  • molecules
  • antigen-antibody reaction the reversible binding of antigen to homologous antibody by the formation of weak bonds between antigenic determinants on antigen molecules and antigen binding sites on immunoglobulin molecules. (thefreedictionary.com)
  • They regulate the killing function of these cells by interacting with major histocompatibility (MHC) class I molecules, which are expressed on all nucleated cell types. (wikipedia.org)
  • Most KIRs are inhibitory, meaning that their recognition of MHC molecules suppresses the cytotoxic activity of their NK cell. (wikipedia.org)
  • Only a limited number of KIRs are activating, meaning that their recognition of MHC molecules activates the cytotoxic activity of their cell. (wikipedia.org)
  • Inhibitory receptors recognize self-MHC class I molecules on target self cells, causing the activation of signaling pathways that stop the cytolytic function of NK cells. (wikipedia.org)
  • Activating receptors recognize ligands that indicate host cell aberration, including induced-self antigens (which are markers of infected self cells and include MICA, MICB, and ULBP, all of which are related to MCH class 1 molecules), altered-self antigens (MHC class I antigens laden with foreign peptide), and/or non-self (pathogen encoded molecules). (wikipedia.org)
  • Transformation can also affect the cytoskeleton and change in the quantity of signal molecules. (wikipedia.org)
  • The major histocompatibility complex (MHC) is a set of cell surface proteins essential for the acquired immune system to recognize foreign molecules in vertebrates, which in turn determines histocompatibility. (wikipedia.org)
  • The main function of MHC molecules is to bind to antigens derived from pathogens and display them on the cell surface for recognition by the appropriate T-cells. (wikipedia.org)
  • MHC molecules mediate interactions of leukocytes, also called white blood cells (WBCs), which are immune cells, with other leukocytes or with body cells. (wikipedia.org)
  • In a cell, protein molecules of the host's own phenotype or of other biologic entities are continually synthesized and degraded. (wikipedia.org)
  • By interacting with CD4 molecules on surfaces of helper T cells, MHC class II mediates establishment of specific immunity (also called acquired immunity or adaptive immunity). (wikipedia.org)
  • By interacting with CD8 molecules on surfaces of cytotoxic T cells, MHC class I mediates destruction of infected or malignant host cells, the aspect of specific immunity termed cellular immunity. (wikipedia.org)
  • interaction
  • Like STag, MTag has no enzymatic activity of its own, but has a number of protein-protein interaction sites that mediate interactions with proteins in the host cell. (wikipedia.org)
  • However, MTag's best-studied functions center on its interaction with host cell proteins to activate cellular signaling pathways. (wikipedia.org)
  • Similar to large T antigen, a role for interaction with cellular proteins has been shown. (aacrjournals.org)
  • MHC interacts with TCR and its co-receptors to optimize binding conditions for the TCR-antigen interaction, in terms of antigen binding affinity and specificity, and signal transduction effectiveness. (wikipedia.org)
  • for example, the JC virus is believed to require interaction with the 5HT2A receptor and the Merkel cell virus with heparan sulfate. (wikipedia.org)
  • Examples of such experiments include: Effects of a drug on sodium channels Inducible RNA interference system Isoform-selective protein kinase C agonist Interaction between two proteins Nuclear export signal in a protein A more specific use of HEK 293 cells is in the propagation of adenoviral vectors. (wikipedia.org)
  • glycoprotein
  • cancer antigen 125 (CA 125) a glycoprotein antigen found in normal adult tissues such as the epithelium of the fallopian tubes, the endometrium, the endocervix, the pleura, and the peritoneum. (thefreedictionary.com)
  • carcinoembryonic antigen (CEA) an oncofetal glycoprotein antigen originally thought to be specific for adenocarcinoma of the colon, but now known to be found in many other cancers and some nonmalignant conditions. (thefreedictionary.com)
  • infects
  • Poliovirus-wild type infects intestinal cells/neurons Note: Most virus gain entry to the body via the respiratory pathway (lungs). (coursehero.com)
  • mechanisms
  • It is unclear how exactly having the HLA-B27 tissue type increases the risk of ankylosing spondylitis and other associated inflammatory diseases, but mechanisms involving aberrant antigen presentation or T cell activation have been hypothesized. (wikipedia.org)
  • epithelial
  • The present study compares the frequency of immortalization of cells from two different human lineages, lung fibroblasts and mammary epithelial cells. (isharonline.org)
  • Squamous epithelial cells are a flat type of cell found in the skin and the membranes that line some body cavities. (wikipedia.org)
  • The detection of nuclear antigen associated with Epstein-Barr virus (EBNA) and viral DNA in NPC type 2 and 3, has revealed that EBV can infect epithelial cells and is associated with their transformation. (wikipedia.org)
  • The Papillomavirus life cycle begins with cells actively multiplying in epithelial cells of basal and parabasal layers. (wikipedia.org)
  • The infected, differentiating cells travel towards the epithelial surface during the viral cycle's late stage. (wikipedia.org)
  • For many years it was assumed that HEK 293 cells were generated by transformation of either a fibroblastic, endothelial or epithelial cell, all of which are abundant in kidneys. (wikipedia.org)
  • Adenoviruses transform neuronal lineage cells much more efficiently than typical human kidney epithelial cells. (wikipedia.org)
  • nucleus
  • A possible interpretation is that, due to the damage caused by resveratrol to the plasma membrane, the transfer of the virus from the endoplasmic reticulum to the nucleus, may be hindered thus inhibiting the production of viral DNA. (biomedcentral.com)
  • This unstructured linker region also contains a nuclear localization sequence, which triggers the host cell to transport the protein from the cytoplasm where is it translated to the nucleus where it performs its replication-related functions. (wikipedia.org)
  • genetic
  • It is vastly more common in certain regions of East Asia and Africa than elsewhere, with viral, dietary and genetic factors implicated in its causation. (wikipedia.org)
  • pathogen
  • It was the first example of a human viral pathogen discovered using unbiased metagenomic next-generation sequencing with a technique called digital transcriptome subtraction. (wikipedia.org)
  • TLRs are transmembrane proteins, expressed on the cell surface and the endocytic compartment and recognize pathogen-associated molecular patterns (PAMPs) that are expressed on infectious agents and initiate signalling to induce production of cytokines necessary for the innate immunity and subsequent adaptive immunity. (wikipedia.org)
  • nuclear
  • Cytopathic Effects, often include a change in cell's morphology such as fusion with adjacent cells to form polykaryocytes as well as the synthesis of nuclear and cytoplasmic inclusion bodies. (wikipedia.org)
  • immune system
  • Like T cells, NK cells have many qualities characteristic of the adaptive immune system, including the production of "memory" cells that persist following encounter with antigens and the ability to create a secondary recall response. (wikipedia.org)
  • The presented antigen can be either self or non-self, thus preventing an organism's immune system targeting its own cells. (wikipedia.org)
  • MHC is the tissue-antigen that allows the immune system (more specifically T cells) to bind to, recognize, and tolerate itself (autorecognition). (wikipedia.org)
  • As a result, the immune system treats these unfamiliar antigens as foreign and mounts an immune response. (wikipedia.org)
  • TLR9 is expressed intracellularly, within the endosomal compartments and functions to alert the immune system of viral and bacterial infections by binding to DNA rich in CpG motifs. (wikipedia.org)
  • Merkel
  • In other polyomaviruses, such as Merkel cell polyomavirus, which causes Merkel cell carcinoma in humans, STag appears to be important for replication and to be an oncoprotein in its own right. (wikipedia.org)
  • In Merkel cell polyomavirus, it appears to play a significant role in oncogenesis, a function performed primarily by LTag in other polyomaviruses. (wikipedia.org)
  • Merkel cell carcinoma of the head and neck: emphasizing the risk of undertreatment [published online March 11, (mdedge.com)
  • A unique case of Merkel cell carcinoma with ovarian metastasis [published online December 1, (mdedge.com)
  • Merkel cell polyomavirus in Merkel cell carcinoma: clinical and therapeutic perspectives [published online Dec 31, (mdedge.com)
  • Focus on Merkel cell carcinoma: diagnosis and staging [published online January 30, (mdedge.com)
  • An unusual case of diffuse Merkel cell carcinoma successfully treated with low dose radiotherapy [published online May 14, (mdedge.com)
  • Pang C, Sharma D, Sankar T. Spontaneous regression of Merkel cell carcinoma: a case report and review of the literature [published online November 13, (mdedge.com)
  • Complete remission of Merkel cell carcinoma on the upper lip treated with radiation monotherapy and a literature review of Japanese cases. (mdedge.com)
  • Inflammatory monocytes are a reservoir for Merkel cell polyomavirus [published online December 17, (mdedge.com)
  • Merkel cell carcinoma showing regression after biopsy: evaluation of programmed cell death 1-positive cells [published online February 24, (mdedge.com)
  • Merkel cells are slow-responding mechanoreceptors located within the basal layer of the epidermis and are the source of a rare aggressive cutaneous malignancy. (mdedge.com)
  • 1 Merkel cell carcinoma was first noted in 1972 and termed trabecular carcinoma of the skin , and it accounts for less than 1% of all nonmelanoma skin cancer. (mdedge.com)
  • Merkel cell polyomavirus (MCV or MCPyV) was first described in January 2008 in Pittsburgh, Pennsylvania. (wikipedia.org)
  • It is suspected to cause the majority of cases of Merkel cell carcinoma, a rare but aggressive form of skin cancer. (wikipedia.org)
  • The cancer may derive from the microscopic Merkel cell nervous organ in the skin and viscera which is responsible for touch and pressure sensation. (wikipedia.org)
  • Although rare compared with other skin cancers, the incidence of Merkel cell carcinoma in the USA tripled between 1986 and 2001, to around 1400 cases per year. (wikipedia.org)
  • Merkel cell carcinoma is mainly seen in older individuals. (wikipedia.org)
  • BK virus is associated with nephropathy in renal transplant and non-renal solid organ transplant patients, JC virus with progressive multifocal leukoencephalopathy, and Merkel cell virus with Merkel cell cancer. (wikipedia.org)
  • latent
  • There are three types of persistent infections, latent, chronic and slow, in which the virus stays inside the host cell for prolonged periods of time. (wikipedia.org)
  • During latent infections there is minimal to no expression of infected viral genome. (wikipedia.org)
  • human embryonic kidney
  • The 58-kDa mutant virus was not defective when its growth was assayed on human embryonic kidney (HEK) cells. (uu.nl)
  • Human embryonic kidney cells 293, also often referred to as HEK 293, HEK-293, 293 cells, or less precisely as HEK cells, are a specific cell line originally derived from human embryonic kidney cells grown in tissue culture. (wikipedia.org)
  • mutations
  • Plasmids containing region Ela only or a plasmid carrying mutations in the genes for major Elb proteins all transformed primary cells with an efficiency of approximately 5% of wild type. (uu.nl)
  • helicase
  • Coordinated actions of the OBD and helicase regions result in physical manipulation of the viral genome, melting the DNA double helix at the origin of replication and unwinding the circular DNA chromosome in a bidirectional fashion. (wikipedia.org)
  • receptors
  • Killer-cell immunoglobulin-like receptors (KIRs), are a family of type I transmembrane glycoproteins expressed on the plasma membrane of natural killer (NK) cells and a minority of T cells. (wikipedia.org)
  • Natural killer cell cytolysis of target cells and cytokine production is controlled by a balance of inhibitory and activating signals, which are facilitated by NK cell receptors. (wikipedia.org)
  • NK cell inhibitory receptors are part of either the immunoglobulin-like (IgSF) superfamily or the C-type lectin-like receptor (CTLR) superfamily. (wikipedia.org)
  • KIR and CD94 (CTLR) receptors are expressed by 5% of peripheral blood T cells. (wikipedia.org)
  • MHC is also the chaperone for intracellular peptides that are complexed with MHCs and presented to T cell receptors (TCRs) as potential foreign antigens. (wikipedia.org)
  • encode
  • The majority of gammaherpesviruses encode a specific protein that is critical for maintenance of the viral genome within latently infected cells termed the genome maintenance protein (GMP). (wikipedia.org)