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Viral Strategies For Immune Response Evasion
The mammalian immune system has evolved complex methods for addressing and adapting to foreign antigens. At the same time, viruses have co-evolved evasion machinery to address the many ways that host organisms attempt to eradicate them. DNA and RNA viruses use complex methods to evade immune cell detection through disruption of the Interferon Signaling Pathway, remodeling of cellular architecture, targeted gene silencing, and recognition protein cleavage. Interferon system The human immune system relies on a plethora of cell-cell signaling pathways to transmit information about a cell's health and microenvironment. Many of these pathways are mediated by soluble ligands, cytokines, that fit like a lock-and-key into adjacent cell surface receptors. This language of cell communication imparts both specificity and spatiotemporal control for the transmission of data. The Interferon System is composed of a family of cytokines. Type-I Interferons, IFN-α/β, and Type-III Interferons, I ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
RNA Signal Transduction
Ribonucleic acid (RNA) is a polymeric molecule essential in various biological roles in coding, decoding, regulation and expression of genes. RNA and deoxyribonucleic acid ( DNA) are nucleic acids. Along with lipids, proteins, and carbohydrates, nucleic acids constitute one of the four major macromolecules essential for all known forms of life. Like DNA, RNA is assembled as a chain of nucleotides, but unlike DNA, RNA is found in nature as a single strand folded onto itself, rather than a paired double strand. Cellular organisms use messenger RNA (''mRNA'') to convey genetic information (using the nitrogenous bases of guanine, uracil, adenine, and cytosine, denoted by the letters G, U, A, and C) that directs synthesis of specific proteins. Many viruses encode their genetic information using an RNA genome. Some RNA molecules play an active role within cells by catalyzing biological reactions, controlling gene expression, or sensing and communicating responses to cellular signal ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Interferon
Interferons (IFNs, ) are a group of signaling proteins made and released by host cells in response to the presence of several viruses. In a typical scenario, a virus-infected cell will release interferons causing nearby cells to heighten their anti-viral defenses. IFNs belong to the large class of proteins known as cytokines, molecules used for communication between cells to trigger the protective defenses of the immune system that help eradicate pathogens. Interferons are named for their ability to "interfere" with viral replication by protecting cells from virus infections. However, virus-encoded genetic elements have the ability to antagonize the IFN response contributing to viral pathogenesis and viral diseases. IFNs also have various other functions: they activate immune cells, such as natural killer cells and macrophages, and they increase host defenses by up-regulating antigen presentation by virtue of increasing the expression of major histocompatibility complex (M ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cytokine
Cytokines are a broad and loose category of small proteins (~5–25 kDa) important in cell signaling. Cytokines are peptides and cannot cross the lipid bilayer of cells to enter the cytoplasm. Cytokines have been shown to be involved in autocrine, paracrine and endocrine signaling as immunomodulating agents. Cytokines include chemokines, interferons, interleukins, lymphokines, and tumour necrosis factors, but generally not hormones or growth factors (despite some overlap in the terminology). Cytokines are produced by a broad range of cells, including immune cells like macrophages, B lymphocytes, T lymphocytes and mast cells, as well as endothelial cells, fibroblasts, and various stromal cells; a given cytokine may be produced by more than one type of cell. They act through cell surface receptors and are especially important in the immune system; cytokines modulate the balance between humoral and cell-based immune responses, and they regulate the maturation, growth, and res ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Protein Kinase R
Protein kinase RNA-activated also known as protein kinase R (PKR), interferon-induced, double-stranded RNA-activated protein kinase, or eukaryotic translation initiation factor 2-alpha kinase 2 (EIF2AK2) is an enzyme that in humans is encoded by the ''EIF2AK2'' gene. PKR protects against viral infections. Mechanism of action Protein kinase-R is activated by double-stranded RNA (dsRNA), introduced to the cells by a viral infection. PKR can also be activated by the protein PACT or by heparin. PKR contains an N-terminal dsRNA binding domain (dsRBD) and a C-terminal kinase domain, that gives it pro-apoptotic (cell-killing) functions. The dsRBD consists of two tandem copies of a conserved double stranded RNA binding motif, dsRBM1 and dsRBM2. PKR is induced by interferon in a latent state. Binding to dsRNA is believed to activate PKR by inducing dimerization and subsequent auto-phosphorylation reactions. In situations of viral infection, the dsRNA created by viral replication and g ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Virology
Virology is the Scientific method, scientific study of biological viruses. It is a subfield of microbiology that focuses on their detection, structure, classification and evolution, their methods of infection and exploitation of host (biology), host cell (biology), cells for reproduction, their interaction with host organism physiology and immunity, the diseases they cause, the techniques to isolate and culture them, and their use in research and therapy. The identification of the causative agent of tobacco mosaic disease (TMV) as a novel pathogen by Martinus Beijerinck (1898) is now acknowledged as being the history of virology, official beginning of the field of virology as a discipline distinct from bacteriology. He realized the source was neither a bacterial nor a fungal infection, but something completely different. Beijerinck used the word "virus" to describe the mysterious agent in his 'contagium vivum fluidum' ('contagious living fluid'). Rosalind Franklin proposed the f ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
