Big Chemical Encyclopedia

Chemical substances, components, reactions, process design ...

Articles Figures Tables About

Receptors, membrane virus attachment

In general, virus receptors carry out normal functions in the cell. For example, in bacteria some phage receptors are pili or flagella, others are cell-envelope components, and others are transport binding proteins. The receptor for influenza vims is a glycoprotein found on red blood cells and on cells of the mucous membrane of susceptible animals, whereas the receptor site of poliovirus is a lipoprotein. However, many animal and plant viruses do not have specific attachment sites at all and the vims enters passively as a result of phagocytosis or some other endocytotic process. [Pg.124]

Since cellular immunity results in the release of chemotactic lymphocytes that in turn enhance phagocytosis, a deficiency in cellular immunity may also result in chronic infections. Cellular immunity is mediated by T cells, macrophages, and NK cells involved in complex compensatory networks and secondary changes. Immunosuppressive agents may act directly by lethality to T cells, or indirectly by blocking mitosis, lymphokine synthesis, lymphokine release, or membrane receptors to lymphokines. In addition, cellular immunity is involved in the production and release of interferon, a lymphokine that ultimately results in blockage of viral replication (Table 15.4). Viruses are particularly susceptible to cytolysis by T cells since they often attach to the surface of infected cells. Thus, immunosuppression of any of the components of cellular immunity may result in an increase in protozoan, fungal, and viral infections as well as opportunistic bacterial infections. [Pg.543]

Viral replication consists of several steps (Figure 49-1) (1) attachment of the vims to receptors on the host cell surface (2) entry of the virus through the host cell membrane (3) uncoating of viral nucleic acid (4) synthesis of early regulatory proteins, eg, nucleic acid polymerases (5) synthesis of new viral RNA or DNA (6) synthesis of late, structural proteins (7) assembly (maturation) of viral particles and (8) release from the cell. Antiviral agents can potentially target any of these steps. [Pg.1067]

The initial event in the entry of viruses into cells is the attachment of the virus to specific receptors on the cell membrane. The chemical structures of most receptors for animal viruses are poorly defined. Cell surface glycoprotein, glycolipids, and phospholipids have been implicated. Very recently Helenius et al. (29) could identify human HLA and murine H-2 histocompatibility antigens as receptors for Semliki Forest virus these antigens are well-defined membrane glycoproteins. [Pg.383]

GSLs play crucial roles in functions of the nervous system and skin, cell growth and differentiation, infections, cancer, and immune response [1, 2, 12], Owing to their strategic position in membranes, they interact with toxins, bacteria, and viruses. They form membrane lipid rafts and present the attached carbohydrates as cell-surface receptors and, thus, serve as portals of entry for pathogens through carbohydrate-protein interactions [13]. For example, HIV entry is mediated by GalCer receptors of the host cells [14],... [Pg.296]

Viral and cellular lipid membranes must first fuse to allow entry of the viral core into a host cell. The primary receptor required for the entry of primate lentiviruses, HIV-1, HIV-2, and SIV, into cells is the CD4 molecule (1). The interaction of viral envelope protein with CD4 not only attaches virus particles to the cell surface but also induces conformational changes in the envelope protein. These structural alterations allow a secondary interaction with a coreceptor to occur which triggers the fusion process. [Pg.209]

In addition to the lipid bilayer, enveloped viruses generally have two or more distinct layers of protein that are organized across the membrane. Thus, most viruses have an outer layer of proteins, usually glycoproteins, which are anchored in the membrane as integral membrane proteins. These proteins function to attach the virion to target host cell receptors and facilitate the entry or fusion of the viral membrane with that of the host cell. In addition, some viruses also contain enzymatic activities associated with this outer layer of protein. For example, influenza virus carries with it a neuraminidase that is responsible for cleaving sialic acid residues on host cells. [Pg.364]

Unfortunately, there are no structures available for either the flaviviruses or alphaviruses under conditions approximating the fusion state. For both groups of viruses, entry is believed to occur following attachment of the virus to the cellular receptor and internalization of the particle into an endosome (Kielian, 1995 Heinz and Allison, 2001). Acidification of the endosome results in rearrangement of envelope proteins and subsequent insertion of the fusion peptide into the endosomal membrane (Levy-Mintz and Kielian, 1991 Allison et al., 2001). Ultimately this results in fusion of cellular and viral membranes and release of the nucleocapsid core and genome RNA into the cytoplasm of the infected cell. In vitro experiments... [Pg.372]

The role of bioreceptor can be also played by viruses covalently attached to the electrode surface, which was shown for resistance detection of antibody and prostate-specific membrane antigen.135 Taking into account up to 1020 unique species, phage-displayed libraries provide a vast pool of candidate receptors to practically any analyte, including small molecules, proteins and nucleic acids. Piezoelectric virus sensor has been developed e.g. for detection of distinctive antigens of the human cytomegalovirus.136... [Pg.51]

Viruses (from the Latin virus referring to poison) are nonliving obligate intracellular parasites composed of protein and nucleic acid (DNA or RNA) that manipulate the host cell to produce and manufacture more viruses. Viral infection occurs by tire attachment of virus particles to specific cell receptors within the host cell. After fusion of the host cell plasma membrane with the virus outer envelope, the protein-based viral nucleocapsid (containing the viral DNA) is transported to the host cell nucleus, where components of the viral particle inhibit macromolecular synthesis by tire host cell. Herpes viral DNA and new viral nucleocapsid synthesis occurs within the host nucleus, with the acquisition of new viral envelopes via a budding process through the inner membrane of the host nucleus. The mature newly synthesized viral particles are subsequently... [Pg.81]


See other pages where Receptors, membrane virus attachment is mentioned: [Pg.272]    [Pg.401]    [Pg.270]    [Pg.296]    [Pg.853]    [Pg.401]    [Pg.387]    [Pg.363]    [Pg.6392]    [Pg.280]    [Pg.228]    [Pg.1919]    [Pg.329]    [Pg.223]    [Pg.196]    [Pg.197]    [Pg.331]    [Pg.69]    [Pg.102]    [Pg.232]    [Pg.297]    [Pg.339]    [Pg.206]    [Pg.388]    [Pg.318]    [Pg.100]    [Pg.196]    [Pg.197]    [Pg.159]    [Pg.160]    [Pg.365]    [Pg.457]    [Pg.476]    [Pg.549]    [Pg.830]    [Pg.388]    [Pg.371]    [Pg.72]    [Pg.264]    [Pg.1475]    [Pg.174]   
See also in sourсe #XX -- [ Pg.474 ]




SEARCH



Membrane receptors

Viruses attachment

Viruses receptors

© 2024 chempedia.info