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Immunity to viruses dr erly SpMK

Immunity to viruses dr erly SpMK. Viruses Obligatory intracellular m.o replicate within cells often using the NA&protein of the host utilizing normal cell surface molecules as receptors to enter the cell. Surface proteins as receptors : CD4 molecule on T cells CR2,CD21 on B cells

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Immunity to viruses dr erly SpMK

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  1. Immunity to virusesdr erly SpMK Viruses Obligatory intracellular m.o replicate within cells often using the NA&protein of the host utilizing normal cell surface molecules as receptors to enter the cell.

  2. Surface proteins as receptors : • CD4 molecule on T cells • CR2,CD21 on B cells • ICAM-1 , CD 54  variety of cell types

  3. After entering cells  tissue injury to and death of the infected cell ( CPE )  lytic • Non CP viruses  latent infectionsreside in host cells&produce protein stimulate spesific immunity. • CP&non CP viruses elicit different types of spesific immune responses.

  4. Innate Immunity to Viruses • Production IFN-1 by infected cells inhibit viral replication 2. NK cells lyse infected cells IFN-1 enhance NK cells to lyse infected cells

  5. Interferon(IFN) • Glikcoprotein • Alpha,Betha and Gamma IFN • Are produced within a few hours of the initiation of viral replication. • Antibody positive in blood several days after • Double stranded RNA viruses the most potent inducers of IFN • Act by binding to a receptor on the cell surface

  6. Do not enter the cell • No effect to the extracellular viruses • Alpha and betha IFN stronger antiviral action • Activates macrophages • Human IFN for human therapy

  7. NK Cells • Lymphocyte • Destroy cells infected by viruses(secreting perforins & granzymes.

  8. 3. Phgocytosis by macrophage 4. Clearance of mucus by the cilia of perpiratory tract also important defences • Increased corticosteroid levelssuppress host defences and predispose to severe viral infection. • Malnutrition  predispose measles • Very young&very old have more severe viral infections

  9. Spesific Immune Responces to viruses • A combination of humoral&cellular immune mechanisms. • Spesific antibodiesdefence againts viruses early of infection defence againts cytopathic viruses • Netralizing antibodiesprevent viral attachment&entry into host cells

  10. Opsonizing Antibodiesenhance phagocytic • Secretory IgA  netralizing viruses enter respiratory & intestinal tract • Antibodies effective againts viruses before enter cells & block spread from cell to cell.

  11. Evasion of Immune Mechanism by Viruses • Many viruse are capable of great antigenic variation. • Some viruses inhibit class I MHC • Some viruses produce molecules that inhibit innate or spesific immunity • Viruses may infect & either lyse or inactivate,immunocompetent cells

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