immunity to microbes (mechanisms of defense against viral, parasitic and fungal infections)

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Immunity to microbes (mechanisms of defense against viral, parasitic and fungal infections)

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Immunity to microbes (mechanisms of defense against viral, parasitic and fungal infections). Goal. To understand basic principles of defense against infections induced by :. ba c teri a - e x tracel l ular - intracel l ular. virus es. para sites protozoa helmint s. fungi. Virus es. - PowerPoint PPT Presentation

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Page 1: Immunity to microbes (mechanisms of defense against viral, parasitic and fungal infections)

Immunity to microbes

(mechanisms of defense against viral, parasitic and fungal infections)

Page 2: Immunity to microbes (mechanisms of defense against viral, parasitic and fungal infections)

Goal

bacteria - extracellular- intracellular

viruses

parasites- protozoa- helmints

fungi

To understand basic principles of defense againstinfections induced by:

Page 3: Immunity to microbes (mechanisms of defense against viral, parasitic and fungal infections)

Viruses

- unable to replicate outside cells

Simple structure (subcellular level)

Obligate intracellular agents

- enter cells via receptors

- acute

Infections

- chronic (active and latent)

- damage of cells in which they replicate

Induce diseases through

- induction of immune response

Page 4: Immunity to microbes (mechanisms of defense against viral, parasitic and fungal infections)

Mechanisms of defense against viruses

- inhibition of infection and induction of antiviral state type I interferons (IFN-α and β)

- killing of infected cells (NK cells)

Mechanisms of innate immunity

Page 5: Immunity to microbes (mechanisms of defense against viral, parasitic and fungal infections)

Antiviral action of type I interferons

Expression ofclass I MHC molecules

Expression of enzimes that inhibit viral replication

Uninfected cells

Infectedcells

Protection frominfection

Killing of infected cells by

CTLs

Page 6: Immunity to microbes (mechanisms of defense against viral, parasitic and fungal infections)

Destruction of infected cells by NK cells

Page 7: Immunity to microbes (mechanisms of defense against viral, parasitic and fungal infections)

Destruction of infected cells by NK cells

Page 8: Immunity to microbes (mechanisms of defense against viral, parasitic and fungal infections)

Destruction of infected cells by NK cells

Page 9: Immunity to microbes (mechanisms of defense against viral, parasitic and fungal infections)

- neutralization (IgG and IgA), ADCC (IgG) and opsonization (IgG)

Mechanisms of defense against viruses

Mechanisms of adaptive immunity

Humoral immunity

B cells and antibodies

Cell-mediated immunity

Page 10: Immunity to microbes (mechanisms of defense against viral, parasitic and fungal infections)

Neutralization of viruses

Page 11: Immunity to microbes (mechanisms of defense against viral, parasitic and fungal infections)

Protective mechanisms of antibodies

Page 12: Immunity to microbes (mechanisms of defense against viral, parasitic and fungal infections)

- neutralization (IgG and IgA), ADCC (IgG) and opsonization (IgG)

- activation of CD8+ T cells and and B cells (CD4+ helper T cells)

CD8+ and CD4+ T cells

Mechanisms of defense against viruses

Mechanisms of adaptive immunity

Humoral immunity

B cells and antibodies

Cell-mediated immunity

- killing of infected cells (CD8+ T cells)

Page 13: Immunity to microbes (mechanisms of defense against viral, parasitic and fungal infections)

Mechanism of killing by CTLs

Page 14: Immunity to microbes (mechanisms of defense against viral, parasitic and fungal infections)

Mechanism of killing by CTLs

Page 15: Immunity to microbes (mechanisms of defense against viral, parasitic and fungal infections)

Mechanism of killing by CTLs

Page 16: Immunity to microbes (mechanisms of defense against viral, parasitic and fungal infections)

Mechanism of killing by CTLs

Page 17: Immunity to microbes (mechanisms of defense against viral, parasitic and fungal infections)

Mechanism of killing by CTLs

Page 18: Immunity to microbes (mechanisms of defense against viral, parasitic and fungal infections)

perforin

CD8+ CTLTarget cell

apoptosis

granzymes

Mechanism of killing by CTLs

Page 19: Immunity to microbes (mechanisms of defense against viral, parasitic and fungal infections)

CD8+ CTLTarget cell

FasL Fas apoptosis

Mechanism of killing by CTLs

Page 20: Immunity to microbes (mechanisms of defense against viral, parasitic and fungal infections)

Mechanisms of innate and adaptive immunity against viruses

Page 21: Immunity to microbes (mechanisms of defense against viral, parasitic and fungal infections)

- antigenic variation (influenza virus, HIV...)

Mechanisms of immune evasion

Mechanisms of defense against viruses

Page 22: Immunity to microbes (mechanisms of defense against viral, parasitic and fungal infections)

Antigenic variations of influenza virus

Page 23: Immunity to microbes (mechanisms of defense against viral, parasitic and fungal infections)

- antigenic variation (influenza virus, HIV...)

Mechanisms of immune evasion

Mechanisms of defense against viruses

- inhibition of antigen processing and presentation (many viruses)

Page 24: Immunity to microbes (mechanisms of defense against viral, parasitic and fungal infections)

Inhibition of antigen

processing and

presentation by viruses

Page 25: Immunity to microbes (mechanisms of defense against viral, parasitic and fungal infections)

- antigenic variation (influenza virus, HIV...)

- inhibition of antigen processing and presentation (many viruses)

- inhibition of immune response (many viruses)

Mechanisms of immune evasion

Mechanisms of defense against viruses

Page 26: Immunity to microbes (mechanisms of defense against viral, parasitic and fungal infections)

Inhibition of immune response through production ofvirokines and viroreceptors

Page 27: Immunity to microbes (mechanisms of defense against viral, parasitic and fungal infections)

- antigenic variation (influenza virus, HIV...)

- inhibition of antigen processing and presentation (many viruses)

- inhibition of immune response (many viruses)

- infection of immune cells (HIV...)

- establishment of latency (HSV, HIV...)

- inhibition of apoptosis (Herpes and Pox viruses...)

Mechanisms of immune evasion

Mechanisms of defense against viruses

Page 28: Immunity to microbes (mechanisms of defense against viral, parasitic and fungal infections)

- tissue damage due to CD8+ CTL activity (HBV...)

- immune complexes formation (HBV...)

- „molecular mimicry” (many viruses and various autoimmune diseases)

Injurious effects of immune response

Mechanisms of defense against viruses

Page 29: Immunity to microbes (mechanisms of defense against viral, parasitic and fungal infections)

Parasites

- protozoa (unicellular) – intra- and extracellular agents

- complex eukaryotic organisms

- helmints (multicellular warms) – extracellular agents

- most common infectious diseases (30% of world population)

- complex life cycles

- constant exposure (endemic areas)

- need for vaccines (immunoparasitology)

- direct exposure or via vectors

- often induce chronic infections

Page 30: Immunity to microbes (mechanisms of defense against viral, parasitic and fungal infections)

Mehanisms of innate immunity

Protozoa and helmints – mostly resistant

- complement and phagocytosis (protozoa)

- eosinophils and macrophages (helmints)

Mechanisms of defense against parasites

Page 31: Immunity to microbes (mechanisms of defense against viral, parasitic and fungal infections)

-IFN-γ production and macrophage stimulation (CD4+TH1 cells) - Leishmania sp.

Protozoa

Helmints

- cytotoxicity (CD8+ T cells) – Plasmodium sp.

Mehanisms of adaptive immunity

- antibodies (B-cells) – Entamoeba sp., Plasmodium sp.

B-cells, CD4+ TH1 and CD8+ T cells

B-cells and CD4+ TH2 cells

- stimulation of eosinophils (IL-5 and IgE)

- stimulation of B-cells to produce IgE (IL-4)

- degranulation of mast cells (IgE)

Mechanisms of defense against parasites

Page 32: Immunity to microbes (mechanisms of defense against viral, parasitic and fungal infections)

Immunity against helmints

(TH2 response)

Page 33: Immunity to microbes (mechanisms of defense against viral, parasitic and fungal infections)

Immunity against helmints(function of eosinophils)

Page 34: Immunity to microbes (mechanisms of defense against viral, parasitic and fungal infections)

Injurious effect of immune response

Mechanisms of immune evasion

- granuloma formation and fibrosis (Schistosoma sp.)

- alteration of surface antigens (Trypanosoma sp....)

- complement resistance (many parasites)

-“concealing” – cysts (Toxoplasma sp.), residence in gut (intestinal parasites)

- immune complex formation (Plasmodium sp.)

- existence of different forms/stages (Plasmodium sp...)

Mechanisms of defense against parasites

Page 35: Immunity to microbes (mechanisms of defense against viral, parasitic and fungal infections)

Fungi

- yeast (unicellular)

- molds (multicellular)

- extracellular agents (some survive phagocytosis)

- most systemic infection - opportunistic some endemic (dimorphic fungi)

- risk factor - immunodeficiency (neutropenia)

- local and systemic mycoses

Page 36: Immunity to microbes (mechanisms of defense against viral, parasitic and fungal infections)

Mechanisms of defanseagainst fungi

Fungi – mostly susceptible

Mechanisms of innate immunity

- phagocytosis (neutrophils)

Mechanisms of adaptive immunity

- macrophage and neutrophil activation (CD4+ TH1 and TH17 cells)

Injurious effect of immune response

- granuloma formation and fibrosis (Histoplasma capsulatum)

Mechanisms of immune evasion

- inhibition of phagocytosis (C. neoformans...)

- complement

Cell-mediated immunity

Page 37: Immunity to microbes (mechanisms of defense against viral, parasitic and fungal infections)

Thanks for your attention!

Questions?