1 / 10

Problems for Intracellular Pathogens

Problems for Intracellular Pathogens. Entry into Host Cell Surviving Host Defenses Metabolism and Proliferation Preserving Host Cell Function Cell-to-Cell Transit. Entry into the Host Cell. specialized structures apical complex (Apicomplexa) polar tube (Microsporidia)

amos
Download Presentation

Problems for Intracellular Pathogens

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Problems for Intracellular Pathogens • Entry into Host Cell • Surviving Host Defenses • Metabolism and Proliferation • Preserving Host Cell Function • Cell-to-Cell Transit

  2. Entry into the Host Cell • specialized structures • apical complex (Apicomplexa) • polar tube (Microsporidia) • phagocytosis (endocytosis) • ie, macrophages • Macrophages as host cells? • detect, ingest, and destroy infectious agents • antigen presentation • secrete pro-inflammatory cytokines

  3. Survival in the Phagolysosome • Leishmania: • has proton pump to maintain intraparasite pH • amastigote surface resistant to proteases • degrades host hydrolases • down regulates oxidative burst and cytokine response

  4. Invasion by T. cruzi • phagocytosis followed by escape from phagolysosome • parasite replicates in host cytoplasm • Tc-TOX: • T. cruzi protein with hemolytic activity • pH 5.5 optimum •  pH of phagolysosome blocks escape • C9 antibodies cross-react • Andrews et al (1990) Cell 61:1277

  5. tachyzoites tachyzoites + Ab ò ò phagocytosis invasion L Tg L Tg å F æ M fusion no fusion PL parasite replication parasite death TOXOPLASMA AND MACROPHAGES Joiner et al (1990) Science 249:641

  6. Tachyzoite invasion involves apical organelles and formation of parasititophorous vacuole devoid of host membrane proteins.

  7. Ingestion of Host Cytoplasm cytostome Malaria parasite ingests host erythrocyte cytoplasm. food vacuole pinocytosis

  8. ATP hemoglobin H+ plasmepsin Fe2+ O2 ADP globin fragments Fe3+ heme + amino acids -O2 O2 heme polymerase falcipain plasmepsin falcilysin superoxide dismutase? H2O2 hemazoin ATP catalase? small fragments (6-8 amino acids) Pfmdr-1? H2O + O2 ADP The Food VacuoleA Specialized Lysosome amino- peptidase

  9. Natural Resistance to Malaria • inherited erythrocyte disorders associated with protection against malaria: • sickle-cell anemia • thalassemia • G6PD deficiency • all 3 may make the erythrocyte more sensitive to oxidative stress

  10. Problems for Intracellular Pathogens • Entry into Host Cell • Surviving Host Defenses • Metabolism and Proliferation • Preserving Host Cell Function • Cell-to-Cell Transit

More Related