Parasite Immunology Overview

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Questions and Answers

How do Leishmania species avoid destruction inside immune cells?

By using host cell nutrients to destroy immune cells

By replicating outside the host cells

By altering the host cell nucleus

By producing molecules that neutralize reactive oxygen species (correct)

Which mechanism is primarily used by Trypanosoma brucei to evade the immune response?

Occupy receptor sites on immune cells

Alter the blood pH to incapacitate immune cells

Induce the production of antibodies against itself

Shed old VSG proteins and undergo antigenic variation (correct)

What role do regulatory T cells (Tregs) play in the presence of helminths like Schistosoma mansoni?

Inducing apoptosis in infected cells

Activating antibodies to neutralize parasites

Enhancing the immune response against the parasite

Suppressing effector immune responses (correct)

How does Toxoplasma gondii replicate without triggering an immune response?

By modifying the host cell environment to form a parasitophorous vacuole Signup and view all the answers

What strategy does Entamoeba histolytica use to escape immune detection?

Releasing surface antigens to divert immune attention Signup and view all the answers

What effect does Fasciola hepatica have on dendritic cells?

Inhibits dendritic cell maturation and T cell activation Signup and view all the answers

How does Leishmania major affect the processing and presentation of antigens?

Interferes with the function of MHC class II molecules Signup and view all the answers

What is a common characteristic of Echinococcus granulosus in its interaction with immune cells?

Secretes molecules that alter dendritic cell function Signup and view all the answers

What mechanism involves parasites changing their surface proteins to avoid being recognized by the host's immune system?

Antigenic Variation Signup and view all the answers

Which parasite is known for altering the expression of its PfEMP1 protein to evade host immunity?

Plasmodium falciparum Signup and view all the answers

What is the process by which parasites resemble host molecules to avoid immune detection called?

Molecular Mimicry Signup and view all the answers

Which parasite is known to coat itself with host proteins like immunoglobulins for immune evasion?

Schistosoma species Signup and view all the answers

Which mechanism involves parasites preventing effective immune responses by manipulating the host's immune cells?

Immunosuppression Signup and view all the answers

What term describes areas in the host's body where immune access is limited, allowing certain parasites to reside?

Immune Privilege Signup and view all the answers

Which of the following parasites is known to sequester in the liver to avoid immune cells?

Plasmodium falciparum Signup and view all the answers

Which of the following strategies involves reducing the production of cytokines and nitric oxide in macrophages?

Immunosuppression Signup and view all the answers

Study Notes

Antigenic Variation

Parasites change surface proteins to avoid host immune recognition
Plasmodium falciparum (Malaria) alters expression of PfEMP1 protein on infected red blood cells
Trypanosoma brucei (African trypanosomiasis) frequently switches Variant Surface Glycoprotein (VSG) coat

Molecular Mimicry

Parasites produce molecules resembling host molecules, evading immune detection
Schistosoma species (Blood flukes) coat themselves with host proteins like immunoglobulins and complement proteins
Entamoeba histolytica expresses host-like carbohydrates on its surface

Immunosuppression

Parasites actively suppress host immune response
Leishmania donovani (Leishmaniasis) manipulates macrophages, decreasing antigen presentation and pro-inflammatory cytokine production (diminished T-cell response)
Toxoplasma gondii (Toxoplasmosis) inhibits nitric oxide and IL-12 production in macrophages, dampening immune response

Immune Privilege/Sequestration

Some parasites reside in areas of the host's body where the immune system has limited access
Plasmodium species sequester in the liver and deep tissues
Trypanosoma cruzi (Chagas disease) hides inside muscle cells and other tissues

Inhibition of Phagocytosis and Intracellular Killing

Parasites avoid destruction inside macrophages by preventing phagocytosis or surviving intracellularly
Leishmania species survive within macrophage phagolysosomes by producing molecules that neutralize reactive oxygen species (ROS)
Toxoplasma gondii modifies the host cell environment to form a specialized parasitophorous vacuole

Shedding of Surface Antigens

Parasites shed surface antigens to escape antibody-mediated immune responses
Entamoeba histolytica releases surface antigens
Trypanosoma brucei sheds old VSG proteins

Induction of Regulatory T Cells (Tregs)

Some parasites induce Tregs, downregulating the immune response and promoting tolerance
Helminths (e.g., Schistosoma mansoni) induce Tregs secreting IL-10 and TGF-β, suppressing effector immune responses
Filarial worms (e.g., Wuchereria bancrofti) trigger regulatory pathways, resulting in immunosuppression

Modulation of Host Immune Cells

Parasites alter the behavior and function of host immune cells
Echinococcus granulosus (Hydatid disease) secretes molecules that modulate dendritic cell function, preventing T cell activation
Fasciola hepatica (Liver fluke) produces molecules that inhibit dendritic cell maturation and T cell activation, promoting immune tolerance

Blocking Antigen Processing and Presentation

Parasites interfere with the host's ability to process and present antigens to T cells
Leishmania major disrupts the function of MHC class II molecules in infected macrophages, preventing activation

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Description

Explore the mechanisms of how parasites evade the host's immune system. This quiz covers antigenic variation, molecular mimicry, and immunosuppression strategies utilized by various parasites like Plasmodium falciparum and Leishmania donovani. Test your knowledge on these fascinating immune evasion tactics!