Parasite Immunology

Abstract

Immunology of parasitic infections deals with the protective mechanisms of the body which help in preventing the parasite to gain a stronghold in the body and, as a tradeoff, the possible detrimental effects produced by the immune response on the body and resulting immunopathology. The innate immune response and the adaptive mechanisms play important roles in determining the outcome, but one type of adaptive response may be predominant over the other. In general, protozoan parasites are frequently intracellular, and hence the cell-mediated response plays a prominent role, while for the larval or adult forms of the helminthic parasites which are large enough to be extracellular, the antibody response predominates. In the event the parasite surmounts the onslaught of protective mechanisms, it can establish an acute or chronic infection. The parasite has evolved multiple mechanisms to evade the immune system of the body through which it can survive in the host. In addition, many parasites tend to establish a chronic infection in the host causing minimal damage to the host by a mechanism of immunoregulation and downplaying the immune response in the body.

Case Study

Lipophosphoglycan (LPG) is an important component of Leishmania envelope and has a significant effect on impairment of macrophage function by various mechanisms like cytokine cleavage, prevention of phagolysosome maturation, and activation of negative regulatory factors. Thus it plays an important role in survival of the parasite inside the macrophages. In an experimental mouse model, LPG induced an increased production of IFN-γ and TNF-α by producing reactive nitrogen intermediates and a killing effect on L. major. LPG along with BCG has been shown to raise TH1 immune response in mice as well as hamster models. Thus LPG is an important target for the future vaccine development for visceral leishmaniasis.

• 1. What are the various candidate Leishmania vaccines which have entered Phase 1 or 2 of vaccine trials?

• 2. What is a therapeutic vaccine?

• 3. Name the parasite vaccine which has shown the most promise to date. What is its composition?

Research Questions

• 1. What are the PAMPs which are important in different helminth parasites?

• 2. What is the exact role, if any, of eosinophils in parasitic infections?

• 3. What is the efficacy of therapeutic worm infection in the treatment of autoimmune diseases and metabolic disorders?