Host Parasite Cellular And Molecular Interactions In Protozoal Infections

Tropical diseases such as leishmaniasis, malaria. trypanosomiasis, toxoplasmosis and amebiasis continue to plague the world, resulting in considerable morbidity and mortality, especially in the third world countries. These diseases are caused by a group of protozoa which have, over the years, undergone evolutionary adaptation to live often intracellularly in a parasitic way of life. So well-adapted have they become that they recognize the right hosts or cells to parasitize, yet at the same time they escape recognition and destruction by the host immune system. The mechanisms of such recognition and the escape of recognition are governed largely by host-parasite surface membrane interactions at the cellular and molecular level. Unique molecules produced by unusual pathways of these parasites have also been discovered and found to play important roles in their survival in the host. Understanding these mechanisms and pathways is essential not only to formulate a rational strategy for chemo- and immuno-prophylaxis and -therapy but also to unravel the mystery of biological evolution in symbiosis and parasitism. In the advent of our knowledge on the molecular biology and biochemistry of parasite membrane and other molecules, it is opportune to examine and discuss their possible roles in host-parasite recognition and interaction in a comparative approach. To highlight the recent advances of this area in various host-parasite systems, a NATO advanced Research Workshop was held from September 27 to October 1, 1986 at Hotel Villa del Mare, Acquafredda di Maratea, Italy.

Protozoan and helminth parasites infect animals and humans and cause debilitating pathologies that cause a variety of morbidities and deaths worldwide. The ability of parasites to establish infection and cause disease in mammalian hosts is a result of a series of intricate mechanisms evolved by parasitic species to confront and evade the host's defensive responses, along with the ability to use the host’s metabolic and catabolic processes and host cellular organelles to their benefit. For instance, parasites may have predilection sites in the host that are not accessible to immune effector molecules and mechanisms, may acquire host-derived "masking" molecules, can vary their surface molecules, and can produce molecules that block or misguide the host immune responses. The host's interactions with the parasite, on the other hand, are critical for the initiation and induction of host signaling events that are critical in mounting formidable defensive immune responses against the invading parasite. Therefore, the ability of a parasite to successfully establish infection and cause disease largely depends on its interaction with the host and the ability of the host to mount successful and effective resistance. Thus, studying host-parasite interactions and cross-talks is critical for understanding parasite infection and adaptation mechanisms within the host, as well as for developing strategies for effective prevention and control of parasitic infections in humans and animals. The topic will cover a wide spectrum of parasitic protozoa and helminths and provide an opportunity to share new molecular and translational advances in parasitic infections and diseases.

Immune Recognition and Evasion: Molecular Aspects of Host-Parasite Interaction reviews recent advances in understanding the genetic basis of host-parasite interactions, with emphasis on antigenic epitopes, the genetics of parasites, the molecular mechanisms of immune recognition and evasion, and the way that cytokines and hormones act on host-parasite interactions. Organized into four parts encompassing 25 chapters, this volume begins with an overview of the genomic organization of the T cell receptor genes and the contribution of non-B DNA structures to switch recombination in immunoglobulin genes. It then discusses signal transduction by class II molecules encoded by the major histocompatibility complex la and the biological consequences of this process; allelic polymorphism of HLA class II antigens and its connection to the molecular basis of autoimmunity; mimicry between HLAB27 and bacteria; and genetic control of susceptibility to helminth infection. The reader is also introduced to recognition of protein antigens by antibodies; recognition of influenza antigens by class I-restricted cytotoxic T lymphocytes; the biochemical basis of cachexia of infection; mechanisms of antigenic variation in Plasmodium; and rational design of trypanocidal drugs. Geneticists and molecular biologists will gain valuable information from this book.

This volume summarizes current research into the physiology and molecular biology of host-parasite interactions. Brought together by leading international experts in the field, the first section outlines fundamental processes, followed by specific examples in the concluding section. Covering a wide range of organisms, Host-Parasite Interactions is essential reading for researchers in the field.

In the past years, genome projects for numerous human parasites have been completed and now allow first in depth comparisons and evolutionary conclusions. The genomes of parasites reflect the coevolution with their host, metabolic capacities depending on their respective habitat in the host. Gut parasites usually have an anaerobic metabolism, while blood parasites have an aerobic metabolism, intracellular parasites escape the immune system, while extracellular parasites evade the immune system, usually by antigenic variation. Comprehensive genome data now being available allow us to address profound scientific questions, such as which traits enable the parasite to survive in the human host, which to cause disease and which can be used as drug targets. This book intends to give an overview of the state of knowledge on “the molecules” of protozoan parasites – on their genomes, proteomes, glycomes and lipidomes.

All of the parasitic organisms highlighted in this new book represent medically important human pathogens that contribute significantly to the global burden of disease. As such there is intense interest in understanding the molecular basis of infection by these pathogens—not only with regard to their clinical relevance but also the fascinating biology they reveal. For most of the parasites discussed here the ability to penetrate biological barriers and/or to establish intracellular residence is critical to survival of the pathogen in the mammalian hosts. For other parasites, a tissue invasive phenotype is a key virulence determinant. In the ensuing 18 chapters, select members of this diverse set of protozoan parasites, as well as some examples of the extremely reduced fungal parasites classified as Microsporidia, are discussed within the context of the fascinating molecular strategies employed by these organisms to migrate across biological barriers and to establish residence within target host cells.