The genus Entamoeba comprises a lineage of single cell anaerobic amoebae that are mostly parasites in the intestines of animals. Most are harmless gut-dwellers, but a few species are pathogens. The best known and studied species are those that infect vertebrae hosts, including the human pathogen Entamoeba histolytica, which is responsible for approximately 100,000 deaths/year. The current study will focus on describing and determining the evolutionary history of Entamoeba infecting invertebrates. Entamoeba ribosomal gene sequences (SSU) and cultures of invertebrate-infecting Entamoeba will be acquired from known and suspected hosts. Amoebae will be fully characterized and documented by light microscopy. Specific probes will enable SSU gene acquisition from most species of Entamoeba, whether isolated from cultured amoebae or directly from the host gut. Comparative gene analyses will be utilized to infer the evolutionary history in this lineage of parasites and this history will inform knowledge of the evolution of key features such as degree of pathogenicity.
This study will begin to clarify Entamoeba systematics and taxonomy. The vastly underappreciated biodiversity of these organisms will be illuminated. Characterization of Entamoeba infections in invertebrates may identify unexpected natural reservoirs of human infection and will open up avenues of research on Entamoeba in the entomological research community (e.g., pathology, bio-control). Genetic and morphologic criteria will serve to delineate and describe species new to science and will provide a paradigm for the taxonomy of other Amoebozoans.
