A Sequential Model of Host Cell Killing and Phagocytosis by Entamoeba histolytica

The protozoan parasite Entamoeba histolytica is responsible for invasive intestinal and extraintestinal amebiasis. The virulence of Entamoeba histolytica is strongly correlated with the parasite's capacity to effectively kill and phagocytose host cells. The process by which host cells are killed and phagocytosed follows a sequential model of adherence, cell killing, initiation of phagocytosis, and engulfment. This paper presents recent advances in the cytolytic and phagocytic processes of Entamoeba histolytica in context of the sequential model

Editorial: disruptive technologies for the study of host-pathogen interactions

No abstract available

Update on Cryptosporidium spp.: highlights from the Seventh International Giardia and Cryptosporidium Conference

While cryptosporidiosis is recognized as being among the most common causes of human parasitic diarrhea in the world, there is currently limited knowledge on Cryptosporidium infection mechanisms, incomplete codification of diagnostic methods, and a need for additional therapeutic options. In response, the Seventh International Giardia and Cryptosporidium Conference (IGCC 2019) was hosted from 23 to 26 June 2019, at the Rouen Normandy University, France. This trusted event brought together an international delegation of researchers to synthesize recent advances and identify key research questions and knowledge gaps. The program of the interdisciplinary conference included all aspects of host-parasite relationships from basic research to applications to human and veterinary medicine, and environmental issues associated with waterborne parasites and their epidemiological consequences. In relation to Cryptosporidium and cryptosporidiosis, the primary research areas for which novel findings and the most impressive communications were presented and discussed included: Cryptosporidium in environmental waters, seafood, and fresh produce; Animal epidemiology; Human cryptosporidiosis and epidemiology; Genomes and genomic evolution encompassing: Comparative genomics of Cryptosporidium spp., Genomic insights into biology, Acquiring and utilizing genome sequences, Genetic manipulation; Host-parasite interaction (immunology, microbiome); and Diagnosis and treatment. High quality presentations discussed at the conference reflected decisive progress and identified new opportunities that will engage investigators and funding agencies to spur future research in a “one health” approach to improve basic knowledge and the clinical and public health management of zoonotic cryptosporidiosis

Entamoeba histolytica

The protozoan parasite Entamoeba histolytica is responsible for invasive intestinal and extraintestinal amebiasis. The virulence of Entamoeba histolytica is strongly correlated with the parasite's capacity to effectively kill and phagocytose host cells. The process by which host cells are killed and phagocytosed follows a sequential model of adherence, cell killing, initiation of phagocytosis, and engulfment. This paper presents recent advances in the cytolytic and phagocytic processes of Entamoeba histolytica in context of the sequential model

Horizontally transferred genes and their proposed functions in <i>Cryptosporidium</i> biology.

<p><b>A. Anaerobic metabolism</b>. <i>Cryptosporidium</i> can regenerate oxidized NAD either directly from pyruvate via lactate dehydrogenase (LDH, <i>cgd7_480</i>) or from acetyl-CoA via a bifunctional alcohol dehydrogenase (ADHE, <i>cgd8_1720</i>). B. Nucleotide salvage. <i>Cryptosporidium</i> relies on inosine 5′ monophosphate dehydrogenase (IMPDH) to convert deoxyadenosine monophosphate (dAMP) to guanosine monophosphate (dGMP) within the parasitophorous vacuole. Dihydrofolate reductase-thymidylate synthase (DHFR-TS, <i>cgd4_4460</i>) and thymidine kinase (TK, <i>cgd5_4440</i>) can both produce deoxythymidine monophospohate (dTMP); however, the presence of TK allows <i>Cryptosporidium</i> to survive treatment with dihydrofolate reductase (DHFR) inhibitors such as pyrimethamine and trimethoprim. C. Immune evasion. Interferon gamma (IFNγ) induces the production of indoleamine 2,3-deoxygenase (IDO) within infected host cells, which converts host tryptophan to kynurenine and starves intracellular organisms. <i>Cryptosporidium</i> has a horizontally acquired tryptophan synthase B (TrpB, <i>cgd5_4560</i>), possibly to evade this starvation. TrpB is capable of synthesizing tryptophan from exogenous serine and indole produced by gut microbiota.</p

SNAP-tag technology optimized for use in Entamoeba histolytica.

Entamoeba histolytica is a protozoan parasite responsible for invasive intestinal and extraintestinal amebiasis. The pathology of amebiasis is still poorly understood, which can be largely attributed to lack of molecular tools. Here we present the optimization of SNAP-tag technology via codon optimization specific for E. histolytica. The resultant SNAP protein is highly expressed in amebic trophozoites, and shows proper localization when tagged with an endoplasmic reticulum retention signal. We further demonstrate the capabilities of this system using super resolution microscopy, done for the first time in E. histolytica

STORM imaging of an <i>E. histolytica</i> trophozoite.

<p>Super resolution microscopy of the amebic endoplasmic reticulum (ER) using a SNAP-tag protein with a KDEL ER retention signal. Inlayed boxes and arrows show the three way bifurcations that are characteristic of the ER, and the improved resolution that the STORM method provided (scale bar is 500 nm).</p