A Gene-Based Positive Selection Detection Approach to Identify Vaccine Candidates Using Toxoplasma gondii as a Test Case Protozoan Pathogen

Toxoplasma gondii is a zoonotic protozoan pathogen that infects many endothermic vertebrates, including humans; the domestic cat and other felids serve as the definitive host. Macropodids are considered highly susceptible to toxoplasmosis. Here, we describe the clinical, pathologic, and immunohistochemical findings of an outbreak of systemic toxoplasmosis in a mob of 11 red kangaroos ( Macropus rufus), with high morbidity (73%) and mortality (100%) rates. Affected animals had either severe and rapidly deteriorating clinical conditions or sudden death, which was correlated with widespread necrotizing lesions in multiple organs and intralesional T. gondii organisms identified via MIC3-specific immunohistochemistry and confirmed by REP529-specific rtPCR. Quantification of parasites demonstrated the highest parasite density in pulmonary parenchyma compared with other tissues. Our study highlights the continued importance of this severe condition in Australian marsupials.

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Toxoplasma gondii GRA28 is required for specific induction of the regulatory chemokine CCL22 in human and mouse cells

10.1101/2020.10.14.335802 ◽

2020 ◽

Author(s):

Elizabeth N. Rudzki ◽

Stephanie E. Ander ◽

Rachel S. Coombs ◽

Hisham I. Alrubaye ◽

Leah F. Cabo ◽

...

Keyword(s):

Toxoplasma Gondii ◽

Immune Tolerance ◽

Inflammatory Responses ◽

Severe Disease ◽

Transcriptional Level ◽

Placental Cells ◽

Host Signaling ◽

Mouse Cells ◽

Protozoan Pathogen ◽

The Impact

ABSTRACTToxoplasma gondii is an intracellular protozoan pathogen of humans that causes severe disease in immunocompromised patients and in the developing fetus. T. gondii specifically alters production of the immunomodulatory chemokine CCL22 in human placental cells during infection. Using a combination of bioinformatics and molecular genetics, we have now identified T. gondii GRA28 as the gene product required for CCL22 induction. GRA28 is strongly co-regulated at the transcriptional level along with other known secreted effectors and their chaperones. GRA28 is secreted into the host cell where it localizes to the nucleus, and deletion of this gene results in reduced CCL22 secretion from human monocytes and second trimester placental explants. The impact of GRA28 on CCL22 is also conserved in mouse immune and placental cells and the deletion of GRA28 results in increased inflammatory responses and reduced CNS burden during mouse infectionsAUTHOR SUMMARYToxoplasma gondii is a globally ubiquitous pathogen that can cause severe disease in HIV/AIDS patients and can also cross the placenta and infect the developing fetus. We have found that placental and immune cells infected with T. gondii secrete signfiicant amounts of a chemokine (called “CCL22”) that is critical for immune tolerance during pregnancy. In order to better understand whether this is a response by the host or a process that is driven by the parasite, we have identified a T. gondii gene that is absolutely required to induce CCL22 production in human cells, indicating that CCL22 production is a process driven almost entirely by the parasite rather than the host. Consistent with its role in immune tolerance, we also found that T. gondii parasites lacking this gene are less able to proliferate and disseminate throughout the host. Taken together these data illustrate a direct relationship between CCL22 levels in the infected host and a key parasite effector, and provide an interesting example of how T. gondii can directly modulate host signaling pathways in order to facilitate its growth and dissemination.

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Proteomic and transcriptomic analyses of early and late-chronic Toxoplasma gondii infection shows novel and stage specific transcripts

BMC Genomics ◽

10.1186/s12864-019-6213-0 ◽

2019 ◽

Vol 20 (1) ◽

Cited By ~ 4

Author(s):

Andrew L. Garfoot ◽

Gary M. Wilson ◽

Joshua J. Coon ◽

Laura J. Knoll

Keyword(s):

Toxoplasma Gondii ◽

Chronic Infection ◽

Time Course ◽

Protozoan Pathogen ◽

Toxoplasma Gondii Infection ◽

High Level ◽

Protein Rich ◽

The Brain ◽

Unique Ability

Abstract Background The protozoan pathogen Toxoplasma gondii has the unique ability to develop a chronic infection in the brain of its host by transitioning from the fast growing tachyzoite morphology to latent bradyzoite morphology. A hallmark of the bradyzoite is the development of neuronal cysts that are resilient against host immune response and current therapeutics. The bradyzoite parasites within the cyst have a carbohydrate and protein-rich wall and a slow-replication cycle, allowing them to remain hidden from the host. The intracellular, encysted lifestyle of T. gondii has made them recalcitrant to molecular analysis in vivo. Results Here, we detail the results from transcriptional and proteomic analyses of bradyzoite-enriched fractions isolated from mouse brains infected with T. gondii over a time course of 21 to 150 days. The enrichment procedure afforded consistent identification of over 2000 parasitic peptides from the mixed-organism sample, representing 366 T. gondii proteins at 28, 90, and 120 day timepoints. Deep sequencing of transcripts expressed during these three timepoints revealed that a subpopulation of genes that are transcriptionally expressed at a high level. Approximately one-third of these transcripts are more enriched during bradyzoite conditions compared to tachyzoites and approximately half are expressed at similar levels during each phase. The T. gondii transcript which increased the most over the course of chronic infection, sporoAMA1, shows stage specific isoform expression of the gene. Conclusions We have expanded the transcriptional profile of in vivo bradyzoites to 120 days post-infection and provided the first in vivo proteomic profile of T. gondii bradyzoites. The RNA sequencing depth of in vivo bradyzoite T. gondii was over 250-fold greater than previous reports and allowed us to identify low level transcripts and a novel bradyzoite-specific isoform of sporoAMA1.

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Rapid Identification of Virulent Type I Strains of the Protozoan Pathogen Toxoplasma gondii by PCR-Restriction Fragment Length Polymorphism Analysis at the B1 Gene

Journal of Clinical Microbiology ◽

10.1128/jcm.39.1.398-400.2001 ◽

2001 ◽

Vol 39 (1) ◽

pp. 398-400 ◽

Cited By ~ 92

Author(s):

M. E. Grigg ◽

J. C. Boothroyd

Keyword(s):

Toxoplasma Gondii ◽

Restriction Fragment Length Polymorphism ◽

Fragment Length Polymorphism ◽

Rapid Identification ◽

Polymorphism Analysis ◽

Type I ◽

Virulent Type ◽

B1 Gene ◽

Protozoan Pathogen ◽

Restriction Fragment Length

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Proteomic as an Exploratory Approach to Develop Vaccines Against Tick-Borne Diseases Using Lyme Borreliosis as a Test Case

Vaccines ◽

10.3390/vaccines8030463 ◽

2020 ◽

Vol 8 (3) ◽

pp. 463

Author(s):

Emilie Talagrand-Reboul ◽

Benoit Westermann ◽

Matthieu A. Raess ◽

Gilles Schnell ◽

Paola Cantero ◽

...

Keyword(s):

Lyme Borreliosis ◽

Control Measure ◽

Effective Control ◽

Test Case ◽

Hard Tick ◽

Tick Saliva ◽

Vaccine Candidates ◽

Vector Borne Diseases ◽

Proteomic Approach ◽

Vector Borne

Tick-borne diseases affecting humans and animals are on the rise worldwide. Vaccines constitute an effective control measure, but very few are available. We selected Lyme borreliosis, a bacterial infection transmitted by the hard tick Ixodes, to validate a new concept to identify vaccine candidates. This disease is the most common tick-borne disease in the Northern Hemisphere. Although attempts to develop a vaccine exist, none have been successfully marketed. In tick-borne diseases, the skin constitutes a very specific environment encountered by the pathogen during its co-inoculation with tick saliva. In a mouse model, we developed a proteomic approach to identify vaccine candidates in skin biopsies. We identified 30 bacterial proteins after syringe inoculation or tick inoculation of bacteria. Discovery proteomics using mass spectrometry might be used in various tick-borne diseases to identify pathogen proteins with early skin expression. It should help to better develop sub-unit vaccines based on a cocktail of several antigens, associated with effective adjuvant and delivery systems of antigens. In all vector-borne diseases, the skin deserves further investigation to better define its role in the elaboration of protective immunity against pathogens.

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A Model-Based Anomaly Detection Approach for Analyzing Streaming Aircraft Engine Measurement Data

Volume 6: Ceramics; Controls, Diagnostics and Instrumentation; Education; Manufacturing Materials and Metallurgy ◽

10.1115/gt2014-27172 ◽

2014 ◽

Cited By ~ 9

Author(s):

Donald L. Simon ◽

Aidan W. Rinehart

Keyword(s):

Steady State ◽

Anomaly Detection ◽

Piecewise Linear ◽

Measurement Data ◽

Aircraft Engine ◽

Dynamic State ◽

Test Case ◽

Model Based ◽

Detection Approach ◽

Case Data

This paper presents a model-based anomaly detection architecture designed for analyzing streaming transient aircraft engine measurement data. The technique calculates and monitors residuals between sensed engine outputs and model predicted outputs for anomaly detection purposes. Pivotal to the performance of this technique is the ability to construct a model that accurately reflects the nominal operating performance of the engine. The dynamic model applied in the architecture is a piecewise linear design comprising steady-state trim points and dynamic state space matrices. A simple curve-fitting technique for updating the model trim point information based on steady-state information extracted from available nominal engine measurement data is presented. Results from the application of the model-based approach for processing actual engine test data are shown. These include both nominal fault-free test case data and seeded fault test case data. The results indicate that the updates applied to improve the model trim point information also improve anomaly detection performance. Recommendations for follow-on enhancements to the technique are also presented and discussed.

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X-ray crystal structure and specificity of the Toxoplasma gondii ME49 TgAPN2

Biochemical Journal ◽

10.1042/bcj20200569 ◽

2020 ◽

Vol 477 (19) ◽

pp. 3819-3832

Author(s):

Emilia M. Marijanovic ◽

Karolina Weronika Swiderska ◽

James Andersen ◽

Jasmin C. Aschenbrenner ◽

Chaille T. Webb ◽

...

Keyword(s):

Crystal Structure ◽

Toxoplasma Gondii ◽

Drug Target ◽

Structure And Function ◽

Parasitic Disease ◽

Vaccine Candidates ◽

X Ray ◽

Structure Activity ◽

Comparative Structure ◽

And Function

Toxoplasmosis is a parasitic disease caused by infection with Toxoplasma gondii that currently has few therapeutic options. The M1 aminopeptidase enzymes have been shown to be attractive targets for anti-parasitic agents and/or vaccine candidates, suggesting potential to re-purpose inhibitors between parasite M1 aminopeptidase targets. The M1 aminopeptidase TgAPN2 has been suggested to be a potential new drug target for toxoplasmosis. Here we investigate the structure and function of TgAPN2, a homologue of the antimalarial drug target PfA-M1, and evaluate the capacity to use inhibitors that target PfA-M1 against TgAPN2. The results show that despite a similar overall fold, the TgAPN2 has a unique substrate specificity and inhibition profile. Sequence and structure differences are investigated and show how comparative structure-activity relationships may provide a route to obtaining potent inhibitors of TgAPN2.

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