scholarly journals CRISPR-Mediated Transcriptional Repression in Toxoplasma gondii

mSphere ◽  
2021 ◽  
Author(s):  
Benedikt M. Markus ◽  
Elizabeth A. Boydston ◽  
Sebastian Lourido
Keyword(s):  
Toxoplasma Gondii ◽  
Transcriptional Repression ◽  
Functional Annotation ◽  
Immunocompromised Patients ◽  
Intracellular Parasite ◽  
Content Type ◽  
Fetal Abnormalities ◽  
Health Implications ◽  
Life Threatening ◽  
Eye Lesions

Toxoplasma gondii is a ubiquitous intracellular parasite of humans and animals that causes life-threatening disease in immunocompromised patients, fetal abnormalities when contracted during gestation, and recurrent eye lesions in some patients. Despite its health implications, about half of the Toxoplasma genome still lacks functional annotation.

scholarly journals Toxoplasma gondii Development of Its Replicative Niche: in Its Host Cell and Beyond

2014 ◽  
Vol 13 (8) ◽  
pp. 965-976 ◽  
Author(s):  
Ira J. Blader ◽  
Anita A. Koshy
Keyword(s):  
Toxoplasma Gondii ◽  
Host Cell ◽  
Host Cells ◽  
Content Type ◽  
Obligate Intracellular ◽  
Cellular Processes ◽  
High Prevalence ◽  
Life Threatening ◽  
Cell Processes ◽  
Cellular Pathways

ABSTRACTIntracellular pathogens can replicate efficiently only after they manipulate and modify their host cells to create an environment conducive to replication. While diverse cellular pathways are targeted by different pathogens, metabolism, membrane and cytoskeletal architecture formation, and cell death are the three primary cellular processes that are modified by infections.Toxoplasma gondiiis an obligate intracellular protozoan that infects ∼30% of the world's population and causes severe and life-threatening disease in developing fetuses, in immune-comprised patients, and in certain otherwise healthy individuals who are primarily found in South America. The high prevalence ofToxoplasmain humans is in large part a result of its ability to modulate these three host cell processes. Here, we highlight recent work defining the mechanisms by whichToxoplasmainteracts with these processes. In addition, we hypothesize why some processes are modified not only in the infected host cell but also in neighboring uninfected cells.

scholarly journals Pseudomonas aeruginosa AlgU Contributes to Posttranscriptional Activity by IncreasingrsmAExpression in amucA22Strain

2016 ◽  
Vol 198 (13) ◽  
pp. 1812-1826 ◽  
Author(s):  
Sean D. Stacey ◽  
Christopher L. Pritchett
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Biofilm Formation ◽  
Laboratory Strain ◽  
Immunocompromised Patients ◽  
Chronic Infections ◽  
Rnase Protection ◽  
Content Type ◽  
Mutant Strains ◽  
Life Threatening ◽  
Severe Infections

ABSTRACTPseudomonas aeruginosathrives in multiple environments and is capable of causing life-threatening infections in immunocompromised patients. RsmA is a posttranscriptional regulator that controls virulence factor production and biofilm formation. In this study, we investigated the expression and activity ofrsmAand the protein that it encodes, RsmA, inP. aeruginosamucAmutant strains, which are common in chronic infections. We determined that AlgU regulates a previously unknownrsmApromoter inP. aeruginosa. Western blot analysis confirmed that AlgU controlsrsmAexpression in both a laboratory strain and a clinical isolate. RNase protection assays confirmed the presence of tworsmAtranscripts and suggest that RpoS and AlgU regulatersmAexpression. Due to the increased amounts of RsmA inmucAmutant strains, a translational leader fusion of the RsmA target,tssA1, was constructed and tested inmucA,algU,retS,gacA, andrsmAmutant backgrounds to examine posttranscriptional activity. From these studies, we determined that RsmA is active inmucA22mutants, suggesting a role for RsmA inmucAmutant strains. Taken together, we have demonstrated that AlgU controlsrsmAtranscription and is responsible for RsmA activity inmucAmutant strains. We propose that RsmA is active inP. aeruginosamucAmutant strains and that RsmA also plays a role in chronic infections.IMPORTANCEP. aeruginosacauses severe infections in immunocompromised patients. The posttranscriptional regulator RsmA is known to control virulence and biofilm formation. We identify a newrsmApromoter and determine that AlgU is important in the control ofrsmAexpression. MutantmucAstrains that are considered mucoid were used to confirm increasedrsmAexpression from the AlgU promoter. We demonstrate, for the first time, that there is RsmA activity in mucoidP. aeruginosastrains. Our work suggests that RsmA may play a role during chronic infections as well as acute infections.

scholarly journals Efficacy of Liposomal Amphotericin B and Posaconazole in Intratracheal Models of Murine Mucormycosis

2013 ◽  
Vol 57 (7) ◽  
pp. 3340-3347 ◽  
Author(s):  
Guanpingsheng Luo ◽  
Teclegiorgis Gebremariam ◽  
Hongkyu Lee ◽  
Samuel W. French ◽  
Nathan P. Wiederhold ◽  
...  
Keyword(s):  
Fungal Infection ◽  
Amphotericin B ◽  
Liposomal Amphotericin ◽  
Intratracheal Instillation ◽  
Cortisone Acetate ◽  
Liposomal Amphotericin B ◽  
Immunocompromised Patients ◽  
Content Type ◽  
Pulmonary Mucormycosis ◽  
Life Threatening

ABSTRACTMucormycosis is a life-threatening fungal infection almost uniformly affecting diabetics in ketoacidosis or other forms of acidosis and/or immunocompromised patients. Inhalation ofMucoralesspores provides the most common natural route of entry into the host. In this study, we developed an intratracheal instillation model of pulmonary mucormycosis that hematogenously disseminates into other organs using diabetic ketoacidotic (DKA) or cyclophosphamide-cortisone acetate-treated mice. Various degrees of lethality were achieved for the DKA or cyclophosphamide-cortisone acetate-treated mice when infected with different clinical isolates ofMucorales. In both DKA and cyclophosphamide-cortisone acetate models, liposomal amphotericin B (LAmB) or posaconazole (POS) treatments were effective in improving survival, reducing lungs and brain fungal burdens, and histologically resolving the infection compared with placebo. These models can be used to study mechanisms of infection, develop immunotherapeutic strategies, and evaluate drug efficacies against life-threateningMucoralesinfections.

scholarly journals Impact of Engineered Expression of Mitochondrial Association Factor 1b on Toxoplasma gondii Infection and the Host Response in a Mouse Model

mSphere ◽  
2018 ◽  
Vol 3 (5) ◽  
Author(s):  
Elizabeth D. English ◽  
Jon P. Boyle
Keyword(s):  
Toxoplasma Gondii ◽  
Chronic Infection ◽  
Acute Infection ◽  
Chronic Phase ◽  
Parasite Burden ◽  
Cytokine Signaling ◽  
Parasite Protein ◽  
Content Type ◽  
Life Threatening ◽  
The Impact

ABSTRACT The opportunistic intracellular parasite Toxoplasma gondii causes a lifelong chronic infection capable of reactivating in immunocompromised individuals, which can lead to life-threatening complications. Following invasion of the host cell, host mitochondria associate with the parasitophorous vacuole membrane. This phenotype is T. gondii strain specific and is mediated by expression of a host mitochondrial association-competent (HMA+) paralog of the parasite protein mitochondrial association factor 1 (MAF1b). Previous work demonstrated that expression of MAF1b in strains that do not normally associate with host mitochondria increases their fitness during acute infection in vivo. However, the impact of MAF1b expression during chronic T. gondii infection is unclear. In this study, we assess the impact of MAF1b expression on cyst formation and cytokine production in mice. Despite generally low numbers of cysts generated by the in vitro culture-adapted strains used in this study, we find that parasites expressing MAF1b have higher numbers of cysts in the brains of chronically infected mice and that MAF1b+ cyst burden significantly increases during the course of chronic infection. Consistent with this, mice infected with MAF1b+ parasites have higher levels of the serum cytokines RANTES and VEGF (vascular endothelial growth factor) at day 57 postinfection, although this could be due to higher parasite burden at this time point rather than direct manipulation of these cytokines by MAF1b. Overall these data indicate that MAF1b expression may also be important in determining infection outcome during the chronic phase, either by directly altering the cytokine/signaling environment or by increasing proliferation during the acute and/or chronic phase. IMPORTANCE The parasite Toxoplasma gondii currently infects approximately one-third of the world’s population and causes life-threatening toxoplasmosis in individuals with undeveloped or weakened immune systems. Current treatments are unable to cure T. gondii infection, leaving infected individuals with slow-growing tissue cysts for the remainder of their lives. Previous work has shown that expression of the parasite protein mitochondrial association factor 1 (MAF1b) is responsible for the association of T. gondii parasites with host mitochondria and provides a selective advantage during acute infection. Here we examine the impact of MAF1b expression during chronic T. gondii infection. We find that mice infected with MAF1b-expressing parasites have higher cyst burden and cytokine levels than their wild-type counterparts. A better understanding of the genes involved in establishing and maintaining chronic infection will aid in discovering effective therapeutics for chronically infected individuals.

scholarly journals Stage-Specific and Selective Delivery of Caged Azidosugars into the Intracellular Parasite Toxoplasma gondii by Using an Esterase-Ester Pair Technique

mSphere ◽  
2019 ◽  
Vol 4 (3) ◽  
Author(s):  
Tadakimi Tomita ◽  
Hua Wang ◽  
Peng Wu ◽  
Louis M. Weiss
Keyword(s):  
Toxoplasma Gondii ◽  
Small Molecules ◽  
Click Chemistry ◽  
Cell Biology ◽  
Host Cells ◽  
Intracellular Parasite ◽  
Content Type ◽  
Intracellular Parasites ◽  
Specific Manner ◽  
Selective Delivery

ABSTRACT Toxoplasma gondii is an obligate intracellular parasite that chronically infects up to a third of the human population. The parasites persist in the form of cysts in the central nervous system and serve as a reservoir for the reactivation of toxoplasmic encephalitis. The cyst wall is known to have abundant O-linked N-acetylgalactosamine glycans, but the existing metabolic labeling methods do not allow selective labeling of intracellular parasite glycoproteins without labeling of host glycans. In this study, we have integrated Cu(I)-catalyzed bioorthogonal click chemistry with a specific esterase-ester pair system in order to selectively deliver azidosugars to the intracellular parasites. We demonstrated that α-cyclopropyl modified GalNAz was cleaved by porcine liver esterase produced in the parasites but not in the host cells. Our proof-of-concept study demonstrates the feasibility and potential of this esterase-ester click chemistry approach for the selective delivery of small molecules in a stage-specific manner. IMPORTANCE Selective delivery of small molecules into intracellular parasites is particularly problematic due to the presence of multiple membranes and surrounding host cells. We have devised a method that can deliver caged molecules into an intracellular parasite, Toxoplasma gondii, that express an uncaging enzyme in a stage-specific manner without affecting host cell biology. This system provides a valuable tool for studying many intracellular parasites.

scholarly journals Detection of Pneumocystis jirovecii by Quantitative PCR To Differentiate Colonization and Pneumonia in Immunocompromised HIV-Positive and HIV-Negative Patients

2016 ◽  
Vol 54 (6) ◽  
pp. 1487-1495 ◽  
Author(s):  
T. Fauchier ◽  
L. Hasseine ◽  
M. Gari-Toussaint ◽  
V. Casanova ◽  
P. M. Marty ◽  
...  
Keyword(s):  
Hiv Infection ◽  
Quantitative Pcr ◽  
Pneumocystis Jirovecii ◽  
Hiv Positive ◽  
Immunocompromised Patients ◽  
Infection Status ◽  
Content Type ◽  
Fungal Burden ◽  
Life Threatening ◽  
Hiv Negative

Pneumocystisjiroveciipneumonia (PCP) is an acute and life-threatening lung disease caused by the fungusPneumocystis jirovecii. The presentation of PCP in HIV-positive patients is well-known and consists of a triad of dyspnea, fever, and cough, whereas the presentation of PCP in HIV-negative patients is atypical and consists of a sudden outbreak, O2desaturation, and a rapid lethal outcome without therapy. Despite the availability of direct and indirect identification methods, the diagnosis of PCP remains difficult. The cycle threshold (CT) values obtained by quantitative PCR (qPCR) allow estimation of the fungal burden. The more elevated that the fungal burden is, the higher the probability that the diagnosis is pneumonia. The purposes of the present study were to evaluate theCTvalues to differentiate colonization and pneumonia in a population of immunocompromised patients overall and patients stratified on the basis of their HIV infection status. Testing of bronchoalveolar lavage (BAL) fluid samples from the whole population of qPCR-positive patients showed a meanCTvalue for patients with PCP of 28 (95% confidence interval [CI], 26 to 30) and a meanCTvalue for colonized patients of 35 (95% CI, 34 to 36) (P< 10−3). For the subgroup of HIV-positive patients, we demonstrated that aCTvalue below 27 excluded colonization and aCTvalue above 30 excluded PCP with a specificity of 100% and a sensitivity of 80%, respectively. In the subgroup of HIV-negative patients, we demonstrated that aCTvalue below 31 excluded colonization and aCTvalue above 35 excluded PCP with a specificity of 80% and a sensitivity of 80%, respectively. Thus, qPCR of BAL fluid samples is an important tool for the differentiation of colonization and pneumonia inP. jirovecii-infected immunocompromised patients and patients stratified on the basis of HIV infection status with differentCTvalues.

scholarly journals Interactions of Both Pathogenic and Nonpathogenic CUG Clade Candida Species with Macrophages Share a Conserved Transcriptional Landscape

mBio ◽  
2021 ◽  
Author(s):  
Andrew W. Pountain ◽  
John R. Collette ◽  
William M. Farrell ◽  
Michael C. Lorenz
Keyword(s):  
Fungal Infection ◽  
Candida Species ◽  
Invasive Disease ◽  
Immunocompromised Patients ◽  
Common Cause ◽  
Content Type ◽  
Life Threatening ◽  
Transcriptional Landscape

Candidiasis is a major fungal infection by Candida species, causing life-threatening invasive disease in immunocompromised patients. C. albicans , which is adapted to commensalism of human mucosae, is the most common cause. While several other species cause infection, most are less prevalent or less virulent.

scholarly journals Unraveling Caspofungin Resistance in Cryptococcus neoformans

mBio ◽  
2021 ◽  
Vol 12 (2) ◽  
Author(s):  
Nicolas Papon ◽  
Gustavo H. Goldman
Keyword(s):  
Cell Wall ◽  
Cryptococcus Neoformans ◽  
Posttranscriptional Regulation ◽  
Fungal Infections ◽  
Cell Wall Biosynthesis ◽  
Immunocompromised Patients ◽  
Efficient Treatment ◽  
Content Type ◽  
Great Hope ◽  
Life Threatening

ABSTRACT Cryptococcus neoformans is a basidiomycetous yeast responsible for hundreds of thousands of deaths a year and is particularly threatening in immunocompromised patients. There are few families of antifungals that are available to fight fungal infections, and the unique efficient treatment for the most deadly cerebral forms of cryptococcosis is based on a combination of 5-fluorocytosine and amphotericin B. The toxicities of both compounds are elevated, and more therapeutic options are urgently needed for better management of life-threatening cryptococcosis. The newest class of antifungals, i.e., echinocandins, has initially led to great hope. Unfortunately, C. neoformans was rapidly confirmed to be naturally resistant to these molecules, notably caspofungin. In this respect, we discuss here the recent key findings of the Panepinto research group published in mBio (M. C. Kalem et al., mBio 12:e03225-20, 2021, https://doi:10.1128/mBio.03225-20) that provide an unprecedented view of how C. neoformans regulates caspofungin resistance through a complex posttranscriptional regulation of cell wall biosynthesis genes.

scholarly journals Differential Impacts on Host Transcription by ROP and GRA Effectors from the Intracellular Parasite Toxoplasma gondii

mBio ◽  
2020 ◽  
Vol 11 (3) ◽  
Author(s):  
Suchita Rastogi ◽  
Yuan Xue ◽  
Stephen R. Quake ◽  
John C. Boothroyd
Keyword(s):  
Toxoplasma Gondii ◽  
Host Cell ◽  
Cell Biology ◽  
Parasitophorous Vacuole ◽  
Effector Proteins ◽  
Transcriptomic Analysis ◽  
Host Cells ◽  
Intracellular Parasite ◽  
Content Type ◽  
I Cells

ABSTRACT The intracellular parasite Toxoplasma gondii employs a vast array of effector proteins from the rhoptry and dense granule organelles to modulate host cell biology; these effectors are known as ROPs and GRAs, respectively. To examine the individual impacts of ROPs and GRAs on host gene expression, we developed a robust, novel protocol to enrich for ultrapure populations of a naturally occurring and reproducible population of host cells called uninfected-injected (U-I) cells, which Toxoplasma injects with ROPs but subsequently fails to invade. We then performed single-cell transcriptomic analysis at 1 to 3 h postinfection on U-I cells (as well as on uninfected and infected controls) arising from infection with either wild-type parasites or parasites lacking the MYR1 protein, which is required for soluble GRAs to cross the parasitophorous vacuole membrane (PVM) and reach the host cell cytosol. Based on comparisons of infected and U-I cells, the host’s earliest response to infection appears to be driven primarily by the injected ROPs, which appear to induce immune and cellular stress pathways. These ROP-dependent proinflammatory signatures appear to be counteracted by at least some of the MYR1-dependent GRAs and may be enhanced by the MYR-independent GRAs (which are found embedded within the PVM). Finally, signatures detected in uninfected bystander cells from the infected monolayers suggest that MYR1-dependent paracrine effects also counteract inflammatory ROP-dependent processes. IMPORTANCE This work performs transcriptomic analysis of U-I cells, captures the earliest stage of a host cell’s interaction with Toxoplasma gondii, and dissects the effects of individual classes of parasite effectors on host cell biology.

Sign in / Sign up

Export Citation Format

Share Document