scholarly journals Biological Diagnosis of Ocular Toxoplasmosis: a Nine-Year Retrospective Observational Study

mSphere ◽  
2019 ◽  
Vol 4 (5) ◽  
Author(s):  
Valentin Greigert ◽  
Alexander W. Pfaff ◽  
Arnaud Sauer ◽  
Denis Filisetti ◽  
Ermanno Candolfi ◽  
...  
Keyword(s):  
Toxoplasma Gondii ◽  
Parasitic Infection ◽  
Posterior Uveitis ◽  
Ocular Toxoplasmosis ◽  
Antibody Detection ◽  
Diagnostic Tools ◽  
Content Type ◽  
Study Results ◽  
Biological Tests ◽  
Single Positive

ABSTRACT Ocular toxoplasmosis (OT), i.e., the ocular manifestation of Toxoplasma gondii infection, is one of the leading causes of posterior uveitis. While ocular lesions are often typical, atypical forms often require biological confirmation of the diagnosis. Our study sought to review the biological OT diagnoses made in our laboratory to further assess the role of each test in the diagnostic procedure. All ocular samples sent to our laboratory over the last 9 years for OT diagnosis were included. These samples were analyzed using T. gondii PCR and antibody detection by means of immunoblotting and Candolfi coefficient (CC) determinations, either alone or in combination. Since serum analysis is required to interpret both the CC and immunoblotting, blood serology for T. gondii was also performed in most cases. Of the 249 samples analyzed, 80 (32.1%; 95% confidence interval [95%CI], 26.3 to 37.9) were positive for OT. Of these 80 cases, 52/80 (65.0%; 54.6 to 74.5) displayed a positive PCR, 15/80 (18.8%; 10.2 to 27.3) a positive CC, and 33/80 (41.3%; 95%CI, 30.5 to 52.0) a positive immunoblot result. Overall, 63 of the 80 OT diagnoses (78.8%; 95%CI, 69.8 to 87.7) were made on the basis of a single positive test result. Our study results remind us that current biological diagnostic tools for OT must be employed in combination to obtain an optimal diagnosis based on the precious ocular fluids sampled by ophthalmologists. Clinicobiological studies that are focused on correlating the performances of the different tests with clinical features are critically needed to improve our understanding of the pathophysiology and diagnosis of OT. IMPORTANCE Ocular toxoplasmosis (OT), a parasitic infection of the eye, is considered to be the most important infectious cause of posterior uveitis worldwide. Its prevalence is particularly high in South America, where aggressive Toxoplasma gondii strains are responsible for more-severe presentations. The particular pathophysiology of this infection leads, from recurrence to recurrence, to potentially severe vision impairment. The diagnosis of this infection is usually exclusively based on the clinical examination. However, the symptoms may be misleading and are not always sufficient to confirm a diagnosis of OT. In such cases, biological tests performed by means of several techniques on blood and ocular samples may facilitate the diagnosis. In this study, we analyzed the tests that were performed in our laboratory over a 9-year period every time OT was suspected. Our report highlights that the quality of ocular sampling by ophthalmologists and combinations of several techniques are critical for a reliable biological OT diagnosis.

Toxoplasmosis Related Uveitis: Clinic, Diagnosis, and Treatment

2019 ◽  
pp. 237-243
Keyword(s):  
Toxoplasma Gondii ◽  
Treatment Options ◽  
Protozoan Parasite ◽  
Posterior Uveitis ◽  
Ocular Toxoplasmosis ◽  
Diagnosis And Treatment ◽  
Frequent Form

Ocular toxoplasmosis (OT) is considered the most frequent form of infectious posterior uveitis and is caused by the protozoan parasite Toxoplasma gondii. Despite large advances in the field of OT, large gaps still exist in our knowledge concerning the epidemiology and pathophysiology of this potentially blinding infectious old disease. In this review, we aimed to investigate the current clinical understanding of OT, diagnosis treatment options.

scholarly journals Pantothenic Acid Biosynthesis in the Parasite Toxoplasma gondii: a Target for Chemotherapy

2014 ◽  
Vol 58 (11) ◽  
pp. 6345-6353 ◽  
Author(s):  
Sarmad N. Mageed ◽  
Fraser Cunningham ◽  
Alvin Wei Hung ◽  
Hernani Leonardo Silvestre ◽  
Shijun Wen ◽  
...  
Keyword(s):  
Toxoplasma Gondii ◽  
Drug Target ◽  
Parasitic Infection ◽  
Pantothenic Acid ◽  
Acid Biosynthesis ◽  
Content Type ◽  
Pantothenate Synthetase ◽  
Genes Encoding ◽  
Range Of Values ◽  
Important Parasite

ABSTRACTToxoplasma gondiiis a major food pathogen and neglected parasitic infection that causes eye disease, birth defects, and fetal abortion and plays a role as an opportunistic infection in AIDS. In this study, we investigated pantothenic acid (vitamin B5) biosynthesis inT. gondii. Genes encoding the full repertoire of enzymes for pantothenate synthesis and subsequent metabolism to coenzyme A were identified and are expressed inT. gondii. A panel of inhibitors developed to targetMycobacterium tuberculosispantothenate synthetase were tested and found to exhibit a range of values for inhibition ofT. gondiigrowth. Two inhibitors exhibited lower effective concentrations than the currently used toxoplasmosis drug pyrimethamine. The inhibition was specific for the pantothenate pathway, as the effect of the pantothenate synthetase inhibitors was abrogated by supplementation with pantothenate. Hence,T. gondiiencodes and expresses the enzymes for pantothenate synthesis, and this pathway is essential for parasite growth. These promising findings increase our understanding of growth and metabolism in this important parasite and highlight pantothenate synthetase as a new drug target.

scholarly journals CD40 Induces Anti-Toxoplasma gondii Activity in Nonhematopoietic Cells Dependent on Autophagy Proteins

2013 ◽  
Vol 81 (6) ◽  
pp. 2002-2011 ◽  
Author(s):  
Jennifer Van Grol ◽  
Luis Muniz-Feliciano ◽  
Jose-Andres C. Portillo ◽  
Vera L. Bonilha ◽  
Carlos S. Subauste
Keyword(s):  
Endothelial Cells ◽  
Toxoplasma Gondii ◽  
Umbilical Vein ◽  
Retinal Pigment ◽  
Beclin 1 ◽  
Retinal Pigment Epithelial Cells ◽  
Ocular Toxoplasmosis ◽  
Content Type ◽  
Key Factor ◽  
Umbilical Vein Endothelial Cells

ABSTRACTToxoplasma gondiiinfects both hematopoietic and nonhematopoietic cells and can cause cerebral and ocular toxoplasmosis, as a result of either congenital or postnatally acquired infections. Host protection likely acts at both cellular levels to control the parasite. CD40 is a key factor for protection against cerebral and ocular toxoplasmosis. We determined if CD40 induces anti-T. gondiiactivity at the level of nonhematopoietic cells. Engagement of CD40 on various endothelial cells including human microvascular brain endothelial cells, human umbilical vein endothelial cells, and a mouse endothelial cell line as well as human and mouse retinal pigment epithelial cells resulted in killing ofT. gondii. CD40 stimulation increased expression of the autophagy proteins Beclin 1 and LC3 II, enhanced autophagy flux, and led to recruitment of LC3 around the parasite. The late endosomal/lysosomal marker LAMP-1 accumulated around the parasite in CD40-stimulated cells. This was accompanied by killing ofT. gondiidependent on lysosomal enzymes. Accumulation of LAMP-1 and killing ofT. gondiiwere dependent on the autophagy proteins Beclin 1 and Atg7. Together, these studies revealed that CD40 induces toxoplasmacidal activity in various nonhematopoietic cells dependent on proteins of the autophagy machinery.

scholarly journals TgPRELID, a Mitochondrial Protein Linked to Multidrug Resistance in the Parasite Toxoplasma gondii

mSphere ◽  
2017 ◽  
Vol 2 (1) ◽  
Author(s):  
Victoria Jeffers ◽  
Edwin T. Kamau ◽  
Ananth R. Srinivasan ◽  
Jonathan Harper ◽  
Preethi Sankaran ◽  
...  
Keyword(s):  
Drug Resistance ◽  
Multidrug Resistance ◽  
Toxoplasma Gondii ◽  
Mitochondrial Protein ◽  
Parasitic Infection ◽  
Common Mechanism ◽  
Parasitic Diseases ◽  
Content Type ◽  
New Therapies ◽  
Resistant Mutants

ABSTRACT We report the discovery of TgPRELID, a previously uncharacterized mitochondrial protein linked to multidrug resistance in the parasite Toxoplasma gondii. Drug resistance remains a major problem in the battle against parasitic infection, and understanding how TgPRELID mutations augment resistance to multiple, distinct compounds will reveal needed insights into the development of new therapies for toxoplasmosis and other related parasitic diseases. New drugs to control infection with the protozoan parasite Toxoplasma gondii are needed as current treatments exert toxic side effects on patients. Approaches to develop novel compounds for drug development include screening of compound libraries and targeted inhibition of essential cellular pathways. We identified two distinct compounds that display inhibitory activity against the parasite’s replicative stage: F3215-0002, which we previously identified during a compound library screen, and I-BET151, an inhibitor of bromodomains, the “reader” module of acetylated lysines. In independent studies, we sought to determine the targets of these two compounds using forward genetics, generating resistant mutants and identifying the determinants of resistance with comparative genome sequencing. Despite the dissimilarity of the two compounds, we recovered resistant mutants with nonsynonymous mutations in the same domain of the same gene, TGGT1_254250, which we found encodes a protein that localizes to the parasite mitochondrion (designated TgPRELID after the name of said domain). We found that mutants selected with one compound were cross resistant to the other compound, suggesting a common mechanism of resistance. To further support our hypothesis that TgPRELID mutations facilitate resistance to both I-BET151 and F3215-0002, CRISPR (clustered regularly interspaced short palindromic repeat)/CAS9-mediated mutation of TgPRELID directly led to increased F3215-0002 resistance. Finally, all resistance mutations clustered in the same subdomain of TgPRELID. These findings suggest that TgPRELID may encode a multidrug resistance factor or that I-BET151 and F3215-0002 have the same target(s) despite their distinct chemical structures. IMPORTANCE We report the discovery of TgPRELID, a previously uncharacterized mitochondrial protein linked to multidrug resistance in the parasite Toxoplasma gondii. Drug resistance remains a major problem in the battle against parasitic infection, and understanding how TgPRELID mutations augment resistance to multiple, distinct compounds will reveal needed insights into the development of new therapies for toxoplasmosis and other related parasitic diseases.

scholarly journals Development of an Immunochromatographic Assay Based on Dense Granule Protein 7 for Serological Detection of Toxoplasma gondii Infection

2013 ◽  
Vol 20 (4) ◽  
pp. 596-601 ◽  
Author(s):  
Mohamad Alaa Terkawi ◽  
Kyohko Kameyama ◽  
Nazim Hamza Rasul ◽  
Xuean Xuan ◽  
Yoshifumi Nishikawa
Keyword(s):  
Toxoplasma Gondii ◽  
Neospora Caninum ◽  
Latex Agglutination ◽  
Dense Granule ◽  
Diagnostic Tools ◽  
Enzyme Linked Immunosorbent Assay ◽  
Serum Samples ◽  
Content Type ◽  
Specificity And Sensitivity ◽  
Field Samples

ABSTRACTDense granule antigen proteins derived fromToxoplasma gondii(TgGRAs) are potential antigens for the development of diagnostic tools. TgGRA7 and TgGRA14 were detected in the peritoneal fluid ofT. gondii-infected mice, suggesting that TgGRAs may be highly antigenic proteins. Here, TgGRA7 and TgGRA14 were evaluated as candidates for the development of a marker for a rapid diagnostic test. The specificity and sensitivity of purified recombinant proteins of TgGRA7 and TgGRA14 were compared in an indirect enzyme-linked immunosorbent assay (iELISA) using a series of serum samples fromT. gondii-experimentally infected mice and using recombinantT. gondiimajor surface antigen 2 (TgSAG2) as a reference control. The iELISA with TgGRA7 showed the greatest diagnostic accuracy and could detect anti-TgGRA7 antibody in acute and chronic infections. A total of 59 field samples from pigs were also examined by the iELISAs, and the results compared with those of the latex agglutination test (LAT). Among the three recombinant antigens, TgGRA7 had the highest rates of positivity, with significant concordance (88.14) and kappa value (0.76) in comparison with the results using LAT. Furthermore, an immunochromatographic test (ICT) based on recombinant TgGRA7 was developed for rapid detection of antibodies to the infection. The ICT differentiated clearly between sera fromT. gondii-infected mice and uninfected orNeospora caninum-infected mice. Pig sera were examined with the ICT, and the results compared favorably with those of LAT and iELISA for TgGRA7, with kappa values of 0.66 and 0.70 to 0.79, respectively. These data suggest that the ICT based on TgGRA7 is a promising diagnostic tool for routine testing in the clinic and mass screening of samples in the field.

scholarly journals Seroprevalence and associated risk factors of Toxoplasma gondii infection in domestic animals in southeastern South Africa

2019 ◽  
Vol 86 (1) ◽  
Author(s):  
Whatmore M. Tagwireyi ◽  
Eric Etter ◽  
Luis Neves
Keyword(s):  
Risk Factors ◽  
South Africa ◽  
Toxoplasma Gondii ◽  
Production Systems ◽  
Parasitic Infection ◽  
Domestic Animals ◽  
Latex Agglutination ◽  
Antibody Detection ◽  
Household Level ◽  
Associated Risk Factors

Toxoplasma gondii is a major neglected parasitic infection occurring in settings of extreme poverty in Africa. Apart from causing reproductive failure in animals it is also a significant zoonotic concern. The objective of this study was to determine the seroprevalence and associated risk factors of T. gondii infection in cats, chickens, goats, sheep and pigs in the southeast of South Africa, of which little is known. Sera was obtained from 601 domestic animals including 109 cats, 137 chickens, 128 goats, 121 sheep and 106 pigs managed under different production systems in different agro-ecological regions and evaluated by the Toxoreagent, a latex agglutination test for T. gondii antibody detection. Household-level and animal-level data were collected by interviewing animal owners and/or herders using a closed-ended questionnaire. The study revealed an overall farm seroprevalence of 83.33% (125/150 farms) with the highest rate of infection for the parasite found in sheep with 64.46% (78/121), followed by goats with 53.91% (69/128), pigs with 33.96% (36/106), cats with 32.11% (35/109 cats) and chickens with 33.58% (46/137). The risk factors that were found to be statistically significant (p 0.05) to different species of seropositivites were age, location, climate, animal production system, rodent control, seropositive cat, cat-feed access and cat faecal disposal. The relatively high seroprevalence of T. gondii detected in this region suggests that domestic animals may pose a substantial public health risk through the consumption of T. gondii-infected raw meat as well as via contact with cat faeces.

scholarly journals TOXOPLASMA NEURO-RETINITIS IN AN IMMUNO-COMPETENT ADULT- A CASE REPORT AND REVIEW OF LITERATURE

2020 ◽  
pp. 1-2
Author(s):  
Tharini Senthamizh ◽  
Subashini Kaliaperumal
Keyword(s):  
Parasitic Infection ◽  
Posterior Uveitis ◽  
Ocular Toxoplasmosis ◽  
Review Of Literature ◽  
Igg Antibody ◽  
Hard Exudates ◽  
Prompt Treatment ◽  
Optic Disc Swelling ◽  
Eye Examination ◽  
Cooked Meat

Toxoplasmosis is a protozoan parasitic infection caused by Toxoplasma gondii. It is transmitted congenitally or acquired in later stages of life either by ingestion of oocysts from cat’s feces attached or by eating under cooked meat. Ocular toxoplasmosis presents most commonly as posterior uveitis and rarely involves the optic nerve. We report a case of 45-year-old female, who is immuno-competent, presented with painless diminution vision in her left eye. Her best corrected vision was 6/36 in left eye and 6/6 in right eye. Examination of left eye revealed a clear media with optic disc swelling and hard exudates arranged in stellate fashion around the macula and inferior altitudinal field defects. Investigations revealed elevated titres of toxoplasma IgG antibody. Patient showed significant improvement with medical therapy. Since this neuroretinitis type of presentation in ocular toxoplasmosis is rare, awareness about this condition among clinicians can help prompt treatment and prevent significant blindness.

scholarly journals Peptide Microarray Analysis ofIn Silico-Predicted Epitopes for Serological Diagnosis of Toxoplasma gondii Infection in Humans

2012 ◽  
Vol 19 (6) ◽  
pp. 865-874 ◽  
Author(s):  
Pavlo Maksimov ◽  
Johannes Zerweck ◽  
Aline Maksimov ◽  
Andrea Hotop ◽  
Uwe Groß ◽  
...  
Keyword(s):  
Toxoplasma Gondii ◽  
Human Serum ◽  
Clinical Symptoms ◽  
Serological Diagnosis ◽  
Ocular Toxoplasmosis ◽  
Serum Samples ◽  
Peptide Microarray ◽  
Content Type ◽  
Human Serum Samples ◽  
Diagnostic Potential

ABSTRACTToxoplasma gondiiinfections occur worldwide in humans and animals. In immunocompromised or prenatally infected humans,T. gondiican cause severe clinical symptoms. The identification of specific epitopes onT. gondiiantigens is essential for the improvement and standardization of the serological diagnosis of toxoplasmosis. We selected 20 peptides mimicking linear epitopes on GRA1, GRA2, GRA4, and MIC3 antigenicT. gondiiproteinsin silicousing the software ABCpred. A further 18 peptides representing previously published epitopes derived from GRA1, SAG1, NTPase1, and NTPase2 antigens were added to the panel. A peptide microarray assay was established to prove the diagnostic performance of the selected peptides with human serum samples. Seropositive human serum samples (n= 184) were collected from patients presenting with acute toxoplasmosis (n= 21), latentT. gondiiinfection (n= 53), and inactive ocular toxoplasmosis (n= 10) and from seropositive forest workers (n= 100). To adjust the cutoff values for each peptide, sera from seronegative forest workers (n= 75) and patients (n= 65) were used. Univariate logistic regression suggested the significant diagnostic potential of eight novel and two previously published peptides. A test based on these peptides had an overall diagnostic sensitivity of 69% (100% in ocular toxoplasmosis patients, 86% in acutely infected patients, 81% in latently infected patients, and 57% in seropositive forest workers). The analysis of seronegative sera performed with these peptides revealed a diagnostic specificity of 84%. The results of our study suggest that the use of a bioinformatic approach for epitope prediction in combination with peptide microarray testing is a powerful method for the selection ofT. gondiiepitopes as candidate antigens for serological diagnosis.

scholarly journals Loss of the Conserved Alveolate Kinase MAPK2 Decouples Toxoplasma Cell Growth from Cell Division

mBio ◽  
2020 ◽  
Vol 11 (6) ◽  
Author(s):  
Xiaoyu Hu ◽  
William J. O’Shaughnessy ◽  
Tsebaot G. Beraki ◽  
Michael L. Reese
Keyword(s):  
Toxoplasma Gondii ◽  
Protein Kinases ◽  
Daughter Cell ◽  
Protozoan Parasite ◽  
Productive Infection ◽  
Centrosome Duplication ◽  
Loss Of Function ◽  
Content Type ◽  
Mitogen Activated Protein ◽  
Parasite Replication

ABSTRACT Mitogen-activated protein kinases (MAPKs) are a conserved family of protein kinases that regulate signal transduction, proliferation, and development throughout eukaryotes. The apicomplexan parasite Toxoplasma gondii expresses three MAPKs. Two of these, extracellular signal-regulated kinase 7 (ERK7) and MAPKL1, have been implicated in the regulation of conoid biogenesis and centrosome duplication, respectively. The third kinase, MAPK2, is specific to and conserved throughout the Alveolata, although its function is unknown. We used the auxin-inducible degron system to determine phenotypes associated with MAPK2 loss of function in Toxoplasma. We observed that parasites lacking MAPK2 failed to duplicate their centrosomes and therefore did not initiate daughter cell budding, which ultimately led to parasite death. MAPK2-deficient parasites initiated but did not complete DNA replication and arrested prior to mitosis. Surprisingly, the parasites continued to grow and replicate their Golgi apparatus, mitochondria, and apicoplasts. We found that the failure in centrosome duplication is distinct from the phenotype caused by the depletion of MAPKL1. As we did not observe MAPK2 localization at the centrosome at any point in the cell cycle, our data suggest that MAPK2 regulates a process at a distal site that is required for the completion of centrosome duplication and the initiation of parasite mitosis. IMPORTANCE Toxoplasma gondii is a ubiquitous intracellular protozoan parasite that can cause severe and fatal disease in immunocompromised patients and the developing fetus. Rapid parasite replication is critical for establishing a productive infection. Here, we demonstrate that a Toxoplasma protein kinase called MAPK2 is conserved throughout the Alveolata and essential for parasite replication. We found that parasites lacking MAPK2 protein were defective in the initiation of daughter cell budding and were rendered inviable. Specifically, T. gondii MAPK2 (TgMAPK2) appears to be required for centrosome replication at the basal end of the nucleus, and its loss causes arrest early in parasite division. MAPK2 is unique to the Alveolata and not found in metazoa and likely is a critical component of an essential parasite-specific signaling network.

scholarly journals Autophagy-Related Protein ATG8 Has a Noncanonical Function for Apicoplast Inheritance in Toxoplasma gondii

mBio ◽  
2015 ◽  
Vol 6 (6) ◽  
Author(s):  
Maude F. Lévêque ◽  
Laurence Berry ◽  
Michael J. Cipriano ◽  
Hoa-Mai Nguyen ◽  
Boris Striepen ◽  
...  
Keyword(s):  
Toxoplasma Gondii ◽  
Growth Conditions ◽  
Model Organisms ◽  
Secondary Endosymbiosis ◽  
Related Protein ◽  
Content Type ◽  
Superresolution Microscopy ◽  
Animal Pathogens ◽  
Cellular Components ◽  
Catabolic Process

ABSTRACT Autophagy is a catabolic process widely conserved among eukaryotes that permits the rapid degradation of unwanted proteins and organelles through the lysosomal pathway. This mechanism involves the formation of a double-membrane structure called the autophagosome that sequesters cellular components to be degraded. To orchestrate this process, yeasts and animals rely on a conserved set of autophagy-related proteins (ATGs). Key among these factors is ATG8, a cytoplasmic protein that is recruited to nascent autophagosomal membranes upon the induction of autophagy. Toxoplasma gondii is a potentially harmful human pathogen in which only a subset of ATGs appears to be present. Although this eukaryotic parasite seems able to generate autophagosomes upon stresses such as nutrient starvation, the full functionality and biological relevance of a canonical autophagy pathway are as yet unclear. Intriguingly, in T. gondii, ATG8 localizes to the apicoplast under normal intracellular growth conditions. The apicoplast is a nonphotosynthetic plastid enclosed by four membranes resulting from a secondary endosymbiosis. Using superresolution microscopy and biochemical techniques, we show that TgATG8 localizes to the outermost membrane of this organelle. We investigated the unusual function of TgATG8 at the apicoplast by generating a conditional knockdown mutant. Depletion of TgATG8 led to rapid loss of the organelle and subsequent intracellular replication defects, indicating that the protein is essential for maintaining apicoplast homeostasis and thus for survival of the tachyzoite stage. More precisely, loss of TgATG8 led to abnormal segregation of the apicoplast into the progeny because of a loss of physical interactions of the organelle with the centrosomes. IMPORTANCE By definition, autophagy is a catabolic process that leads to the digestion and recycling of eukaryotic cellular components. The molecular machinery of autophagy was identified mainly in model organisms such as yeasts but remains poorly characterized in phylogenetically distant apicomplexan parasites. We have uncovered an unusual function for autophagy-related protein ATG8 in Toxoplasma gondii: TgATG8 is crucial for normal replication of the parasite inside its host cell. Seemingly unrelated to the catabolic autophagy process, TgATG8 associates with the outer membrane of the nonphotosynthetic plastid harbored by the parasite called the apicoplast, and there it plays an important role in the centrosome-driven inheritance of the organelle during cell division. This not only reveals an unexpected function for an autophagy-related protein but also sheds new light on the division process of an organelle that is vital to a group of important human and animal pathogens.

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