Saturday, September 27, 2014

Recurrent headaches may be caused by cerebral toxoplasmosis

 2014 Aug 8;3(3):59-68. doi: 10.5409/wjcp.v3.i3.59. eCollection 2014.



To establish seroprevalence and provide characteristics of Toxoplasma gondii (TG) infection in children with recurrent headaches.


The study was performed in 178 children aged 7-17 years admitted consecutively to the Department of Pediatric Neurology from November 2009 to July 2011. The children were surveyed with a questionnaire with the help and assistance of their parents and blood samples taken on admission were studied for the presence of specific anti-TG IgM, IgG antibodies and IgG avidity using enzyme immunoassay Platelia Toxo IgM, IgG.


The study showed that 19 children (8 boys, 11 girls; 8-17 years old, mean age 14.36 years) had high serum anti-TG IgG antibody levels (range: 32.2 > 240 UI/mL, mean 120.18 UI/mL; positive value for IgG was ≥ 9 UI/mL). The avidity index (AI) ranged from 0.202 to 0.925 (scale: ≥ 0.5 high AI). The results for IgM antibodies were all negative and the obtained results ranged from 0.113 to 0.25 U/mL (mean = 0.191 IU/mL) and all values below 0.8 IU/mL were considered negative. The most frequent complaints found in the seropositive patients were headaches that affected the frontal (13 children), occipital (4) and parietal areas (5). Headaches usually had a pulsating (in 7 patients) and squeezing (6) character and rarely were piercing, dull or expanding. Interestingly, 8 children did not feel discomfort during the headaches, probably because they did not have sufficiently increased intracranial pressure yet. The headaches usually appeared 1-2 times/mo, lasted for 2-6 h, and had a mean intensity of 5.5 points in a 10 point subjective scale. The comorbidities included epilepsy (5 patients), various infections in 3 children (chronic eustachitis, chronic rhinitis, chronic purulent tonsillitis, streptococcal pharyngitis, meningitis, allergic diseases), disturbances of behavior, deficits of attention, and ocular and motor concentration disorders in 1 child. The electroencephalographic and neuroimaging studies performed in our patients had a very limited value in establishing cerebral toxoplasmosis.


Ten point six seven percent of the studied children had markedly increased serum anti-TG IgG antibodies and high AI indicated chronic infestation. It is suggested that tests for TG infection should be introduced to routine diagnostics in patients with recurrent headaches.


Cerebral toxoplasmosis; Children; Chronic Toxoplasma gondii infection; IgG avidity; Recurrent headaches; Seroprevalence of anti-Toxoplasma gondii IgG antibodies

Large, rapidly evolving gene families are at the forefront of host-parasite interactions in Apicomplexa

 2014 Sep 26:1-14. [Epub ahead of print]


SUMMARY The Apicomplexa is a phylum of parasitic protozoa, which includes the malaria parasite Plasmodium, amongst other species that can devastate human and animal health. The past decade has seen the release of genome sequences for many of the most important apicomplexan species, providing an excellent basis for improving our understanding of their biology. One of the key features of each genome is a unique set of large, variant gene families. Although closely related species share the same families, even different types of malaria parasite have distinct families. In some species they tend to be found at the ends of chromosomes, which may facilitate aspects of gene expression regulation and generation of sequence diversity. In others they are scattered apparently randomly across chromosomes. For some families there is evidence they are involved in antigenic variation, immune regulation and immune evasion. For others there are no known functions. Even where function is unknown these families are most often predicted to be exposed to the host, contain much sequence diversity and evolve rapidly. Based on these properties it is clear that they are at the forefront of host-parasite interactions. In this review I compare and contrast the genomic context, gene structure, gene expression, protein localization and function of these families across different species.
[PubMed - as supplied by publisher]

Wednesday, September 24, 2014

Dual transcriptional profiling of mice and Toxoplasma gondii during acute and chronic infection

 2014 Sep 20;15(1):806. [Epub ahead of print]



The obligate intracellular parasite Toxoplasma gondii establishes a life-long chronic infection within any warm-blooded host. After ingestion of an encysted parasite, T. gondii disseminates throughout the body as a rapidly replicating form during acute infection. Over time and after stimulation of the host immune response, T. gondii differentiates into a slow growing, cyst form that is the hallmark of chronic infection. Global transcriptome analysis of both host and parasite during the establishment of chronic T. gondii infection has not yet been performed. Here, we conducted a dual RNA-seq analysis of T. gondii and its rodent host to better understand host and parasite responses during acute and chronic infection.


We obtained nearly one billion paired-end RNA sequences from the forebrains of uninfected, acutely and chronically infected mice, then aligned them to the genomic reference files of both T. gondii and Mus musculus. Gene ontology (GO) analysis of the 100 most highly expressed T. gondii genes showed less than half were shared between acute and chronic infection. The majority of the highly expressed genes common in both acute and chronic infection were involved in transcription and translation, underscoring that parasites in both stages are actively synthesizing proteins. Similarly, most of the T. gondii genes highly expressed during chronic infection were involved in metabolic processes, again highlighting the activity of the cyst stage at 28 days post-infection. Comparative analyses of host genes using uninfected forebrain revealed over twice as many immune regulatory genes were more abundant during chronic infection compared to acute. This demonstrates the influence of parasite development on host gene transcription as well as the influence of the host environment on parasite gene transcription.


RNA-seq is a valuable tool to simultaneously analyze host and microbe transcriptomes. Our data shows that T. gondii is metabolically active and synthesizing proteins at 28 days post-infection and that a distinct subset of host genes associated with the immune response are more abundant specifically during chronic infection. These data suggest host and pathogen interplay is still present during chronic infection and provides novel T. gondii targets for future drug and vaccine development.
[PubMed - as supplied by publisher] 

Animals are key to human toxoplasmosis

 2014 Sep 10. pii: S1438-4221(14)00118-0. doi: 10.1016/j.ijmm.2014.09.002. [Epub ahead of print]


Toxoplasma gondii is an extremely sucessfull protozoal parasite which infects almost all mamalian species including humans. Approximately 30% of the human population worldwide is chronically infected with T. gondii. In general, human infection is asymptomatic but the parasite may induce severe disease in fetuses and immunocompromised patients. In addition, T. gondii may cause sight-threatening posterior uveitis in immunocompetent patients. Apart from few exceptions, humans acquire T. gondii from animals. Both, the oral uptake of T. gondii oocysts released by specific hosts, i.e. felidae, and of cysts persisting in muscle cells of animals result in human toxoplasmosis. In the present review, we discuss recent new data on the cell biology of T. gondii and parasite diversity in animals. In addition, we focus on the impact of these various parasite strains and their different virulence on the clinical outcome of human congenital toxoplasmosis and T. gondii uveitis.
Copyright © 2014 Elsevier GmbH. All rights reserved.


Congenital toxoplasmosis; Epidemiology; Toxoplasma; Toxoplasma eye infection; Zoonotic infection
[PubMed - as supplied by publisher]

Saturday, September 20, 2014

2014 Ig Nobel Prize Winners: Jaroslav Flegr & toxoplasmosis

The 2014 Ig Nobel Prizes were awarded on Thursday night, September 18th, 2014 at the 24th First Annual Ig Nobel Prize Ceremonyat Harvard’s Sanders Theatre. The ceremony was webcast live.
The Ig Nobel Prizes honor achievements that first make peoplelaugh, and then makes them think. The prizes are intended to celebrate the unusual, honor the imaginative — and spur people's interest in science, medicine, and technology.
PUBLIC HEALTH PRIZE [CZECH REPUBLIC, JAPAN, USA, INDIA]: Jaroslav Flegr, Jan Havlíček and Jitka Hanušova-Lindova, and to David Hanauer, Naren Ramakrishnan, Lisa Seyfried, for investigating whether it is mentally hazardous for a human being to own a cat.
REFERENCE: “Changes in personality profile of young women with latent toxoplasmosis,” Jaroslav Flegr and Jan Havlicek, Folia Parasitologica, vol. 46, 1999, pp. 22-28.
REFERENCE: “Decreased level of psychobiological factor novelty seeking and lower intelligence in men latently infected with the protozoan parasite Toxoplasma gondii Dopamine, a missing link between schizophrenia and toxoplasmosis?” Jaroslav Flegr, Marek Preiss, Jiřı́ Klose, Jan Havlı́ček, Martina Vitáková, and Petr Kodym, Biological Psychology, vol. 63, 2003, pp. 253–268.
REFERENCE: “Describing the Relationship between Cat Bites and Human Depression Using Data from an Electronic Health Record,” David Hanauer, Naren Ramakrishnan, Lisa Seyfried, PLoS ONE, vol. 8, no. 8, 2013, e70585. 
WHO ATTENDED THE CEREMONY: Jaroslav Flegr, David Hanauer, Naren Ramakrishnan

A Toxoplasma gondii Class XIV Myosin, Expressed in Sf9 Cells with a Parasite Co-chaperone, Requires Two Light Chains for Fast Motility

 2014 Sep 17. pii: jbc.M114.572453. [Epub ahead of print]


Many diverse myosin classes can be expressed using the baculovirus/Sf9 insect cell expression system, while others have been recalcitrant. We hypothesized that most myosins utilize Sf9 cell chaperones, but others require an organism-specific co-chaperone. TgMyoA, a class XIVa myosin from the parasite Toxoplasma gondii, is required for the parasite to efficiently move and invade host cells. The T. gondii genome contains one UCS family myosin co-chaperone (TgUNC). TgMyoA expressed in Sf9 cells was soluble and functional only if the heavy and light chain(s) were co-expressed with TgUNC. The tetratricopeptide repeat (TPR) domain of TgUNC was not essential to obtain functional myosin, implying that there are other mechanisms to recruit Hsp90. Purified TgMyoA heavy chain complexed with its regulatory light chain (TgMLC1) moved actin in a motility assay at a speed of ~1.5 μm/s. When a putative essential light chain (TgELC1) was also bound, TgMyoA moved actin at more than twice that speed (~3.4 μm/s). This result implies that two light chains bind to and stabilize the lever arm, the domain that amplifies small motions at the active site into the larger motions that propel actin at fast speeds. Our results shows that the TgMyoA domain structure is more similar to other myosins than previously appreciated, and provides a molecular explanation for how it moves actin at fast speeds. The ability to express milligram quantities of a class XIV myosin in a heterologous system paves the way for detailed structure-function analysis of TgMyoA and identification of small-molecule inhibitors.
Copyright © 2014, The American Society for Biochemistry and Molecular Biology.


ATPase; Toxoplasma gondii; UCS proteins; class XIV myosin; molecular chaperone; molecular motor; myosin chaperones; myosin motor complex; protein expression; protein folding
[PubMed - as supplied by publisher] 

Wednesday, September 17, 2014

Selective and strain-specific NFAT4 activation by the Toxoplasma gondii polymorphic dense granule protein GRA6

 2014 Sep 15. pii: jem.20131272. [Epub ahead of print]


Toxoplasma gondii infection results in co-option and subversion of host cellular signaling pathways. This process involves discharge of T. gondii effector molecules from parasite secretory organelles such as rhoptries and dense granules. We report that the T. gondii polymorphic dense granule protein GRA6 regulates activation of the host transcription factor nuclear factor of activated T cells 4 (NFAT4). GRA6 overexpression robustly and selectively activated NFAT4 via calcium modulating ligand (CAMLG). Infection with wild-type (WT) but not GRA6-deficient parasites induced NFAT4 activation. Moreover, GRA6-deficient parasites failed to exhibit full virulence in local infection, and the treatment of WT mice with an NFAT inhibitor mitigated virulence of WT parasites. Notably, NFAT4-deficient mice displayed prolonged survival, decreased recruitment of CD11b+ Ly6G+ cells to the site of infection, and impaired expression of chemokines such as Cxcl2 and Ccl2. In addition, infection with type I parasites culminated in significantly higher NFAT4 activation than type II parasites due to a polymorphism in the C terminus of GRA6. Collectively, our data suggest that GRA6-dependent NFAT4 activation is required for T. gondii manipulation of host immune responses to maximize the parasite virulence in a strain-dependent manner.
© 2014 Ma et al.
[PubMed - as supplied by publisher]

Sustained Translational Repression of Lactate Dehydrogenase 1 in Toxoplasma gondii Bradyzoites is Conferred by a Small Regulatory RNA Hairpin

 2014 Sep 15. doi: 10.1111/febs.13048. [Epub ahead of print]


In response to environmental stresses, Toxoplasma gondii induces a global translational repression which allows for the remodeling of its transcriptome. While some transcripts are preferentially translated, another subset is translationally repressed and maintained in bradyzoites. Although little is known of how transcripts are targeted for sustained translational repression, the targeting likely operates through an RNA-centric mechanism relying on the recognition of cis-acting elements. In this study, we sought to determine if the targeting of transcripts through recognizable cis-acting elements could be responsible for the transcript-specific sustained translational repression displayed by Toxoplasma bradyzoites. We examined the UTRs of a translationally repressed gene, lactate dehydrogenase 1, and found a 40 nucleotide regulatory element in its 5'UTR. This element specifically induces translational repression in otherwise constitutively expressed transcripts. Mutational studies revealed that the formation of a small 16 nucleotide regulatory RNA hairpin is essential for this activity. We suggest that this hairpin may act as the nucleation site for the binding of a yet to be identified trans-acting factor that allows for the transcript to be targeted for translational repression removal from the active translational pool. To our knowledge, this is the first report characterizing a specific cis-acting element contributing to post-transcriptional gene regulation in Toxoplasma and suggests the presence of a pathway by which the parasites can recognize, identify, and specifically target transcripts for sustained translational repression under stressful conditions. This article is protected by copyright. All rights reserved.
This article is protected by copyright. All rights reserved.


Toxoplasma gondii ; 5'UTR; RNA hairpin; lactate dehydrogenase; translational repression
[PubMed - as supplied by publisher]

Expanded task battery in the Morris water maze reveals effects of Toxoplasma gondii infection on learning and memory in rats

 2014 Sep 8. pii: S1383-5769(14)00113-5. doi: 10.1016/j.parint.2014.09.002. [Epub ahead of print]


Infection with the neurotropic parasite Toxoplasma gondii is wide spread among human populations; however, the impacts of latent central nervous system (CNS) T. gondii infection have only recently come to light. Epidemiological evidence in humans and experimental studies in rodents have revealed a number of neurological and behavioral sequelae following the establishment of latent CNS toxoplasmosis. Here, we report alterations in learning and memory task performance in latently infected rats using the Morris water maze. While simple spatial reference learning was intact, infected rodents exhibited poor performance compared to controls in probe trials requiring spatial memory recall and progressively poorer performance with increasing time intervals before memory testing, but, surprisingly, enhanced performance in reversal learning tasks. Despite obvious changes to memory task performance, no cysts were detected in the hippocampi of infected rats. Instead, cysts were stochastically distributed across the entire brain, suggesting that behavioral alterations in this study were due to accumulated changes in neurophysiology across multiple anatomical regions. Together, these data provide new evidence that latent toxoplasmosis contributes to neurocognitive symptoms in mammalian hosts, and does so on a broad anatomical scale within the CNS.
Copyright © 2014. Published by Elsevier Ireland Ltd.


Morris water maze; Toxoplasma gondii; behavior; toxoplasmosis
[PubMed - as supplied by publisher]

Monday, September 08, 2014


Indiana University School of Medicine
POSTDOCTORAL POSITION available to investigate gene expression and cellular signaling in the protozoan parasite Toxoplasma gondii. Related to the malaria parasite, Plasmodium, Toxoplasma causes birth defects and life-threatening infection in immunocompromised patients. We have shown that lysine acetylation is required for parasite growth and development, representing an exciting new drug target (Wang et al., PLoS Pathogens 2014; Jeffers & Sullivan, Eukaryotic Cell 2012; Naguleswaran et al., PLoS Pathogens 2010). Current projects involve analyzing the role of lysine acetylation in cellular signaling and gene expression, as well as the regulation of lysine acetyltransferase (KAT) enzymes.
Position requires a Ph.D., strong expertise in molecular biology, biochemistry, and cell signaling, and excellent communication skills (speaking and writing English). Experience in microbiology/parasitology or epigenetics is a plus, but not required. Please read this before applying. Submit CV and contact information for three references to Dr. Bill Sullivan (
Our lab is part of the “Intracellular Pathogens Group” at IU, which meets regularly to foster innovation and collaboration. Visit for more information.
Located in downtown Indianapolis, Indiana University School of Medicine (IUSM) is the second largest medical school in the US and boasts an outstanding intellectual atmosphere and core facilities. IUSM was nationally ranked in the Top 30 Best Places to Work for Postdocs. IUSM is an equal opportunity employer.

Wednesday, September 03, 2014

Toxoplasma, or the discovery of a heterophage

2014 Aug 29. pii: S1471-4922(14)00143-3. doi: 10.1016/ [Epub ahead of print
In mammalian cells, the protozoan pathogen Toxoplasma resides in a nonfusiogenic vacuole that segregates it from host cell resources. How the parasite acquires nutrients and whether it is capable of internalizing host macromolecules have been long-standing mysteries. By exploiting a mutant of Toxoplasma lacking the cathepsin protease L, Dou et al. observed the accumulation of host cytosolic-derived proteins in a multivesicular post-Golgi compartment, which establishes the existence of a functional heterophagic pathway in Toxoplasma.


Toxoplasma; intracellular parasitism; macromolecule digestion; nutrient uptake; protease cathepsins
[PubMed - as supplied by publisher]