Thursday, November 29, 2007

Congenital and acquired toxoplasmosis: diversity and role of antibodies in different compartments of the host

Parasite Immunol. 2007 Dec;29(12):651-60

Congenital and acquired toxoplasmosis: diversity and role of antibodies in different compartments of the host

Correa D, Cañedo-Solares I, Ortiz-Alegría LB, Caballero-Ortega H, Rico-Torres CP

Laboratorio de Inmunología Experimental, Subdirección de Medicina Experimental, Instituto Nacional de Pediatría, Secretaría de Salud, México DF, México.

The apicomplexan parasite Toxoplasma gondii is remarkable in several aspects, since it is a protozoan that infects most nucleated cells in many warm-blooded animals, worldwide. Although the cellular immune response against T. gondii is critical for infection control, antibodies may either enhance or block protective mechanisms, and even mediate immunological damage, directly or indirectly. Since cytokines regulate the class/subclass switch, antibodies may also be the biomarkers of protective or pathological cellular immune events. There is a scientific and clinical interest in the presence of natural and autoreactive antibodies, as well as in the 'chronic' immunoglobulin M (IgM) response and the post-treatment 'rebound'. Another interesting aspect is compartmentalization; certain immunoglobulins may uniquely be found in specific host fluids. Local synthesis has been demonstrated, but antibodies may also traverse several cell layers, like the blood-brain and haemato-ocular barriers, and the placenta. In some instances, Fc receptors (FcRs) facilitate transport and may even have a concentrator effect, which can be related to resistance or pathology. These aspects of the humoral response against T. gondii are reviewed in the present paper.

PMID: 18042171 [PubMed - in process]

Characterization of secreted recombinant SAG2 heterologously expressed by the yeast

Biotechnol Lett. 2007 Nov 28; [Epub ahead of print]

Characterization of secreted recombinant Toxoplasma gondii surface antigen 2 (SAG2) heterologously expressed by the yeast Pichia pastoris

Fong MY, Lau YL, Zulqarnain M

Department of Parasitology, Faculty of Medicine, University of Malaya, Kuala Lumpur, 50603, Malaysia,

The surface antigen 2 (SAG2) gene of the protozoan parasite, Toxoplasma gondii, was cloned and extracellularly expressed in the yeast Pichia pastoris. The effectiveness of the secreted recombinant SAG2 (rSAG2-S) as a serodiagnosis reagent was assessed by western blots and ELISA. In the western blot assay, rSAG2-S reacted with all Toxoplasma-antibody positive human serum samples but not with Toxoplasma-negative samples. In the ELISA, rSAG2-S yielded sensitivity rates ranging from 80% (IgG negative, IgM positive) to 100% (IgG positive, IgM negative). In vivo experiments showed that serum from mice immunized with rSAG2-S reacted specifically with the native SAG2 of T. gondii. These mice were protected when challenged with live cells of T. gondii.

PMID: 18043869 [PubMed - as supplied by publisher]

Tuesday, November 27, 2007

The polypeptides COX2A and COX2B are essential components of the mitochondrial cytochrome c oxidase of Toxo

Biochim Biophys Acta. 2007 Nov 5; [Epub ahead of print]

The polypeptides COX2A and COX2B are essential components of the mitochondrial cytochrome c oxidase of Toxoplasma gondii

Morales-Sainz L, Escobar-Ramírez A, Cruz-Torres V, Reyes-Prieto A, Vázquez-Acevedo M, Lara-Martínez R, Jiménez-García LF, González-Halphen D

Departamento de Genética Molecular, Instituto de Fisiología, Celular, Universidad Nacional Autónoma de México, Mexico.

Two genes encoding cytochrome c oxidase subunits, Cox2a and Cox2b, are present in the nuclear genomes of apicomplexan parasites and show sequence similarity to corresponding genes in chlorophycean algae. We explored the presence of COX2A and COX2B subunits in the cytochrome c oxidase of Toxoplasma gondii. Antibodies were raised against a synthetic peptide containing a 14-residue fragment of the COX2A polypeptide and against a hexa-histidine-tagged recombinant COX2B protein. Two distinct immunochemical stainings localized the COX2A and COX2B proteins in the parasite's mitochondria. A mitochondria-enriched fraction exhibited cyanide-sensitive oxygen uptake in the presence of succinate. T. gondii mitochondria were solubilized and subjected to Blue Native Electrophoresis followed by second dimension electrophoresis. Selected protein spots from the 2D gels were subjected to mass spectrometry analysis and polypeptides of mitochondrial complexes III, IV and V were identified. Subunits COX2A and COX2B were detected immunochemically and found to co-migrate with complex IV; therefore, they are subunits of the parasite's cytochrome c oxidase. The apparent molecular mass of the T. gondii mature COX2A subunit differs from that of the chlorophycean alga Polytomella sp. The data suggest that during its biogenesis, the mitochondrial targeting sequence of the apicomplexan COX2A precursor protein may be processed differently than the one from its algal counterpart.

PMID: 18036550 [PubMed - as supplied by publisher]

Selective Targeting of Tachyzoites Using Antibody-Functionalized Gold Nanorods

Nano Lett. 2007 Nov 23; [Epub ahead of print]

A Golden Bullet? Selective Targeting of Toxoplasma gondii Tachyzoites Using Antibody-Functionalized Gold Nanorods

Pissuwan D, Valenzuela SM, Miller CM, Cortie MB

Institute for Nanoscale Technology, Department of Medical and Molecular Biosciences, Institute for the Biotechnology of Infectious Diseases, University of Technology Sydney, Australia.

Conjugates of gold nanoparticles and antibodies have useful functionalities. Here, we show how they can be used to selectively target and destroy parasitic protozoans. Gold nanorods were conjugated with an anti-Toxoplasma gondii antibody and used to target the extracellular tachyzoite which is an infectious form of an obligate parasite Toxoplasma gondii. Subsequent laser irradiation was used to kill the targeted protozoans. This concept provides a new paradigm for the treatment of parasitic protozoans.

PMID: 18034505 [PubMed - as supplied by publisher]

Wednesday, November 21, 2007

Cell-autonomous immunity to Toxoplasma gondii in mouse and man

Microbes Infect. 2007 Sep 14; [Epub ahead of print]

Cell-autonomous immunity to Toxoplasma gondii in mouse and man

Könen-Waisman S, Howard JC

Institute for Genetics, University of Cologne, Zülpicher Strasse 47, 50674 Cologne, Germany.

The protozoan, Toxoplasma gondii, is a natural pathogen of mouse and a zoonosis of man. Immunity against the pathogen is largely mediated by interferon-stimulated cell-autonomous mechanisms that are strikingly different between man and mouse. There are many poorly understood host and pathogen variables that affect the outcome of infection.

PMID: 18024121 [PubMed - as supplied by publisher]

Detection of the initial site of Toxoplasma gondii reactivation in brain tissue

Int J Parasitol. 2007 Oct 14; [Epub ahead of print]

Detection of the initial site of Toxoplasma gondii reactivation in brain tissue

Takashima Y, Suzuki K, Xuan X, Nishikawa Y, Unno A, Kitoh K

Department of Veterinary Parasitological Diseases, Gifu University, Yanagido 1-1, Gifu 501-1193, Japan.

Detection of the initial site of Toxoplasma gondii reactivation in brain tissue is difficult because the number of latent cysts is small and reactivation is a transient event. To detect the early stage of reactivation in mouse brain tissue, we constructed a cyst-forming strain of T. gondii in the tachyzoite stage, specifically expressing red fluorescence. The PLK strain of T. gondii was stably transfected with a red fluorescent protein gene, DsRed Express, under the control of a tachyzoite-specific SAG-1 promoter and the resulting parasite was designated as PLK/RED. Tachyzoites of PLK/RED growing in Vero cells showed red fluorescence. When C57BL/6J mice were i.p. infected with tachyzoites of PLK/RED, red fluorescent tachyzoites were detected in their brains at the fourth day p.i. However, red fluorescent tachyzoites were not detected in BALB/c mice latently infected with PLK/RED, although non-fluorescent cysts were detected in their brains. After treatment of latently infected mice with dexamethasone for 1 month, the mice showed neurological symptoms. In mice with symptoms, red fluorescent tachyzoites were again detected in their brains and in other organs. To detect the initial site of reactivation, BALB/c mice latently infected with the strain were treated with dexamethasone for 3 weeks, and brains were excised before any symptoms appeared. Excised brains were examined for red fluorescence-positive sites. By a histological study of red fluorescent-positive sites, we detected a cyst containing red fluorescent zoites, which still had a PAS stain-positive cyst wall. A few red fluorescent zoites breaking away from the cyst were also observed. The stage-specific expression of fluorescent protein facilitates detection of a rare transient event and makes it possible to detect the initial site of reactivation.

PMID: 18022177 [PubMed - as supplied by publisher]

Tuesday, November 20, 2007

Toxo exploits UHRF1 and induces host cell cycle arrest at G2 to enable its proliferation

Cell Microbiol. 2007 Nov 14; [Epub ahead of print]

Toxoplasma gondii exploits UHRF1 and induces host cell cycle arrest at G2 to enable its proliferation

Brunet J, Pfaff AW, Abidi A, Unoki M, Nakamura Y, Guinard M, Klein JP, Candolfi E, Mousli M

Institut de Parasitologie et de Pathologie Tropicale de Strasbourg, UPRES E.A. 3950 Interactions Cellulaires et Moléculaires Hôte-Parasite, Faculté de Médecine. Université Louis Pasteur, 67000 Strasbourg, France.

Toxoplasma gondii is an obligate intracellular parasite that causes severe disease in humans. It is able to infect all nucleated mammalian cells leading to lifelong persistence of the parasite in the host. Here, we studied the effect of T. gondii infection on host cell proliferation and explored the molecular mechanisms involved in host cell cycle progression. We found that T. gondii induced G1/S transition in host cells in the presence of UHRF1, followed by G2 arrest after cyclin B1 downregulation which is probably the major cause of the arrest. Other molecules at the G2/M checkpoint including p53, p21, and Cdk1 were normally regulated. Interestingly, while parasite proliferation was normal in cells that were in the G2 phase, it was suppressed in G1-arrested cells induced by UHRF1-siRNA, indicating the importance of the G2 phase via UHRF1-induced G1/S transition for T. gondii growth.

PMID: 18005238 [PubMed - as supplied by publisher]

Fatal disseminated toxoplasmosis in a cardiac transplantation with seropositive match for Toxoplasma: Should prophylaxis be extended?

Transpl Immunol. 2007 Nov;18(2):193-197. Epub 2007 Jun 14.

Fatal disseminated toxoplasmosis in a cardiac transplantation with seropositive match for Toxoplasma: Should prophylaxis be extended?

Castagnini M, Bernazzali S, Ginanneschi C, Marchi B, Maccherini M, Tsioulpas C, Tanganelli P

Department of Human Pathology and Oncology, Section of Anatomical Pathology, University of Siena, Policlinico “Le Scotte”, via delle Scotte, 53100, Siena, Italy.

In cardiac transplant, toxoplasmosis in the immunocompromised recipient can result either from the transmission of the parasite from a seropositive donor (D+) to a seronegative recipient (R-) with the transplanted organ (more common) or from the reactivation of a pre-transplant latent infection (D-/R+ or D+/R+). In the immunocompromised patient, toxoplasmosis is a life-threatening disease. We report a case of disseminated toxoplasmosis following heart transplantation in a Toxoplasma seropositive recipient before transplantation (R+) (IgG 1:160, IgM negative) who received an organ from a Toxoplasma seropositive donor (D+) (IgG 1:640, IgM negative). No anti-Toxoplasma prophylactic treatment was administered. A number of complications arose in the postoperative period, as well as Enterobacter cloacae and Cytomegalovirus (CMV) (reactivation) infections, but neither serological nor histological toxoplasma recrudescence was evidenced. The patient died on post transplant day 41. Post-autopsy histological examinations revealed an unexpected diffuse toxoplasmosis (lungs, brain, heart).

PMID: 18005867 [PubMed - as supplied by publisher]

Decreased infarct size after focal cerebral ischemia in mice chronically infected with Toxo

Neuroscience. 2007 Oct 11; [Epub ahead of print]

Decreased infarct size after focal cerebral ischemia in mice chronically infected with Toxoplasma gondii

Arsenijevic D, de Bilbao F, Vallet P, Hemphill A, Gottstein B, Richard D, Giannakopoulos P, Langhans W

Department of Medicine, Division of Physiology, University of Fribourg, Chemin Du Musée 5, 1700 Fribourg, Switzerland.

To determine whether Toxoplasma gondii infection could modify biological phenomena associated with brain ischemia, we investigated the effect of permanent middle cerebral artery occlusion (MCAO) on neuronal survival, inflammation and redox state in chronically infected mice. Infected animals showed a 40% to 50% decrease of infarct size compared with non-infected littermates 1, 4 and 14 days after MCAO. The resistance of infected mice may be associated with increased basal levels of anti-inflammatory cytokines and/or a marked reduction of the MCAO-related brain induction of two pro-inflammatory cytokines, tumor necrosis factor-alpha and interferon-gamma (IFNgamma). In addition, potential anti-inflammatory/neuroprotective factors such as nerve growth factor, suppressor of cytokine signaling-3, superoxide dismutase activity, uncoupling protein-2 and glutathione (GSH) were upregulated in the brain of infected mice. Consistent with a role of GSH in central cytokine regulation, GSH depletion by diethyl maleate inhibited Toxoplasma gondii lesion resistance by increasing the proinflammatory cytokine IFNgamma brain levels. Overall, these findings indicate that chronic toxoplasmosis decisively influences both the inflammatory molecular events and outcome of cerebral ischemia.

PMID: 18006239 [PubMed - as supplied by publisher]

Construction of bradyzoite expressing the green fluorescent protein

Parasitol Int. 2007 Oct 18; [Epub ahead of print]

Construction of Toxoplasma gondii bradyzoite expressing the green fluorescent protein

Nishikawa Y, Zhang H, Ibrahim HM, Ui F, Ogiso A, Xuan X

National Research Center for Protozoan Diseases, Obihiro University of Agriculture and Veterinary Medicine, Inada-cho, Obihiro, Hokkaido 080-8555, Japan.

The bradyzoite stage of Toxoplasma gondii is a key step in the parasite life cycle. For a better understanding of this stage, a sensitive system to detect the tissue cysts would be required. In this study, we generated the T. gondii cyst-forming strain PLK expressing green fluorescent protein (GFP) under control of the dense granule protein 1 promoter, which works at both the tachyzoite and the bradyzoite stages. The bradyzoites with GFP fluorescence within both small and large cysts were detectable in the brain of mice infected with the recombinant PLK. Indeed, the bradyzoites expressing GFP had infectivity to mice. This study shows that transfection of the cyst-forming strain with GFP gene under control of the GRA1 promoter could be a useful approach for the study of the bradyzoite stage of T. gondii.

PMID: 18006371 [PubMed - as supplied by publisher]

Friday, November 16, 2007

ToxoDB: an integrated Toxoplasma gondii database resource

Nucleic Acids Res. 2007 Nov 14; [Epub ahead of print]

ToxoDB: an integrated Toxoplasma gondii database resource

Gajria B, Bahl A, Brestelli J, Dommer J, Fischer S, Gao X, Heiges M, Iodice J, Kissinger JC, Mackey AJ, Pinney DF, Roos DS, Stoeckert CJ Jr, Wang H, Brunk BP

Department of Biology, Department of Genetics, Center for Bioinformatics, University of Pennsylvania, Philadelphia, PA, Center for Tropical & Emerging Global Diseases and Department of Genetics, University of Georgia, Athens, GA, USA.

ToxoDB ( is a genome and functional genomic database for the protozoan parasite Toxoplasma gondii. It incorporates the sequence and annotation of the T. gondii ME49 strain, as well as genome sequences for the GT1, VEG and RH (Chr Ia, Chr Ib) strains. Sequence information is integrated with various other genomic-scale data, including community annotation, ESTs, gene expression and proteomics data. ToxoDB has matured significantly since its initial release. Here we outline the numerous updates with respect to the data and increased functionality available on the website.

PMID: 18003657 [PubMed - as supplied by publisher]

Tuesday, November 13, 2007

Exit from host cells by the pathogenic parasite Toxo does not require motility

Eukaryot Cell. 2007 Nov 9; [Epub ahead of print]

Exit from host cells by the pathogenic parasite Toxoplasma gondii does not require motility

Lavine MD, Arrizabalaga G

Department of Microbiology, Molecular Biology and Biochemistry, University of Idaho, Moscow, ID 83843, USA.

The process by which the intracellular parasite Toxoplasma gondii exits its host cell is central to its propagation and pathogenesis. Experimental induction of motility in intracellular parasites results in parasite egress, leading to the hypothesis that egress depends on the parasite's actin-dependent motility. Using a novel assay to monitor egress without experimental induction, we have established that inhibiting parasite motility does not block this process, although treatment with actin disrupting drugs does delay egress. However, using an irreversible actin inhibitor, we show that this delay is due to the disruption of host cell actin alone, apparently resulting from the consequent loss of membrane tension. Accordingly, by manipulating osmotic pressure we show that parasite egress is delayed by releasing membrane tension and promoted by increasing it. Therefore, without artificial induction, egress does not depend on parasite motility and can proceed by mechanical rupture of the host membrane.

PMID: 17993573 [PubMed - as supplied by publisher]

Rapid control of protein level in the apicomplexan Toxo

Nat Methods. 2007 Nov 11; [Epub ahead of print]

Rapid control of protein level in the apicomplexan Toxoplasma gondii

Herm-Götz A, Agop-Nersesian C, Münter S, Grimley JS, Wandless TJ, Frischknecht F, Meissner M

[1] Hygieneinstitut, Department of Parasitology, University Hospital Heidelberg, Im Neuenheimer Feld 324, D-69120 Heidelberg, Germany. [2] These authors contributed equally to this work.

Analysis of gene function in apicomplexan parasites is limited by the absence of reverse genetic tools that allow easy and rapid modulation of protein levels. The fusion of a ligand-controlled destabilization domain (ddFKBP) to a protein of interest enables rapid and reversible protein stabilization in T. gondii. This allows an efficient functional analysis of proteins that have a dual role during host cell invasion and/or intracellular growth of the parasite.

PMID: 17994029 [PubMed - as supplied by publisher]

A transient forward targeting element for microneme regulated secretion in Toxo

Biol Cell. 2007 Nov 12; [Epub ahead of print]

A transient forward targeting element for microneme regulated secretion in Toxoplasma gondii

Brydges SD, Harper JM, Parussini F, Coppens I, Carruthers VB

Background information. Accurate sorting of proteins to the three types of secretory granules in Toxoplasma gondii is crucial for successful cell invasion by this obligate intracellular parasite. As in other eukaryotic systems, propeptide sequences are a common yet poorly understood feature of proteins destined for regulated secretion, which for Toxoplasma occurs through two distinct invasion organelles, rhoptries and micronemes. Microneme discharged during parasite apical attachment plays a pivotal role in cell invasion by delivering adhesive proteins for host receptor engagement. Results. We show here that the small micronemal proprotein MIC5 undergoes proteolytic maturation at a site beyond the Golgi and only the processed form of MIC5 is secreted via the micronemes. Proper cleavage of the MIC5 propeptide relies on an arginine residue in the P1' position, though P1' mutants are still cleaved to a lesser extent at an alternative site downstream of the primary site. Nonetheless, this aberrantly cleaved species still correctly traffics to the micronemes, indicating that correct cleavage is not necessary for micronemal targeting. In contrast, a deletion mutant lacking the propeptide was retained within the secretory system, principally in the endoplasmic reticulum. The MIC5 propeptide also supported correct trafficking when exchanged for the M2AP propeptide, which was recently shown to also be required for micronemal trafficking of the TgMIC2-M2AP complex (Harper et al., Mol Biol Cell (2006) 4551-63). Conclusion. Our results illuminate common and unique features of micronemal propeptides in their role as trafficking facilitators.

PMID: 17995454 [PubMed - as supplied by publisher]

Toxo Seropositivity Among Heart Transplant Recipients Is Associated With Increased Risk

J Am Coll Cardiol. 2007 Nov 13;50(20):1967-1972. Epub 2007 Oct 29

Pre-Transplant Toxoplasma gondii Seropositivity Among Heart Transplant Recipients Is Associated With an Increased Risk of All-Cause and Cardiac Mortality

Arora S, Jenum PA, Aukrust P, Rollag H, Andreassen AK, Simonsen S, Gude E, Fiane AE, Geiran O, Gullestad L

Department of Cardiology, Rikshospitalet-Radiumhospitalet Medical Center, Oslo, Norway.

OBJECTIVES: We evaluated the risk of mortality, development of cardiac allograft vasculopathy (CAV), and acute cellular rejection among Toxoplasma gondii (T. gondii) seropositive heart transplant (HTx) recipients and the 4 donor/recipient seropairing groups. BACKGROUND: Chronic T. gondii infection is known to trigger potentially adverse immunoregulatory changes, but the long-term implication for HTx recipients has not been assessed previously. METHODS: Frozen pre-HTx serum samples of 288 recipients and 246 donors were evaluated for T. gondii serostatus using Platelia immunoglobulin G immunoassay. Patients had undergone prospective serotesting using alternative assays, and results determined by the 2 methods were compared. Data regarding mortality, CAV, and acute cellular rejection were available for all patients. RESULTS: Overall, 211 recipients (73%) were seronegative and 77 (27%) were seropositive. In total, 82 recipients died, 76 developed CAV, and 82 had 1 or more episode of treated cellular rejection. Recipient seropositivity was associated with a significantly higher risk of all-cause (hazard ratio [HR] 1.9, 95% confidence interval [CI] 1.1 to 3.4; p = 0.02) and CAV mortality (HR 4.4, 95% CI 1.3 to 15.6; p = 0.02) and a higher risk of developing advanced CAV (HR 2.7, 95% CI 1.2 to 5.8; p = 0.01). Seropositivity did not influence the number of rejection episodes, and donor/recipient seropairing was not a risk factor for any end point. CONCLUSIONS: T. gondii seropositivity among HTx recipients is associated with an increased risk of all-cause and CAV mortality and of development of advanced CAV. This may be mediated via immunoregulatory changes triggered by chronic T. gondii infection and needs to be explored further.

PMID: 17996562 [PubMed - as supplied by publisher]

Rhoptries: an arsenal of secreted virulence factors

Curr Opin Microbiol. 2007 Nov 8; [Epub ahead of print]

Rhoptries: an arsenal of secreted virulence factors

Bradley PJ, Sibley LD

Department of Microbiology, Immunology and Molecular Genetics, UCLA School of Medicine, Los Angeles, CA 90095, United States.

Apicomplexan parasites use actin-based motility coupled with regulated protein secretion from apical organelles to actively invade host cells. Crucial in this process are rhoptries, club-shaped secretory organelles that discharge their contents during parasite invasion into host cells. A proteomic analysis of the rhoptries in Toxoplasma gondii demonstrated that this organelle contains a number of novel rhoptry proteins (ROPs) including serine-threonine kinases and protein phosphatases. A subset of rhoptry proteins called RONs have been shown to target the moving junction, which plays a key role in invasion and parasitophorous vacuole formation. Other ROP proteins have various destinations in the host cell including the host cell nucleus and the parasitophorous vacuole, probably reflecting their distinct targets and roles. Forward genetic analysis recently revealed that secretory ROP kinases dramatically influence host gene expression and are the major parasite virulence factors. Thus, ROP proteins are functionally analogous (though not homologous) to effectors released by type III and IV secretion systems, which are factors that play an important role in bacterial virulence. Deciphering the role of ROP effectors may allow specific disruption of these factors, thus offering new options for preventing disease.

PMID: 17997128 [PubMed - as supplied by publisher]

Friday, November 09, 2007

Lipidomic Analysis of Toxo Reveals Unusual Polar Lipids

Biochemistry. 2007 Nov 8; [Epub ahead of print]

Lipidomic Analysis of Toxoplasma gondii Reveals Unusual Polar Lipids

Welti R, Mui E, Sparks A, Wernimont S, Isaac G, Kirisits M, Roth M, Roberts CW, Botté C, Maréchal E, McLeod R

Kansas Lipidomics Research Center, Division of Biology, Kansas State University, Manhattan, Kansas 66506, Departments of Ophthalmology and Visual Sciences, Pediatrics (Infectious Diseases) Committees on Molecular Medicine, Immunology and Genetics and The College, University of Chicago, Chicago, Illinois 60637, Strathclyde Institute of Pharmacy & Biomedical Sciences, University of Strathclyde, Glasgow, Scotland, UK, and Laboratoire de Physiologie Cellulaire Végétale, UMR 5168 CNRS-CEA-INRA-Université J. Fourier, Institut de Recherches en Technologies et Sciences pour le Vivant, CEA-Grenoble, Grenoble, France.

Analysis of the polar lipids of Toxoplasma gondii by electrospray ionization tandem mass spectrometry provides a detailed picture of the lipid molecular species of this parasitic protozoan. Most notably, T. gondii contains a relatively high level, estimated to about 2% of the total polar lipid, of ceramide phosphoethanolamine. The ceramide phosphoethanolamine has a fatty amide profile with only 16- and 18-carbon species. Compared with the host fibroblasts in which it was grown, T. gondii also has higher levels of phosphatidylcholine but lower levels of sphingomyelin and phosphatidylserine. Analysis at the molecular species level indicated that T. gondii has greater amounts of shorter-chain fatty acid in its polar lipid molecular species than the host fibroblasts. Shorter-chain fatty acids with a combined total of 30 or fewer acyl carbons make up 21% of Toxoplasma's, but only 3% of the host's, diacyl phosphatidylcholine. Furthermore, diacyl phosphatidylcholine with two saturated acyl chains with 12, 14, or 16 carbons make up over 11% of parasite phosphatidylcholine but less than 3% of the host phosphatidylcholine molecular species. The distinctive T. gondii tachyzoite lipid profile may be particularly suited to the function of parasitic membranes and the interaction of the parasite with the host cell and the host's immune system. Combined with T. gondii genomic data, these lipidomic data will assist in elucidation of metabolic pathways for lipid biosynthesis in this important human pathogen.

PMID: 17988103 [PubMed - as supplied by publisher]

Alteration in circulating soluble Fas level in Toxoplasma seropositive pregnant women

J Egypt Soc Parasitol. 2007 Aug;37(2):511-21

Alteration in circulating soluble Fas level in Toxoplasma seropositive pregnant women

El-Taweel HA, Abou-Holw SA, Ghoniem HM

Department of Parasitology, Medical Research Institute, Alexandria University, Alexandria, Egypt.

The role of sFas in human toxoplasmosis was designed, included 23 pregnant women serologically positive for anti-Toxoplasma antibodies, and ten sero-negative pregnant females constituted the control group. Antibody titer was assessed by indirect haemagglutination test. The presence of specific IgM antibodies was determined by comparing antibody titer before and after serum treatment with 2-mercapto-ethanol. sFas was quantified in sera of cases and controls by enzyme linked immunosorbent assay. Antibody titers. ranged from 1/160 to 1/640. All cases were negative for specific IgM antibodies indicating that they had passed the acute stage of infection Statistical analysis revealed significant elevation in sFas level in cases compared to controls. The sFas role in establishment of a stable host parasite interaction in toxoplasmosis was discussed.

PMID: 17985584 [PubMed - in process]

Wednesday, November 07, 2007

Parasitosis, dopaminergic modulation and metabolic disturbances in schizophrenia: evolution of a hypothesis

Neuro Endocrinol Lett. 2007 Oct 6;28(5) [Epub ahead of print]

Parasitosis, dopaminergic modulation and metabolic disturbances in schizophrenia: evolution of a hypothesis

Treuer T, Martenyi F, Karagianis J

Neuroscience Research, Area Medical Center Vienna, Eli Lilly Regional GmbH, Venna, Austria.

Recent meta-analyses have provided a comprehensive overview of studies investigating Toxoplasma gondii antibodies in schizophrenic patients, thus attempting to clarify the potential role these infections might play in causing schizophrenia. Issues for further research have been suggested. Associations and theories that may enrich the current level of knowledge with regard to this significant subject deserve attention. Anti-parasitic agents as well as antipsychotics are effective in treating parasitosis. Both classes of drugs have been shown to exert dopaminergic activity. Parasites and human organisms have a long history of mutual contact. The effect of parasitosis on the host and the host's response to infection are undoubtedly the product of a long evolutionary process. The neurochemical background of delusions of parasitosis is potentially similar to ancient evolutionary traces of altered neurotransmission and neuropeptide gene expression caused by parasites; these include fungal and viral infections. This is very unique in medicine if a class of drugs is effective in the treatment of an illness but also cures the delusion of the same disorder as well. Furthermore, metabolic disturbances such as hyperglycemia and insulin resistance were reported several decades before the antipsychotic era. Toxoplasmosis may also be linked to insulin resistance. Schizophrenia research can benefit from understanding this evolutionary link. New chemical entities that are liable to alter neurochemical changes related to the brain's perception of the risk of predation secondary to parasites may result in new approaches for the treatment of psychosis. These findings suggest that further research is needed to clarify this evolutionary link between parasite infection and delusions of parasitosis. We believe this model may well open up new avenues of research in the discovery of drugs to counteract schizophrenia.

PMID: 17984933 [PubMed - as supplied by publisher]

An emerging cyberinfrastructure for biodefense pathogen and pathogen host data

Nucleic Acids Res. 2007 Nov 4; [Epub ahead of print]

An emerging cyberinfrastructure for biodefense pathogen and pathogen host data

Zhang C, Crasta O, Cammer S, Will R, Kenyon R, Sullivan D, Yu Q, Sun W, Jha R, Liu D, Xue T, Zhang Y, Moore M, McGarvey P, Huang H, Chen Y, Zhang J, Mazumder R, Wu C, Sobral B

Virginia Bioinformatics Institute at Virginia Polytechnic Institute and State University, Washington Street (0477), Blacksburg, VA 24061, Social & Scientific Systems, Inc., 8757 Georgia Avenue, 12th Floor Silver Spring, MD 20910 and Protein Information Resource, Department of Biochemistry and Molecular & Cellular Biology, Georgetown University Medical Center, 3300 Whitehaven Street NW, Suite 1200, Washington, DC 20007, USA.

The NIAID-funded Biodefense Proteomics Resource Center (RC) provides storage, dissemination, visualization and analysis capabilities for the experimental data deposited by seven Proteomics Research Centers (PRCs). The data and its publication is to support researchers working to discover candidates for the next generation of vaccines, therapeutics and diagnostics against NIAID's Category A, B and C priority pathogens. The data includes transcriptional profiles, protein profiles, protein structural data and host-pathogen protein interactions, in the context of the pathogen life cycle in vivo and in vitro. The database has stored and supported host or pathogen data derived from Bacillus, Brucella, Cryptosporidium, Salmonella, SARS, Toxoplasma, Vibrio and Yersinia, human tissue libraries, and mouse macrophages. These publicly available data cover diverse data types such as mass spectrometry, yeast two-hybrid (Y2H), gene expression profiles, X-ray and NMR determined protein structures and protein expression clones. The growing database covers over 23 000 unique genes/proteins from different experiments and organisms. All of the genes/proteins are annotated and integrated across experiments using UniProt Knowledgebase (UniProtKB) accession numbers. The web-interface for the database enables searching, querying and downloading at the level of experiment, group and individual gene(s)/protein(s) via UniProtKB accession numbers or protein function keywords. The system is accessible at

PMID: 17984082 [PubMed - as supplied by publisher]

Tuesday, November 06, 2007

ProtozoaDB: dynamic visualization and exploration of protozoan genomes

Nucleic Acids Res. 2007 Nov 2; [Epub ahead of print]

ProtozoaDB: dynamic visualization and exploration of protozoan genomes

Dávila AM, Mendes PN, Wagner G, Tschoeke DA, Cuadrat RR, Liberman F, Matos L, Satake T, Ocaña KA, Triana O, Cruz SM, Jucá HC, Cury JC, Silva FN, Geronimo GA, Ruiz M, Ruback E, Silva FP Jr, Probst CM, Grisard EC, Krieger MA, Goldenberg S, Cavalcanti MC, Moraes MO, Campos ML, Mattoso M

Oswaldo Cruz Institute, FIOCRUZ, CCB, Federal University of Santa Catarina (UFSC), ACBS/UNOESC/SC, COPPE, Federal University of Rio de Janeiro, NCE, Federal University of Rio de Janeiro, Instituto de Biologia Molecular do Paraná, FIOCRUZ, Engineering Military Institute (IME), DCC, Federal University of Rio de Janeiro, Brazil, Knoesis Center, Wright State University, USA, Antioquia University, Colombia and Federal University of Paraná (UFPR), Brazil.

ProtozoaDB ( is being developed to initially host both genomics and post-genomics data from Plasmodium falciparum, Entamoeba histolytica, Trypanosoma brucei, T. cruzi and Leishmania major, but will hopefully host other protozoan species as more genomes are sequenced. It is based on the Genomics Unified Schema and offers a modern Web-based interface for user-friendly data visualization and exploration. This database is not intended to duplicate other similar efforts such as GeneDB, PlasmoDB, TcruziDB or even TDRtargets, but to be complementary by providing further analyses with emphasis on distant similarities (HMM-based) and phylogeny-based annotations including orthology analysis. ProtozoaDB will be progressively linked to the above-mentioned databases, focusing in performing a multi-source dynamic combination of information through advanced interoperable Web tools such as Web services. Also, to provide Web services will allow third-party software to retrieve and use data from ProtozoaDB in automated pipelines (workflows) or other interoperable Web technologies, promoting better information reuse and integration. We also expect ProtozoaDB to catalyze the development of local and regional bioinformatics capabilities (research and training), and therefore promote/enhance scientific advancement in developing countries.

PMID: 17981844 [PubMed - as supplied by publisher]

Detection of MIC10 antigen in sera of experimentally infected mice

Exp Parasitol. 2007 Oct 1; [Epub ahead of print]

Toxoplasma gondii: Detection of MIC10 antigen in sera of experimentally infected mice

Dautu G, Ueno A, Miranda A, Mwanyumba S, Munyaka B, Carmen G, Kariya T, Omata Y, Saito A, Xuan X, Igarashi M

National Research Center for Protozoan Diseases, Obihiro University of Agriculture and Veterinary Medicine, Hokkaido, 080-8555 Japan.

We developed a sandwich ELISA for the detection of circulating Toxoplasma gondii MIC10 antigens. In T. gondii culture supernatant, MIC10 was detected in a growth dependent manner. Mice were infected with a lethal dose of either a virulent RH strain, an avirulent Beverley strain or a sub-lethal dose of a PLK strain of T. gondii. MIC10 appeared 2 days after infection and increased gradually in the sera of RH-infected mice. A detectable but significantly lower amount of MIC10 was observed in the sera of mice infected intraperitoneally with Beverley tachyzoites. In contrast, the MIC10 antigen in mice sera following oral infection with Beverley cysts was below detectable levels during the course of the experiment. In sera of PLK-infected mice, MIC10 was predominantly observed between late acute and early chronic phase. Our data show that the kinetics of circulating MIC10 differs depending on the strain and route of infection.

PMID: 17976597 [PubMed - as supplied by publisher]

Inhibition of Toxo growth by pyrrolidine dithiocarbamate is cell cycle specific and leads to population synchronization

Mol Biochem Parasitol. 2007 Sep 21; [Epub ahead of print]

Inhibition of Toxoplasma gondii growth by pyrrolidine dithiocarbamate is cell cycle specific and leads to population synchronization

Conde de Felipe MM, Lehmann MM, Jerome ME, White MW

Department of Veterinary Molecular Biology, Montana State University, Bozeman, MT 59717-3610, United States.

Successful completion of the Toxoplasma cell cycle requires the coordination of a series of complex and ordered processes that results in the formation of two daughters by internal budding. Although we now understand the order and timing of intracellular events associated with the parasite cell cycle, the molecular details of the checkpoints that regulate each step in Toxoplasma gondii division is still uncertain. In other eukaryotic cells, the use of cytostatic inhibitors that are able to arrest replication at natural checkpoints have been exploited to induce synchronization of population growth. Herein, we describe a novel method to synchronize T. gondii tachyzoites based on the reversible growth inhibition by the drug and pyrrolidine dithiocarbamate. This method is an improvement over other strategies developed for this parasites as no prior genetic manipulation of the parasite was required. RH tachyzoites blocked by pyrrolidine dithiocarbamate exhibited a near uniform haploid DNA content and single centrosome indicating that this compound arrests parasites in the G1 phase of the tachyzoite cell cycle with a minor block in late cytokinesis. Thus, these studies support the existence of a natural checkpoint that regulates passage through the G1 period of the cell cycle. Populations released from pyrrolidine dithiocarbamate inhibition completed progression through G1 and entered S phase approximately 2h post-drug release. The transit of drug-synchronized populations through S phase and mitosis followed a similar timeframe to previous studies of the tachyzoite cell cycle. Tachyzoites treated with pyrrolidine dithiocarbamate were fully viable and completed two identical division cycles post-drug release demonstrating that this is a robust method for synchronizing population growth in Toxoplasma.

PMID: 17976834 [PubMed - as supplied by publisher]

Effectiveness of health education on Toxoplasma-related knowledge, behaviour, and risk of seroconversion in pregnancy

Eur J Obstet Gynecol Reprod Biol. 2007 Oct 29; [Epub ahead of print]

Effectiveness of health education on Toxoplasma-related knowledge, behaviour, and risk of seroconversion in pregnancy

Gollub EL, Leroy V, Gilbert R, Chêne G, Wallon M; the European Toxoprevention Study Group (EUROTOXO)

INSERM, U593, Bordeaux, Université Victor Segalen Bordeaux 2, Institut de Santé Publique, d’Epidémiologie et de Développement (ISPED), Bordeaux, F-33076 Bordeaux cedex, France.

We conducted a bibliographic literature search using MEDLINE to review the effectiveness of health education on Toxoplasma-related knowledge, behaviour, and risk of seroconversion in pregnant women. We pre-selected studies that used comparative study designs (randomized clinical trial, quasi-experimental design or historical control), that were conducted among pregnant women, and which employed specific, Toxoplasma-related outcome measures: knowledge, behaviour, or Toxoplasma infection rate. Four studies met the inclusion criteria. All had serious methodological flaws. A Belgian study reported a significant decrease in the incidence of Toxoplasma seroconversion after the introduction of intensive counselling for pregnant women about toxoplasmosis. In Poland, a significant increase in knowledge was observed after a multi-pronged, public health educational program was launched. In Canada, an increase in knowledge and prevention behaviours was reported in the intervention group receiving counselling by trained facilitators compared with the control group. In France, no significant changes in risk behaviour were observed following a physician-delivered intervention. This review highlights the weakness of the literature in the area and the lack of studies measuring actual seroconversion. There is suggestive evidence that health education approaches may help reduce risk of congenital toxoplasmosis but this problem requires further study using more rigorous research design and methodology.

PMID: 17977641 [PubMed - as supplied by publisher]

Thursday, November 01, 2007

New host nuclear functions are not required for the modifications of the parasitophorous vacuole of Toxoplasma

Cell Microbiol. 2007 Oct 28; [Epub ahead of print]

New host nuclear functions are not required for the modifications of the parasitophorous vacuole of Toxoplasma

Romano JD, Bano N, Coppens I

Department of Molecular Microbiology and Immunology, Johns Hopkins University Bloomberg School of Public Health, 615 N. Wolfe Street, Baltimore, MD 21205, USA.

The obligate intracellular parasite Toxoplasma develops within a parasitophorous vacuole (PV) uniquely adapted for its survival in mammalian cells. Post-invasion events extensively modify the PV, resulting in interactions with host cell structures. Recent studies emphasized that Toxoplasma is able to co-opt host gene expression, suggesting that host transcriptional activities are required for parasite infection. By using an experimental enucleation model, we investigated the potential need for Toxoplasma to modify its PV by modulating gene expression in the cell wherein it resides. Unexpectedly, cytoplasts can be actively invaded by Toxoplasma and sustain its replication inside a vacuole until egress and transmission to neighbouring cells. Although randomly distributed in the cytoplast, the PV associates with host centrosomes and the Golgi, is surrounded by host microtubules, and recruits host endoplasmic reticulum and mitochondria. Parasites are proficient in diverting exogenous nutrients from the endocytic network of cytoplasts. In enucleated cells invaded by an avirulent strain of T. gondii, the PV can normally transform into cysts. These observations suggest that new host nuclear functions are not proximately required for the post-invasion events underlying the remodelling of the host cell in which the parasites are confined, and therefore for the generation of infectious parasites in vitro.

PMID: 17970763 [PubMed - as supplied by publisher]