Int J Parasitol. 2013 Sep 23. pii: S0020-7519(13)00222-1. doi: 10.1016/j.ijpara.2013.08.002. [Epub ahead of print]

Identification of three novel Toxoplasma gondii rhoptry proteins

Camejo A, Gold DA, Lu D, McFetridge K, Julien L, Yang N, C Jensen KD, Saeij JP.

Source

Department of Biology, Massachusetts Institute of Technology, Cambridge, MA, 02139 USA.

Abstract

The rhoptries are key secretory organelles from apicomplexan parasites that contain proteins involved in invasion and modulation of the host cell. Some rhoptry proteins are restricted to the posterior bulb (ROPs) and others to the anterior neck (RONs). As many rhoptry proteins have been shown to be key players in Toxoplasma invasion and virulence, it is important to identify, understand and characterize the biological function of the components of the rhoptries. In this report, we identified putative novel rhoptry candidate genes by identifying Toxoplasma genes with similar cyclical expression profiles as known rhoptry protein encoding genes across its cell cycle. Using this approach we identified two new rhoptry bulb (ROP47 and ROP48) and one new rhoptry neck protein (RON12). ROP47 is secreted and traffics to the host cell nucleus, RON12 was not detected at the moving junction during invasion. Deletion of ROP47 or ROP48 in a type II strain did not show major influence in in vitro growth or virulence in mice. Highlights: Three novel Toxoplasma gondii rhoptry proteins, ROP47, ROP48 and RON12, were identified. ROP47 is secreted into the host cell and traffics to the host nucleus. Deletion of ROP47 or ROP48 did not influence in vitro growth or virulence in mice.

Int J Parasitol. 2013 Sep 23. pii: S0020-7519(13)00222-1. doi: 10.1016/j.ijpara.2013.08.002. [Epub ahead of print]

Identification of three novel Toxoplasma gondii rhoptry proteins

Camejo A, Gold DA, Lu D, McFetridge K, Julien L, Yang N, C Jensen KD, Saeij JP.

Source

Department of Biology, Massachusetts Institute of Technology, Cambridge, MA, 02139 USA.

Abstract

The rhoptries are key secretory organelles from apicomplexan parasites that contain proteins involved in invasion and modulation of the host cell. Some rhoptry proteins are restricted to the posterior bulb (ROPs) and others to the anterior neck (RONs). As many rhoptry proteins have been shown to be key players in Toxoplasma invasion and virulence, it is important to identify, understand and characterize the biological function of the components of the rhoptries. In this report, we identified putative novel rhoptry candidate genes by identifying Toxoplasma genes with similar cyclical expression profiles as known rhoptry protein encoding genes across its cell cycle. Using this approach we identified two new rhoptry bulb (ROP47 and ROP48) and one new rhoptry neck protein (RON12). ROP47 is secreted and traffics to the host cell nucleus, RON12 was not detected at the moving junction during invasion. Deletion of ROP47 or ROP48 in a type II strain did not show major influence in in vitro growth or virulence in mice. Highlights: Three novel Toxoplasma gondii rhoptry proteins, ROP47, ROP48 and RON12, were identified. ROP47 is secreted into the host cell and traffics to the host nucleus. Deletion of ROP47 or ROP48 did not influence in vitro growth or virulence in mice.

Eukaryot Cell. 2013 Sep 20. [Epub ahead of print]

Evidence for Intraflagellar Transport and Apical Complex formation in a Free Living Relative of the Apicomplexa

Portman N, Foster C, Walker G, Slapeta J.

Source

Faculty of Veterinary Science, McMaster Building B14, University of Sydney, New South Wales 2006, Australia.

Abstract

Since its first description, Chromera velia has attracted keen interest as the closest free-living relative of parasitic Apicomplexa. The life cycle of this unicellular alga is complex and involves a motile bi-flagellate form. Flagella are thought to be formed in the cytoplasm, a rare phenomenon shared with Plasmodium in which the canonical mode of flagellar assembly, intraflagellar transport, is dispensed with. Here we demonstrate the expression of intraflagellar transport components in C. velia, answering the question of whether this organism has the potential to assemble flagella via the canonical route. We have developed and characterised a culturing protocol that favours the generation of flagellate forms. From this we have determined a marked shift in the mode of daughter cell production from two to four daughter cells per division as a function of time after passage. We conduct an ultrastructural examination of the C. velia flagellate form using serial TEM and show that flagellar biogenesis in C. velia occurs prior to cytokinesis. We demonstrate a close association of the flagellar apparatus with a complex system of apical structures including a micropore, conoid and a complex endomembrane system reminiscent of the apical complex of parasitic apicomplexans. Recent work has begun to elucidate the possible flagellar origins of the apical complex and in C. velia we show that these structures are contemporaneous within a single cell and share multiple connections. We propose that Chromera velia therefore represents a vital piece in the puzzle of the origins of the apical complex.

PMID:

24058169

[PubMed - as supplied by publisher]

PLoS One. 2013 Sep 18;8(9):e75246. doi: 10.1371/journal.pone.0075246.

Mice Infected with Low-Virulence Strains of Toxoplasma gondii Lose Their Innate Aversion to Cat Urine, Even after Extensive Parasite Clearance

Ingram WM, Goodrich LM, Robey EA, Eisen MB.

Source

Department of Molecular and Cell Biology, University of California, Berkeley, California, United States of America.

Abstract

Toxoplasma gondii chronic infection in rodent secondary hosts has been reported to lead to a loss of innate, hard-wired fear toward cats, its primary host. However the generality of this response across T. gondii strains and the underlying mechanism for this pathogen-mediated behavioral change remain unknown. To begin exploring these questions, we evaluated the effects of infection with two previously uninvestigated isolates from the three major North American clonal lineages of T. gondii, Type III and an attenuated strain of Type I. Using an hour-long open field activity assay optimized for this purpose, we measured mouse aversion toward predator and non-predator urines. We show that loss of innate aversion of cat urine is a general trait caused by infection with any of the three major clonal lineages of parasite. Surprisingly, we found that infection with the attenuated Type I parasite results in sustained loss of aversion at times post infection when neither parasite nor ongoing brain inflammation were detectable. This suggests that T. gondii-mediated interruption of mouse innate aversion toward cat urine may occur during early acute infection in a permanent manner, not requiring persistence of parasite cysts or continuing brain inflammation.

PMID:

24058668

[PubMed - in process]

First Three-Dimensional Structure of Toxoplasma gondii thymidylate synthase-dihydrofolate reductase

Biochemistry. 2013 Sep 20. [Epub ahead of print]

First Three-Dimensional Structure of Toxoplasma gondii thymidylate synthase-dihydrofolate reductase: Insights for Catalysis, Interdomain Interactions, and Substrate Channeling

Sharma H, Landau MJ, Vargo MA, Spasov KA, Anderson KS.

Abstract

Most species, such as humans, have monofunctional forms of thymidylate synthase (TS) and dihydrofolate reductase (DHFR) that are key folate metabolism enzymes making critical folate components required for DNA synthesis. In contrast, several parasitic protozoa, including Toxoplasma gondii, contain a unique bifunctional thymidylate synthase-dihydrofolate reductase (TS-DHFR) having the catalytic activities contained on a single polypeptide chain. The prevalence of T. gondii infection across the world, especially for those immunocompromised, underscores the need to understand TS-DHFR enzyme function and to find new avenues to exploit for the design of novel antiparasitic drugs. As a first step, we have solved the first three-dimensional structures of T. gondii TS-DHFR at 3.7 Å and of a loop truncated TS-DHFR, removing several flexible surface loops in the DHFR domain, improving resolution to 2.2 Å. Distinct structural features of the TS-DHFR homodimer include a junctional region containing a kinked crossover helix between the DHFR domains of the two adjacent monomers, a long linker connecting the TS and DHFR domains, and a DHFR domain that is positively charged. The roles of these unique structural features were probed by site-directed mutagenesis coupled with pre-steady state and steady state kinetics. Mutational analysis of the crossover helix region combined with kinetic characterization established the importance of this region not only in DHFR catalysis but also in modulating the distal TS activity, suggesting a role for TS-DHFR interdomain interactions. Additional kinetic studies revealed that substrate channeling occurs in which dihydrofolate is directly transferred from the TS to DHFR active site without entering bulk solution. The crystal structure suggests that the positively charged DHFR domain governs this electrostatically mediated movement of dihydrofolate, preventing release from the enzyme. Taken together, these structural and kinetic studies reveal unique, functional regions on the T. gondii TS-DHFR enzyme that may targeted for inhibition, thus paving the way for designing species specific inhibitors.

PMID:

24053355

[PubMed - as supplied by publisher]

J Exp Med. 2013 Sep 16. [Epub ahead of print]

A Toxoplasma dense granule protein, GRA24, modulates the early immune response to infection by promoting a direct and sustained host p38 MAPK activation

Braun L, Brenier-Pinchart MP, Yogavel M, Curt-Varesano A, Curt-Bertini RL, Hussain T, Kieffer-Jaquinod S, Coute Y, Pelloux H, Tardieux I, Sharma A, Belrhali H, Bougdour A, Hakimi MA.

Source

Centre National de la Recherche Scientifique (CNRS), UMR5163, Laboratoire Adaptation et Pathogénie des Microorganismes, F-38041 Grenoble, France.

Abstract

Toxoplasma gondii, the causative agent of toxoplasmosis, is an obligate intracellular protozoan parasite that resides inside a parasitophorous vacuole. During infection, Toxoplasma actively remodels the transcriptome of its hosting cells with profound and coupled impact on the host immune response. We report that Toxoplasma secretes GRA24, a novel dense granule protein which traffics from the vacuole to the host cell nucleus. Once released into the host cell, GRA24 has the unique ability to trigger prolonged autophosphorylation and nuclear translocation of the host cell p38α MAP kinase. This noncanonical kinetics of p38α activation correlates with the up-regulation of the transcription factors Egr-1 and c-Fos and the correlated synthesis of key proinflammatory cytokines, including interleukin-12 and the chemokine MCP-1, both known to control early parasite replication in vivo. Remarkably, the GRA24-p38α complex is defined by peculiar structural features and uncovers a new regulatory signaling path distinct from the MAPK signaling cascade and otherwise commonly activated by stress-related stimuli or various intracellular microbes.

PMID:

24043761

[PubMed - as supplied by publisher]

Infect Immun. 2013 Sep 16. [Epub ahead of print]

Cell death of interferon-gamma stimulated human fibroblasts upon Toxoplasma gondii infection induces early parasite egress and limits parasite replication

Niedelman W, Sprokholt JK, Clough B, Frickel EM, Saeij JP.

Source

Department of Biology, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA.

Abstract

The intracellular protozoan parasite Toxoplasma gondii is a major foodborne illness and opportunistic infection for the immunosuppressed. Resistance to Toxoplasma is dependent on interferon-γ (IFNγ) activation of both hematopoietic and non-hematopoietic cells. While IFNγ-induced innate immunity in non-hematopoietic cells has been extensively studied in mice, it remains unclear what resistance mechanisms are relied on in non-hematopoietic human cells. Here, we report an IFNγ-induced mechanism of resistance to Toxoplasma in primary human foreskin fibroblasts (HFFs) that does not depend on deprivation of tryptophan or iron. Additionally, infection is still controlled in HFFs deficient in the p65 guanylate binding proteins GBP1 or GBP2 and the autophagic protein ATG5. Resistance is coincident with host cell death that is not dependent on the necroptosis mediator RIPK3 or caspases, and is correlated with early egress of the parasite before replication. This IFNγ-induced cell death and early egress limits replication in HFFs and could promote clearance of the parasite by immune cells.

PMID:

24042117

[PubMed - as supplied by publisher]

J Biol Chem. 2013 Sep 10. [Epub ahead of print]

Toxoplasma transcription factor TgAP2XI-5 regulates the expression of genes involved in parasite virulence and host invasion

Walker R, Gissot M, Huot L, Alayi TD, Hot D, Marot G, Schaeffer-Reiss C, Van Dorsselaer A, Kim K, Tomavo S.

Source

Pasteur Institute Lille, France;

Abstract

Gene regulation in apicomplexan parasites, a phylum containing important protozoan parasites such as Plasmodium and Toxoplasma, is poorly understood. The life cycle of T. gondii is complex, with multiple proliferation and differentiation steps of which tachyzoite proliferation is the most relevant to pathogenesis in humans and animals. Tachyzoites express invasion and virulence factors that are crucial for their survival and manipulation of host cell functions. The expression of those factors is tightly controlled during the tachyzoite cell cycle to permit their correct packaging in newly formed apical secretory organelles named micronemes and rhoptries in the daughter cells. However, little is known about the factors that control the expression of genes encoding the virulence factors present in these parasite-specific secretory organelles. We report that the plant-like nuclear factor TgAP2XI-5 targets more than 300 gene promoters and actively controls the transcription of these genes. Most of these target genes, including those that are essential for parasite virulence, showed a peak of expression in S and M phases of the cell cycle. Furthermore, we identified the cis-regulatory element recognized by TgAP2XI-5 and demonstrated its ability to actively drive gene transcription. Our results demonstrated that TgAP2XI-5 is a novel DNA sequence-specific transcription factor associated with promoter activation. TgAP2XI-5 may regulate gene transcription of crucial virulence factors in T. gondii.

KEYWORDS:

Gene expression, Gene regulation, Gene transcription, Infectious diseases, Promoters

PMID:

 

24025328

 

[PubMed - as supplied by publisher] 

J Nat Prod. 2013 Sep 10. [Epub ahead of print]

Synthetic Chondramide A Analogues Stabilize Filamentous Actin and Block Invasion by Toxoplasma gondii

Ma CI, Diraviyam K, Maier ME, Sept D, Sibley LD.

Source

Department of Molecular Microbiology, Washington University School of Medicine , St. Louis, Missouri 63110, United States.

Abstract

Apicomplexan parasites such as Toxoplasma gondii rely on actin-based motility to cross biological barriers and invade host cells. Key structural and biochemical differences in host and parasite actins make this an attractive target for small-molecule inhibitors. Here we took advantage of recent advances in the synthesis of cyclic depsipeptide compounds that stabilize filamentous actin to test the ability of chondramides to disrupt growth of T. gondii in vitro. Structural modeling of chondramide A (2) binding to an actin filament model revealed variations in the binding site between host and parasite actins. A series of 10 previously synthesized analogues (2b-k) with substitutions in the β-tyrosine moiety blocked parasite growth on host cell monolayers with EC₅₀ values that ranged from 0.3 to 1.3 μM. In vitro polymerization assays using highly purified recombinant actin from T. gondii verified that synthetic and natural product chondramides target the actin cytoskeleton. Consistent with this, chondramide treatment blocked parasite invasion into host cells and was more rapidly effective than pyrimethamine, a standard therapeutic agent. Although the current compounds lack specificity for parasite vs host actin, these studies provide a platform for the future design and synthesis of synthetic cyclic peptide inhibitors that selectively disrupt actin dynamics in parasites.

PMID:

24020843

[PubMed - as supplied by publisher]

Int Rev Cell Mol Biol. 2013;306:333-69. doi: 10.1016/B978-0-12-407694-5.00008-0.

Cell biology of chromerids: autotrophic relatives to apicomplexan parasites

Oborník M, Lukeš J.

Source

Biology Centre, Institute of Parasitology, Academy of Sciences of the Czech Republic, České Budějovice, Czech Republic; Faculty of Science, University of South Bohemia, České Budějovice, Czech Republic; Institute of Microbiology, Academy of Sciences of the Czech Republic, Třeboň, Czech Republic. Electronic address: obornik@paru.cas.cz.

Abstract

Chromerida are algae possessing a complex plastid surrounded by four membranes. Although isolated originally from stony corals in Australia, they seem to be globally distributed. According to their molecular phylogeny, morphology, ultrastructure, structure of organellar genomes, and noncanonical pathway for tetrapyrrole synthesis, these algae are thought to be the closest known phototrophic relatives to apicomplexan parasites. Here, we summarize the current knowledge of cell biology and evolution of this novel group of algae, which contains only two formally described species, but is apparently highly diverse and virtually ubiquitous in marine environments.
© 2013 Elsevier Inc. All rights reserved.

KEYWORDS:

Apicomplexa, Apicoplast, Chromerida, Evolution, Parasitism, Plastid

PMID:

24016529

[PubMed - in process]

Cell Microbiol. 2013 Aug 23. doi: 10.1111/cmi.12186. [Epub ahead of print]

The Toxoplasma gondii calcium-dependent protein kinase 7 is involved in early steps of parasite division and is crucial for parasite survival

Morlon-Guyot J, Berry L, Chen CT, Gubbels MJ, Lebrun M, Daher W.

Source

Dynamique des Interactions Membranaires Normales et Pathologiques, UMR5235 CNRS, Université de Montpellier I et II, Montpellier, France.

Abstract

Apicomplexan parasites express various calcium-dependent protein kinases (CDPKs), and some of them play essential roles in invasion and egress. Five of the six CDPKs conserved in most Apicomplexa have been studied at the molecular and cellular levels in Plasmodium species and/or in Toxoplasma gondii parasites, but the function of CDPK7 was so far uncharacterized. In T. gondii, during intracellular replication, two parasites are formed within a mother cell through a unique process called endodyogeny. Here we demonstrate that the knock-down of CDPK7 protein in T. gondii results in pronounced defects in parasite division and a major growth deficiency, while it is dispensable for motility, egress and microneme exocytosis. In cdpk7-depleted parasites, the overall DNA content was not impaired, but the polarity of daughter cells budding and the fate of several subcellular structures or proteins involved in cell division were affected, such as the centrosomes and the kinetochore. Overall, our data suggest that CDPK7 is crucial for proper maintenance of centrosome integrity required for the initiation of endodyogeny. Our findings provide a first insight into the probable role of calcium-dependent signalling in parasite multiplication, in addition to its more widely explored role in invasion and egress.
© 2013 John Wiley & Sons Ltd.

PMID:

24011186

[PubMed - as supplied by publisher]

Cell Microbiol. 2013 Aug 23. doi: 10.1111/cmi.12185. [Epub ahead of print]

The Toxoplasma gondii kinetochore is required for centrosome association with the centrocone (spindle pole)

Farrell M, Gubbels MJ.

Source

Department of Biology, Boston College, 140 Commonwealth Avenue, Higgins Hall 355, Chestnut Hill, MA, 02467, USA.

Abstract

The kinetochore is a multi-protein structure assembled on eukaryotic centromeres mediating chromosome attachment to spindle microtubules. Here we identified the kinetochore proteins Nuf2 and Ndc80 in the apicomplexan parasite Toxoplasma gondii. Localization revealed that kinetochores remain clustered throughout the cell cycle and colocalize with clustered centromeres at the centrocone, a structure containing the spindle pole embedded in the nuclear envelope. Pharmacological disruption of microtubules resulted in partial loss of some kinetochore and centromere clustering, indicating microtubules are necessary but not strictly required for kinetochore clustering. Generation of a TgNuf2 conditional knock-down strain revealed it is essential for chromosome segregation, but dispensable for centromere clustering. The centromeres actually remained associated with the centrocone suggesting microtubule binding is not required for their interaction with the spindle pole. The most striking observation upon TgNuf2 depletion was that the centrosome behaved normally, but that it lost its association with the centrocone. This suggests that microtubules are essential to maintain contact between the centrosome and chromosomes, and this interaction is critical for the partitioning of the nuclei into the two daughter parasites. Finally, genetic complementation experiments with mutated TgNuf2 constructs highlighted an apicomplexan-specific motif with a putative role in nuclear localization.
© 2013 John Wiley & Sons Ltd.

PMID:

24015880

[PubMed - as supplied by publisher]

MBio. 2013 Sep 3;4(5). pii: e00387-13. doi: 10.1128/mBio.00387-13.

Evidence for a structural role for Acid-fast lipids in oocyst walls of cryptosporidium, toxoplasma, and eimeria

Bushkin GG, Motari E, Carpentieri A, Dubey JP, Costello CE, Robbins PW, Samuelson J.

Source

Department of Molecular and Cell Biology, Boston University Goldman School of Dental Medicine, Boston, Massachusetts, USA.

Abstract

ABSTRACT Coccidia are protozoan parasites that cause significant human disease and are of major agricultural importance. Cryptosporidium spp. cause diarrhea in humans and animals, while Toxoplasma causes disseminated infections in fetuses and untreated AIDS patients. Eimeria is a major pathogen of commercial chickens. Oocysts, which are the infectious form of Cryptosporidium and Eimeria and one of two infectious forms of Toxoplasma (the other is tissue cysts in undercooked meat), have a multilayered wall. Recently we showed that the inner layer of the oocyst walls of Toxoplasma and Eimeria is a porous scaffold of fibers of β-1,3-glucan, which are also present in fungal walls but are absent from Cryptosporidium oocyst walls. Here we present evidence for a structural role for lipids in the oocyst walls of Cryptosporidium, Toxoplasma, and Eimeria. Briefly, oocyst walls of each organism label with acid-fast stains that bind to lipids in the walls of mycobacteria. Polyketide synthases similar to those that make mycobacterial wall lipids are abundant in oocysts of Toxoplasma and Eimeria and are predicted in Cryptosporidium. The outer layer of oocyst wall of Eimeria and the entire oocyst wall of Cryptosporidium are dissolved by organic solvents. Oocyst wall lipids are complex mixtures of triglycerides, some of which contain polyhydroxy fatty acyl chains like those present in plant cutin or elongated fatty acyl chains like mycolic acids. We propose a two-layered model of the oocyst wall (glucan and acid-fast lipids) that resembles the two-layered walls of mycobacteria (peptidoglycan and acid-fast lipids) and plants (cellulose and cutin). IMPORTANCE Oocysts, which are essential for the fecal-oral spread of coccidia, have a wall that is thought responsible for their survival in the environment and for their transit through the stomach and small intestine. While oocyst walls of Toxoplasma and Eimeria are strengthened by a porous scaffold of fibrils of β-1,3-glucan and by proteins cross-linked by dityrosines, both are absent from walls of Cryptosporidium. We show here that all oocyst walls are acid fast, have a rigid bilayer, dissolve in organic solvents, and contain a complex set of triglycerides rich in polyhydroxy and long fatty acyl chains that might be synthesized by an abundant polyketide synthase. These results suggest the possibility that coccidia build a waxy coat of acid-fast lipids in the oocyst wall that makes them resistant to environmental stress.

PMID: 24003177

 

Exp Parasitol. 2013 Aug 30. pii: S0014-4894(13)00233-6. doi: 10.1016/j.exppara.2013.08.012. [Epub ahead of print]

A potential association between Toxoplasma gondii infection and schizophrenia in mouse models

Wang T, Tang ZH, Li JF, Li XN, Wang X, Zhao ZJ.

Source

Key Laboratory of Jiangxi Province for the Systems Biology Clinical Application, Jiujiang 33200, PR China; Department of Parasitology, School of Basic Medical Sciences, Jiujiang University, Jiujiang 33200, PR China. Electronic address: comwangtaocom@163.com.

Abstract

Schizophrenia is a serious neuropsychiatric disease of uncertain etiology, which causes human mental disorder and affects about 1% of the population. In recently years, some studies showed that some cases of schizophrenia may be associated with Toxoplasma gondii infection. In order to investigate a potential association between Toxoplasma infection and schizophrenia, we investigated the relative clinical symptom of schizophrenia such as learning and memory capability, depression and stereotypy to find some useful information by behavioral test in mouse models. Our results demonstrated that mice from Toxoplasma infection and MK-801 administration (as the model of schizophrenia) were impaired in learning and memory capability, and they had more serious depression and stereotypy compared with the control mice, especially the mice from congenital Toxoplasma infection. In addition, our results clearly showed that the number of cysts in brain tissue of congenital Toxoplasma infection mice was significantly low than in acquired Toxoplasma infected mice. Collectively, these results suggested a potential association between Toxoplasma infection and schizophrenia.
Copyright © 2013. Published by Elsevier Inc.

KEYWORDS:

Behavior, Mouse models, Schizophrenia, Toxoplasma gondii infection

PMID:

23999146

[PubMed - as supplied by publisher]

Clin Evid (Online). 2013 Aug 29;2013. pii: 0906.

Congenital toxoplasmosis

Kravetz J.

Source

Yale University, New Haven, CT, USA.

Abstract

INTRODUCTION:

Infection with Toxoplasma gondii is asymptomatic or mild in immunocompetent people and leads to lifelong immunity, but it can have serious consequences in pregnancy. About five per 1000 non-immune pregnant women may acquire toxoplasma infection, with a 10% to 100% risk of transmission to the baby. Risks of transmission to the baby are higher later in pregnancy, but risks of infection causing harm to the baby are greater earlier in pregnancy.

METHODS AND OUTCOMES:

We conducted a systematic review and aimed to answer the following clinical questions: What are the effects on mother and baby of treating toxoplasmosis during pregnancy to reduce risk of vertical transmission and treat fetal infection? What are the effects of treating toxoplasmosis in neonates infected with toxoplasmosis prenatally? We searched: Medline, Embase, The Cochrane Library, and other important databases up to June 2013 (Clinical Evidence reviews are updated periodically; please check our website for the most up-to-date version of this review). We included harms alerts from relevant organisations such as the US Food and Drug Administration (FDA) and the UK Medicines and Healthcare products Regulatory Agency (MHRA).

RESULTS:

We found six systematic reviews, RCTs, or observational studies that met our inclusion criteria. We performed a GRADE evaluation of the quality of evidence for interventions.

CONCLUSIONS:

In this systematic review we present information relating to the effectiveness and safety of the following interventions: antiparasitic drugs in pregnancy, and antiparasitic drugs in neonates.

PMID:

23987732

[PubMed - in process]

PLoS Pathog. 2013 Aug;9(8):e1003557. doi: 10.1371/journal.ppat.1003557. Epub 2013 Aug 22.

The Protein Kinase Double-Stranded RNA-Dependent (PKR) Enhances Protection against Disease Cause by a Non-Viral Pathogen

Ogolla PS, Portillo JA, White CL, Patel K, Lamb B, Sen GC, Subauste CS.

Source

Department of Pathology, Case Western Reserve University, Cleveland, Ohio, United States of America ; Division of Infectious Diseases and HIV Medicine, Department of Medicine, Case Western Reserve University School of Medicine, Cleveland, Ohio, United States of America.

Abstract

PKR is well characterized for its function in antiviral immunity. Using Toxoplasma gondii, we examined if PKR promotes resistance to disease caused by a non-viral pathogen. PKR(-/-) mice infected with T. gondii exhibited higher parasite load and worsened histopathology in the eye and brain compared to wild-type controls. Susceptibility to toxoplasmosis was not due to defective expression of IFN-γ, TNF-α, NOS2 or IL-6 in the retina and brain, differences in IL-10 expression in these organs or to impaired induction of T. gondii-reactive T cells. While macrophages/microglia with defective PKR signaling exhibited unimpaired anti-T. gondii activity in response to IFN-γ/TNF-α, these cells were unable to kill the parasite in response to CD40 stimulation. The TRAF6 binding site of CD40, but not the TRAF2,3 binding sites, was required for PKR phosphorylation in response to CD40 ligation in macrophages. TRAF6 co-immunoprecipitated with PKR upon CD40 ligation. TRAF6-PKR interaction appeared to be indirect, since TRAF6 co-immunoprecipitated with TRAF2 and TRAF2 co-immunoprecipitated with PKR, and deficiency of TRAF2 inhibited TRAF6-PKR co-immunoprecipitation as well as PKR phosphorylation induced by CD40 ligation. PKR was required for stimulation of autophagy, accumulation the autophagy molecule LC3 around the parasite, vacuole-lysosomal fusion and killing of T. gondii in CD40-activated macrophages and microglia. Thus, our findings identified PKR as a mediator of anti-microbial activity and promoter of protection against disease caused by a non-viral pathogen, revealed that PKR is activated by CD40 via TRAF6 and TRAF2, and positioned PKR as a link between CD40-TRAF signaling and stimulation of the autophagy pathway.

PMID:

23990781

[PubMed - in process]

PMCID:

PMC3749959