Emerging food-borne parasites

Vet Parasitol. 2009 Jun 6. [Epub ahead of print]

Emerging food-borne parasites

Dorny P, Praet N, Deckers N, Gabriel S.

Department of Animal Health, Institute of Tropical Medicine, 155 Nationalestraat, B-2000 Antwerp, Belgium.

Parasitic food-borne diseases are generally underrecognised, however they are becoming more common. Globalization of the food supply, increased international travel, increase of the population of highly susceptible persons, change in culinary habits, but also improved diagnostic tools and communication are some factors associated with the increased diagnosis of food-borne parasitic diseases worldwide. This paper reviews the most important emerging food-borne parasites, with emphasis on transmission routes. In a first part, waterborne parasites transmitted by contaminated food such as Cyclospora cayetanensis, Cryptosporidium and Giardia are discussed. Also human fasciolosis, of which the importance has only been recognised in the last decades, with total numbers of reported cases increasing from less than 3000 to 17 million, is looked at. Furthermore, fasciolopsiosis, an intestinal trematode of humans and pigs belongs to the waterborne parasites as well. A few parasites that may be transmitted through faecal contamination of foods and that have received renewed attention, such as Toxoplasma gondii, or that are (re-)emerging, such as Trypanosoma cruzi and Echinococcus spp., are briefly reviewed. In a second part, meat-borne parasite infections are reviewed. Humans get infected by eating raw or undercooked meat infected with cyst stages of these parasites. Meat inspection is the principal method applied in the control of Taenia spp. and Trichinella spp. However, it is often not very sensitive, frequently not practised, and not done for T. gondii and Sarcocystis spp. Meat of reptiles, amphibians and fish can be infected with a variety of parasites, including trematodes (Opisthorchis spp., Clonorchis sinensis, minute intestinal flukes), cestodes (Diphyllobothrium spp., Spirometra), nematodes (Gnathostoma, spp., anisakine parasites), and pentastomids that can cause zoonotic infections in humans when consumed raw or not properly cooked. Another important zoonotic food-borne trematode is the lungfluke (Paragonimus spp.). Traditionally, these parasitic zoonoses are most common in Asia because of the particular food practices and the importance of aquaculture. However, some of these parasites may emerge in other continents through aquaculture and improved transportation and distribution systems. Because of inadequate systems for routine diagnosis and monitoring or reporting for many of the zoonotic parasites, the incidence of human disease and parasite occurrence in food is underestimated. Of particular concern in industrialised countries are the highly resistant waterborne protozoal infections as well as the increased travel and immigration, which increase the exposure to exotic diseases. The increased demand for animal proteins in developing countries will lead to an intensification of the production systems in which the risk of zoonotic infections needs to be assessed. Overall, there is an urgent need for better monitoring and control of food-borne parasites using new technologies.

PMID: 19559535 [PubMed - as supplied by publisher]

A novel family Of apicomplexan glideosome associated proteins With an inner-membrane anchoring role

J Biol Chem. 2009 Jun 26. [Epub ahead of print]

A novel family Of apicomplexan glideosome associated proteins With an inner-membrane anchoring role

Bullen HE, Tonkin CJ, O'Donnell RA, Tham WH, Papenfuss AT, Gould S, Cowman AF, Crabb BS, Gilson PR.

The Burnet Institute, Australia;

The phylum Apicomplexa are a group of obligate intracellular parasites responsible for a wide range of important diseases. Central to the lifecycle of these unicellular parasites is their ability to migrate through animal tissue and invade target host cells. Apicomplexan movement is generated by a unique system of gliding motility in which substrate adhesins and invasion-related proteins are pulled across the plasma membrane by an underlying actin-myosin motor. The myosins of this motor are inserted into a dual membrane layer called the inner membrane complex (IMC) that is sandwiched between the plasma membrane and an underlying cytoskeletal basket. Central to our understanding of gliding motility is the characterisation of proteins residing within the IMC but to date only a few proteins are known. We report here a novel family of six-pass-transmembrane proteins, termed the GAPM family, which are highly conserved and specific to Apicomplexa. In Plasmodium falciparum and Toxoplasma gondii the GAPMs localise to the IMC where they form highly SDS-resistant oligomeric complexes. The GAPMs co-purify with the cytoskeletal alveolin proteins and also to some degree with the actin-myosin motor itself. Hence, these proteins are strong candidates for an IMC anchoring role, either directly or indirectly tethering the motor to the cytoskeleton.

PMID: 19561073 [PubMed - as supplied by publisher]

Toxoplasma gondii: host-parasite interaction and behavior manipulation

Parasitol Res. 2009 Jun 23. [Epub ahead of print]

Toxoplasma gondii: host-parasite interaction and behavior manipulation

da Silva RC, Langoni H.

Department of Veterinary Hygiene and Animal Science (DHVSP), College of Veterinary Medicine and Animal Science (FMVZ), São Paulo State University (UNESP), Campus of Botucatu, Botucatu, São Paulo, Brazil, silva_rcd@yahoo.com.br.

Toxoplasma gondii is an obligate intracellular parasite that causes different lesions in men and other warm-blooded animals. Humoral and cellular immune response of the host against the parasite keeps the protozoan in a latent stage, and clinical disease ensues when immunological response is compromised. Brain parasitism benefits the parasite causing behavioral changes in the host, not only in animals but also in humans. Schizophrenia and epilepsy are two neurological disorders that have recently been reported to affect humans coinfected with T. gondii. Further studies based on host-parasite interaction in several wild or domestic warm-blooded species are still necessary in order to better understand parasitism and behavioral changes caused by T. gondii.

PMID: 19548003 [PubMed - as supplied by publisher]

The IFN-gamma +874T/A gene polymorphism is associated with retinochoroiditis toxoplasmosis susceptibility

Mem Inst Oswaldo Cruz. 2009 May;104(3):451-5

The IFN-gamma +874T/A gene polymorphism is associated with retinochoroiditis toxoplasmosis susceptibility

de Albuquerque MC, Aleixo AL, Benchimol EI, Leandro AC, das Neves LB, Vicente RT, Bonecini-Almeida Mda G, Amendoeira MR.

Laboratório de Toxoplasmose, Instituto Oswaldo Cruz, Fiocruz, Rio de Janeiro, RJ, Brasil.

Toxoplasmosis is a worldwide zoonosis that generally produces an asymptomatic infection. In some cases, however, toxoplasmosis infection can lead to ocular damage. The immune system has a crucial role in both the course of the infection and in the evolution of toxoplasmosis disease. In particular, IFN-gamma plays an important role in resistance to toxoplasmosis. Polymorphisms in genes encoding cytokines have been shown to have an association with susceptibility to parasitic diseases. The aim of this work was to analyse the occurrence of polymorphisms in the gene encoding IFN-gamma (+874T/A) among Toxoplasma gondii seropositive individuals, including those with ocular lesions caused by the parasite, from a rural population of Santa Rita de Cássia, Barra Mansa, state of Rio de Janeiro, Brazil. Further, we verified which of these polymorphisms could be related to susceptibility to the development of ocular toxoplasmosis. This study included 34 individuals with ocular toxoplasmosis (ocular group) and 134 without ocular lesions (control group). The differences between A and T allele distributions were not statistically significant between the two groups. However, we observed that a higher frequency of individuals from the ocular group possessed the A/A genotype, when compared with the control group, suggesting that homozygocity for the A allele could enhance susceptibility to ocular toxoplasmosis in T. gondii infection.

Publication Types:
Research Support, Non-U.S. Gov't

PMID: 19547871 [PubMed - in process]

In vitro culture combined with quantitative TaqMan PCR for the assessment of Toxoplasma gondii tissue cyst viability

Vet Parasitol. 2009 Jun 6. [Epub ahead of print]

In vitro culture combined with quantitative TaqMan PCR for the assessment of Toxoplasma gondii tissue cyst viability

Zintl A, Halova D, Mulcahy G, O'Donovan J, Markey B, Dewaal T.

School of Agriculture, Food Science and Veterinary Medicine, University College Dublin, Belfield, Dublin 4, Ireland.

Toxoplasma gondii is a serious food-borne pathogen with a worldwide distribution. In order to assess the risk of contracting toxoplasmosis from certain foods, many studies rely on the molecular detection of T. gondii DNA. However, determining the viability of parasites in positive samples is much more problematic. In this paper we describe a novel viability assay that relies on semi-quantitative comparison of the amount of parasite DNA present in samples used to infect host cell monolayers in vitro, and the amount of DNA detected in the same monolayers after 23 days incubation. Our assay is robust, easy to perform and interpret and offers a viable alternative to bioassays, for use in epidemiological studies, or the evaluation of specific food safety treatments.

PMID: 19545946 [PubMed - as supplied by publisher]

Toxoplasma gondii: Proteomic analysis of antigenicity of soluble tachyzoite antigen

Exp Parasitol. 2009 Jan 29. [Epub ahead of print]

Toxoplasma gondii: Proteomic analysis of antigenicity of soluble tachyzoite antigen

Ma GY, Zhang JZ, Yin GR, Zhang JH, Meng XL, Zhao F.

Research Institute of Medical Parasitology, Shanxi Medical University, P. R. China; National Institute for Communicable Disease Control and Prevention (ICDC), Chinese Center for Disease Control and Prevention (China CDC), P. R. China.

The obligate intracellular parasite Toxoplasma gondii is an important pathogen of humans and animals. The tachyzoite of T. gondii is the main life-cycle stage that is responsible for toxoplasmosis. Study of the antigenicity of soluble tachyzoite antigen (STAg) is important for discovery of protective antigens which will aid in the detection and prevention of toxoplasmosis. At present, no complete proteome map of T. gondii STAg is established, although a large-scale whole proteomic analysis of tachyzoites is underway. In this study, 1227 protein spots of T. gondii soluble tachyzoite antigen (STAg) were fractionated by 2-dimensional electrophoresis (2-DE) at pH range 3-10. By mass spectrometry (MS) analysis, among the separated 1227 protein spots, 426 were identified by searching the Swissport and NCBI nr databases. 230 of these identified spots (230/426, 54%) were demonstrated to be T. gondii protein by MS. Of the 21 Toxoplasma protein spots identified by western blot with rabbit anti-T. gondii serum, 16 had immunoregulatory functions and 5 had immune defense functions. Due to multiple spots for a single protein, these 16 spots represented 11 proteins: a putative protein disulfide isomerase (PDIs), a heat shock protein 60 (Hsp60), a pyruvate kinase (PK), a putative glutamate dehydrogenase (GDH), a coronin, a heat shock protein 70 (Hsp70), a protein kinase C receptor 1 (RACK1), a malate dehydrogenase (MDH), a major surface antigen 1 (SAG1), an uridine phosphorylase (UPase) and a peroxiredoxin (Prx). Among the identified 11 proteins, except that the antigenicity and immunogenicity of the SAG1 has been reported and antigenicity of Hsp70 has disputed, the remaining antigenic proteins were first identified in this study. In conclusion, we obtained 9 novel types of immunogenic proteins that might be potential candidates of vaccine development for toxoplasmosis, which we will confirm in later studies.

PMID: 19545523 [PubMed - as supplied by publisher]

Toxoplasma gondii: Sensitive and rapid detection of infection by loop-mediated isothermal amplification (LAMP) method

Exp Parasitol. 2009 Jan 31. [Epub ahead of print]

Toxoplasma gondii: Sensitive and rapid detection of infection by loop-mediated isothermal amplification (LAMP) method

Zhang H, M Thekisoe OM, Aboge GO, Kyan H, Yamagishi J, Inoue N, Nishikawa Y, Zakimi S, Xuan X.

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

Loop-mediated isothermal amplification (LAMP) method amplifies DNA with high specificity, sensitivity and rapidity. In this study, we used a conserved sequence in the 200 to 300 fold repetitive 529 bp gene of Toxoplasma gondii to design primers for LAMP test. Detection limit of T. gondii LAMP assay with the primers is 1 pg/muL of T. gondii DNA, which was evaluated using ten-fold serially diluted DNA of cultured parasites. Furthermore, LAMP and conventional PCR methods were applied for amplification of the T. gondii DNA extracted from the lymph nodes taken from pigs which were suspected to be Toxoplasma infection. As a result, 76.9% (70/91) and 85.7% (78/91) of the samples were positive on PCR and LAMP analyses, respectively. Therefore, the LAMP has a potential to be applied as an alternative molecular diagnostic tool for detection of T. gondii infection from veterinary samples. This is the first study, which applies the LAMP method to diagnose Toxoplasma from veterinary samples.

PMID: 19545521 [PubMed - as supplied by publisher]

Over-expression of lactate dehydrogenase enhances differentiation under alkaline conditions

Exp Parasitol. 2009 Feb 5. [Epub ahead of print]

Toxoplasma gondii : over-expression of lactate dehydrogenase enhances differentiation under alkaline conditions

Liwak U, Ananvoranich S.

Department of Chemistry and Biochemistry, University of Windsor, 401 Sunset Avenue, Windsor, ON, N9B 3P4, Canada.

Toxoplasma gondii, an intracellular parasite, has two distinctive growth stages, namely rapidly growing tachzyoites and slowly growing bradyzoites. Here we report a unique physiological function of the last committed glycolytic enzyme of T. gondii, lactate dehydrogenase (TgLDH), which is present in two isoforms and expressed in a stage-specific manner. TgLDH1 is present in tachyzoites while TgLDH2 is found in bradyzoites. Using clonal transgenic parasites over-expressing either TgLDH1 or TgLDH2, we showed that the enzymatic activity, growth and virulence of tachyzoites were unaffected by the presence of the recombinant protein. Interestingly, under alkaline conditions the presence of the recombinant TgLDH proteins increased the differentiation, as detected by the formation of cyst structures in vitro, while green fluorescent protein did not. The differentiation enhancement of the recombinant TgLDH1 and TgLDH2 strongly suggests that TgLDH1 and TgLDH2 have an important physiological function, in addition to being glycolytic enzymes and differentiation markers.

PMID: 19545518 [PubMed - as supplied by publisher]

Persistent toxoplasma bradyzoite cysts in the brain

Clin Neuropathol. 2009 May-Jun;28(3):210-2

Persistent toxoplasma bradyzoite cysts in the brain: incidental finding in an immunocompetent patient without evidence of a toxoplasmosis

Pusch L, Romeike B, Deckert M, Mawrin C.

Department of Neuropathology, Friedrich-Schiller University, Jena, Germany.

We report on a 72-year-old patient in whom autopsy demonstrated incidentally intracerebral Toxoplasma gondii cysts, locally restricted in the occipital lobe, in association with only a few CD4+ and CD8+ T cells and a mild microglial activation. The patient was HIV-negative. Serologically, there was no evidence for an active inflammation (Toxoplasma gondii specific antibody IgG-positive, IgM-negative). This unusual observation may indicate that in patients with sepsis, who may yield to a state of immunodysbalance, a focal reactivation of parasites may ensue in the absence of conditions predisposing for opportunistic infection.

PMID: 19537140

Role of the parasite and host cytoskeleton in apicomplexa parasitism

Cell Host Microbe. 2009 Jun 18;5(6):602-11

Role of the parasite and host cytoskeleton in apicomplexa parasitism

Frénal K, Soldati-Favre D.

Department of Microbiology and Molecular Medicine, CMU, University of Geneva, 1 rue Michel-Servet, 1211 Geneva 4, Switzerland.

The phylum Apicomplexa includes a large and diverse group of obligate intracellular parasites that rely on actomyosin-based motility to migrate, enter host cells, and egress from infected cells. To ensure their intracellular survival and replication, the apicomplexans have evolved sophisticated strategies for subversion of the host cytoskeleton. Given the properties in common between the host and parasite cytoskeleton, dissecting their individual contribution to the establishment of parasitic infection has been challenging. Nevertheless, recent studies have provided new insights into the mechanisms by which parasites subvert the dynamic properties of host actin and tubulin to promote their entry, development, and egress.

PMID: 19527887 [PubMed - in process]

Kinetics and phenotype of vaccine-induced CD8+ T cell responses to Toxoplasma

Infect Immun. 2009 Jun 15. [Epub ahead of print]

Kinetics and phenotype of vaccine-induced CD8+ T cell responses to Toxoplasma gondii

Jordan KA, Wilson EH, Tait ED, Fox BA, Roos DS, Bzik DJ, Dzierszinski F, Hunter CA.

Department of Pathobiology, University of Pennsylvania, 380 South University Ave, Philadelphia, PA 19104, USA; Division of Biomedical Sciences, University of California, Riverside, 900 University Ave, Riverside, CA 92521, USA; Department of Microbiology and Immunology, Dartmouth Medical School, 1 Medical Center Drive, Lebanon, HH 03756; Department of Biology, 304B Carolyn Lynch Laboratories, University of Pennsylvania, 380 South University Ave, Philadelphia, PA 19104, USA; Institute of Parasitology, McGill University, 21111 Lakeshore Road, Sainte-Anne-de-Bellevue, Québec H9X 3V9, Canada.

Multiple studies have established that the ability of CD8(+) T cells to act as cytolytic effectors and produce IFN-gamma is important in mediating resistance to the intracellular parasite Toxoplasma gondii. To better understand the generation of the antigen-specific CD8(+) T cell responses induced by T. gondii, mice were immunized with replication-deficient parasites that express the model antigen ovalbumin. Class I tetramers specific for SIINFEKL were used to track the OVA-specific endogenous CD8(+) T cells. The peak CD8(+) T cell response was found at day 10 post-immunization, after which the frequency and numbers of antigen-specific cells declined. Unexpectedly, replication-deficient parasites were found to induce antigen-specific cells with faster kinetics than replicating parasites. Generation of optimal numbers of antigen-specific CD8(+) effector T cells was found to require CD4(+) T cell help. At 7 days following immunization, antigen-specific cells were found to be CD62L(low), KLRG1(+) and CD127(low), and maintained this phenotype for more than 70 days. Antigen-specific CD8(+) effectors T cells in immunized mice exhibited potent perforin-dependent OVA-specific cytolytic activity in vivo. Perforin-dependent cytolysis appeared to be the major cytolytic mechanism; however, a perforin-independent pathway that was not mediated via Fas-FasL was also detected. This study provides further insight into vaccine-induced cytotoxic T lymphocyte (CTL) responses that correlate with protective immunity to T. gondii, and identifies a critical role for CD4(+) T cells in the generation of protective CD8(+) T cell responses.

PMID: 19528214 [PubMed - as supplied by publisher]

Evolving insights into protein trafficking to the multiple compartments of the apicomplexan plastid

J Eukaryot Microbiol. 2009 May-Jun;56(3):214-20

Evolving insights into protein trafficking to the multiple compartments of the apicomplexan plastid

Parsons M, Karnataki A, Derocher AE.

Seattle Biomedical Research Institute, Washington 98109, USA. marilyn.parsons@sbri.org

The apicoplast is a relict plastid found in many medically important apicomplexan parasites, such as Plasmodium and Toxoplasma. Phylogenetic analysis and the presence of four bounding membranes indicate that the apicoplast arose from a secondary endosymbiosis. Here we review what has been discovered about the complex journey proteins take to reach compartments of the apicoplast. The targeting sequences for luminal proteins are well-defined, but those routing proteins to other compartments are only beginning to be studied. Recent work suggests that the trafficking mechanisms involve a variety of molecules of different phylogenetic origins. We highlight some remaining questions regarding protein trafficking to this divergent organelle.

Publication Types:
Research Support, N.I.H., Extramural

PMID: 19527348 [PubMed - in process]

The role of acidocalcisomes in parasitic protists

J Eukaryot Microbiol. 2009 May-Jun;56(3):208-13

The role of acidocalcisomes in parasitic protists

Moreno SN, Docampo R.

Department of Cellular Biology and Center for Tropical and Global Emerging Diseases, University of Georgia, Athens, 30602, USA. smoreno@cb.uga.edu

Acidocalcisomes are acidic organelles with a high concentration of phosphorus present as pyrophosphate (PP(i)) and polyphosphate (poly P) complexed with calcium and other cations. The acidocalcisome membrane contains a number of pumps (Ca(2+)-ATPase, V-H(+)-ATPase, H(+)-PPase), exchangers (Na(+)/H(+), Ca(2+)/H(+)), and channels (aquaporins), while its matrix contains enzymes related to PP(i) and poly P metabolism. Acidocalcisomes have been observed in pathogenic, as well as non-pathogenic prokaryotes and eukaryotes, e.g. Chlamydomonas reinhardtii, and Dictyostelium discoideum. Some of the potential functions of the acidocalcisome are the storage of cations and phosphorus, the participation of phosphorus in PP(i) and poly P metabolism, calcium homeostasis, maintenance of intracellular pH homeostasis, and osmoregulation. In addition, acidocalcisomes resemble lysosome-related organelles (LRO) from mammalian cells in many of their properties. For example, we found that platelet dense granules, which are LROs, are very similar to acidocalcisomes. They share a similar size, acidic properties, and both contain PP(i), poly P, and calcium. Recent work that indicates that they also share the system for targeting of their membrane proteins through adaptor protein 3 reinforces this concept. The fact that acidocalcisomes interact with other organelles in parasitic protists, e.g. the contractile vacuole in Trypanosoma cruzi, and other vacuoles observed in Toxoplasma gondii, suggests that these cellular compartments may be associated with the endosomal/lysosomal pathway.

Publication Types:
Research Support, N.I.H., Extramural

PMID: 19527347 [PubMed - in process]

Plants, endosymbionts and parasites: Abscisic acid and calcium signaling

Commun Integr Biol. 2008 Jul;1(1):62-5.

Plants, endosymbionts and parasites: Abscisic acid and calcium signaling

Nagamune K, Xiong L, Chini E, Sibley LD.

Graduate School of Life and Environmental Sciences; University of Tsukuba; Tsukuba, Ibaraki, Japan.

It was recently discovered that the protozoan parasite, Toxoplasma gondii produces and uses the plant hormone, abscisic acid (ABA), for communication. Following intracellular replication, ABA production influences the timing of parasite egress from the host cell. This density-dependent signal may serve to coordinate exit from the host cell in a synchronous manner by triggering calcium-dependent activation of motility. In the absence of ABA production, parasites undergo differentiation to the semidormant, tissue cyst. The pathway for ABA production in T. gondii may be derived from a relict endosymbiont, acquired by ingestion of a red algal cell. Although the parasite has lost the capacity for photosynthesis, the plant-like nature of this signaling pathway may be exploited to develop new drugs. In support of this idea, an inhibitor of ABA biosynthesis protected mice against lethal infection with T. gondii. Here, we compare the role of ABA in parasites to its activities in plants, where it is know to control development and stress responses.

PMID: 19513200 [PubMed - in process]

Mic1-3KO tachyzoite a live attenuated vaccine candidate against toxoplasmosis derived from a type I strain shows features of type II strain

Exp Parasitol. 2009 Jun 6. [Epub ahead of print]

Mic1-3KO tachyzoite a live attenuated vaccine candidate against toxoplasmosis derived from a type I strain shows features of type II strain

Moiré N, Dion S, Lebrun M, Dubremetz JF, Poisson ID.

Université François Rabelais de Tours, INRA UMR 483 Université-INRA d'Immunologie Parasitaire et Vaccinologie, Biothérapie anti-infectieuse, IFR agents transmissibles et infectiologie, UFR de Pharmacie, Parc Grandmont, 37200 Tours. FRANCE.

Vaccination with live attenuated parasites has been shown to induce high level of protection against Toxoplasma gondii. In this study we compared the Mic1-3KO tachyzoite (a live attenuated strain) with the parental wild type (WT) tachyzoite in terms of virulence in mice in vivo, dissemination in mouse tissues and persistence in mouse brain. Survival of mice infected with the Mic1-3KO parasites correlated with reduced parasite burden in mouse tissues compared to the parental strain. Like the WT parasite, Mic1-3KO is able to form tissue cysts in vivo which are not, in our experimental conditions, infectious when given by oral route. Infection with the attenuated tachyzoite induced lower levels of cytokine and chemokine than with the parental strain. These data demonstrate that the deleted strain derived from a type I strain behaves like type II strain in outbred mice in terms of virulence, dissemination in mouse tissue and persistence in brain.

PMID: 19508866 [PubMed - as supplied by publisher]

Immunogenic and protective efficacy of recombinant ROP2 and ROP4 rhoptry proteins in murine experimental toxoplasmosis

Exp Parasitol. 2009 Jun 6. [Epub ahead of print]

Toxoplasma gondii: the immunogenic and protective efficacy of recombinant ROP2 and ROP4 rhoptry proteins in murine experimental toxoplasmosis

Dziadek B, Gatkowska J, Brzostek A, Dziadek J, Dzitko K, Dlugonska H.

Department of Immunoparasitology, University of Lodz, Lodz, Poland.

Toxoplasmosis is a one of the most world-wide spread zoonosis representing a very serious clinical and veterinary problem. In the presented study we evaluated the protective efficacy of a combined recombinant ROP2 and ROP4 subunit vaccine in a chronic Toxoplasma gondii infection in mice. The recombinant ROP2 (rROP2) and ROP4 (rROP4) proteins were cloned and expressed in Escherichia coli and then used for the immunization of C3H/HeJ mice. Both antigens generated a strong systemic mixed Th1/Th2 response polarized towards IgG1 antibody isotype. In contrast to rROP2 stimulating only the specific IL-2 release, rROP4 and crude TLA (Toxoplasma Lysate Antigen) used as a source of native forms of the parasite proteins induced significant proliferation of splenocytes and specific production of IFN-gamma as well as IL-2, the Th1 type cytokines. Challenge of rROP2 and rROP4-vaccinated mice with cysts of low virulent T. gondii DX strain resulted in a partial protection effect with a significantly lower brain parasites load when compared with control animals. In the immunized group of mice the brain cysts number was reduced by nearly 46% as was determined in two independent experiments. These results suggest that, similar to ROP2, rhoptry protein ROP4 could be a very good candidate for future anti-T. gondii multicomponent vaccine based on the recombinant forms of different parasite proteins.

PMID: 19508869 [PubMed - as supplied by publisher]

The role of IFN- gamma TNFRp55 and iNOS in inflammatory changes during infection

Exp Parasitol. 2009 Jun 3. [Epub ahead of print]

Toxoplasma gondii: The role of IFN- gamma TNFRp55 and iNOS in inflammatory changes during infection

Silva NM, Vieira JC, Carneiro CM, Tafuri WL.

Immunopathology Laboratory, Institute of Biomedical Sciences, Universidade Federal de Uberlândia, 38 400-902, Uberlândia, Minas Gerais, Brazil.

In order to examine the role of IFN-gamma, TNFRp55 and iNOS in inflammatory reaction during toxoplasmosis, IFN-gamma(-/-), TNFRp55(-/-) and iNOS(-/-) mice were experimentally infected with Toxoplasma gondii ME-49 strain. The organs of the mice were evaluated for histology and immunohistochemistry in detection of tissue parasitism and iNOS positive cells. IFN-gamma(-/-) mice presented mild inflammation in peripheral organs associated with a high parasitism and mortality in the acute phase of infection. In contrast, the peripheral organs of WT, TNFRp55(-/-) and iNOS(-/-) mice, presented a significant inflammatory reaction and low tissue parasitism in the same period of infection. The inflammatory lesions and tissue parasitism were increased and more severe in the Central Nervous System (CNS) of TNFRp55(-/-) and iNOS(-/-) with a progression of infection, when compared to WT mice. In these knockout animals, the inflammatory changes were associated with low levels or no expression of iNOS in TNFRp55(-/-) and iNOS(-/-) mice, respectively.

PMID: 19501090 [PubMed - as supplied by publisher]

UHRF1 as a drug target in cancers and toxoplasmosis

Biochem Pharmacol. 2009 Jun 3. [Epub ahead of print]

Drug discovery targeting epigenetic codes: The great potential of UHRF1, which links DNA methylation and histone modifications, as a drug target in cancers and toxoplasmosis

Unoki M, Brunet J, Mousli M.

Laboratory for Biomarker Development, The Institute of Physical and Chemical Research Center for Genomic Medicine, RIKEN, Tokyo 108-8639, Japan.

UHRF1 plays a central role in transferring methylation status from mother cells to daughter cells. Its SRA domain recognizes hemi-methylated DNA that appears in daughter DNA strands during duplication of DNA. UHRF1 recruits DNMT1 to the site and methylates both strands. UHRF1 also binds to HDAC1 and di- and tri-methyl K9 histone H3, ubiquitinates histone H3, and associates with heterochromatin formation, indicating that UHRF1 links histone modifications, DNA methylation, and chromatin structure. UHRF1 is a direct target of E2F1 and promotes G1/S transition. The tumor suppressor p53, which is deficient in 50% of cancers, down-regulates UHRF1 through up-regulation of p21/WAF1 and subsequent deactivation of E2F1. The expression levels of UHRF1 are up-regulated in many cancers, probably partially because of the absence of wild type p53, but it is probably regulated by several other factors. Knockdown of UHRF1 expression in cancer cells suppressed cell growth, suggesting that UHRF1 can be a useful anticancer drug target. Recently, it was revealed that UHRF1 plays important roles not only in carcinogenesis, but also in toxoplasmosis, which is occasionally fatal to people with a weakened immune system, and can cause blindness in the major pathology of ocular toxoplasmosis. Toxoplasma gondii, which causes toxoplasmosis, utilizes UHRF1 to control the cell cycle phase and enhance its proliferation. Thus, knockdown of UHRF1 can be effective at stopping the proliferation of the parasites in infected cells. In this review, we discuss several possible methods that can inhibit the multiple unique functions of UHRF1, which can be utilized for treating cancers and toxoplasmosis.

PMID: 19501055 [PubMed - as supplied by publisher]

Toxoplasma gondii proteomics

Expert Rev Proteomics. 2009 Jun;6(3):303-13

Toxoplasma gondii proteomics

Weiss LM, Fiser A, Angeletti RH, Kim K.

Division of Infectious Diseases, Department of Medicine, Albert Einstein College of Medicine, 1300 Morris Park Avenue, Forchheimer 504, 1300 Morris Park Avenue, Bronx, NY 10461, USA. lmweiss@aecom.yu.edu

Toxoplasma gondii is a ubiquitous, Apicomplexan parasite that, in humans, can cause several clinical syndromes, including encephalitis, chorioretinitis and congenital infection. T. gondii was described a little over 100 years ago in the tissues of the gundi (Ctenodoactylus gundi). There are a large number of applicable experimental techniques available for this pathogen and it has become a model organism for the study of intracellular pathogens. With the completion of the genomes for a type I (GT-1), type II (ME49) and type III (VEG) strains, proteomic studies on this organism have been greatly facilitated. Several subcellular proteomic studies have been completed on this pathogen. These studies have helped elucidate specialized invasion organelles and their composition, as well as proteins associated with the cytoskeleton. Global proteomic studies are leading to improved strategies for genome annotation in this organism and an improved understanding of protein regulation in this pathogen. Web-based resources, such as EPIC-DB and ToxoDB, provide proteomic data and support for studies on T. gondii. This review will summarize the current status of proteomic research on T. gondii.

Publication Types:
Research Support, N.I.H., Extramural
Research Support, U.S. Gov't, Non-P.H.S.

PMID: 19489701 [PubMed - in process]

Selection of polymorphic peptides from GRA6 and GRA7 sequences of Toxoplasma gondii strains to be used in serotyping

Clin Vaccine Immunol. 2009 Jun 3. [Epub ahead of print]

Selection of polymorphic peptides from GRA6 and GRA7 sequences of Toxoplasma gondii strains to be used in serotyping

Sousa S, Ajzenberg D, Marle M, Aubert D, Villena I, Correia da Costa J, Dardé ML.

Center for Parasite Immunology and Biology, INSA, 4000-055 Porto, Portugal; Laboratoire de Parasitologie-Mycologie, EA 3174-NETEC, Faculté de Médecine, Université de Limoges, Limoges, 87025, France; Laboratoire Parasitologie-Mycologie, EA 3800, CHU Reims, 51 rue Cognacq-Jay, 51095 Reims Cedex, France; Centre National de Référence (CNR) Toxoplasmose/Toxoplasma Biological Resource Center (BRC).

Toxoplasma gondii isolates obtained from other geographical environments than Europe and North America revealed the existence of atypical strains that are not included in the 3 archetypal clonal lineages (I, II, III). GRA6 and GRA7 are polymorphic genes that have been used for Toxoplasma genotyping. The coding region of GRA6 and GRA7 from 49 non-archetypal strains was sequenced and compared with type I, II and III reference strains. Eighteen and ten different amino acid sequences were found for GRA6 and GRA7 respectively. The polymorphisms found between the different sequences were analysed, with the objective to define peptides to be used in serotyping of Toxoplasma infections. Two peptides specific for clonal lineages I and III were selected from GRA7 locus (GRA7I and GRA7III). Three peptides, specific for some atypical strains were selected from both GRA6 and GRA7 loci (Am6, Af6 and Am7). Serum samples from humans infected with Toxoplasma strains with known genotype were serotyped with the selected peptides. Peptide GRA7III seems to be a good candidate for serotyping type III infections. Peptide GRA7I had a very low sensitivity. Peptides Am6 and Af6 had low specificity, since they reacted with serum samples from patients infected with strains belonging to the three archetypal lineages. Peptide Am7, although specific had low sensitivity.

PMID: 19494084 [PubMed - as supplied by publisher]