Copaifera spp. oleoresins impair Toxoplasma gondii infection in both human trophoblastic cells and human placental explants.

The combination of pyrimethamine and sulfadiazine is the standard care in cases of congenital toxoplasmosis. However, therapy with these drugs is associated with severe and sometimes life-threatening side effects. The investigation of phytotherapeutic alternatives to treat parasitic diseases without acute toxicity is essential for the advancement of current therapeutic practices. The present study investigates the antiparasitic effects of oleoresins from different species of Copaifera genus against T. gondii. Oleoresins from C. reticulata, C. duckei, C. paupera, and C. pubiflora were used to treat human trophoblastic cells (BeWo cells) and human villous explants infected with T. gondii. Our results demonstrated that oleoresins were able to reduce T. gondii intracellular proliferation, adhesion, and invasion. We observed an irreversible concentration-dependent antiparasitic action in infected BeWo cells, as well as parasite cell cycle arrest in the S/M phase. The oleoresins altered the host cell environment by modulation of ROS, IL-6, and MIF production in BeWo cells. Also, Copaifera oleoresins reduced parasite replication and TNF-α release in villous explants. Anti-T. gondii effects triggered by the oleoresins are associated with immunomodulation of the host cells, as well as, direct action on parasites.

Treatment with Lycopodium clavatum 200dH Intensifies Kidney and Liver Injury in Mice Infected with Toxoplasma gondii.

The effects of infection with Toxoplasma gondii vary from asymptomatic to the development of alterations in various organs (including the liver and kidneys) which may be irreversible, and lead to the death of the host. Whereas homeopathy is an alternative and effective method for treating various diseases, including those caused by protozoa, we questioned the effect of using Lycopodium clavatum in mice infected with T. gondii. One hundred male Swiss mice, 60 days old, were divided into four groups (n = 25/group): NIC (uninfected and untreated control), IC (infected and treated with un-dynamized 7% alcohol solution [vehicle]), G48 (infected and treated 48 h before infection and treated three more times; at 2, 4, and 6 days post-infection (dpi) with L. clavatum 200dH), and G72 (infected and treated for 3 consecutive days before infection with L. clavatum 200dH). In this study, physiological, histopathological, and immunological parameters were evaluated. The L. clavatum 200dH intensified renal damage in mice infected with T. gondii from 7 dpi, causing severe and progressive alterations during this period, such as various degrees of inflammation, edema, atrophy, and tubular cystic dilation, degenerated tubules with intra-cytoplasmic vacuoles and coalescing spots, severe vascular lesions, glomerulonephritis, and peri-glomerular congestion. In the G72 animals, which received L. clavatum 200dH, more severe cortex damage was observed (91.66-96.66%) as compared to the IC group (55-80%) and more renal corpuscle, and renal tubule injury was observed (80 ± 5 to 96.7% ± 2.89 of the total area) during all periods, as compared to the IC group (p < 0.05). Both groups presented high liver enzyme levels, and the highest values for AST were observable at 60 dpi. We observed significant increases of type I and III collagen, as well as high levels of TGF-ß1 in both organs of the treated animals, the main factor involved in fibrosis in areas damaged by the process. L. clavatum 200dH intensifies kidney and liver alterations in mice infected with T. gondii. Our results reinforce caution when indicating administration schemes and dosages for ultra-diluted drugs.

Intestinal delta-6-desaturase activity determines host range for Toxoplasma sexual reproduction.

Many eukaryotic microbes have complex life cycles that include both sexual and asexual phases with strict species specificity. Whereas the asexual cycle of the protistan parasite Toxoplasma gondii can occur in any warm-blooded mammal, the sexual cycle is restricted to the feline intestine. The molecular determinants that identify cats as the definitive host for T. gondii are unknown. Here, we defined the mechanism of species specificity for T. gondii sexual development and break the species barrier to allow the sexual cycle to occur in mice. We determined that T. gondii sexual development occurs when cultured feline intestinal epithelial cells are supplemented with linoleic acid. Felines are the only mammals that lack delta-6-desaturase activity in their intestines, which is required for linoleic acid metabolism, resulting in systemic excess of linoleic acid. We found that inhibition of murine delta-6-desaturase and supplementation of their diet with linoleic acid allowed T. gondii sexual development in mice. This mechanism of species specificity is the first defined for a parasite sexual cycle. This work highlights how host diet and metabolism shape coevolution with microbes. The key to unlocking the species boundaries for other eukaryotic microbes may also rely on the lipid composition of their environments as we see increasing evidence for the importance of host lipid metabolism during parasitic lifecycles. Pregnant women are advised against handling cat litter, as maternal infection with T. gondii can be transmitted to the fetus with potentially lethal outcomes. Knowing the molecular components that create a conducive environment for T. gondii sexual reproduction will allow for development of therapeutics that prevent shedding of T. gondii parasites. Finally, given the current reliance on companion animals to study T. gondii sexual development, this work will allow the T. gondii field to use of alternative models in future studies.

The 14th International Workshops on Opportunistic Protists (IWOP 14).

The 14th International Workshops on Opportunistic Protists (IWOP-14) was held August 10-12, 2017 in Cincinnati, OH, USA. The IWOP meetings focus on opportunistic protists (OIs); for example, free-living amoebae, Pneumocystis spp., Cryptosporidium spp., Toxoplasma, the Microsporidia, and kinetoplastid flagellates. The highlights of Pneumocystis spp. research included the reports of primary homothallism for mating; a potential requirement for sexual replication in its life cycle; a new antigen on the surface of small asci; roles for CLRs, Dectin-1, and Mincle in host responses; and identification of MSG families and mechanisms used for surface variation. Studies of Cryptosporidia spp. included comparative genomics, a new cryopreservation method; the role of mucin in attachment and invasion, and epidemiological surveys illustrating species diversity in animals. One of the five identified proteins in the polar tube of Microsporidia, PTP4, was shown to play a role in host infection. Zebrafish were used as a low cost vertebrate animal model for an evaluation of potential anti-toxoplasma drugs. Folk medicine compounds with anti-toxoplasma activity were presented, and reports on the chronic toxoplasma infection provided evidence for increased tractability for the study of this difficult life cycle stage. Escape from the parasitophorus vacuole and cell cycle regulation were the topics of the study in the acute phase.

Lectins from Synadenium carinatum (ScLL) and Artocarpus heterophyllus (ArtinM) Are Able to Induce Beneficial Immunomodulatory Effects in a Murine Model for Treatment of Toxoplasma gondii Infection.

Infection by Toxoplasma gondii affects around one-third of world population and the treatment for patients presenting toxoplasmosis clinically manifested disease is mainly based by a combination of sulfadiazine, pyrimethamine, and folinic acid. However, this therapeutic protocol is significantly toxic, causing relevant dose-related bone marrow damage. Thus, it is necessary to improve new approaches to investigate the usefulness of more effective and non-toxic agents for treatment of patients with toxoplasmosis. It has been described that lectins from plants can control parasite infections, when used as immunological adjuvants in vaccination procedures. This type of lectins, such as ArtinM and ScLL is able to induce immunostimulatory activities, including efficient immune response against parasites. The present study aimed to evaluate the potential immunostimulatory effect of ScLL and ArtinM for treatment of T. gondii infection during acute phase, considering that there is no study in the literature accomplishing this issue. For this purpose, bone marrow-derived macrophages (BMDMs) were treated with different concentrations from each lectin to determine the maximum concentration without or with lowest cytotoxic effect. After, it was also measured the cytokine levels produced by these cells when stimulated by the selected concentrations of lectins. We found that ScLL showed high capacity to induce of pro-inflammatory cytokine production, while ArtinM was able to induce especially an anti-inflammatory cytokines production. Furthermore, both lectins were able to increase NO levels. Next, we evaluated the treatment effect of ScLL and ArtinM in C57BL/6 mice infected by ME49 strain from T. gondii. The animals were infected and treated with ScLL, ArtinM, ArtinM plus ScLL, or sulfadiazine, and the following parameters analyzed: Cytokines production, brain parasite burden and survival rates. Our results demonstrated that the ScLL or ScLL plus ArtinM treatment induced production of pro-inflammatory and anti-inflammatory cytokines, showing differential but complementary profiles. Moreover, when compared with non-treated mice, the parasite burden was significantly lower and survival rates higher in mice treated with ScLL or ScLL plus ArtinM, similarly with sulfadiazine treatment. In conclusion, the results demonstrated the suitable potential immunotherapeutic effect of ScLL and ArtinM lectins to control acute toxoplasmosis in this experimental murine model.

Review of Experimental Compounds Demonstrating Anti-Toxoplasma Activity.

Toxoplasma gondii is a ubiquitous apicomplexan parasite capable of infecting humans and other animals. Current treatment options for T. gondii infection are limited and most have drawbacks, including high toxicity and low tolerability. Additionally, no FDA-approved treatments are available for pregnant women, a high-risk population due to transplacental infection. Therefore, the development of novel treatment options is needed. To aid this effort, this review highlights experimental compounds that, at a minimum, demonstrate inhibition of in vitro growth of T. gondii When available, host cell toxicity and in vivo data are also discussed. The purpose of this review is to facilitate additional development of anti-Toxoplasma compounds and potentially to extend our knowledge of the parasite.

The FIKK kinase of Toxoplasma gondii is not essential for the parasite's lytic cycle.

FIKK kinases are a novel family of kinases unique to the Apicomplexa. While most apicomplexans encode a single FIKK kinase, Plasmodium falciparum expresses 21 and piroplasms do not encode a FIKK kinase. FIKK kinases share a conserved C-terminal catalytic domain, but the N-terminal region is highly variable and contains no known functional domains. To date, FIKK kinases have been primarily studied in P. falciparum and Plasmodium berghei. Those that have been studied are exported from the parasite and associate with diverse locations in the infected erythrocyte cytosol or membrane. Deletion of individual P. falciparum FIKK kinases indicates that they may play a role in modification of the infected erythrocyte. The current study characterises the single FIKK gene in Toxoplasma gondii to evaluate the importance of the FIKK kinase in an apicomplexan that has a single FIKK kinase. The TgFIKK gene encoded a protein of approximately 280kDa. Endogenous tagging of the FIKK protein with Yellow Fluorescent Protein showed that the FIKK protein exclusively localised to the posterior end of tachyzoites. A Yellow Fluorescent Protein-tagged FIKK and a Ty-tagged FIKK both co-localised with T. gondii membrane occupation and recognition nexus protein to the basal complex and were localised apical to inner membrane complex protein-5 and Centrin2. Deletion of TgFIKK, surprisingly, had no detectable effect on the parasite's lytic cycle in vitro in human fibroblast cells or in acute virulence in vivo. Thus, our results clearly show that while the FIKK kinase is expressed in tachyzoites, it is not essential for the lytic cycle of T. gondii.

Effect of Nigella sativa oil on experimental toxoplasmosis.

Toxoplasmosis is a parasitic infection caused by Toxoplasma gondii protozoon. It is most commonly treated by pyrimethamine (PYR); however, this was intolerable by many patients. The aim of this study was to assess therapeutic effects of Nigella sativa oil (NSO) alone and combined with pyrimethamine (PYR) compared to a previous combination of clindamycin (CLN) and (PYR). One hundred Albino mice were used in the current study and were equally divided into five groups: normal (I), infected untreated control (II); infected, treated with NSO-only (III); infected, treated with NSO + PYR (IV); and infected, treated with CLN + PYR (V). The virulent RH Toxoplasma strain was used in infection survival rates estimation, impression smears from liver and spleen, and histopathological and ultrastructural studies were done. Liver malondialdehyde (MDA) level and total antioxidant capacity (TAC) were determined. Interferon-γ and specific IgM were also measured in sera by ELISA. Results showed that NSO alone has no direct anti-Toxoplasma effect, whereas its combination with PYR produced potent effect that is comparable to CLN + PYR. It significantly increased the survival rate and decreased the parasite density and pathological insult in both liver and spleen. Also, significant increase in interferon-γ level denotes stimulation of cellular immunity. NSO + PYR combination markedly improved the antioxidant capacity of Toxoplasma infected mice compared to the infected untreated ones and to CLN/PYR. In conclusion, although NSO, if administered alone, has significant immunostimulant and antioxidant properties, it failed to decrease tachyzoite counts. Combination of NSO and PYR had synergistic effect in treatment of toxoplasmosis.

Evaluation of colostrum as an alternative biological sample for the diagnosis of human congenital toxoplasmosis.

BACKGROUND: Toxoplasmosis is a zoonosis caused by Toxoplasma gondii, an intracellular protozoan parasite able to infect a wide range of hosts, including humans. Congenital infection can cause severe damage to the fetus. Thus, it is important to detect antibodies against the parasite to confirm clinical manifestations. Considering that all immunoglobulin isotypes may be present in biological samples from newborns and their mothers, this study aimed to evaluate the ability to diagnose recent toxoplasmosis by using colostrum, as an alternative noninvasive way to obtain biological samples, as well as to determine correlation rates between antibodies from serum samples to detect IgG, IgM and IgA isotypes against T. gondii. METHODS: A total of 289 puerperal women from Clinical Hospital of Federal University of Uberlândia (mean age: 24.8 years, range: 14 - 43 years) took part in this study. Serum and colostrum samples from these patients were analyzed using ELISA and immunoblotting assays for soluble antigens from T. gondii. RESULTS: ELISA immunoassays with serum samples showed reactivity in 47.0, 6.9 and 2.8 % of samples to anti-T. gondii IgG, IgM and IgA, respectively, in comparison with colostrum samples, which showed reactivity in 46.0, 7.9 and 2.8 % of samples to the same isotypes. Also, significant correlation rates of anti-T. gondii antibody levels between serum and colostrum samples were observed. Interestingly, reactivity to IgM and/or IgA in colostrum and/or serum confirmed clinical manifestations of congenital toxoplasmosis in three newborns. Immunoblotting assays showed that it is possible to detect IgG, IgM and IgA antibodies against various antigens of T. gondii in serum and colostrum samples. IgG antibodies in serum and colostrum samples recognized more antigenic fractions than IgM and IgA antibodies. Serum IgG detected more antigenic fractions than IgG antibodies present in the colostrum of the same patient. In contrast, specific IgA present in colostrum recognized a higher number of antigens than IgA present in serum samples of the same patient. CONCLUSIONS: Overall, the results show that it is important to investigate the occurrence of congenital toxoplasmosis, even at puerperal period. Furthermore, this study demonstrates that T. gondii-specific IgG, IgM and IgA antibodies in serum and colostrum samples from puerperal women may be detected with a significant correlation, suggesting that colostrum may also be used as an alternative biological sample to efficiently diagnose recent human toxoplasmosis.

Immunoglobulin and cytokine changes induced following immunization with a DNA vaccine encoding Toxoplasma gondii selenium-dependent glutathione reductase protein.

Toxoplasma gondii Glutathione Reductase (TgGR) plays important role during the survival of the parasite. In this investigation, immunological changes and protection efficiency of this protein delivered as a DNA vaccine (pTgGR) have been evaluated. Mice were immunized with pTgGR, followed by challenge with virulent T. gondii RH strain, 2 weeks after the booster immunization. Compared to the control groups pVAX1, PBS and Blank groups, the results showed that pTgGR stimulated specific humoral response defined by significant titers of total IgG, subclasses IgG1 and IgG2a, classes IgA and IgM, but not IgE. Analysis of IFN-γ, IL-4, IL-17 and TGF-ß1 cytokines after immunization and compared with the control groups showed significant increments in pTgGR group. Additionally, T lymphocytes subpopulation CD4(+) T was positively recruited with significant percentage detected, while subset CD8(+) appeared not to be involved in response to this antigen. Vaccinated mice showed a significantly longer survival time, 15 days, in contrast with control groups which died within 8-10 days after challenge. These results demonstrated that TgGR could induce significant humoral and cell mediated responses leading to a considerable level of resistance against toxoplasmosis infection.

Comparative study on the antioxidant and anti-Toxoplasma activities of vanillin and its resorcinarene derivative.

A resorcinarene derivative of vanillin, resvan, was synthesized and characterized by spectroscopic techniques. We measured the cytotoxicity (in vivo and in vitro), antioxidant and anti-Toxoplasma activities of vanillin and the resorcinarene compound. Here we show that vanillin has a dose-dependent behavior with IC50 of 645 µg/mL through an in vitro cytotoxicity assay. However, we could not observe any cytotoxic response at higher concentrations of resvan (IC50 > 2,000 µg/mL). The in vivo acute toxicity assays of vanillin and resvan exhibited a significant safety margin indicated by a lack of systemic and behavioral toxicity up to 300 mg/kg during the first 30 min, 24 h or 14 days after administration. The obtained derivative showed greater antioxidative activity (84.9%) when comparing to vanillin (19.4%) at 1,000 µg/mL. In addition, vanillin presents anti-Toxoplasma activity, while resvan does not show that feature. Our findings suggest that this particular derivative has an efficient antioxidant activity and a negligible cytotoxic effect, making it a potential target for further biological investigations.

Anti-Toxoplasma activity of natural products: a review.

Toxoplasma gondii is an intracellular parasite widely distributed in nature. Infection is asymptomatic in immunocompetent individuals; however, various clinical manifestations may occur in immunocompromised individuals. Although there are medications for the treatment of toxoplasmosis, such as pyrimethamine and sulfonamide, they cannot always be used due to adverse reactions or to therapeutic failures related to intolerance or malabsorption of drugs and to parasite drug resistance. In recent years, the search for new antimicrobial agents derived from plants has intensified because a quarter of synthetic drugs that are currently prescribed have been isolated from a plant source, demonstrating that natural products are important in the development of new drugs. A systematic literature search was conducted to evaluate the use of natural products as an alternative for the treatment of T. gondii infection. The search was conducted for the 2000-2014 period in Science Direct, Scopus, PubMed, EMBASE, and SciELO databases, using the following MeSH terms: anti-Toxoplasma activity, toxoplasma AND natural products, toxoplasma AND plant extracts. Ethnobotanical and experimental evidence (in vitro/in vivo) was found supporting the use of natural products as a source for the discovery of new therapies against T. gondii.

Two methods for attenuating Toxoplasma gondii tachyzoites RH strain by using ethanol extract of Curcuma longa.

The ethanol extract of Curcuma longa proved to be an attenuated agent against Toxoplasma gondii (RH strain) tachyzoites in the mice peritoneal fluid by two incubation methods. Groups of female mice were injected by attenuated tachyzoites as 200 tachyzoites / ml, which treated with the ethanol extract of Curcuma longa was previously treated. The result was observed after one week, as no tachyzoites were found in the peritoneal fluid of the experimental infected mice.

Toxoplasmosis congénita: revisión / Congenital toxoplasmosis: a review

La forma congénita de infección por Toxoplasma gondii se produce a partir de una primo infección gestacional con consecuencias en distintos órganos del feto, especialmente oculares (coriorretinitis), SNC (hidrocefalia, convulsiones) y sistémicos(hepatoesplenomegalia), aunque entre el 80 y 90% son formas subclínicas. El diagnóstico se realiza mediante estudio serológico materno, dependiendo el riesgo de infección fetal del trimestre en que se produzca la seroconversión. Debido a la ausencia de estudios sobre la eficacia del tratamiento prenatal, se administrará a la madre con primoinfección tratamiento con espiramicina hasta conocer los resultados delos estudios complementarios. Ante infección en el recién nacido, se instaurará tratamiento con pirimetamina, sulfadiazina y ácido fólico, siendo el objetivo la disminución del riesgo de secuelas a largo plazo. El cribado gestacional es uno de los puntos de controversia, ya que tanto el gasto sanitario como el nivel de falsos + es elevado. Los programas de educación sanitaria han logrado disminuir en algunos países la tasa de infección al 50%

The congenital form of Toxoplasmga ondii infection is caused by primary maternal infection, with consequences in different fetal systems, especially the ocular system (chorioretinitis) and central nervous system (hydrocephalu, seizures), as well as systemic involvement(hepatosplenomegaly), although between 80% and 90% of the resulting disorders are subclinical. The diagnosis involves maternal serology, as the risk of fetal infection depends on the trimester in which seroconversion occurs. Given the lack of studies on the efficacy of prenatal treatment, spiramycin should be administered to pregnant women with primary infection until the results of complementary studies are known. Should the new born be infected, treatment with pyrimethamine, sulfadiazine and folic acid should be begunin the attempt to reduce the risk of long-term sequelae. Prenatal screening is a controversial issue since both the health care costs and rate of false positives are high. In some countries, health education programs have resulted in a decrease in the rate of infection of 50%

Transferrin receptor induction in Toxoplasma gondii-infected HFF is associated with increased iron-responsive protein 1 activity and is mediated by secreted factors.

Infection with the apicomplexan parasite Toxoplasma gondii results in a significant alteration of the host-cell transcriptional profile. We have previously shown that the transferrin receptor (TfR) is specifically up-regulated in T. gondii-infected human fibroblasts but not in host cells infected with the bacterial pathogens Salmonella Typhimurium and Chlamydia trachomatis. In this report, we describe the prerequisites and physiological conditions that are associated with this pathogen-specific gene induction. Band-shift assays revealed that T. gondii infection resulted in increased activity in the iron response protein IRP1, which, in this state, stabilizes TfR mRNA from degradation. Although T. gondii depends on host-cell iron as demonstrated by sensitivity to deferoxamine, a parasite-induced iron starvation is not responsible for TfR up-regulation. The increased iron availability due to treatment with holotransferrin and FeNTA did not prevent TfR induction nor was the transferrin-independent iron-transporter NRAMP2 up-regulated in infected host cells. In addition, inhibition of parasite replication by drug treatment did not prevent TfR up-regulation. Instead, TfR induction was sensitive to cycloheximide and could be induced by treatment with conditioned media from infected human fibroblasts. Together our findings suggest that the T. gondii-specific TfR up-regulation is not due to a direct interaction of parasitic factors with the iron-uptake machinery of the host cell but is instead mediated indirectly as a result of secreted host cell- or parasite-derived factors.

Tachyzoite calcium changes during cell invasion by Toxoplasma gondii.

The invasion of host cells by the obligate intracellular protozoan parasite Toxoplasma gondii is calcium dependent. We have identified two calcium storage areas in tachyzoites, the endoplasmic reticulum and vesicles that contain high concentrations of calcium as amorphous calcium phosphate precipitates. Our data indicate that these vesicles slowly lose their calcium during the intracellular development of the tachyzoite as their nucleus phosphorus content increases. We found fluctuations in the sulfur content of the tachyzoite during invasion following the exocytosis of protein from the secretory organelles, with a loss of sodium and chlorine, and the uptake of potassium from the host cell cytoplasm. We demonstrated that penetration of the tachyzoite into the host cell was accompanied by increases in the concentrations of phosphorus and sulfur in the host cell nucleus, probably due to increased transcription. The cytosol sodium concentrations decreased, while the potassium content increased. Thus, the subcellular element distribution of tachyzoites and host cells changes during invasion and intracellular growth of the parasites. In addition, our results indicate that tachyzoite calcium might be involved in the egress of the parasite from the host cell.

Atividade parasiticida e/ou parasitostática de fibroblastos e macrofagos humanos ativados por rIFN-y e/ou rTNF-x

Estudamos o papel da degradação do triptofano pela indoleamina 2,3-dioxigenase (INDO) no controle da replicação do T. cruzzi ou T. gondii em fibroblastos e macrófagos humanos estimulados com rIFN-gama e/ou rTNF-alfa. O T. gondii foi utlizado como controle, por ser sensível à degradação do triptofano induzida pelo rIFN-gama. A estimulação de fibroblastos humanos com rIFN-gama e o rTNF-alfa inibiu consideravelmente o desenvolvimento do T. gondii, mas não influenciou o desenvolvimento do T. cruzi. O desenvolvimento do T. gondii foi triptofano dependente, enquanto que o do T. cruzi foi triptofano independente. Ao contrário dos fibroblastos parentais, os fibroblastos defectivos na via de transdução de sinal do IFN-gama (JAKI, JAK2 e STAT1alfa)não modularam o desenvolvimento intracelular de T. gondii e nem expressaram mRNA da INDO quando estimulados pelo rIFN-gama. Houve uma pequena indução de mRNA da INDO em fibroblastos parentais e mutantes (JAK2) estimulados com rTNF-alfa, que provavelmente foi estimulado através da indução da síntese de IFN-es em fibroblastos humanos. O rIFN-gama e/ou rTNF-alfa induziram expressiva atividade tripanosomicida em macrófagos humanos.

A estimulação de macrófagos humanos com rIFN-gama ou rIFN-gama + rTNF-alfa, produziu uma considerável expressão do mRNA da INDO, e pouca expressão foi detectada quando as células foram estimuladas apenas com rTNF-alfa. A adição de triptofano, ou do inibidor da INDO, norharmane, à cultura de macrófagos humanos ativados com rIFN-gama e/ou rTNF-alfa, não reverteu a inibição do crescimento do parasita , mostrando que a degradação do triptofano não é um mecanismo responsável pelo efeito tripanosomicida de macrófagos humanos ativados com rIFN-gama e/ou rTNF-alfa. Os catabólitos do triptofano (ácido quinolínico, ácido quinurênico e L-quinurenina)inibiram parcialmente o desenvolvimento do T. cruzi em macrófagos humanos. A amplificação por PCR do DNA T. cLsintese de Escherichia coli ou Neurospora crassa e Saccharomyces cerevisae e a hibridização cruzada via dot blot utilizando como sondas os produtos de PCR, sugerem a possibilidade da existência da enzima triptofano sintetase em T. cruzi, o que explicaria a insensibilidade do parasita à depleção do triptofano. Alternativamente reconhecemos que mais estudos devam ser feitos para a comprovação da existência da enzima em T. cruzi

A clinical-parasitological monotherapy cure in the treatment of experimental infection by a highly virulent strain of Toxoplasma gondii.

Toxoplasmic encephalitis in patients with the acquired immunodeficiency syndrome (AIDS) is treated classically with pyrimethamine plus sulfadiazine. Unfortunately, up to 40% of these patients are unable to complete the course of therapy because of adverse reactions to sulfonamides. This study considers the possible usefulness of monotherapies in the treatment of acute toxoplasmosis, producing parasitological cures 2-3 months after the date of infection. With this therapy, the main adverse effects are suppressed. Groups of mice infected with the RH strain of Toxoplasma gondii were treated with pyrimethamine alone, sulfadiazine alone, and pyrimethamine plus sulfadiazine for 7 d. Treatment with pyrimethamine plus sulfadiazine produced clinical cures in 100% of the infected mice 1 month after infection. Treatment with pyrimethamine gave a 60% survival rate (clinical cure) at 1 month postinfection. Finally, treatment with sulfadiazine produced a 60% survival rate at 1 month postinfection. Although the antitoxoplasmic regimen with pyrimethamine plus sulfadiazine has proven to be effective in intensive treatment of toxoplasmic encephalitis, relapses occur in more than 80% of cases after cessation of antitoxoplasmic therapy, making secondary prophylaxis mandatory. In this study the efficacy of treatment was also evaluated in terms of parasitological cure. None of the three therapies showed parasitological cure after 1 month of treatment. When the intervals were extended to a 3-month observation, monotherapy with pyrimethamine and sulfadiazine alone produced a parasitological cure.

Toxoplasmosis congénita: un problema vigente en Chile: análisis de 15 casos clínicos / Congenital toxoplasmosis: a current problem in Chile: analysis of 15 clinical cases

Se analiza el problema de la toxoplasmosis congénita mediante el estudio de quince casos, cuatro lactantes con infección aguda y once niños con compromiso acular. La importancia del reconocimiento oportuno de la infección en el recién nacido y lactante, basada en la sospecha clínica (síndrome de TORCH y examen de fondo de ojo) y el diagnóstico serológico precoz que confirma la etiología, se discute en relación con el efecto curativo del tratamiento específico. La mayoría de los casos se diagnosticaron y trataron en forma tardía. En cinco niños tratados precozmente se obtuvo resultado satisfactorio, evitándose la muerte del recién nacido, disminuyendo el desarrollo de la infección y la aparición de reactivaciones, aunque persistieron secuelas a nivel del SNC. En los casos restantes, se observó sólo un efecto parcial del tratamiento. Se concluye que la toxoplasmosis congénita es un problema vigente en Chile y que la mayoría de los casos no se diagnostican oportunamente. Se recomienda intensificar su detección a nivel clínico, porque se dispone de drogas específicas que, aplicadas en forma precoz, pueden prevenir o aminorar el desarrollo de secuelas en el SNC

Effects of immobilization stress on the pathogenesis of acute murine toxoplasmosis.

Stress modulates a variety of immune responses. We investigated the effects of immobilization stress on the pathogenesis of acute murine toxoplasmosis, an infection in which cell-mediated immunity is of major importance in host defense. Repetitive overnight immobilization beginning 3 days prior to infection enhanced (p less than 0.05) the mortality of mice infected with a virulent strain (C56) of Toxoplasma gondii (77% vs 15% mortality in restrained and control mice, respectively). Daily immobilization for 14 days prior to infection abrogated (p less than 0.05) the lethal effect of immobilization, suggesting an adaptive mechanism. To explore the effect of immobilization with a less virulent strain, the Me49 strain of T. gondii was studied. Acute infection with T. gondii Me49 resulted in anorexia and weight loss, while spleen size and respiratory burst activity of peritoneal exudate cells were enhanced (p less than 0.01). Immobilization (twice daily for 2 h) did not significantly alter survival or other clinical features of acute T. gondii infection. In addition, immobilization suppressed (p less than 0.05) phorbol myristate acetate-stimulated release of superoxide anion by peritoneal exudate cells in healthy naive mice, but not in infected mice. These findings indicate that immobilization stress can alter the pathogenesis of acute T. gondii infection in healthy mice, but the effect of this stress paradigm will be influenced, in part, by the timing of the immobilization and the virulence of the strain of T. gondii.