Toxoplasma effectors targeting host signaling and transcription

Early electron microscopy studies revealed the elaborate cellular features that define the unique adaptations of apicomplexan parasites. Among these were bulbous rhoptry (ROP) organelles and small, dense granules (GRAs), both of which are secreted during invasion of host cells. These early morphological studies were followed by the exploration of the cellular contents of these secretory organelles, revealing them to be comprised of highly divergent protein families with few conserved domains or predicted functions. In parallel, studies on host-pathogen interactions identified many host signaling pathways that were mysteriously altered by infection. It was only with the advent of forward and reverse genetic strategies that the connections between individual parasite effectors and the specific host pathways that they targeted finally became clear. The current repertoire of parasite effectors includes ROP kinases and pseudokinases that are secreted during invasion and that block host immune pathways. Similarly, many secretory GRA proteins alter host gene expression by activating host transcription factors, through modification of chromatin, or by inducing small noncoding RNAs. These effectors highlight novel mechanisms by whichhas learned to harness host signaling to favor intracellular survival and will guide future studies designed to uncover the additional complexity of this intricate host-pathogen interaction

Urogenital schistosomiasis in Cabo Delgado, northern Mozambique: baseline findings from the SCORE study.

BACKGROUND: The results presented here are part of a five-year cluster-randomised intervention trial that was implemented to understand how best to gain and sustain control of schistosomiasis through different preventive chemotherapy strategies. This paper presents baseline data that were collected in ten districts of Cabo Delgado province, northern Mozambique, before treatment. METHODS: A cross-sectional study of 19,039 individuals was sampled from 144 villages from May to September 2011. In each village prevalence and intensity of S. haematobium were investigated in 100 children first-year students (aged 5-8 years), 100 school children aged 9-12 years (from classes 2 to 7) and 50 adults (20-55 years). Prevalence and intensity of S. haematobium infection were evaluated microscopically by two filtrations, each of 10 ml, from a single urine specimen. Given that individual and community perceptions of schistosomiasis influence control efforts, community knowledge and environmental risk factors were collected using a face-to-face interview. Data were entered onto mobile phones using EpiCollect. Data summary was made using descriptive statistics. Chi-square and logistic regression were used to determine the association between dependent and independent variables. RESULTS: The overall prevalence of urogenital schistosomiasis was 60.4% with an arithmetic mean intensity of infection of 55.8 eggs/10 ml of urine. Heavy infections were detected in 17.7%, of which 235 individuals (6.97%) had an egg count of 1000 eggs/10 ml or more. There was a significantly higher likelihood of males being infected than females across all ages (62% vs 58%; P < 0.0005). Adolescents aged 9-12 years had a higher prevalence (66.6%) and mean infection intensity (71.9 eggs/10 ml) than first-year students (63.1%; 58.2 eggs/10 ml). This is the first study in Mozambique looking at infection rates among adults. Although children had higher levels of infection, it was found here that adults had a high average prevalence and intensity of infection (44.5%; 23.9 eggs/10 ml). Awareness of schistosomiasis was relatively high (68.6%); however, correct knowledge of how schistosomiasis is acquired was low (23.2%) among those who had heard of the disease. Schistosomiasis risk behaviour such as washing (91.3%) and bathing (86.7%) in open water sources likely to be infested with host snails was high. CONCLUSIONS: Urogenital schistosomiasis is widespread in Cabo Delgado. In addition, poor community knowledge about the causes of schistosomiasis and how to prevent it increases the significant public health challenge for the national control program. This was the first study in Mozambique that examined infection levels among adults, where results showed that S. haematobium infection was also extremely high. Given that this controlled trial aims to understand the impact of different combinations of schistosomiasis control through treatment of communities, schools, and treatment holidays over a five-year period, these findings highlight the importance of examining the impact of different treatment approaches also in adults. TRIAL REGISTRATION: The trials have been registered with the International Standard Randomised Controlled Trial registry under ISRCT 14117624 Mozambique (14 December 2015)

T-cell production of matrix metalloproteinases and inhibition of parasite clearance by TIMP-1 during chronic Toxoplasma infection in the brain

Chronic infection with the intracellular protozoan parasite Toxoplasma gondii leads to tissue remodelling in the brain and a continuous requirement for peripheral leucocyte migration within the CNS (central nervous system). In the present study, we investigate the role of MMPs (matrix metalloproteinases) and their inhibitors in T-cell migration into the infected brain. Increased expression of two key molecules, MMP-8 and MMP-10, along with their inhibitor, TIMP-1 (tissue inhibitor of metalloproteinases-1), was observed in the CNS following infection. Analysis of infiltrating lymphocytes demonstrated MMP-8 and -10 production by CD4+ and CD8+ T-cells. In addition, infiltrating T-cells and CNS resident astrocytes increased their expression of TIMP-1 following infection. TIMP-1-deficient mice had a decrease in perivascular accumulation of lymphocyte populations, yet an increase in the proportion of CD4+ T-cells that had trafficked into the CNS. This was accompanied by a reduction in parasite burden in the brain. Taken together, these findings demonstrate a role for MMPs and TIMP-1 in the trafficking of lymphocytes into the CNS during chronic infection in the brain

Assessing the benefits of five years of different approaches to treatment of urogenital schistosomiasis: A SCORE project in Northern Mozambique.

BACKGROUND: In Mozambique, schistosomiasis is highly endemic across the whole country. The Schistosomiasis Consortium for Operational Research and Evaluation (SCORE) coordinates a five-year study that has been implemented in various African countries, including Mozambique. The overall goal of SCORE was to better understand how to best apply preventive chemotherapy with praziquantel (PZQ) for schistosomiasis control by evaluating the impact of alternative treatment approaches. METHODS: This was a cluster-randomised trial that compared the impact of different treatment strategies in study areas with prevalence among school children of ≥21% S. haematobium infection by urine dipstick. Each village was randomly allocated to one of six possible combinations of community-wide treatment (CWT), school-based treatment (SBT), and/or drug holidays over a period of four years, followed by final data collection in the fifth year. The most intense intervention arm involved four years of CWT, while the least intensive arm involved two years of SBT followed by two consecutive years of PZQ holiday. Each study arm included 25 villages randomly assigned to one of the six treatment arms. The primary outcome of interest was change in prevalence and intensity of S. haematobium among 100 children aged 9-to-12-years that were sampled each year in every village. In addition to children aged 9-to-12 years, 100 children aged 5-8 years in their first-year of school and 50 adults (aged 20-55 years) were tested in the first and final fifth year of the study. Prevalence and intensity of S. haematobium infection was evaluated by two filtrations, each of 10mL, from a single urine specimen. PRINCIPAL FINDINGS: In total, data was collected from 81,167 individuals across 149 villages in ten districts of Cabo Delgado province, Northern Mozambique. Overall PZQ treatment resulted in a significant reduction in the prevalence of S. haematobium infection from Year 1 to Year 5, where the average prevalence went from 60.5% to 38.8%, across all age groups and treatment arms. The proportion of those heavily infected also reduced from 17.6% to 11.9% over five years. There was a significantly higher likelihood of males being infected than females at baseline, but no significant difference between the sexes in their response to treatment. The only significant response based on a study arm was seen in both the 9-to-12-year-old and first-year cross sections, where two consecutive treatment holidays resulted in a significantly higher final prevalence of S. haematobium than no treatment holidays. When the arms were grouped together, four rounds of treatment (regardless of whether it was CWT or SBT), however, did result in a significantly greater reduction in S. haematobium prevalence than two rounds of treatment (i.e. with two intermittent or consecutive holiday years) over a five-year period. CONCLUSIONS: Although PC was successful in reducing the burden of active infection, even among those heavily infected, annual CWT did not have a significantly greater impact on disease prevalence or intensity than less intense treatment arms. This may be due to extremely high starting prevalence and intensity in the study area, with frequent exposure to reinfection, or related to challenges in achieving high treatment coverage More frequent treatment had a greater impact on prevalence and intensity of infection when arms were grouped by number of treatments, however, cost efficiency was greater in arms only receiving two treatments. Finally, a significant reduction in prevalence of S. haematobium was seen in adults even in the SBT arms implying the rate of transmission in the community had been decreased, even where only school children have been treated, which has significant logistical and cost-saving implications for a national control programme in justifying CWT

Discrimination between patients with acquired toxoplasmosis and congenital toxoplasmosis on the basis of the immune response to parasite antigens

Many persons infected with Toxoplasma gondii develop ocular lesions, Immunologic parameters in the response to I gondii were evaluated in infected persons with and without ocular lesions and in noninfected controls. Subjects were divided into groups on the basis of presence of serum antibodies to I: gondii, presence of ocular lesions, and clinical history. Production of interleukin-2 and interferon-gamma by peripheral blood mononuclear cells from patients with probable congenital toxoplasmosis was decreased, compared with that in persons with presumed acquired infection. Cell proliferation and delayed-type skin reaction induced by soluble toxoplasma tachyzoite antigen followed the same pattern. Asymptomatic persons showed high levels of interleukin-12 and interferon-gamma, whereas persons with ocular lesions had high interleukin-1 and tumor necrosis factor-alpha responses toward soluble toxoplasma tachyzoite antigen. These data suggest that patients with ocular disease due to congenital infection show tolerance toward the parasite. Furthermore, susceptibility to ocular lesions after acquired toxoplasmosis is associated with high levels of interleukin-1 and tumor necrosis factor-alpha, whereas resistance is associated with high levels of interleukin-12 and interferon-gamma.Univ São Paulo, ICB, Dept Immunol, BR-05509890 São Paulo, BrazilUniv São Paulo, Inst Heart, Lab Transplant Immunol, São Paulo, BrazilUniv São Paulo, Fac Med, Dept Ophthalmol, São Paulo, BrazilUniversidade Federal de São Paulo, Dept Ophthalmol, São Paulo, BrazilUniv São Paulo, Sch Med, Div Clin Immunol & Allergy, Lab Med Invest, São Paulo, BrazilFundacao EJ Zerbini, São Paulo, BrazilUniv Fed Minas Gerais, Dept Biochem & Immunol, Belo Horizonte, MG, BrazilFundacao Osvaldo Cruz, Ctr Pesquisas Rene Rachou, Belo Horizonte, MG, BrazilNEI, Immunol Lab, NIH, Bethesda, MD 20892 USAUniversidade Federal de São Paulo, Dept Ophthalmol, São Paulo, BrazilWeb of Scienc

DNA-Containing Immunocomplexes Promote Inflammasome Assembly and Release of Pyrogenic Cytokines by CD14+ CD16+ CD64high CD32low Inflammatory Monocytes from Malaria Patients

High levels of circulating immunocomplexes (ICs) are found in patients with either infectious or sterile inflammation. We report that patients with either Plasmodium falciparum or Plasmodium vivax malaria have increased levels of circulating anti-DNA antibodies and ICs containing parasite DNA. Upon stimulation with malaria-induced ICs, monocytes express an NF-kappaB transcriptional signature. The main source of IC-induced proinflammatory cytokines (i.e., tumor necrosis factor alpha [TNF-alpha] and interleukin-1beta [IL-1beta])in peripheral blood mononuclear cells from acute malaria patients was found to be a CD14(+) CD16 (FcgammaRIIIA)(+) CD64 (FcgammaRI)(high) CD32 (FcgammaRIIB)(low) monocyte subset. Monocytes from convalescent patients were predominantly of the classical phenotype (CD14(+) CD16(-)) that produces high levels of IL-10 and lower levels of TNF-alpha and IL-1beta in response to ICs. Finally, we report a novel role for the proinflammatory activity of ICs by demonstrating their ability to induce inflammasome assembly and caspase-1 activation in human monocytes. These findings illuminate our understanding of the pathogenic role of ICs and monocyte subsets and may be relevant for future development of immunity-based interventions with broad applications to systemic inflammatory diseases. IMPORTANCE: Every year, there are approximately 200 million cases of Plasmodium falciparum and P. vivax malaria, resulting in nearly 1 million deaths, most of which are children. Decades of research on malaria pathogenesis have established that the clinical manifestations are often a consequence of the systemic inflammation elicited by the parasite. Recent studies indicate that parasite DNA is a main proinflammatory component during infection with different Plasmodium species. This finding resembles the mechanism of disease in systemic lupus erythematosus, where host DNA plays a central role in stimulating an inflammatory process and self-damaging reactions. In this study, we disclose the mechanism by which ICs containing Plasmodium DNA activate innate immune cells and consequently stimulate systemic inflammation during acute episodes of malaria. Our results further suggest that Toll-like receptors and inflammasomes have a central role in malaria pathogenesis and provide new insights toward developing novel therapeutic interventions for this devastating disease

Spontaneous symmetry breaking and the local freeze-out in Tl2+ -doped KH2AsO4

The slowing down of the local order-parameter fluctuations and the spontaneous dynamic symmetry breaking at a defect site in an order-disorder hydrogen-bonded system describable by an Ising model in a transverse-field Hamiltonian has been evaluated and shown to depend on the range of the forces with which the defect couples to the host lattice. The spontaneous symmetry breaking observed far above Tc in the EPR spectra of defect centers in KH2AsO4-type crystals is shown to be compatible with such a local slowing down and "pseudo-freeze-out" around defects which couple to the surrounding pseudospins via short-range forces which are significantly stronger than the interaction forces in the undisturbed lattice. No such freeze-out occurs for the Tl2+ ions which are coupled to the surrounding pseudospins via long-range forces. © 1982 The American Physical Society

Vaccines against toxoplasma gondii : challenges and opportunities

Development of vaccines against Toxoplasma gondii infection in humans is of high priority, given the high burden of disease in some areas of the world like South America, and the lack of effective drugs with few adverse effects. Rodent models have been used in research on vaccines against T. gondii over the past decades. However, regardless of the vaccine construct, the vaccines have not been able to induce protective immunity when the organism is challenged with T. gondii, either directly or via a vector. Only a few live, attenuated T. gondii strains used for immunization have been able to confer protective immunity, which is measured by a lack of tissue cysts after challenge. Furthermore, challenge with low virulence strains, especially strains with genotype II, will probably be insufficient to provide protection against the more virulent T. gondii strains, such as those with genotypes I or II, or those genotypes from South America not belonging to genotype I, II or III. Future studies should use animal models besides rodents, and challenges should be performed with at least one genotype II T. gondii and one of the more virulent genotypes. Endpoints like maternal-foetal transmission and prevention of eye disease are important in addition to the traditional endpoint of survival or reduction in numbers of brain cysts after challenge