The biological characterization of the Trypanosoma cruzi clone Dm 28c in terms of its growth in LIT medium, cell-cycle, infectivity to mice and interaction with professional and non-professional phagocytic cells shows that it behaves as a bona fide T. cruzi representant. The biological properties of this myotropic clone do not change according to the origin of the trypomastigote forms (i. e., from triatomines, infected mice, cell-culture or from the chemically defined TAUP and TAU3AAG media). In addition Dm 28c metacyclic trypomastigotes from TAU3AAG medium display a high infectivity level to fibroblasts and muscle cells. Experiments on binding of cationized ferritin to trypomastigotes surface show the existence of cap-like structures of ferritin in regions near the kinetoplast, however the nature and role of these anionic sites remain to be determined. The results indicate that metacyclic trypomastigotes from the Dm 28c clone obtained under chemically defined conditions reproduce the biological behaviour of T. cruzi, rendering this system very suitable for the study of cell-parasite interactions and for the isolation of trypanosome relevant macromolecules.

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Toxoplasma gondii is a ubiquitous intracellular parasite which chronically infects 30 to 50% of the human population. While acquired infection is primarily asymptomatic several studies have suggested that such infections may contribute to neurological and psychiatric symptoms. Previous studies in rodents have demonstated that T. gondii infection does not just kill its host, but alters the behavioral repertoire of an infected animal making it more likely that predation with occur completing the parasite life cycle. The aim of the present study was to evaluate the behavioral changes in C57BL/ 6 mice chronically infected with the avirulent T. gondii (ME49, a type II strain), in a comprehensive test battery. Infected mice demonstrated profound and widespread brain pathology, motor coordination and sensory deficits. In contrast, cognitive function, anxiety levels, social behavior and the motivation to explore novel objects were normal. The observed changes in behavior did not represent "gross" brain damage or dysfunction and were not due to targeted destruction of specific areas of the brain. Such changes point out the subtle interaction of this parasite with its intermediate hosts and are consistent with ideas about increased predation being an outcome of infection.

The alkylglycerophosphocholines edelfosine and ilmofosine were more active than the alkylphosphocholine miltefosine against promastigotes and intracellular amastigotes of L. amazonensis, and ultrastructural and flow cytometry data indicate the mitochondrion as a target of edelfosine.

BackgroundThe interest in the mechanisms involved in Toxoplasma gondii lipid acquisition has steadily increased during the past few decades, but it remains not completely understood. Here, we investigated the biogenesis and the fate of lipid droplets (LD) of skeletal muscle cells (SkMC) during their interaction with T. gondii by confocal and electron microscopy. We also evaluated whether infected SkMC modulates the production of prostaglandin E2 (PGE2), cytokines interleukin-12 (IL-12) and interferon-gamma (INF-g), and also the cyclooxygenase-2 (COX-2) gene induction.MethodsPrimary culture of skeletal muscle cells were infected with tachyzoites of T. gondii and analysed by confocal microscopy for observation of LD. Ultrastructural cytochemistry was also used for lipid and sarcoplasmatic reticulum (SR) detection. Dosage of cytokines (IL-12 and INF-g) by ELISA technique and enzyme-linked immunoassay (EIA) for PGE2 measurement were employed. The COX-2 gene expression analysis was performed by real time reverse transcriptase polymerase chain reaction (qRT-PCR).ResultsWe demonstrated that T. gondii infection of SkMC leads to increase in LD number and area in a time course dependent manner. Moreover, the ultrastructural analysis demonstrated that SR and LD are in direct contact with parasitophorous vacuole membrane (PVM), within the vacuolar matrix, around it and interacting directly with the membrane of parasite, indicating that LD are recruited and deliver their content inside the parasitophorous vacuole (PV) in T. gondii-infected SkMC. We also observed a positive modulation of the production of IL-12 and IFN-g, increase of COX-2 mRNA levels in the first hour of T. gondii-SkMC interaction and an increase of prostaglandin E2 (PGE2) synthesis from 6 h up to 48 h of infection.ConclusionsTaken together, the close association between SR and LD with PV could represent a source of lipids as well as other nutrients for the parasite survival, and together with the increased levels of IL-12, INF-g and inflammatory indicators PGE2 and COX-2 might contribute to the establishment and maintenance of chronic phase of the T. gondii infection in muscle cell.

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Toxoplasma gondii is an obligatory intracellular parasitic protozoan that infects a variety of avian and mammalian hosts including up to one third of the human population worldwide. Developmental differentiation between distinct stages, i.e. sporozoites, tachyzoites and bradyzoites is fundamental for the parasite life cycle and for transmission between hosts. It is also interconnected with the pathogenesis of overt toxoplasmosis and makes T. gondii an important opportunistic pathogen of humans. In order to delineate the underlying mechanisms, several cell culture differentiation systems have been developed which mimic the transition from fast-replicating tachyzoites to slowly proliferating bradyzoites in vitro. Since exogenous stress factors, i.e. alkaline pH, IFN-gamma and other proinflammatory cytokines, chemicals or drugs, heat shock, and deprivation of nutrients have been shown to increase the efficacy of bradyzoite development in vitro, Toxoplasma stage differentiation is largely viewed as a stress-related response to hostile environmental conditions. However, tachyzoite to bradyzoite differentiation also occurs spontaneously in vitro and this raises questions about the importance of stress conditions for triggering stage conversion. High frequencies of spontaneous bradyzoite development in primary and permanent skeletal muscle cells, i.e. cells that preferentially harbour bradyzoite-containing tissue cysts in vivo suggest that the host cell type may be critical. Furthermore, the host cell transcriptome, including the expression of distinct host cell genes, has recently been shown to trigger bradyzoite development and cyst formation. Together, these results strongly indicate that the complex cellular environment, besides exogenous stress factors, may govern the developmental differentiation of T. gondii.

Staphylococcus spp. play an important role in the etiology of bovine mastitis. Staphylococcus aureus is considered the most relevant species due to the production of virulence factors such as slime, which is required for biofilm formation. This study aimed to evaluate biofilm production and its possible relation to beta-lactamic resistance in 20 S. aureus isolates from bovine mastitic milk. The isolates were characterized by pheno-genotypic and MALDI TOF-MS assays and tested for genes such as icaA, icaD, bap, agr RNAIII, agr I, agr II, agr III, and agr IV, which are related to slime production and its regulation. Biofilm production in microplates was evaluated considering the intervals determined along the bacterial growth curve. In addition, to determine the most suitable time interval for biofilm analysis, scanning electron microscopy was performed. Furthermore, genes such as mecA and blaZ that are related to beta-lactamic resistance and oxacillin susceptibility were tested. All the studied isolates were biofilm producers and mostly presented icaA and icaD. The Agr type II genes were significantly prevalent. According to the SEM, gradual changes in the bacterial arrangement were observed during biofilm formation along the growth curve phases, and the peak was reached at the stationary phase. In this study, the penicillin resistance was related to the production of beta-lactamase, and the high minimal bactericidal concentration for cefoxitin was possibly associated with biofilm protection. Therefore, further studies are warranted to better understand biofilm formation, possibly contributing to our knowledge about bacterial resistance in vivo.