Ginkgo biloba attenuated detrimental inflammatory and oxidative events due to Trypanosoma brucei rhodesiense in mice treated with melarsoprol.

BACKGROUND: The severe late stage Human African Trypanosomiasis (HAT) caused by Trypanosoma brucei rhodesiense (T.b.r) is characterized by damage to the blood brain barrier, severe brain inflammation, oxidative stress and organ damage. Melarsoprol (MelB) is currently the only treatment available for this disease. MelB use is limited by its lethal neurotoxicity due to post-treatment reactive encephalopathy. This study sought to assess the potential of Ginkgo biloba (GB), a potent anti-inflammatory and antioxidant, to protect the integrity of the blood brain barrier and ameliorate detrimental inflammatory and oxidative events due to T.b.r in mice treated with MelB. METHODOLOGY: Group one constituted the control; group two was infected with T.b.r; group three was infected with T.b.r and treated with 2.2 mg/kg melarsoprol for 10 days; group four was infected with T.b.r and administered with GB 80 mg/kg for 30 days; group five was given GB 80mg/kg for two weeks before infection with T.b.r, and continued thereafter and group six was infected with T.b.r, administered with GB and treated with MelB. RESULTS: Co-administration of MelB and GB improved the survival rate of infected mice. When administered separately, MelB and GB protected the integrity of the blood brain barrier and improved neurological function in infected mice. Furthermore, the administration of MelB and GB prevented T.b.r-induced microcytic hypochromic anaemia and thrombocytopenia, as well as T.b.r-driven downregulation of total WBCs. Glutathione analysis showed that co-administration of MelB and GB prevented T.b.r-induced oxidative stress in the brain, spleen, heart and lungs. Notably, GB averted peroxidation and oxidant damage by ameliorating T.b.r and MelB-driven elevation of malondialdehyde (MDA) in the brain, kidney and liver. In fact, the co-administered group for the liver, registered the lowest MDA levels for infected mice. T.b.r-driven elevation of serum TNF-α, IFN-γ, uric acid and urea was abrogated by MelB and GB. Co-administration of MelB and GB was most effective in stabilizing TNFα levels. GB attenuated T.b.r and MelB-driven up-regulation of nitrite. CONCLUSION: Utilization of GB as an adjuvant therapy may ameliorate detrimental effects caused by T.b.r infection and MelB toxicity during late stage HAT.

Angiostrongylus cantonensis induces energy imbalance and dyskinesia in mice by reducing the expression of melanin-concentrating hormone.

BACKGROUND: Infection with Angiostrongylus cantonensis (AC) in humans or mice can lead to severe eosinophilic meningitis or encephalitis, resulting in various neurological impairments. Developing effective neuroprotective drugs to improve the quality of life in affected individuals is critical. METHODS: We conducted a Gene Ontology enrichment analysis on microarray gene expression (GSE159486) in the brains of AC-infected mice. The expression levels of melanin-concentrating hormone (MCH) were confirmed through real-time quantitative PCR (RT-qPCR) and immunofluorescence. Metabolic parameters were assessed using indirect calorimetry, and mice's energy metabolism was evaluated via pathological hematoxylin and eosin (H&E) staining, serum biochemical assays, and immunohistochemistry. Behavioral tests assessed cognitive and motor functions. Western blotting was used to measure the expression of synapse-related proteins. Mice were supplemented with MCH via nasal administration. RESULTS: Postinfection, a marked decrease in Pmch expression and the encoded MCH was observed. Infected mice exhibited significant weight loss, extensive consumption of sugar and white fat tissue, reduced movement distance, and decreased speed, compared with the control group. Notably, nasal administration of MCH countered the energy imbalance and dyskinesia caused by AC infection, enhancing survival rates. MCH treatment also increased the expression level of postsynaptic density protein 95 (PSD95) and microtubule-associated protein-2 (MAP2), as well as upregulated transcription level of B cell leukemia/lymphoma 2 (Bcl2) in the cortex. CONCLUSIONS: Our findings suggest that MCH improves dyskinesia by reducing loss of synaptic proteins, indicating its potential as a therapeutic agent for AC infection.

Efficacy of artemether against toxocariasis in mice: parasitological and immunopathological changes in brain, liver, and lung.

Toxocariasis is a zoonosis that represents a serious threat to public health particularly in tropical and subtropical areas. Currently, albendazole, the most effective drug for treating visceral toxocariasis, shows moderate efficacy against the larvae in tissues and has some adverse effects. Artemether is an antiparasitic drug mainly used in the treatment of malaria and showed effectiveness against numerous helminthic infections. Besides, it possesses potent anti-inflammatory, antiapoptotic, antifibrotic, and neuroprotective properties. Thus, the study's aim was to investigate artemether's effects in comparison with albendazole on the therapeutic outcome of experimental toxocariasis. For this aim, 140 laboratory-bred mice were divided into four main groups: uninfected control, treatment control, albendazole-treated, and artemether-treated groups. The treatment regimens were started at the 15th dpi (early treatment), and at the 35th dpi (late treatment). The effectiveness of treatment was determined by brain larval count, histopathological, immunohistochemical, and biochemical examination. Artemether showed more effectiveness than albendazole in reducing brain larval counts, markers of brain injury including NF-κB, GFAP, and caspase-3, the diameter and number of hepatic granulomas, hepatic oxidative stress, hepatic IL-6, and TG2 mRNA, and pulmonary inflammation and fibrosis. The efficacy of artemether was the same when administered early or late in the infection. Finally, our findings illustrated that artemether might be a promising therapy for T. canis infection and it could be a good substitution for albendazole in toxocariasis treatment.

Human neutrophil-like cells demonstrate antimicrobial responses to the chronic cyst form of Toxoplasma gondii.

The protozoan parasite Toxoplasma gondii infects approximately 2.5 billion people worldwide. Infection induces a rapid dissemination of parasites throughout the body followed by the formation of lifelong cysts within neurons of the host brain. Both stages require a dynamic immune response comprised of both innate and adaptive cells. Neutrophils are a primary responding cell to acute infection and have been observed in the brain during murine chronic infection. Previous studies investigating human neutrophils found that invasion by Toxoplasma tachyzoites inhibits apoptosis of neutrophils, prolonging their survival under inflammatory conditions. Here, we demonstrate the differentiation of two distinct subsets following exposure of human neutrophil-like-cells (HNLC) to Toxoplasma cysts. In vitro stimulation and imaging studies show cyst-specific induction of cytokines and cyst clearance by HNLCs. Further testing demonstrates that aged HNLCs perform less phagocytosis of cysts compared to non-aged HNLCs. In conclusion, this study identifies a novel response of HNLCs to Toxoplasma cysts and may indicate a role for neutrophils in the clearance of cysts during human infection with Toxoplasma.

EXPERIMENTAL INFECTIONS WITH EUHAPLORCHIS CALIFORNIENSIS AND A SMALL CYATHOCOTYLID INCREASE CONSPICUOUS BEHAVIORS IN CALIFORNIA KILLIFISH (FUNDULUS PARVIPINNIS).

Some parasites manipulate their host's phenotype to enhance predation rates by the next host in the parasite's life cycle. Our understanding of this parasite-increased trophic transmission is often stymied by study-design challenges. A recurring difficulty has been obtaining uninfected hosts with a coevolutionary history with the parasites, and conducting experimental infections that mimic natural processes. In 1996, Lafferty and Morris provided what has become a classic example of parasite-increased trophic transmission; they reported a positive association between the intensity of a brain-infecting trematode (Euhaplorchis californiensis) in naturally infected California killifish (Fundulus parvipinnis) and the frequency of conspicuous behaviors, which was thought to explain the documented 10-30× increase in predation by the final host birds. Here, we address the primary gap in that study by using experimental infections to assess the causality of E. californiensis infection for increased conspicuous behaviors in F. parvipinnis. We hatched and reared uninfected F. parvipinnis from a population co-occurring with E. californiensis, and infected them 1-2 times/week over half their life span with E. californiensis and a small cyathocotylid trematode (SMCY) that targets the host's muscle tissue. At 3 time points throughout the hosts' lives, we quantified several conspicuous behaviors: contorting, darting, scratching, surfacing, and vertical positioning relative to the water's surface. Euhaplorchis californiensis and SMCY infection caused 1.8- and 2.5-fold overall increases in conspicuous behaviors, respectively. Each parasite was also associated with increases in specific conspicuous behaviors, particularly 1.9- and 1.4-fold more darting. These experimental findings help solidify E. californiensis-F. parvipinnis as a classic example of behavioral manipulation. Yet our findings for E. californiensis infection-induced behavioral change were less consistent and strong than those previously documented. We discuss potential explanations for this discrepancy, particularly the idea that behavioral manipulation may be most apparent when fish are actively attacked by predators. Our findings concerning the other studied trematode species, SMCY, highlight that trophically transmitted parasites infecting various host tissues are known to be associated with conspicuous behaviors, reinforcing calls for research examining how communities of trophically transmitted parasites influence host behavior.

The effect of chronic experimental toxoplasmosis on some brain neurotransmitters level and behavior changes.

Toxoplasma is capable of causing long-lasting brain cysts in its hosts, which can lead to physiological disturbances in brain neurotransmitters and result in changes in the host's behavior. This study aimed to investigate these changes using an experimental model. Twenty-five female Wistar rats, weighing 220-220 g and six weeks old, were selected for the study. The rats were divided into two control and experimental groups. The experimental group was injected with 5 × 105 tachyzoites of Toxoplasma gondii (virulent RH strain) intra-peritoneally. Four months after the injection, the rats were subjected to behavioral tests, including learning, memory, depression, and locomotor activity tests. The rats were then euthanized, and their brain and serum samples were analyzed for dopamine and serotonin levels. To ensure the presence of cysts in the brain tissue, a PCR test and preparation of pathological slides from the brain tissue were performed. The results showed that the amount of dopamine in the brain of the infected group was significantly higher than that of the control group, while the level of serotonin in brain of the infected group was significantly lower than that of the control group (P < 0.05). However, no significant difference was observed in the amount of these neurotransmitters in the blood of the two groups (P > 0.05). Behavioral changes were evaluated, and it was found that the learning and memory levels of the infected rats were significantly lower than those of the control group (P < 0.05), but no difference was observed in locomotor activity between the two groups (P > 0.05). This experimental infection model indicated that changes in neurotransmitter levels lead to behavior changes. CONCLUSION: The presence of parasite cysts in the brain can affect some of the host's behaviors through changes in neurotransmitter levels. Therefore, there is a possibility that there is a relationship between the presence of Toxoplasma cysts in the brain and neurological disorders. The results of this study suggest that chronic toxoplasmosis may play a role in behavior changes in psychotic diseases.

Improving the detection of Angiostrongylus cantonensis in the brain tissues of mammalian hosts.

Angiostrongylus cantonensis is an invasive nematode parasite that causes eosinophilic meningitis in many vertebrate hosts, including humans. This parasite is spreading rapidly through the six continents, with Europe being the final frontier. Sentinel surveillance may be a cost-effective strategy to monitor the pathogen's arrival to new geographical regions. Necropsy, followed by tissue digestion, is often used to recover helminth parasites from vertebrate host tissues, however, to detect brain parasites, this protocol is poorly utilized. Our brain digestion protocol is easily performed and 1) reduces false positivity and negativity, 2) provides accurate estimates of parasite burden and 3) helps establish a more precise prevalence. Early detection of A. cantonensis increases the efficacy of prevention, treatment, and disease control strategies for susceptible animal populations and humans.

Repurposed drug battles 'brain-eating' amoeba.

A drug for urinary tract infections may also treat Balamuthia mandrillaris.

Experimental infection with Neospora caninum in Texel ewes at different stages of gestation.

In this study Texel sheep, at different stages of pregnancy, were experimentally infected with Neospora caninum. Eleven ewes, seronegative for N. caninum and Toxoplasma gondii, were inoculated 30 days before breeding (Group A), or at 65, 100, and 120 days of gestation (Groups B, C, and D). The group E (control) was inoculated with PBS. Blood samples were collected at -2, 2, 5, and 7 days post-infection (dpi), and weekly up to 42 dpi, for hematology, parasitemia (PCR), and serology (RIFI) assessments. Blood and tissue samples were collected from the lambs for molecular and histological analyses. All animals in Groups B, C, and D were seroconverted, whilst those in groups A and E remained seronegative. Parasitic DNA was detected in the blood of two ewes (groups B and D) and a lamb (group D), and in the brain of a lamb (group B). The parasitemia-positive ewe in group B delivered a weak and seropositive lamb, and had parasitic DNA in its placenta. These results confirm the vertical transmission of N. caninum in ewes inoculated at the beginning and end of pregnancy. The absence of abortions and other clinical signs suggest that Texel sheep may potentially have resistance to N. caninum.

Central nervous system commitment in Chagas disease.

The involvement of the central nervous system (CNS) during human acute and chronic Chagas disease (CD) has been largely reported. Meningoencephalitis is a frequent finding during the acute infection, while during chronic phase the CNS involvement is often accompanied by behavioral and cognitive impairments. In the same vein, several studies have shown that rodents infected with Trypanosoma cruzi (T. cruzi) display behavior abnormalities, accompanied by brain inflammation, in situ production of pro-inflammatory cytokines and parasitism in diverse cerebral areas, with involvement of microglia, macrophages, astrocytes, and neurons. However, the mechanisms used by the parasite to reach the brain remain now largely unknown. Herein we discuss the evidence unravelling the CNS involvement and complexity of neuroimmune interactions that take place in acute and chronic CD. Also, we provide some clues to hypothesize brain infections routes in human and experimental acute CD following oral infection by T. cruzi, an infection route that became a major CD related public health issue in Brazil.

Single cell and spatial transcriptomic analyses reveal microglia-plasma cell crosstalk in the brain during Trypanosoma brucei infection.

Human African trypanosomiasis, or sleeping sickness, is caused by the protozoan parasite Trypanosoma brucei and induces profound reactivity of glial cells and neuroinflammation when the parasites colonise the central nervous system. However, the transcriptional and functional responses of the brain to chronic T. brucei infection remain poorly understood. By integrating single cell and spatial transcriptomics of the mouse brain, we identify that glial responses triggered by infection are readily detected in the proximity to the circumventricular organs, including the lateral and 3rd ventricle. This coincides with the spatial localisation of both slender and stumpy forms of T. brucei. Furthermore, in silico predictions and functional validations led us to identify a previously unknown crosstalk between homeostatic microglia and Cd138+ plasma cells mediated by IL-10 and B cell activating factor (BAFF) signalling. This study provides important insights and resources to improve understanding of the molecular and cellular responses in the brain during infection with African trypanosomes.

Monocytes maintain central nervous system homeostasis following helminth-induced inflammation.

Neuroimmune interactions are crucial for regulating immunity and inflammation. Recent studies have revealed that the central nervous system (CNS) senses peripheral inflammation and responds by releasing molecules that limit immune cell activation, thereby promoting tolerance and tissue integrity. However, the extent to which this is a bidirectional process, and whether peripheral immune cells also promote tolerance mechanisms in the CNS remains poorly defined. Here we report that helminth-induced type 2 inflammation promotes monocyte responses in the brain that are required to inhibit excessive microglial activation and host death. Mechanistically, infection-induced monocytes express YM1 that is sufficient to inhibit tumor necrosis factor production from activated microglia. Importantly, neuroprotective monocytes persist in the brain, and infected mice are protected from subsequent lipopolysaccharide-induced neuroinflammation months after infection-induced inflammation has resolved. These studies demonstrate that infiltrating monocytes promote CNS homeostasis in response to inflammation in the periphery and demonstrate that a peripheral infection can alter the immunologic landscape of the host brain.

Plasmodium falciparum and TNF-α Differentially Regulate Inflammatory and Barrier Integrity Pathways in Human Brain Endothelial Cells.

Cerebral malaria is a severe complication of Plasmodium falciparum infection characterized by the loss of blood-brain barrier (BBB) integrity, which is associated with brain swelling and mortality in patients. P. falciparum-infected red blood cells and inflammatory cytokines, like tumor necrosis factor alpha (TNF-α), have been implicated in the development of cerebral malaria, but it is still unclear how they contribute to the loss of BBB integrity. Here, a combination of transcriptomic analysis and cellular assays detecting changes in barrier integrity and endothelial activation were used to distinguish between the effects of P. falciparum and TNF-α on a human brain microvascular endothelial cell (HBMEC) line and in primary human brain microvascular endothelial cells. We observed that while TNF-α induced high levels of endothelial activation, it only caused a small increase in HBMEC permeability. Conversely, P. falciparum-infected red blood cells (iRBCs) led to a strong increase in HBMEC permeability that was not mediated by cell death. Distinct transcriptomic profiles of TNF-α and P. falciparum in HBMECs confirm the differential effects of these stimuli, with the parasite preferentially inducing an endoplasmic reticulum stress response. Our results establish that there are fundamental differences in the responses induced by TNF-α and P. falciparum on brain endothelial cells and suggest that parasite-induced signaling is a major component driving the disruption of the BBB during cerebral malaria, proposing a potential target for much needed therapeutics. IMPORTANCE Cerebral malaria is a severe complication of Plasmodium falciparum infection that causes the loss of blood-brain barrier integrity and frequently results in death. Here, we compared the effect of P. falciparum-infected red blood cells and inflammatory cytokines, like TNF-α, in the loss of BBB integrity. We observed that while TNF-α induced a small increase in barrier permeability, P. falciparum-infected red blood cells led to a severe loss of barrier integrity. Our results establish that there are fundamental differences in the responses induced by TNF-α and P. falciparum on brain endothelial cells and suggest that parasite-induced signaling is a major component driving the disruption of the BBB during cerebral malaria, proposing a potential target for much needed therapeutics.

Brain endothelial STING1 activation by Plasmodium-sequestered heme promotes cerebral malaria via type I IFN response.

Cerebral malaria (CM) is a life-threatening form of Plasmodium falciparum infection caused by brain inflammation. Brain endothelium dysfunction is a hallmark of CM pathology, which is also associated with the activation of the type I interferon (IFN) inflammatory pathway. The molecular triggers and sensors eliciting brain type I IFN cellular responses during CM remain largely unknown. We herein identified the stimulator of interferon response cGAMP interactor 1 (STING1) as the key innate immune sensor that induces Ifnß1 transcription in the brain of mice infected with Plasmodium berghei ANKA (Pba). This STING1/IFNß-mediated response increases brain CXCL10 governing the extent of brain leukocyte infiltration and blood-brain barrier (BBB) breakdown, and determining CM lethality. The critical role of brain endothelial cells (BECs) in fueling type I IFN-driven brain inflammation was demonstrated in brain endothelial-specific IFNß-reporter and STING1-deficient Pba-infected mice, which were significantly protected from CM lethality. Moreover, extracellular particles (EPs) released from Pba-infected erythrocytes activated the STING1-dependent type I IFN response in BECs, a response requiring intracellular acidification. Fractionation of the EPs enabled us to identify a defined fraction carrying hemoglobin degradation remnants that activates STING1/IFNß in the brain endothelium, a process correlated with heme content. Notably, stimulation of STING1-deficient BECs with heme, docking experiments, and in vitro binding assays unveiled that heme is a putative STING1 ligand. This work shows that heme resultant from the parasite heterotrophic activity operates as an alarmin, triggering brain endothelial inflammatory responses via the STING1/IFNß/CXCL10 axis crucial to CM pathogenesis and lethality.

Toxoplasma infection in male mice alters dopamine-sensitive behaviors and host gene expression patterns associated with neuropsychiatric disease.

During chronic infection, the single celled parasite, Toxoplasma gondii, can migrate to the brain where it has been associated with altered dopamine function and the capacity to modulate host behavior, increasing risk of neurocognitive disorders. Here we explore alterations in dopamine-related behavior in a new mouse model based on stimulant (cocaine)-induced hyperactivity. In combination with cocaine, infection resulted in heightened sensorimotor deficits and impairment in prepulse inhibition response, which are commonly disrupted in neuropsychiatric conditions. To identify molecular pathways in the brain affected by chronic T. gondii infection, we investigated patterns of gene expression. As expected, infection was associated with an enrichment of genes associated with general immune response pathways, that otherwise limits statistical power to identify more informative pathways. To overcome this limitation and focus on pathways of neurological relevance, we developed a novel context enrichment approach that relies on a customized ontology. Applying this approach, we identified genes that exhibited unexpected patterns of expression arising from the combination of cocaine exposure and infection. These include sets of genes which exhibited dampened response to cocaine in infected mice, suggesting a possible mechanism for some observed behaviors and a neuroprotective effect that may be advantageous to parasite persistence. This model offers a powerful new approach to dissect the molecular pathways by which T. gondii infection contributes to neurocognitive disorders.

Balamuthia mandrillaris trophozoites ingest human neuronal cells via a trogocytosis-independent mechanism.

BACKGROUND: Environmental protozoa need an adaptation mechanism to survive drastic changes in niches in the human body. In the brain parenchyma, Balamuthia mandrillaris trophozoites, which are causative agents of fatal brain damage, must acquire nutrients through the ingestion of surrounding cells. However, the mechanism deployed by the trophozoites for cellular uptake remains unknown. METHODS: Amoebic ingestion of human neural cell components was investigated using a coculture system of clinically isolated B. mandrillaris trophozoites and human neuroblastoma SH-SY5Y cells. Cell-to-cell interactions were visualized in a three-dimensional manner using confocal and holotomographic microscopes. RESULTS: The B. mandrillaris trophozoites first attached themselves to human neuroblastoma SH-SY5Y cells and then twisted themselves around the cytoplasmic bridge. Based on fluorescence-based cell tracking, the B. mandrillaris trophozoites then inserted invadopodia into the cytoplasm of the human cells. Subsequently, the human protein-enriched components were internalized into the trophozoites in the form of nonmembranous granules, whereas the human lipids were dispersed in the cytoplasm. Intervention of trogocytosis, a process involving nibbling on parts of the target cells, failed to inhibit this cellular uptake. CONCLUSIONS: Human cell ingestion by B. mandrillaris trophozoites likely differs from trogocytosis, suggesting that a pathogen-specific strategy can be used to ameliorate brain damage.

Sulfadiazine Plus Pyrimethamine Therapy Reversed Multiple Behavioral and Neurocognitive Changes in Long-Term Chronic Toxoplasmosis by Reducing Brain Cyst Load and Inflammation-Related Alterations.

Toxoplasma gondii infects one-third of the world population. For decades, it has been considered a silent lifelong infection. However, chronically T. gondii-infected persons may present psychiatric and neurocognitive changes as anxiety, depression, and memory loss. In a model of long-term chronic infection, behavioral alterations parallel neuroinflammation and systemic high cytokine levels, and may reflect brain cyst load. Recent findings support that in chronic infection an active parasite-host interplay involves an immune-mediated control of tissue cysts. Here, we tested the idea that etiological treatment in chronic phase may add advantage to intrinsic immune-mediated cyst control and impact behavioral changes. Thus, we combined sulfadiazine-plus-pyrimethamine (S+P), the first-choice therapy for toxoplasmosis, to study the association of brain cyst load and biological processes related to the immune response (neuroinflammation, blood-brain barrier -BBB- disruption and serum cytokine levels), with behavioral and neurocognitive changes of long-term chronic infection. Female C57BL/6 mice (H-2b) were infected (5 cysts, ME-49 strain) and treated with S+P from 30 to 60 days postinfection (dpi), compared with vehicle (Veh)-treated and noninfected controls. At endpoints (pre-therapy, 30 dpi; S+P therapy, 60 dpi; after ceased therapy, 90 dpi), independent groups were subjected to behavioral tests, and brain tissues and sera were collected. Multiple behavioral and neurocognitive changes were detected in the early (30 dpi) and long-term (60 and 90 dpi) chronic infection. S+P therapy resolved locomotor alterations, anxiety, and depressive-like behavior, partially or transiently ameliorated hyperactivity and habituation memory loss. Analysis after therapy cessation showed that S+P therapy reduced the number of stimuli required for aversive memory consolidation. S+P therapy resulted in reduced brain cyst load, neuroinflammation and BBB disruption, and lowered systemic Th1-cytokine levels. Correlation analysis revealed association between IFNγ, TNF and MCP-1/CCL2 serum levels, brain cyst load and behavioral and neurocognitive alterations. Moreover, principal-component analysis (PCA-2D and 3D projections) highlighted distinction between clusters (noninfected; Veh-treated and S+P-treated infected). Thus, our data suggest that S+P therapy added gain to intrinsic brain cyst control and, direct or indirectly, ameliorated inflammation-related alterations, traits associated with behavioral and neurocognitive alterations.

Morphological and molecular characterization of Austrodiplostomum compactum metacercariae in the eyes and brains of fishes from the Ivaí River, Brazil.

Austrodiplostomum spp. (Platyhelminthes: Digenea) are endoparasites with a broad geographic distribution in South America. During the larval stage, they parasitize the eyes, brains, muscles, gill, kidneys and swim bladder of a wide variety of fishes. The metacercariae of Austrodiplostomum spp. have several morphological characteristics during development, but are very similar among species, which makes it necessary to use molecular tools to contribute to the elucidation during the larval stage. The objective of this study was to perform morphological and molecular analyses of Austrodiplostomum sp. found in specimens of Hypostomus sourced from the Ivaí River in the state of Paraná, Brazil. Of the 93 analyzed specimens (H. hermanni [n = 50], H. albopunctatus [n = 9], Hypostomus sp. 1 [n = 24], and Hypostomus sp. 2 [n = 10]), 60 were parasitized. A total of 577 Austrodiplostomum sp. metacercariae was collected from the infected hosts; DNA from seven of these samples was extracted, amplified, and sequenced. The morphological data associated with the genetic distance values and the relationships observed in the COI gene tree, indicate that all metacercariae were A. compactum. This is the first record of A. compactum parasitizing H. hermanni, H. albopunctatus, Hypostomus sp. 1, and Hypostomus sp. 2 in the Ivaí River.

Role of dense granule antigen 7 in vertical transmission of Neospora caninum in C57BL/6 mice infected during early pregnancy.

Neosporosis is a parasitic disease affecting the health of dogs and cattle worldwide. It is caused by Neospora caninum, an obligate intracellular apicomplexan parasite. Dogs are its definitive host, it mostly infects livestock animals, especially cattle that acts as intermediate host. It is necessary to have well-established models of abortion and vertical transmission in experimental animals, in order to determine basic control measures for the N. caninum infection. We evaluated the role of N. caninum dense granule antigen 7 (NcGRA7) in the vertical transmission of N. caninum using the C57BL/6 pregnant mouse model. We inoculated mice on day 3.5 of pregnancy with parental Nc-1 or NcGRA7-deficient parasites (NcGRA7KO). Post-mortem analyses were performed on day 30 after birth and the surviving pups were kept until day 30 postpartum. The number of parasites in the brain tissues of offspring from NcGRA7KO-infected dams was significantly lower than that of the Nc-1-infected dams under two infection doses (1 × 106 and 1 × 105 tachyzoites/mouse). The vertical transmission rates in the NcGRA7KO-infected group were significantly lower than those of the Nc1-infected group. To understand the mechanism by which the lack of NcGRA7 decreases the vertical transmission, pregnant mice were sacrificed on day 13.5 of pregnancy (10 days after infection), although parasite DNA was detected in the placentas, no significant difference was found between the two parasite lines. Histopathological analysis revealed a greater inflammatory response in the placentas from NcGRA7KO-infected dams than in those from the parental strain. This finding correlates with upregulated chemokine mRNA expression for CCL2, CCL8, and CXCL9 in the placentas from the NcGRA7KO-infected mice. In conclusion, these results suggest that loss of NcGRA7 triggers an inflammatory response in the placenta, resulting in decreased vertical transmission of N. caninum.

Early passage of Toxoplasma gondii across the blood-brain barrier.

The blood-brain barrier (BBB) efficiently protects the central nervous system (CNS) from infectious insults. Yet, the apicomplexan parasite Toxoplasma gondii has a remarkable capability to establish latent cerebral infection in humans and other vertebrates. In addition to the proposed mechanisms for access to the brain parenchyma, recent findings highlight a paramount role played by the BBB in restricting parasite passage and minimizing parasite loads in the brain. Consistent with clinically asymptomatic primary infections in humans, mounting evidence indicates that the original colonization of the brain by T. gondii encompasses previously unappreciated, nondisruptive translocation processes that precede the onset of parasite-limiting immune responses.