Parasite Elimination Research Articles

Gastrointestinal effects of ivermectin treatment in rats infected with Strongyloides venezuelensis

We aimed to evaluate the effects of ivermectin treatment on gastrointestinal morphology and function after Strongyloides venezuelensis infection. Male rats composed Control (C), Parasitized (Sv), Ivermectin (IVM) and Parasitized and treated with Ivermectin (Sv/IVM) groups. IVM and Sv/IVM groups were subdivided according to IVM: single dose of 200 μg/kg (IVM1 and Sv/IVM1) or three repeated doses of 200 μg/kg at 24 h intervals (IVM3 and Sv/IVM3). First dose of IVM was administered after peak of infection. Eggs per gram (EPG), mean gastric emptying time (MGET), mean cecum arrival time (MCAT) and mean small intestinal transit time (MSITT) were evaluated. Measurements were performed before drug and at peak of infection, first day post peak of infection and 30 days post infection. Same time intervals were simulated for uninfected animals. Number of recovered worms and intestinal morphometry were also rated. Data were analyzed by ANOVA and correlated by Dunnett and Pearson (p < 0.05). Sv/IVM1 and Sv/IVM3 showed reduction of EPG and worms, although only group SV/IVM3 eradicate them. Hastened gastric emptying and slowed intestinal transit provoked by S. venezuelensis infection can be reverted by a single administration of IVM after peak of infection, even without total parasite elimination. Although three consecutive doses of IVM were more efficient to eradicate the parasite, drug administration impaired gastrointestinal function and morphology. IVM alone affected gastrointestinal parameters in uninfected animals for prolonged periods, especially in high doses. In control, there were strong negative correlations between MSITT and muscle layers. Strongyloides venezuelensis infection abolishes such correlations. Longitudinal muscle was thinner in IVM3 and Sv/IVM3 groups and circular thicker in Sv group. Revisiting the action of traditional drugs broadens knowledge in the parasite-host interface and may result in the development of more accurate therapeutic strategies.

Molecular characterization and distribution of Schistosoma cercariae collected from naturally infected bulinid snails in northern and central C\xf4te d\u2019Ivoire

BackgroundAccurate identification of schistosome species infecting intermediate host snails is important for understanding parasite transmission, schistosomiasis control and elimination. Cercariae emerging from infected snails cannot be precisely identified morphologically to the species level. We used molecular tools to clarify the distribution of the Schistosoma haematobium group species infecting bulinid snails in a large part of Côte d’Ivoire and confirmed the presence of interspecific hybrid schistosomes.MethodsBetween June 2016 and March 2017, Bulinus snails were sampled in 164 human-water contact sites from 22 villages of the northern and central parts of Côte d’Ivoire. Multi-locus genetic analysis (mitochondrial cox1 and nuclear ITS) was performed on individual schistosome cercariae shed from snails, in the morning and in the afternoon, for species and hybrid identification.ResultsOverall, 1923 Bulinus truncatus, 255 Bulinus globosus and 1424 Bulinus forskalii were obtained. Among 2417 Bulinus screened, 25 specimens (18 B. truncatus and seven B. globosus) shed schistosomes, with up to 14% infection prevalence per site and time point. Globally, infection rates per time point ranged between 0.6 and 4%. Schistosoma bovis, S. haematobium and S. bovis × S. haematobium hybrids infected 0.5%, 0.2% and 0.4% of the snails screened, respectively. Schistosoma bovis and hybrids were more prevalent in B. truncatus, whereas S. haematobium and hybrid infections were more prevalent in B. globosus. Schistosoma bovis-infected Bulinus were predominantly found in northern sites, while S. haematobium and hybrid infected snails were mainly found in central parts of Côte d’Ivoire.ConclusionsThe data highlight the necessity of using molecular tools to identify and understand which schistosome species are transmitted by specific intermediate host snails. The study deepens our understanding of the epidemiology and transmission dynamics of S. haematobium and S. bovis in Côte d’Ivoire and provides the first conclusive evidence for the transmission of S. haematobium × S. bovis hybrids in this West African country.Trial registration ISRCTN, ISRCTN10926858. Registered 21 December 2016; retrospectively registered (see: http://www.isrctn.com/ISRCTN10926858)

Parasites of the digestive tract of sheep and goats from organic farms in Western Pomerania, Poland

The aim of the study was to determine the prevalence and intensity of parasite infection of the digestive tract in sheep and goats from the West Pomerania region following anti-parasite treatment. Feces were freely collected from sheep and goats kept on organic farms and subjected to analysis by the Willis-Schlaf and McMaster’s flotation methods. The mean extensity of infection by gastrointestinal parasites in both sheep and goats was found to be 100%. Both sheep and goats displayed the presence of gastrointestinal nematodes, Eimeria protozoa and Moniezia spp. tapeworms. The intensity of infection of sheep and goats by these parasites was arranged as follows: gastrointestinal nematodes > Eimeria protozoa > Moniezia tapeworms. Our findings confirm that a problem exists regarding the occurrence of parasites of the digestive tract among sheep and goats kept under organic conditions. Therefore, correct implementation of prophylactic programmes should be emphasised to ensure the control or elimination of parasites in animals, particularly those kept on pasture.

Toxocara and its species.

Abstract This systematic review focuses on the nematode genus Toxocara and its zoonotic and non-zoonotic species and provides an update to that published by Warren almost half a century ago. Currently, 26 species of Toxocara have been described morphologically and four differentiated by molecular techniques. The most frequently reported and wide spread zoonotic species is Toxocara canis . Zoonotic infection with T. cati remains controversial and only a few infections, mostly in children with ocular larval migrans (OLM), have been reported. To date, none have been confirmed using molecular techniques. Only a single-suspected case of human infection with T. pteropodis has been reported and this species has yet to be confirmed as zoonotic. Of the non-zoonotic species T. vitulorum is of major economic importance and there are 13 minor species: T. alienata , T. apodemi , T. genettae , T. indica , T. leonine , T. mackerrasae , T. malaysiensis , T. paradoxura , T. pearsei , T. sprenti , T. surkattae , T. tanuki and T. vajrasthirae . Nine species have been reported only once: T. canarisi , T. cynonycteridis , T. elephantis , T. herpestum , T. hippopotami , T. lyncis , T. manzadiensis , T. vincenti and T. warreni . Toxocara occurs in many definitive host species: canids, felids, civets, mongoose, cattle, raccoons, bats and rodents. In humans, T. canis infections can result in four distinct syndromes: visceral larval migrans, OLM, neuro-toxocariasis and covert toxocariasis. Serological tests supplemented by molecular and imaging techniques provide the basis of diagnosis and may also add to the longitudinal monitoring of treatment. Seroprevalence in humans in developed countries ranges from 3 to 22% and in developing countries from 10 to 92%. Vertical transmission of the parasite in definitive hosts facilitates the earliest potential production of eggs from young animals and provides challenging yet important control opportunities. Climate change and increasing human and companion animal populations have facilitated an expansion in the geographical range of this zoonosis. Behavioural changes coupled with increased urbanization enhance potential transmission, as people and dogs become increasingly crowded together facilitating opportunities for T. canis transmission, and a greater understanding of these factors should be examined to facilitate appropriate and cost-effective control programmes. Anthelminthic used in the elimination of adult parasites from dog or cat intestines can provide an effective control with toxocariasis. Control measures using a one health approach coordinating the expertise of physicians, veterinarians, public health workers, dog owners and aided by legislation facilitates a best practice approach to control.

EFEITO DO PARASITISMO POR Haemonchus contortus SOBRE O METABOLISMO OXIDATIVO DE LEUCÓCITOS DE OVINOS

Resumo A resposta imune tardia direcionada para eliminação da hemoncose pode ser modulada pelo perfil Th2, sendo os eosinófilos as principais células efetoras responsáveis pela eficiente eliminação do parasita; ou modulada pelo perfil Th1, sendo os neutrófilos as principais células efetoras, que promovem eliminação parasitária mais deficiente, pois testes in vitro demonstraram que o parasita deprime o metabolismo oxidativo dos fagócitos. Desta maneira, este trabalho objetivou avaliar se o grau de infecção parasitária observado pela quantidade de ovos por grama de fezes (OPG) de Haemonchus contortus interfere no leucograma e se impacta no metabolismo oxidativo leucocitário em ovino naturalmente acometido por hemoncose. Para tanto, 39 ovinos machos adultos e sem alterações no exame físico, excetuando-se a coloração das mucosas, foram separados em 4 grupos conforme a infecção parasitária 0-350 (n=15), 400 a 1000 (n=10), 1100-2000 (n=7) e 2100-4700 (n=7). Notou-se correlação significativa positiva entre OPG e neutrófilos (r=0,56; P=0,0003) e significativa negativa entre OPG e eosinófilos (r=-0,50; P=0,0012) e OPG e metabolismo oxidativo leucocitário (P=0,0001), permitindo concluir que há relação entre as células efetoras e a severidade de infecção parasitária em ovinos naturalmente infectados por hemoncose. Também se verificou que a alta infecção parasitária promove diminuição do metabolismo oxidativo de leucócitos.

THE SITUATION OF LYMPHATIC FILARIASIS IN THE MUNICIPALITY OF PAULISTA, PERNAMBUCO, BRAZIL

Cases of Lymphatic Filariasis (LF) have been notified since 1959 in the municipality of Paulista, yet it is still considered an LF-free area. The purpose of this study was to describe the situation of Paulista Health Department. The data were gathered via antigenic surveys carried out in the town, using POC-ICT-AD12 tests. A total of 1,000 individuals, aged 10 and over, were examined in the neighborhoods of Mirueira, Engenho Maranguape, Janga and Maranguape II (250 individuals in each district). Among the individuals evaluated, seven (0,7%) tested positive for antigens using CFA POC-ICT-AD12, 5 out of 250 (2.0%) in the Engenho Maranguape neighborhood and 2 out of 250 (0.8%) in Janga. In this group, one particular individual presented microfilaremia, quantified at 5 Mf/mL. These results suggest that the municipality of Paulista might be a “silent” source of LF continuous transmission, fact that could impact negatively on the goals of the GPELF program meant to provide certification of parasitic disease control and elimination by the year 2022.

Serine protease inhibitors rich Coccinia grandis (L.) Voigt leaf extract induces protective immune responses in murine visceral leishmaniasis

Leishmaniasis is a parasite-mediated tropical disease affecting millions of individuals worldwide. The available antileishmanial chemotherapeutic modalities exhibit adverse toxicity, exorbitant price and advent of drug-resistant parasites. Hence, plant-derived products are an alternative preference for the emergence of novel and effective antileishmanial agents that rejuvenate the host immunity with limited toxicity. The present work is complementary to our previous report that revealed the in vitro antileishmanial and immunomodulatory activity of Coccinia grandis (L.) Voigt leaf extract (Cg-Ex) rich in serine protease inhibitors. Thus, preliminary objectives of the study were to elucidate the leishmanicidal activity and host effector mechanism in Leishmania donovani infected BALB/c mice treated with Cg-Ex. Oral administration of Cg-Ex significantly reduced the spleen and liver parasite burden at dose-dependently. The parasite elimination was associated with generation of ROS and NO that are interrelated with up-regulation of disease-suppressing Th1 cytokines and down-regulation of disease-promoting Th2 cytokines at both protein and mRNA level. Moreover, Cg-Ex augmented the delayed-type hypersensitivity (DTH) response and serum IgG2a level which are correlated with the diminution of parasite burden with no hepatic and renal toxicity. Additionally, histological analysis of spleen depicted the improvement of structural disorganization of white and red pulp after Cg-Ex treatment. Therefore, our intriguing findings have presented the first indication of in vivo antileishmanial efficacy through activation of pro-inflammatory immune responses of the host by a natural plant leaf extract (Cg-Ex) containing serine protease inhibitors which could have a role as a potential immunomodulator against visceral leishmaniasis.

Micro Array-Assisted Analysis of Anti-Schistosome Glycan Antibodies Elicited by Protective Vaccination With Irradiated Cercariae.

Baboons vaccinated with radiation-attenuated cercariae develop high levels of protection against schistosome infection, correlating to high antibody titres towards schistosome antigens with unknown molecular identity. Using a microarray consisting of glycans isolated from different life-stages of schistosomes, we studied the anti-glycan immunoglobulin (Ig) G and IgM responses in vaccinated and challenged baboons over a time course of 25 weeks. Anti-glycan IgM responses developed early after vaccination, but did not rise in response to later vaccinations. In contrast, anti-glycan IgG developed more slowly, but was boosted by all five subsequent vaccinations. High IgM and IgG levels against O-glycans and glycosphingolipid glycans of cercariae were observed. At the time of challenge, while most antibody levels decreased in the absence of vaccination, IgG towards a subset of glycans containing multiple-fucosylated motifs remained high until 6 weeks post-challenge during challenge parasite elimination, suggesting a possible role of this IgG in protection.

Neutrophils, eosinophils, and mast cells in the intestinal wall of dogs naturally infected with Leishmania infantum.

Visceral leishmaniasis (VL) is a disease caused by the protozoa Leishmania infantum and can cause an inflammatory reaction in the gastrointestinal tract, however the role of granulocytic cells (neutrophils, eosinophils, and mast cells) in the intestine of dogs infected is not fully understood. We performed a quantitative analysis these cells in the intestinal wall of dogs with canine visceral leishmaniasis (CVL). Twenty dogs were assigned to one of three groups: group 1 (G1, n=8), dogs with CVL and L. infantum amastigotes in the intestine; group 2 (G2, n=9), dogs with CVL but without intestinal amastigotes; and group 3 (G3, n=3), uninfected dogs (control group). Granulocytic cells were counted in the crypt-villus unit (mucosa), submucosa, and muscle layer of the intestinal mucosa. Cell counts were higher in the intestinal wall of dogs from G2 followed by G1 and G3 (p≤0.05). In G1, there was a low inverse correlation between parasite burden of the small intestine and granulocyte counts (r= -0.1, p≤0.01). However, in G2 dogs, mast cell and eosinophil numbers showed positive correlation (r=0.85, p≤0.01). The granulocytic cell hyperplasia observed in the intestine of L. infantum-infected dogs suggests that these cells may be involved in the cell-mediated immune response for parasite elimination.

Substantiating freedom from parasitic infection by combining transmission model predictions with disease surveys

Stopping interventions is a critical decision for parasite elimination programmes. Quantifying the probability that elimination has occurred due to interventions can be facilitated by combining infection status information from parasitological surveys with extinction thresholds predicted by parasite transmission models. Here we demonstrate how the integrated use of these two pieces of information derived from infection monitoring data can be used to develop an analytic framework for guiding the making of defensible decisions to stop interventions. We present a computational tool to perform these probability calculations and demonstrate its practical utility for supporting intervention cessation decisions by applying the framework to infection data from programmes aiming to eliminate onchocerciasis and lymphatic filariasis in Uganda and Nigeria, respectively. We highlight a possible method for validating the results in the field, and discuss further refinements and extensions required to deploy this predictive tool for guiding decision making by programme managers.

MicroRNA-155 Protects Group 2 Innate Lymphoid Cells From Apoptosis to Promote Type-2 Immunity.

Group-2 innate lymphoid cells (ILC2) play critical roles in the initiation and maintenance of type-2 immune responses, predominantly through their production of the type-2 cytokines IL-5, IL-9, and IL-13. ILC2 are essential for the efficient elimination of helminth parasites, but also contribute to the detrimental type-2 immune responses that underlie diseases such as asthma and allergy. While several transcription factors have been identified that regulate the development and function of ILC2, less is known about the post-transcriptional mechanisms that regulate these processes. We identified micro-RNAs (miRNAs) that are co-ordinately regulated in ILC2 from mice exposed to two different stimuli, namely IL-33 “alarmin” administration or Nippostrongylus brasiliensis parasitic worm infection. miR-155 is upregulated in ILC2 in response to both stimuli and miR-155−/− mice had impaired IL-33-driven ILC2 responses. Using mixed bone marrow chimeras, we demonstrate that this deficit is intrinsic to ILC2 and that miR-155 protects ILC2 from apoptosis, while having little impact on ILC2 proliferation or cytokine production. These data reveal a subset of miRNAs that are regulated upon ILC2 activation and establish a specific role for miR-155 in regulating ILC2 survival following activation.

Quantifying the value of surveillance data for improving model predictions of lymphatic filariasis elimination.

BackgroundMathematical models are increasingly being used to evaluate strategies aiming to achieve the control or elimination of parasitic diseases. Recently, owing to growing realization that process-oriented models are useful for ecological forecasts only if the biological processes are well defined, attention has focused on data assimilation as a means to improve the predictive performance of these models.Methodology and principal findingsWe report on the development of an analytical framework to quantify the relative values of various longitudinal infection surveillance data collected in field sites undergoing mass drug administrations (MDAs) for calibrating three lymphatic filariasis (LF) models (EPIFIL, LYMFASIM, and TRANSFIL), and for improving their predictions of the required durations of drug interventions to achieve parasite elimination in endemic populations. The relative information contribution of site-specific data collected at the time points proposed by the WHO monitoring framework was evaluated using model-data updating procedures, and via calculations of the Shannon information index and weighted variances from the probability distributions of the estimated timelines to parasite extinction made by each model. Results show that data-informed models provided more precise forecasts of elimination timelines in each site compared to model-only simulations. Data streams that included year 5 post-MDA microfilariae (mf) survey data, however, reduced each model’s uncertainty most compared to data streams containing only baseline and/or post-MDA 3 or longer-term mf survey data irrespective of MDA coverage, suggesting that data up to this monitoring point may be optimal for informing the present LF models. We show that the improvements observed in the predictive performance of the best data-informed models may be a function of temporal changes in inter-parameter interactions. Such best data-informed models may also produce more accurate predictions of the durations of drug interventions required to achieve parasite elimination.SignificanceKnowledge of relative information contributions of model only versus data-informed models is valuable for improving the usefulness of LF model predictions in management decision making, learning system dynamics, and for supporting the design of parasite monitoring programmes. The present results further pinpoint the crucial need for longitudinal infection surveillance data for enhancing the precision and accuracy of model predictions of the intervention durations required to achieve parasite elimination in an endemic location.

Concanavalin-A displays leishmanicidal activity by inducing ROS production in human peripheral blood mononuclear cells

The context of the article: Leishmania amazonensis has a wide geographical distribution throughout South American countries and can cause self-healing to severe cases as mucocutaneous or visceral forms. Leishmaniasis presents a balance of inflammatory and anti-inflammatory cytokines which is responsible for promoting the activation of phagocytes, essential to control the infection and lead to tissue repair/resolution of the disease, respectively.Results and discussion: Our model revealed that the treatment with Con-A was capable to stimulate human PBMC cells by increasing the phagocytic capacity and promoting parasite elimination. The pretreatment with Con-A promoted inflammatory (IFN-γ, TNF-α, IL-2 and IL-6) and anti-inflammatory (IL-4 and IL-10) cytokines production, increased the reactive oxygen species (ROS) sinthesys as well as the expression and presence of iNOS enzyme, but not nitric oxide production.Conclusion: Based on the data obtained, it was possible to infer that Con-A induces the ROS production, responsible for eliminating parasites in addition to regulatory cytokines synthesis which are important for disease resolution.

Native fly parasites are the principal cause of nestling mortality in endangered Tasmanian pardalotes

AbstractEstablished host–parasite interactions at an evolutionary equilibrium are not predicted to result in host population decline. However, parasites may become a major threat to host species weakened by other factors such as habitat degradation or loss of genetic diversity in small populations. We investigate an unusually virulent Tasmanian ectoparasite, Passeromyia longicornis, in its long‐term hosts, the endangered forty‐spotted pardalote (Pardalotus quadragintus) and striated pardalote (Pardalotus striatus) in southeastern Tasmania, Australia. We conducted a parasite elimination experiment to determine the net effect of parasites on forty‐spotted pardalote nestling mortality, and monitored nestling parasite load and mortality in forty‐spotted and striated pardalote nestlings during two breeding seasons (Aug–Jan, 2013–2015). Passeromyia longicornis larvae killed 81% of all forty‐spotted pardalotes nestlings. Across 2 years, forty‐spotted pardalotes fledged fewer nestlings (18%) than sympatric striated pardalotes (26%), and this difference was generated by a combination of higher parasite load and virulence in forty‐spotted pardalote nests. These results show that native ectoparasites can cause substantial and potentially unsustainable mortality in their hosts.

Chronic schistosomiasis suppresses HIV-specific responses to DNA-MVA and MVA-gp140 Env vaccine regimens despite antihelminthic treatment and increases helminth-associated pathology in a mouse model.

Future HIV vaccines are expected to induce effective Th1 cell-mediated and Env-specific antibody responses that are necessary to offer protective immunity to HIV infection. However, HIV infections are highly prevalent in helminth endemic areas. Helminth infections induce polarised Th2 responses that may impair HIV vaccine-generated Th1 responses. In this study, we tested if Schistosoma mansoni (Sm) infection altered immune responses to SAAVI candidate HIV vaccines (DNA and MVA) and an HIV-1 gp140 Env protein vaccine (gp140) and whether parasite elimination by chemotherapy or the presence of Sm eggs (SmE) in the absence of active infection influenced the immunogenicity of these vaccines. In addition, we evaluated helminth-associated pathology in DNA and MVA vaccination groups. Mice were chronically infected with Sm and vaccinated with DNA+MVA in a prime+boost combination or MVA+gp140 in concurrent combination regimens. Some Sm-infected mice were treated with praziquantel (PZQ) prior to vaccinations. Other mice were inoculated with SmE before receiving vaccinations. Unvaccinated mice without Sm infection or SmE inoculation served as controls. HIV responses were evaluated in the blood and spleen while Sm-associated pathology was evaluated in the livers. Sm-infected mice had significantly lower magnitudes of HIV-specific cellular responses after vaccination with DNA+MVA or MVA+gp140 compared to uninfected control mice. Similarly, gp140 Env-specific antibody responses were significantly lower in vaccinated Sm-infected mice compared to controls. Treatment with PZQ partially restored cellular but not humoral immune responses in vaccinated Sm-infected mice. Gp140 Env-specific antibody responses were attenuated in mice that were inoculated with SmE compared to controls. Lastly, Sm-infected mice that were vaccinated with DNA+MVA displayed exacerbated liver pathology as indicated by larger granulomas and increased hepatosplenomegaly when compared with unvaccinated Sm-infected mice. This study shows that chronic schistosomiasis attenuates both HIV-specific T-cell and antibody responses and parasite elimination by chemotherapy may partially restore cellular but not antibody immunity, with additional data suggesting that the presence of SmE retained in the tissues after antihelminthic therapy contributes to lack of full immune restoration. Our data further suggest that helminthiasis may compromise HIV vaccine safety. Overall, these findings suggested a potential negative impact on future HIV vaccinations by helminthiasis in endemic areas.

Faster growth with shorter antigens can explain a VSG hierarchy during African trypanosome infections: a feint attack by parasites

The parasitic African trypanosome, Trypanosoma brucei, evades the adaptive host immune response by a process of antigenic variation that involves the clonal switching of variant surface glycoproteins (VSGs). The VSGs that come to dominate in vivo during an infection are not entirely random, but display a hierarchical order. How this arises is not fully understood. Combining available genetic data with mathematical modelling, we report a VSG-length-dependent hierarchical timing of clonal VSG dominance in a mouse model, consistent with an inverse correlation between VSG length and trypanosome growth-rate. Our analyses indicate that, among parasites switching to new VSGs, those expressing shorter VSGs preferentially accumulate to a detectable level that is sufficient to trigger a targeted immune response. This may be due to the increased metabolic cost of producing longer VSGs. Subsequent elimination of faster-growing parasites then allows slower-growing parasites with longer VSGs to accumulate. This interaction between the host and parasite is able to explain the temporal distribution of VSGs observed in vivo. Thus, our findings reveal a length-dependent hierarchy that operates during T. brucei infection. This represents a ‘feint attack’ diversion tactic utilised by these persistent parasites to out-maneuver the host adaptive immune system.

Combination of paromomycin plus human anti-TNF-α antibodies to control the local inflammatory response in BALB/ mice with cutaneous leishmaniasis lesions

BackgroundCutaneous leishmaniasis (CL) skin lesions are the result of a deregulated immune response, which is unable to eliminate Leishmania parasites. The control of both, parasites and host immune response, is critical to prevent tissue destruction. The skin ulceration has been correlated with high TNF-α level. ObjectiveBecause human anti-TNF-α antibodies (Ab) have been successfully assayed in several mice inflammatory diseases, we hypothesized that their anti-inflammatory effect could optimize the healing of CL lesions achieved after topical application of paromomycin (PM), the current chemotherapy against CL. Methods and resultsWe first compared the in vitro efficacy of PM and Ab alone and the drug given in combination with Ab to assess if the Ab could interfere with PM leishmanicidal activity in L. major-infected bone marrow-derived macrophages. The combination therapy had similar antileishmanial activity to the drug alone and showed no influence on NO production, which allows macrophage-mediated parasite killing. Next, we demonstrated in an in vivo model of Imiquimod®-induced inflammation that topical Ab and PM inhibit the infiltration of inflammatory cells in the skin. In the efficacy studies in L. major-infected BALB/c mice, PM combined with Ab led to a sharp infection reduction and showed a stronger anti-inflammatory activity than PM alone. This was confirmed by the down-regulation of TNF-α, IL-1β, iNOS, IL-17, and CCL3 as well as by a decrease of the neutrophilic infiltrate during infection upon treatment with the Ab. ConclusionsIn terms of parasite elimination and inflammation reduction, topical application of Ab in combination with PM was more effective than the drug alone.

Intracellular development of Trypanosoma cruzi in the presence of metals.

Trypanosoma cruzi is transmitted to vertebrate hosts during the feeding of blood-sucking insects. After the invasion of host cells, the parasite resides within the parasitophorous vacuole until to escape to host cytoplasm and to proliferate, establishing an infection. Studies demonstrated that some intracellular parasites have to acquire all essential nutrients as well as transition metals from the host cell to be pathogenic, to maintain the homeostasis and to replicate. The present study investigated the progressive steps of the intracellular parasite development and establishment of infection in the presence of ZnCl2, CdCl2 and HgCl2. LLC-MK2 cells were infected with trypomastigotes during 6-84h to investigate the steps of intracellular parasite development. After the host cells were infected during 12h and treated with metals during 24 or 60h or they were treated for 24h and cultured for 72h more to observe the reversibility. The results showed that the non-synchronous invasion of trypomastigotes resulted in an increasing number of intracellular parasites in intermediary forms (until 24h post-infection), the appearance (from 36h) and proliferation (84h) of the amastigotes. The 24h-treatments were not enough to impair parasite escape to the host cytoplasm and reproduction. However, 60h of incubations led to a significant reduction in parasite numbers, as well as the reversibility assays. In conclusion, new insights about the intracellular T. cruzi development in the presence of metals were provided, and further studies should be performed to investigate the events involved in parasite death and elimination.

Leishmania Hijacks Myeloid Cells for Immune Escape.

Protozoan parasites of the Leishmania genus are the causative agents of leishmaniasis, a group of neglected tropical diseases whose clinical manifestations vary depending on the infectious Leishmania species but also on host factors. Recognition of the parasite by host myeloid immune cells is a key to trigger an effective Leishmania-specific immunity. However, the parasite is able to persist in host myeloid cells by evading, delaying and manipulating host immunity in order to escape host resistance and ensure its transmission. Neutrophils are first in infiltrating infection sites and could act either favoring or protecting against infection, depending on factors such as the genetic background of the host or the parasite species. Macrophages are the main host cells where the parasites grow and divide. However, macrophages are also the main effector population involved in parasite clearance. Parasite elimination by macrophages requires the priming and development of an effector Th1 adaptive immunity driven by specific subtypes of dendritic cells. Herein, we will provide a comprehensive outline of how myeloid cells regulate innate and adaptive immunity against Leishmania, and the mechanisms used by the parasites to promote their evasion and sabotage. Understanding the interactions between Leishmania and the host myeloid cells may lead to the development of new therapeutic approaches and improved vaccination to leishmaniases, an important worldwide health problem in which current therapeutic or preventive approaches are limited.

Splenocytes from young mice protect immunocompromised mice against death from malaria infection, but they do not proliferate well.

Abstract The immune system plays an essential role in the elimination of malaria parasites. CD4+ T cells are imperative in the immune response to the infection, but immune response to malaria especially in young children is poorly understood, due to a lack of a better young animal model to study the pathogenesis of the disease. We have developed a young mouse (pup) model using day 15 pups to help understand the pathogenesis, and development of protective CD4 T cells in malaria infection. Here, we determined the ability of pup cells to protect immunocompromised RAGKO mice from malaria infection. We infected day 15 old pups with Plasmodium chabudi at 1×105 iRBCs, and transferred splenocytes to RAGKO mice on day 8 post-infection. RAGKO mice were then infected. Mice that received pup cells looked healthier and active throughout the experiment, compared to their counterparts who received adult spleen cells. During the peak of infection, mice that received adult cells lost more weight than the pup cell recipients. On day 60 post-transfer, we observed same numbers of CD4 T cells, central memory and effector memory T cells. There were significantly lower proportions and numbers of IFNγ and TNFα positive cells from pups compared to adult cells. We next determined if there was any difference in the proliferation of CD4 T cells and all splenocytes in pup cells. We purified CD4+ T cells using EasySep kit and cultured them on αCD3/CD28 pre-coated plates, compared to all splenocytes. There was a significant growth in purified CD4 T cells from adult than pup cells. Interestingly, all splenocytes from pups proliferated better than adults. Therefore, our data suggest that pup cells protect RAGKO mice from death, but do not develop into functional memory due to poor proliferation.