Reduction In Parasite Load Research Articles

Plasmodium falciparum malaria: Convergent evolutionary trajectories towards delayed clearance following artemisinin treatment

Malaria is a major global health challenge with 300million new cases every year. The most effective regimen for treating Plasmodium falciparum malaria is based on artemisinin and its derivatives. The drugs are highly effective, resulting in rapid clearance of parasites even in severe P. falciparum malaria patients. During the last five years, artemisinin-resistant parasites have begun to emerge first in Cambodia and now in Thailand and Myanmar. At present, the level of artemisinin resistance is relatively low with clinical presentation of delayed artemisinin clearance (a longer time to reduce parasite load) and a small decrease in artemisinin sensitivity in cultured isolates. Nevertheless, multiple genetic loci associated with delayed parasite clearance have been reported, but they cannot account for a large portion of cases. Even the most well-studied kelch 13 propeller mutations cannot always predict the outcome of artemisinin treatment in vitro and in vivo. Here we propose that delayed clearance by artemisinin could be the result of convergent evolution, driven by multiple trajectories to overcome artemisinin-induced stress, but precluded to become full blown resistance by high fitness cost. Genetic association studies by several genome-wide approaches reveal linkage disequilibrium between multiple loci and delayed parasite clearance. Genetic manipulations at some of these loci already have resulted in loss in artemisinin sensitivity. The notion presented here is by itself consistent with existing evidence on artemisinin resistance and has the potential to be explored using available genomic data. Most important of all, molecular surveillance of artemisinin resistance based on multi-genic markers could be more informative than relying on any one particular molecular marker.

Colonization of Rhodnius prolixus gut by Trypanosoma cruzi involves an extensive parasite killing.

Trypanosoma cruzi, the etiological agent of Chagas disease, is ingested by triatomines during their bloodmeal on an infected mammal. Aiming to investigate the development and differentiation of T. cruzi inside the intestinal tract of Rhodnius prolixus at the beginning of infection we fed insects with cultured epimastigotes and blood trypomastigotes from infected mice to determine the amount of recovered parasites after ingestion. Approximately 20% of the ingested parasites was found in the insect anterior midgut (AM) 3 h after feeding. Interestingly, a significant reduction (80%) in the numbers of trypomastigotes was observed after 24 h of infection suggesting that parasites were killed in the AM. Moreover, few parasites were found in that intestinal portion after 96 h of infection. The evaluation of the numbers of parasites in the posterior midgut (PM) at the same periods showed a reduced parasite load, indicating that parasites were not moving from the AM. Additionally, incubation of blood trypomastigotes with extracts from R. prolixus AMs revealed that components of this tissue could induce significant death of T. cruzi. Finally, we observed that differentiation from trypomastigotes to epimastigotes is not completed in the AM; instead we suggest that trypomastigotes change to intermediary forms before their migration to the PM, where differentiation to epimastigotes takes place. The present work clarifies controversial points concerning T. cruzi development in insect vector, showing that parasite suffers a drastic decrease in population size before epimastigonesis accomplishment in PM.

The effects of sex hormones on immune function: a meta-analysis.

The effects of sex hormones on immune function have received much attention, especially following the proposal of the immunocompetence handicap hypothesis. Many studies, both experimental and correlational, have been conducted to test the relationship between immune function and the sex hormones testosterone in males and oestrogen in females. However, the results are mixed. We conducted four cross-species meta-analyses to investigate the relationship between sex hormones and immune function: (i) the effect of testosterone manipulation on immune function in males, (ii) the correlation between circulating testosterone level and immune function in males, (iii) the effect of oestrogen manipulation on immune function in females, and (iv) the correlation between circulating oestrogen level and immune function in females. The results from the experimental studies showed that testosterone had a medium-sized immunosuppressive effect on immune function. The effect of oestrogen, on the other hand, depended on the immune measure used. Oestrogen suppressed cell-mediated immune function while reducing parasite loads. The overall correlation (meta-analytic relationship) between circulating sex hormone level and immune function was not statistically significant for either testosterone or oestrogen despite the power of meta-analysis. These results suggest that correlational studies have limited value for testing the effects of sex hormones on immune function. We found little evidence of publication bias in the four data sets using indirect tests. There was a weak and positive relationship between year of publication and effect size for experimental studies of testosterone that became non-significant after we controlled for castration and immune measure, suggesting that the temporal trend was due to changes in these moderators over time. Graphical analyses suggest that the temporal trend was due to an increased use of cytokine measures across time. We found substantial heterogeneity in effect sizes, except in correlational studies of testosterone, even after we accounted for the relevant random and fixed factors. In conclusion, our results provide good evidence that testosterone suppresses immune function and that the effect of oestrogen varies depending on the immune measure used.

A vacuolar iron-transporter homologue acts as a detoxifier in Plasmodium.

Iron is an essential micronutrient but is also highly toxic. In yeast and plant cells, a key detoxifying mechanism involves iron sequestration into intracellular storage compartments, mediated by members of the vacuolar iron-transporter (VIT) family of proteins. Here we study the VIT homologue from the malaria parasites Plasmodium falciparum (PfVIT) and Plasmodium berghei (PbVIT). PfVIT-mediated iron transport in a yeast heterologous expression system is saturable (Km∼14.7 μM), and selective for Fe2+ over other divalent cations. PbVIT-deficient P. berghei lines (Pbvit−) show a reduction in parasite load in both liver and blood stages of infection in mice. Moreover, Pbvit− parasites have higher levels of labile iron in blood stages and are more sensitive to increased iron levels in liver stages, when compared with wild-type parasites. Our data are consistent with Plasmodium VITs playing a major role in iron detoxification and, thus, normal development of malaria parasites in their mammalian host.

Antimalarial Potential of Carica papaya and Vernonia amygdalina in Mice Infected with Plasmodium berghei.

The study determined if administration of Vernonia amygdalina and Carica papaya plants provides synergistic effects in ameliorating plasmodium infection in mice. Thirty mice (17.88–25.3 g) were divided into 6 groups of 5 mice each. Group 1 was normal control, while groups 2–6 were intraperitoneally inoculated 2.5 × 107 Plasmodium berghei parasitized red blood cell, followed by daily administration of 350 mg/kg aqueous leaf extracts after establishment of infection. Group 2 was disease control, while group 6 was treated with standard drug for four consecutive days. The results showed significant (P < 0.05) reduction in percentage of parasite load between the infected treatment groups and disease control group at day 3 after infection, which remained consistent until the end of the experiment. All infected treated groups showed significant (P < 0.05) increases in RBC and PCV recovery compared to the disease control, with the exception of WBC. There was insignificant (P > 0.05) change in mean body weight of all treated groups except in disease control group. Histological studies of the infected mice indicate recovery of hepatic cells from congested black pigmentation. The reduction in parasite load and recovery of hepatic cell damage/hematological parameters were induced by these plant extracts. This highlighted the important usage of the plant in traditional remedy of malaria infection.

Immunogenicity and protective efficacy of DNA vaccine against visceral leishmaniasis in BALB/c mice.

The current study was designed to examine the protective efficacy of DNA vaccines based on gp63 and Hsp70 against murine visceral leishmaniasis. Inbred BALB/c mice were immunized subcutaneously twice at an interval of three weeks with pcDNA3.1(+) encoding T cell epitopes of gp63 and Hsp70 individually and in combination. Animals were challenged intracardially with 107 promastigotes of Leishmania donovani 10 days post immunization and sacrificed 1, 2 and 3 months post challenge. The immunized animals revealed a significant reduction (P < 0.05) in splenic and hepatic parasite burden as compared to the infected controls. Maximum reduction in parasite load (P < 0.05) was observed in animals treated with a combination of pcDNA/gp63 and pcDNA/Hsp70. These animals also showed heightened DTH response, increased IgG2a, elevated Th1 cytokines (IFN-γ and IL-2) and reduced IgG1 and IL-10 levels. Thus, mice immunized with the cocktail vaccine exhibited significantly greater protection in comparison to those immunized with individual antigens.

Development of a rapid and reliable assay for in vitro determination of compound cidality against the asexual stages of Plasmodium falciparum.

The pace of anti-malarial drug discovery is often impeded due to the lack of tools to determine the cidality of compounds in vitro. An anti-malarial compound must have a cidal mode of action, i.e. kill parasites, in order to quickly reduce parasite load. A static compound that merely inhibits growth must be identified early on in the discovery cascade. In this paper, we describe a high-throughput fluorescent assay for determination of the cidality of an anti-malarial compound. The assay works on the principle that cultures treated with a static compound will exhibit re-growth while treatment with a cidal compound leads to a marked reduction in parasite number. Parasite cultures are treated with the drug for 48 or 72 h following which the drug is washed off. Cultures are allowed to recover in drug-free media for 72 h and DNA content estimated using the fluorescent dye SyBR Green I. Following estimation of IC50 and IC99 values, we find that the IC99/IC50 ratio is a reliable indicator of the cidality of a compound. Cidal compounds like artemisinin and chloroquine display an IC99/IC50 ratio <5 while the ratio for a static compound like atovaquone is <5. This correlation holds true for various anti-malarial drugs with known modes of action. Importantly, the IC99/IC50 ratio drops to <5 when a compound becomes cidal in action with longer duration of treatment. The assay is robust, reliable and provides a fast and effective means for prioritizing cidal compounds for progression along the drug discovery cascade.

Variable effects of nicotine, anabasine, and their interactions on parasitized bumble bees.

Secondary metabolites in floral nectar have been shown to reduce parasite load in two common bumble bee species. Previous studies on the effects of nectar secondary metabolites on parasitized bees have focused on single compounds in isolation; however, in nature, bees are simultaneously exposed to multiple compounds. We tested for interactions between the effects of two alkaloids found in the nectar of Nicotiana spp. plants, nicotine and anabasine, on parasite load and mortality in bumble bees ( Bombus impatiens) infected with the intestinal parasite Crithidia bombi. Adult worker bees inoculated with C. bombi were fed nicotine and anabasine diet treatments in a factorial design, resulting in four nectar treatment combinations: 2 ppm nicotine, 5 ppm anabasine, 2ppm nicotine and 5 ppm anabasine together, or a control alkaloid-free solution. We conducted the experiment twice: first, with bees incubated under variable environmental conditions ('Variable'; temperatures varied from 10-35°C with ambient lighting); and second, under carefully controlled environmental conditions ('Stable'; 27°C incubator, constant darkness). In 'Variable', each alkaloid alone significantly decreased parasite loads, but this effect was not realized with the alkaloids in combination, suggesting an antagonistic interaction. Nicotine but not anabasine significantly increased mortality, and the two compounds had no interactive effects on mortality. In 'Stable', nicotine significantly increased parasite loads, the opposite of its effect in 'Variable'. While not significant, the relationship between anabasine and parasite loads was also positive. Interactive effects between the two alkaloids on parasite load were non-significant, but the pattern of antagonistic interaction was similar to that in the variable experiment. Neither alkaloid, nor their interaction, significantly affected mortality under controlled conditions. Our results do not indicate synergy between Nicotiana nectar alkaloids; however, they do suggest a complex interaction between secondary metabolites, parasites, and environmental variables, in which secondary metabolites can be either toxic or medicinal depending on context.

Variable effects of nicotine, anabasine, and their interactions on parasitized bumble bees

Secondary metabolites in floral nectar have been shown to reduce parasite load in two common bumble bee species. Previous studies on the effects of nectar secondary metabolites on parasitized bees have focused on single compounds in isolation; however, in nature, bees are simultaneously exposed to multiple compounds. We tested for interactions between the effects of two alkaloids found in the nectar of Nicotiana spp. plants, nicotine and anabasine, on parasite load and mortality in bumble bees ( Bombus impatiens) infected with the intestinal parasite Crithidia bombi. Adult worker bees inoculated with C. bombi were fed nicotine and anabasine diet treatments in a factorial design, resulting in four nectar treatment combinations: 2 ppm nicotine, 5 ppm anabasine, 2ppm nicotine and 5 ppm anabasine together, or a control alkaloid-free solution. We conducted the experiment twice: first, with bees incubated under variable environmental conditions (‘Variable’; temperatures varied from 10-35°C with ambient lighting); and second, under carefully controlled environmental conditions (‘Stable’; 27°C incubator, constant darkness). In ‘Variable’, each alkaloid alone significantly decreased parasite loads, but this effect was not realized with the alkaloids in combination, suggesting an antagonistic interaction. Nicotine but not anabasine significantly increased mortality, and the two compounds had no interactive effects on mortality. In ‘Stable’, nicotine significantly increased parasite loads, the opposite of its effect in ‘Variable’. While not significant, the relationship between anabasine and parasite loads was also positive. Interactive effects between the two alkaloids on parasite load were non-significant, but the pattern of antagonistic interaction was similar to that in the variable experiment. Neither alkaloid, nor their interaction, significantly affected mortality under controlled conditions. Our results do not indicate synergy between Nicotiana nectar alkaloids; however, they do suggest a complex interaction between secondary metabolites, parasites, and environmental variables, in which secondary metabolites can be either toxic or medicinal depending on context.

Apheresis for babesiosis: Therapeutic parasite reduction or removal of harmful toxins or both?

Babesiosis is a potentially life-threatening illness caused by intraerythrocytic protozoan parasites of the genus Babesia that are transmitted most commonly by Ixodes ticks, and rarely from blood transfusion or congenitally. Clinical presentations of babesiosis include asymptomatic infection, mild to moderate disease, or severe disease. Antibiotics such as atovaquone plus azithromycin or clindamycin and quinine can be used effectively to treat this disease in most cases, however in high risk populations, the mortality rate can be as high as 20% despite therapy. Therapeutic exchange transfusion has been used in severe babesiosis and is of apparent therapeutic benefit. It is not entirely clear through what mechanism therapeutic exchange transfusion may help patients. Data suggests that in addition to parasite load reduction, it is possible that therapeutic exchange transfusion removes toxins generated by babesia infection. There are many remaining questions that need to be addressed regarding exchange transfusion for babesiosis. J. Clin. Apheresis 31:454-458, 2016. © 2015 Wiley Periodicals, Inc.

Downregulation of host tryptophan-aspartate containing coat (TACO) gene restricts the entry and survival of Leishmania donovani in human macrophage model.

Leishmania are obligate intracellular protozoan parasites of mammalian hosts. Promastigotes of Leishmania are internalized by macrophages and transformed into amastigotes in phagosomes, and replicate in phagolysosomes. Phagosomal maturation arrest is known to play a crucial role in the survival of pathogenic Leishmania within activated macrophages. Recently, tryptophan–aspartate containing coat (TACO) gene has been recognized as playing a central role in the survival of Mycobacterium tuberculosis within human macrophages by arresting the phagosome maturation process. We postulated that a similar association of TACO gene with phagosomes would prevent the vacuole from maturation in the case of Leishmania. In this study we attempted to define the effect of TACO gene downregulation on the entry/survival of Leishmania donovani intracellularly, by treatment with Vitamin D3 (Vit.D3)/Retinoic acid (RA) and chenodeoxycholic acid (CDCA)/RA combinations in human THP-1 macrophages (in vitro). Treatment with these molecules downregulated the TACO gene in macrophages, resulting in reduced parasite load and marked reduction of disease progression in L. donovani infected macrophages. Taken together, these results suggest that TACO gene downregulation may play a role in subverting macrophage machinery in establishing the L. donovani replicative niche inside the host. Our study is the first to highlight the important role of the TACO gene in Leishmania entry, survival and to identify TACO gene downregulation as potential drug target against leishmaniasis.

Variable effects of nicotine and anabasine on parasitized bumble bees

Secondary metabolites in floral nectar have been shown to reduce parasite load in two common bumble bee species. Previous studies on the effects of nectar secondary metabolites on parasitized bees have focused on single compounds in isolation; however, in nature, bees are simultaneously exposed to multiple compounds. We tested for synergistic effects of two alkaloids found in the nectar of Nicotiana spp. plants, nicotine and anabasine, on parasite load and mortality in bumble bees ( Bombus impatiens) infected with the intestinal parasite Crithidia bombi. Adult worker bees inoculated with C. bombi were fed nicotine and anabasine diet treatments in a factorial design, resulting in four nectar treatment combinations: 2 ppm nicotine, 5 ppm anabasine, 2ppm nicotine and 5 ppm anabasine together, or a control alkaloid-free solution. We conducted the experiment twice: first, with bees incubated under variable environmental conditions ('Variable'; temperatures varied from 10-35°C); and second, under carefully controlled environmental conditions ('Controlled'; 27°C incubator, constant darkness). In 'Variable', each alkaloid alone significantly decreased parasite loads, but this effect was not realized with the alkaloids in combination, suggesting an antagonistic interaction. Nicotine but not anabasine significantly increased mortality, and the two compounds had no interactive effects on mortality. In 'Controlled', nicotine significantly increased parasite loads, the opposite of its effect in 'Variable'. While not significant, the relationship between anabasine and parasite loads was also positive. Interactive effects between the two alkaloids on parasite load were non-significant, but the pattern of antagonistic interaction was similar to that in the variable experiment. Neither alkaloid, nor their interaction, significantly affected mortality under controlled conditions. Our results do not indicate synergy between Nicotiana nectar alkaloids; however, they do suggest a complex interaction between secondary metabolites, parasites, and environmental variables, in which secondary metabolites can be either toxic or medicinal depending on context.

Effect of Propranolol Alone and in Combination with Pyrimethamine on Acute Murine Toxoplasmosis.

Background:Toxoplasmosis is a public health problem worldwide. This complication principally affects immunodeficient patients and pregnant women. Toxoplasma gondii is an opportunistic parasite, causing severe illness among and death of high-risk individuals and treatment is becoming increasingly difficult owing to side effects and low efficacies of drugs.Objectives:In this study, we investigated the anti-Toxoplasma gondii efficacy of propranolol in vivo.Materials and Methods:This study was performed in two separate pre-treatment and post-treatment groups. In each group, 18 female Balb/c mice in six subgroups (n = 3) were used to assess the anti-Toxoplasma effect of propranolol at 2 and 3 mg/kg/day, pyrimethamine at 50 mg/kg/day, propranolol at 2 and 3 mg/kg/day plus pyrimethamine, and phosphate-buffered saline (PBS; as negative control). Treatment was performed 4, 24, and 48 hours before and after an intraperitoneal challenge of 1 × 103 tachyzoites of the virulent RH strain of T. gondii, in pre-treatment and post-treatment groups. Mice peritoneal exudates were collected on the seventh day after the challenge and parasite numbers were recorded as percent of growth inhibition and survival rate.Results:In the pre-treatment group, results showed that propranolol at 2 and 3 mg/kg combined with pyrimethamine was more effective in inhibiting growth of tachyzoites (86% and 98%, respectively) when compared with propranolol at 2 and 3 mg/kg (37% and 39%, respectively) and pyrimethamine (41%) alone. In the post-treatment group, all combined treatments significantly reduced parasite load. The growth inhibition of tachyzoites in mice receiving propranolol (2 and 3 mg/kg) was 75% and 51%, with the mean tachyzoites count being 1526 ± 171.4 and 2948 ± 1452.8, respectively, compared with pyrimethamine treatment outcome, which represents 99.9% growth inhibition.Conclusions:Our results demonstrated the promising prophylactic and therapeutic effects of propranolol against T. gondii infection. Propranolol also increases the efficacy of pyrimethamine in combination therapies.

B-1 cells contribute to susceptibility in experimental infection with Leishmania (Leishmania) chagasi.

The immune response to leishmaniasis is complex, and the result of infection depends on both the genetic composition of the Leishmania species and the immunity of the host. Clinical and experimental evidence suggest that the activation of B cells leads to exacerbation of visceral leishmaniasis. However, the role of B-1 cells (a subtype of B lymphocytes) in the pathogenesis of experimental visceral leishmaniasis has not yet been elucidated. In this study, we investigated the importance of B-1 cells in experimental infection with Leishmania. (L.) chagasi. Our results showed that BALB/XID mice (X-linked immunodeficient mice which are genetically deficient in B-1 cells) infected with L. (L.) chagasi for 45 days had a significant reduction in parasite load in the spleen when compared with control mice. Cytokine analysis showed that the BALB/XID mice had lower amounts of IL-10 in their sera compared with control group. In addition, the transfer of B-1 cells from wild type mice into IL-10KO animals led to an increase in susceptibility to L. (L.) chagasi infection in the IL-10KO mice, suggesting that the IL-10 produced by these cells is important in experimental infection. Our results suggest that B-1 cells may play an important role in susceptibility to L. (L.) chagasi.

EFFICACY OF NITAZOXANIDE AGAINST Toxocara canis: LARVAL RECOVERY AND HUMORAL IMMUNE RESPONSE IN EXPERIMENTALLY INFECTED MICE.

SUMMARYThe efficacy of nitazoxanide (NTZ) against toxocariasis was investigated in an experimental murine model and results were compared to those obtained using mebendazole. Sixty male BALB/c mice, aged six to eight weeks-old, were divided into groups of 10 each; fifty were orally infected with 300 larvaed eggs of T. canisand grouped as follows, G I: infected untreated mice; G II: infected mice treated with MBZ (15 mg/kg/day) 10 days postinfection (dpi); G III: infected mice treated with NTZ (20 mg/kg/day) 10 dpi; G IV: infected mice treated with MBZ 60 dpi; G V: infected mice treated with NTZ 60 dpi; GVI: control group comprising uninfected mice. Mice were bled via retro-orbital plexus on four occasions between 30 and 120 dpi. Sera were processed using the ELISA technique to detect IgG anti- Toxocaraantibodies. At 120 dpi, mice were sacrificed for larval recovery in the CNS, liver, lungs, kidneys, eyes and carcass. Results showed similar levels of anti- ToxocaraIgG antibodies among mice infected but not submitted to treatment and groups treated with MBZ or NTZ, 10 and 60 dpi. Larval recovery showed similar values in groups treated with NTZ and MBZ 10 dpi. MBZ showed better efficacy 60 dpi, with a 72.6% reduction in the parasite load compared with NTZ, which showed only 46.5% reduction. We conclude that administration of these anthelmintics did not modify the humoral response in experimental infection by T. canis. No parasitological cure was observed with either drug; however, a greater reduction in parasite load was achieved following treatment with MBZ.

In vitro and in vivo antiparasitic activity of Physalis angulata L. concentrated ethanolic extract against Trypanosoma cruzi

BackgroundThe current treatment of Chagas disease, endemic in Latin America and emerging in several countries, is limited by the frequent side effects and variable efficacy of benznidazole. Natural products are an important source for the search for new drugs. Aim/hypothesisConsidering the great potential of natural products as antiparasitic agents, we investigated the anti-Trypanosoma cruzi activity of a concentrated ethanolic extract of Physalis angulata (EEPA). MethodsCytotoxicity to mammalian cells was determined using mouse peritoneal macrophages. The antiparasitic activity was evaluated against axenic epimastigote and bloodstream trypomastigote forms of T. cruzi, and against amastigote forms using T. cruzi-infected macrophages. Cell death mechanism was determined in trypomastigotes by flow cytometry analysis after annexin V and propidium iodide staining. The efficacy of EEPA was examined in vivo in an acute model of infection by monitoring blood parasitaemia and survival rate 30 days after treatment. The effect against trypomastigotes of EEPA and benznidazole acting in combination was evaluated. ResultsEEPA effectively inhibits the epimastigote growth (IC50 2.9 ± 0.1 µM) and reduces bloodstream trypomastigote viability (EC50 1.7 ± 0.5 µM). It causes parasite cell death by necrosis. EEPA impairs parasite infectivity as well as amastigote development in concentrations noncytotoxic to mammalian cells. In mice acutely-infected with T. cruzi, EEPA reduced the blood parasitaemia in 72.7%. When combined with benznidazole, EEPA showed a synergistic anti-T. cruzi activity, displaying CI values of 0.8 ± 0.07 at EC50 and 0.83 ± 0.1 at EC90. ConclusionEEPA has antiparasitic activity against T. cruzi, causing cell death by necrosis and showing synergistic activity with benznidazole. These findings were reinforced by the observed efficacy of EEPA in reducing parasite load in T. cruzi-mice. Therefore, this represents an important source of antiparasitic natural products.

Immunogenicity and efficacy of recombinant 78kDa antigen of Leishmania donovani formulated in various adjuvants against murine visceral leishmaniasis.

To analyze the protective efficacy of recombinant 78kDa antigen of Leishmania donovani in combination with two adjuvants, that is, cationic liposomes or MPL-A against visceral leishmaniasis in BALB/c mice. The genomic DNA of promastigotes was isolated and 583bp of T cell epitopes of gene encoding 78kDa was amplified using specific primers. The amplified gene was cloned into pET28c, transformed into Escherichia coli BL21 (DE3) and got expressed after IPTG induction. The recombinant protein was then purified using Ni-NTA and named r78. Three groups of mice were immunized with 10μg of r78 plus MPL-A, r78 encapsulated in positively charged liposomes and control animals immunized with PBS. Two booster doses were given with the respective vaccine at an interval of 2 weeks each. Mice were challenged with 1×10(7)Leishmania promastigotes and sacrificed on different post infection/challenge days. Immunization with r78 along with MPL-A and liposome-encapsulated r78 brought a significant reduction in parasite load. In comparison to the infected controls, the parasite load declined by 96.2% in mice immunized with r78 plus MPL-A and 97.23% in animals immunized with liposome-encapsulated r78. The immunized animals also exhibited profound DTH response. The serum antibody responses increased from 15 to 90 days post infection/challenge. Immunized animals showed greater IgG2a levels and lesser IgG1 levels in comparison to the infected controls. The splenocytes from immunized mice were cultured, stimulated with r78 and analyzed for cytokine profile. The levels of IL-2 and IFN-γ were greater in immunized animals as compared to control mice. The study proves that r78 in combination with suitable adjuvants is a potential vaccine candidate and may be instrumental in control of visceral leishmaniasis.

(-)-α-Bisabolol, a Promising Oral Compound for the Treatment of Visceral Leishmaniasis.

The aim of the present study was to assess the in vitro and in vivo activity of (-)-α-bisabolol (1) against the etiological agents of visceral leishmaniasis. Bone-marrow-derived macrophages were infected with Leishmania infantum or L. donovani promastigotes and incubated with (-)-α-bisabolol at different concentrations. Pentamidine isethionate and meglumine antimoniate were used as reference drugs. Inhibitory concentration 50% (IC50) and cytotoxic concentration 50% (CC50) were calculated. Balb/c mice were infected intraperitoneally with stationary-phase promastigotes. They were treated with (-)-α-bisabolol at different doses orally, meglumine antimoniate at 104 mg Sb(V)/kg, or a combination of both. (-)-α-Bisabolol proved to be innocuous to mammal cells and active against L. infantum and L. donovani intracellular amastigotes (IC50 55 and 39 μM, respectively). Compound 1 also proved to be active in an in vivo model of visceral leishmaniasis due to L. infantum, as it reduced parasite load in the spleen and liver by 71.60% and 89.22%, respectively, at 200 mg/kg without showing toxicity. (-)-α-Bisabolol (1) is a nontoxic compound that was proven to be active against visceral leishmaniasis in an in vivo murine model orally. It was more effective than meglumine antimoniate at reducing spleen parasite load and as effective as this antimonial drug in the liver.

Immunization of Wistar female rats with 255-Gy-irradiated Toxoplasma gondii: Tissue parasitic load and lactogenic quantification

Toxoplasma gondii is one of the most significant parasite, due its importance in veterinary medicine and in public health, considered a food-borne pathogens, there is no available drug treatments to eliminate it from animal tissue, this reinforce the search for a vaccine against this parasite. This study was aimed to evaluate the dynamic of the distribution of T. gondii in tissues of female Wistar rats and their milk, after the immunization by oral rote with irradiated tachyzoites. One week after pregnancy confirmation, rats was challenged by gavage with T. gondii bradyzoites, oocysts or tachyzoites of T. gondii. Forty-eight pregnant rats were grouped as follows: immunized and challenged with bradyzoites (BZ*); non-immunized and challenged with bradyzoites (BZ); immunized and challenged with oocysts (OC*); non-immunized and challenged with oocysts (OC); immunized and challenged with tachyzoites (TZ*); non-immunized and challenged with tachyzoites (TZ); only immunized (I); control group (C). After parturition, milk samples were collected for 3 weeks and then rats were sacrificed and the tissues and milk samples were researched for T. gondii parasite load determined by the quantitative PCR (qPCR). It was verified that the immunization with irradiated tachyzoites of T. gondii induced the reduction of parasitic load in muscle samples in rats challenged by bradyzoites and oocysts, although not enabled the development of sterile immunity. The detection of parasite DNA in milk was found throughout the lactation period, from immunized and non-immunized rats, however no differences were found in the parasite load caused by immunization.

Intestinal Obstruction in a 3-Year-Old Girl by Ascaris lumbricoides Infestation

Ascaris lumbricoides infection affects approximately 1.5 billion people globally. Children with environmental and socio-economic risk factors are more susceptible to infestation, with serious complications such as intestinal obstruction (IO), volvulus, intussusception, and intestinal necrosis.We present the case of a 3-year-old girl who arrived at emergency department with abdominal pain and diarrhea for the last 3 days. The previous day she took an unspecified anthelmintic. Symptoms worsened with vomiting and diarrhea, with expulsion of roundworms through mouth and anus. Physical examination revealed bloating, absence of bowel sounds, abdominal tenderness, and a palpable mass in right hemi-abdomen. Abdominal radiographs showed air-fluid levels with mild bowel distention and shadows of roundworms. The diagnosis of IO by A lumbricoides. infestation was established and surgical approach scheduled. During exploratory laparotomy an intraluminal bolus of roundworms from jejunum to ascendant colon was evident. An ileum enterotomy was performed and worms were removed. Fluid therapy and antibiotics for 72 hours were administered, with posterior albendazol treatment for 3 days. Patient was uneventfully discharged on the tenth day.Reduction in parasitic load by means of improvements in sanitation, health education, and anthelmintic treatment must be implemented in endemic zones to prevent serious life-threatening complications by A lumbricoides. infestation, because some of them require urgent surgical treatment.