RESUMO
Schistosomiasis mansoni presents many clinical manifestations during migration of schistosomes in their hosts, including diarrhea, hepatomegaly, splenomegaly, liver abscesses, skinlesions, brain tumors and myeloradiculopathy. No lesions have been reported in skeletal striated muscles due to schistosomiasis mansoni in the literature. This short communication reports the histopathological findings on skeletal musculature in a murine model of neuroeschistosomiasis mansoni. Lesions were found in the tongue, masseter muscle, buccinator muscle, digastric muscle and temporalis muscle. Worm recovery was carried out to confirm the infection. We describe here, for the first time in the literature, injuries in the skeletal musculature due to Schistosoma mansoni nfection.
Assuntos
Granuloma/patologia , Granuloma/parasitologia , Músculo Estriado/patologia , Músculo Estriado/parasitologia , Neuroesquistossomose/patologia , Esquistossomose mansoni/patologia , Animais , Modelos Animais de Doenças , Masculino , CamundongosRESUMO
The Global Burden of Disease Study 2010 listed schistosomiasis among the leading 100 causes of death in Brazil, responsible for 3.6% of the estimated total of deaths globally. Eye and adnexa are very rarely affected by schistosomiasis mansoni, with limited documentation of ocular pathology in this setting. This short communication reports ocular histolopathological findings in a murine model of neuroschistosomiasis mansoni. Lesions were found in the bulbar conjunctiva, lacrimal gland, choroid and corneoscleral limbus.
Assuntos
Infecções Oculares Parasitárias/parasitologia , Neuroesquistossomose/parasitologia , Esquistossomose mansoni/parasitologia , Animais , Brasil , Modelos Animais de Doenças , Infecções Oculares Parasitárias/patologia , Infecções Oculares Parasitárias/fisiopatologia , Masculino , Camundongos , Neuroesquistossomose/patologia , Neuroesquistossomose/fisiopatologia , Schistosoma mansoni/isolamento & purificação , Esquistossomose mansoni/patologia , Esquistossomose mansoni/fisiopatologiaRESUMO
Imatinib, a drug used for treatment of human chronic myeloid leukaemia, due to its activity against protein kinases, has been also evaluated in vitro against Schistosoma mansoni showing high schistosomicidal activity. In the present experiments imatinib activity in vitro was confirmed at the doses of 25 µM, 50 µM and 100 µM. The first drug activity observed with the lower dose was interruption of egg-laying and with the higher dosages was the death of the worms. In mice infected with S. mansoni no activity was found even with 1,000 mg/kg/day, 500 mg/kg/day, single oral dose or when administered for three consecutive days. This is another example of the difference of results related to in vitro and in vivo trials using S. mansoni worms.
Assuntos
Benzamidas/farmacologia , Piperazinas/farmacologia , Pirimidinas/farmacologia , Schistosoma mansoni/efeitos dos fármacos , Esquistossomose mansoni/tratamento farmacológico , Esquistossomicidas/farmacologia , Animais , Relação Dose-Resposta a Droga , Mesilato de Imatinib , Camundongos , Carga Parasitária , Esquistossomose mansoni/parasitologia , Fatores de TempoRESUMO
Mice infected with Schistosoma mansoni were treated with oxamniquine, praziquantel, artesunate at the pre-patent phase, aiming at observing schistogram alterations. Half of the animals were perfused five days post-treatment for counting and classification of immature worms, based on pre-established morphological criteria (schistogram); the remaining animals were evaluated 42 or 100 days after infection and perfusion of the portal-system was performed for collection and counting of adult worms and oogram. It was observed that oxamniquine and artesunate treatment administered at the pre-postural phase causes significant reduction in the number of immature and adult worms. However, there was little reduction with praziquantel when used at the dose of 400 mg/kg for treatments administered 14, 15, 21 or 23 days post-infection. Artesunate was responsible for significant alterations in development of young worms, as well as for a higher number of worms presenting intestinal damages. Immature adult worms were detected in mice treated with artesunate or oxamniquine at the pre-patent phase of infection and recovered by perfusion 100 days after infection. Schistogram proved to be a very useful tool for experimental evaluation of the activity of antischistosomal drugs and a good model to identify the most sensitive stages to drugs.
Assuntos
Artemisininas/uso terapêutico , Schistosoma mansoni/efeitos dos fármacos , Esquistossomose mansoni/tratamento farmacológico , Esquistossomicidas/uso terapêutico , Animais , Artesunato , Quimioterapia Combinada/métodos , Feminino , Camundongos , Oxamniquine/uso terapêutico , Contagem de Ovos de Parasitas , Parasitemia/tratamento farmacológico , Praziquantel/uso terapêutico , Schistosoma mansoni/crescimento & desenvolvimentoRESUMO
Current schistosomiasis control strategies are largely based on chemotherapeutic agents and a limited number of drugs are available today. Praziquantel (PZQ) is the only drug currently used in schistosomiasis control programs. Unfortunately, this drug shows poor efficacy in patients during the earliest infection phases. The effects of PZQ appear to operate on the voltage-operated Ca2+ channels, which are located on the external Schistosoma mansoni membrane. Because some Ca2+ channels have dihydropyridine drug class (a class that includes nifedipine) sensitivity, an in vitro analysis using a calcium channel antagonist (clinically used for cardiovascular hypertension) was performed to determine the antischistosomal effects of nifedipine on schistosomula and adult worm cultures. Nifedipine demonstrated antischistosomal activity against schistosomula and significantly reduced viability at all of the concentrations used alone or in combination with PZQ. In contrast, PZQ did not show significant efficacy when used alone. Adult worms were also affected by nifedipine after a 24 h incubation and exhibited impaired motility, several lesions on the tegument and intense contractility. These data support the idea of Ca2+ channels subunits as drug targets and favour alternative therapeutic schemes when drug resistance has been reported. In this paper, strong arguments encouraging drug research are presented, with a focus on exploring schistosomal Ca2+ channels.
Assuntos
Bloqueadores dos Canais de Cálcio/farmacologia , Nifedipino/farmacologia , Praziquantel/farmacologia , Schistosoma mansoni/efeitos dos fármacos , Esquistossomicidas/farmacologia , Animais , Camundongos , Testes de Sensibilidade ParasitáriaRESUMO
To elucidate the mechanisms of antischistosoma resistance, drug-resistant Schistosoma mansoni laboratory isolates are essential. We developed a new method for inducing resistance to praziquantel (PZQ) using successive drug treatments of Biomphalaria glabrata snails infected with S. mansoni. Infected B. glabrata were treated three times with 100 mg/kg PZQ for five consecutive days with a one-week interval between them. After the treatment, the cercariae (LE-PZQ) produced from these snails and the LE strains (susceptible) were used to infect mice. Forty-five days after infection, mice were treated with 200, 400 or 800 mg/kg PZQ. Thirty days post-treatment, we observed that the mean number of worms recovered by perfusion was significantly higher in the group of mice infected with the LE-PZQ isolate treated with 200 and 400 mg/kg in comparison to the LE strain with the same treatment. Moreover, there was a significant difference between the ED50 (effective dose required to kill 50% of the worms) of the LE-PZQ isolate (362 mg/kg) and the LE strain (68 mg/kg). In the in vitro assays, the worms of the LE-PZQ isolate were also less susceptible to PZQ. Thus, the use of infected snails as an experimental model for development of resistance to S. mansoni is effective, fast, simple and cheap.
Assuntos
Anti-Helmínticos/farmacologia , Biomphalaria/parasitologia , Resistência a Medicamentos/efeitos dos fármacos , Praziquantel/farmacologia , Schistosoma mansoni/efeitos dos fármacos , Animais , Relação Dose-Resposta a Droga , Camundongos , Testes de Sensibilidade ParasitáriaRESUMO
Granulomas are inflammatory tissue responses directed to a set of antigens. Trapped Schistosoma mansoni eggs promote productive granulomas in the tissues, and they are the main damage caused by schistosomiasis. Some S. mansoni antigenic proteins may have a direct involvement in the resolution of the granulomatous response. The ATP diphosphohydrolases isoforms of this parasite are immunogenic, expressed in all phases of the parasite life cycle and secreted by eggs and adult worms. Potato apyrase is a vegetable protein that cross-reactive with parasite ATP diphosphohydrolases isoforms. In this study, the vegetable protein was purified, before being inoculated in C57BL/6 mice that were later infected with cercariae. Sixty days after infection, adult worms were recovered, antibodies and cytokines were measured, and morphological granuloma alterations evaluated. Immunization of the animals induced significant levels of IgG and IgG1 antibodies and IFN-γ, IL-10 and IL-5 cytokines, but not IL-13, suggesting that potato apyrase is an immunoregulatory protein. Supporting this hypothesis, it was found that liver damage associated with schistosomiasis was mitigated, reducing the size of the areas affected by granuloma to 35% and increasing the presence of multinucleated giant cells in this environment. In conclusion, potato apyrase was found to be effective immunomodulatory antigen for murine schistosomiasis.
Assuntos
Apirase/química , Células Gigantes/efeitos dos fármacos , Doenças dos Roedores/parasitologia , Schistosoma mansoni/fisiologia , Esquistossomose mansoni/veterinária , Solanum tuberosum/química , Animais , Feminino , Camundongos , Camundongos Endogâmicos C57BL , Schistosoma mansoni/efeitos dos fármacos , Esquistossomose mansoni/parasitologia , Solanum tuberosum/enzimologiaRESUMO
Eukaryotic protein kinases (ePKs) are good medical targets for drug development in different biological systems. ePKs participate in many cellular processes, including the p38 MAPK regulation of homeostasis upon oxidative stress. We propose to assess the role of Smp38 MAPK signaling pathway in Schistosoma mansoni development and protection against oxidative stress, parasite survival, and also to elucidate which target genes have their expression regulated by Smp38 MAPK. After a significant reduction of up to 84% in the transcription level by Smp38 MAPK gene knockdown, no visible phenotypic changes were reported in schistosomula in culture. The development of adult worms was tested in vivo in mice infected with the Smp38 knocked-down schistosomula. It was observed that Smp38 MAPK has an essential role in the transformation and survival of the parasites as a low number of adult worms was recovered. Smp38 knockdown also resulted in decreased egg production, damaged adult worm tegument, and underdeveloped ovaries in females. Furthermore, only ~13% of the eggs produced developed into mature eggs. Our results suggest that inhibition of the Smp38 MAPK activity interfere in parasites protection against reactive oxygen species. Smp38 knockdown in adult worms resulted in 80% reduction in transcription levels on the 10th day, with consequent reduction of 94.4% in oviposition in vitro. In order to search for Smp38 MAPK pathway regulated genes, we used an RNASeq approach and identified 1,154 DEGs in Smp38 knockdown schistosomula. A substantial proportion of DEGs encode proteins with unknown function. The results indicate that Smp38 regulates essential signaling pathways for the establishment of parasite homeostasis, including genes related to antioxidant defense, structural composition of ribosomes, spliceosomes, cytoskeleton, as well as, purine and pyrimidine metabolism pathways. Our data show that the Smp38 MAPK signaling pathway is a critical route for parasite development and may present attractive therapeutic targets for the treatment and control of schistosomiasis.
Assuntos
Schistosoma mansoni/fisiologia , Esquistossomose mansoni/parasitologia , Proteínas Quinases p38 Ativadas por Mitógeno/metabolismo , Animais , Biologia Computacional , Expressão Gênica , Perfilação da Expressão Gênica , Técnicas de Silenciamento de Genes , Estágios do Ciclo de Vida , Sistema de Sinalização das MAP Quinases , Camundongos , Oviposição , Estresse Oxidativo , Inibidores de Proteínas Quinases/farmacologia , Schistosoma mansoni/anatomia & histologia , Schistosoma mansoni/efeitos dos fármacos , Esquistossomose mansoni/tratamento farmacológico , Proteínas Quinases p38 Ativadas por Mitógeno/genéticaRESUMO
The antischistosomal activity of clonazepam, when administered alone or in association with oxamniquine and praziquantel, was experimentally evaluated in mice infected with Schistosoma mansoni. The animals were treated 45 days post-infection with a single dose, by oral route, according to three treatment schedules: clonazepam 25 mg/kg and sacrificed 15 min, 1h or 4 h after treatment; clonazepam 1.0, 2.5 or 10.0 mg/kg and sacrificed 15 days post-treatment or with the dose of 10 mg/kg in association with oxamniquine 50 mg/kg or praziquantel 200 mg/kg, single dose, orally, every schedule with a control group. The efficacy of the drugs in vivo was assessed by means of worm counts and their distribution in mesentery and liver, mortality and oogram changes. In the chemotherapeutic schedules used, clonazepam did not present antischistosomal activity and the result of the association of this drug with oxamniquine or praziquantel was not significantly different from the one obtained when these two last drugs were administered alone. In the in vitro experiments, the worms exposed to 0.6 mg/mL clonazepam remained motionless throughout the 8-day-period of observation, without egg-laying, whereas the worms of the control group showed normal movements, egg-laying and hatching of miracidia on the last day of observation. The results obtained in the present study confirm the action of clonazepam on S. mansoni adult worm, in vitro, causing total paralysis of males and females. However, no additive or synergistic effects were observed when clonazepam were used in association with oxamniquine or praziquantel.
Assuntos
Clonazepam/farmacologia , Schistosoma mansoni/efeitos dos fármacos , Esquistossomose mansoni/tratamento farmacológico , Esquistossomicidas/farmacologia , Animais , Clonazepam/administração & dosagem , Avaliação Pré-Clínica de Medicamentos , Quimioterapia Combinada , Feminino , Fígado/parasitologia , Masculino , Mesentério/parasitologia , Camundongos , Oxamniquine/administração & dosagem , Oxamniquine/farmacologia , Praziquantel/administração & dosagem , Praziquantel/farmacologia , Esquistossomicidas/administração & dosagem , Fatores de TempoRESUMO
The activity of lovastatin associated with oxamniquine or praziquantel against schistosomiasis mansoni was evaluated in mice infected with Schistosoma mansoni. Forty days after infection, mice were treated with lovastatin, 400 mg/kg for five consecutive days by oral route, and on the last day of this sequence with 50 mg/kg oxamniquine or with 200 mg/kg praziquantel, both by oral route, single dose. Fifteen days later, the animals were perfused in parallel with an untreated control group. Studies were carried out in vitro, using lovastatin in culture medium containing S. mansoni worms proceeding from experimentally infected mice. In the in vivo trials, the association of lovastatin with oxamniquine or praziquantel did not show any additive action, but there were oogram changes when lovastatin was associated with oxamniquine. In vitro lovastatin was able to interrupt the maturation of S. mansoni eggs, which remained at the 1st or 2nd stages, depending on the dose used. The total number of morphologically dead eggs found in culture of worms exposed to 2 microg/ml or 4 microg/ml concentrations of lovastatin was significantly higher than the number of viable eggs. Using the probe Hoescht 33258 it was observed that 70% of the eggs considered morphologically viable in the treated groups (against 16% in the control group) were labeled, indicating that the majority of the viable eggs had membrane permeability increased due to lovastatin action.
Assuntos
Inibidores de Hidroximetilglutaril-CoA Redutases/uso terapêutico , Lovastatina/uso terapêutico , Schistosoma mansoni/efeitos dos fármacos , Esquistossomose mansoni/tratamento farmacológico , Esquistossomicidas/uso terapêutico , Animais , Quimioterapia Combinada , Camundongos , Oxamniquine/uso terapêutico , Praziquantel/uso terapêutico , Schistosoma mansoni/enzimologiaRESUMO
The helminth Schistosoma mansoni is one of main causes of human schistosomiasis, a health and economic concern in some of the world's poorest countries. Current treatment regimens can lead to serious side effects and are not suitable for breastfeeding mothers. As such, efforts have been undertaken to develop a vaccine to prevent infection. Of these, Sm29 is a promising candidate that has been associated with resistance to infection/reinfection in humans and mice. Its ability to induce resistance to reinfection has also been recently demonstrated using a vaccine formulation containing Freund's adjuvant. However, Freund's adjuvant is unsuitable for use in human vaccines. We therefore evaluated the ability of Sm29 to induce protection against S. mansoni reinfection when formulated with either alum or MPLA as an adjuvant, both approved for human use. Our data demonstrate that, in contrast to Sm29 with MPLA, Sm29 with alum reduced parasite burden after reinfection compared to a control. We next investigated whether the immune response was involved in creating the differences between the protective (Sm29Alum) and non-protective (Sm29MPLA) vaccine formulations. We observed that both formulations induced a similar mixed-profile immune response, however, the Sm29 with alum formulation raised the levels of antibodies against Sm29. This suggests that there is an association between a reduction in worm burden and parasite-specific antibodies. In summary, our data show that Sm29 with an alum adjuvant can successfully protect against S. mansoni reinfection in mice, indicating a potentially effective vaccine formulation that could be applied in humans.
Assuntos
Antígenos de Helmintos/imunologia , Imunidade Humoral , Schistosoma mansoni/fisiologia , Esquistossomose mansoni/imunologia , Vacinas/imunologia , Adjuvantes Imunológicos/administração & dosagem , Adjuvantes Imunológicos/química , Compostos de Alúmen/administração & dosagem , Compostos de Alúmen/química , Animais , Anticorpos Anti-Helmínticos/sangue , Antígenos de Helmintos/química , Resistência à Doença , Feminino , Humanos , Camundongos , Camundongos Endogâmicos BALB C , VacinaçãoRESUMO
The impact of ivermectin on adult snails of the genus Biomphalaria (B. glabrata, B. tenagophila and B. straminea), B. glabrata infected with Schistosoma mansoni, snail egg-masses cercariae and miracidia, as well as on guppy fish (Poecilia reticulata) was examined and evaluated. Biomphalaria snails, egg-masses, parasite stages and guppies were all exposed to different concentrations of ivermectin for 24 h, followed by regular observations of mortality. The calculated lethal doses of ivermectin were around an LD50 of 0.03 µg ml-1, and an LD90 of 0.3 µg ml-1 for the three species of snails. Specimens of B. glabrata actually shedding parasite cercariae all died when exposed to ivermectin at a concentration of a mere 0.01 µg ml-1. Ivermectin B1a, the major (80%) component of commercially available ivermectin, proved to be inactive, and it was the minor (20%) component, ivermectin B1b, which caused snail death. Snail egg-masses were not affected, even at the highest concentration of 100 µg ml-1. With respect to S. mansoni parasite stages, 0.2 µg ml-1 ivermectin killed 50% of cercariae and miracidia within five minutes, rising to 90% after 30 min. Mortality of guppy fish within 24 h of exposure to ivermectin at concentrations of 0.5 µg ml-1 and 0.01 µg ml-1, were 100% and 30%, respectively. The concentration of 0.01 µg ml-1 that killed Schistosoma mansoni-infected snails only caused 30% mortality in guppy fish. Ivermectin can be considered a promising molluscicide, especially as it is more potent against infected snails than uninfected ones, although it has no impact on egg-masses. Ivermectin and its derivatives could be explored in the search for a new agent to help control schistosomiasis transmission.
Assuntos
Antiparasitários/farmacologia , Biomphalaria/parasitologia , Ivermectina/farmacologia , Schistosoma mansoni/efeitos dos fármacos , Esquistossomose mansoni/tratamento farmacológico , Animais , Antiparasitários/administração & dosagem , Relação Dose-Resposta a Droga , Ivermectina/administração & dosagem , Dose Letal Mediana , Schistosoma mansoni/isolamento & purificação , Esquistossomose mansoni/parasitologia , Fatores de TempoRESUMO
Schistosome-host interaction is influenced by multiple factors, such as the type of immune response developed by the host, host genetic background, intensity, and number of infections. Those factors not only affect the development and elimination of Schistosoma mansoni , but also the pathology triggered by infection with this parasite. In the present study, we assessed the parasitological, pathological, and immunological aspects elicited by infection and reinfection in 2 different mouse strains commonly used as models in studies on schistosomiasis: BALB/c and C57BL/6. No differences in worm burden recovery or in the number of eggs per gram of intestine or feces were observed between the strains or between infected and reinfected mice from the same strain. However, the number of eggs trapped in the liver of the reinfected mice was significantly higher than the number of eggs in the liver of the infected animals. But, the granulomatous area was significantly lower in reinfected animals than in infected ones. Additionally, granuloma in the infected BALB/c mice was greater than in infected C57BL/6 animals. Regarding the cytokine profile, spleen cells from the infected/reinfected C57BL/6 mice produced higher interleukin 10 (IL-10) levels against egg antigens than BALB/c-infected/reinfected mice. BALB/c mice, in contrast, produced significantly higher IL-4 and IL-13 cytokines after infection/reinfection than the C57BL/6 mice, with the highest levels of IL-13 being observed after reinfection. Our results demonstrate that, although different host backgrounds did not impact resistance to S. mansoni , they result in different immunological profiles that suggest different pathological impacts on the liver.
Assuntos
Schistosoma mansoni/imunologia , Esquistossomose mansoni/parasitologia , Animais , Citocinas/metabolismo , Fezes/parasitologia , Feminino , Granuloma/parasitologia , Granuloma/patologia , Intestinos/parasitologia , Fígado/parasitologia , Fígado/patologia , Hepatopatias/parasitologia , Hepatopatias/patologia , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Endogâmicos C57BL , Contagem de Ovos de Parasitas , Recidiva , Schistosoma mansoni/isolamento & purificação , Schistosoma mansoni/fisiologia , Esquistossomose mansoni/imunologia , Esquistossomose mansoni/patologia , Baço/citologia , Baço/imunologiaRESUMO
BACKGROUND: A vaccine against schistosomiasis would have a great impact in disease elimination. Sm29 and Sm22.6 are two parasite tegument proteins which represent promising antigens to compose a vaccine. These antigens have been associated with resistance to infection and reinfection in individuals living in endemic area for the disease and induced partial protection when evaluated in immunization trials using naïve mice. METHODOLOGY/PRINCIPALS FINDINGS: In this study we evaluated rSm29 and rSm22.6 ability to induce protection in Balb/c mice that had been previously infected with S. mansoni and further treated with Praziquantel. Our results demonstrate that three doses of the vaccine containing rSm29 were necessary to elicit significant protection (26%-48%). Immunization of mice with rSm29 induced a significant production of IL-2, IFN-γ, IL-17, IL-4; significant production of specific antibodies; increased percentage of CD4+ central memory cells in comparison with infected and treated saline group and increased percentage of CD4+ effector memory cells in comparison with naïve Balb/c mice immunized with rSm29. On the other hand, although immunization with Sm22.6 induced a robust immune response, it failed to induce protection. CONCLUSION/SIGNIFICANCE: Our results demonstrate that rSm29 retains its ability to induce protection in previously infected animals, reinforcing its potential as a vaccine candidate.
Assuntos
Antígenos de Helmintos/imunologia , Proteínas de Helminto/imunologia , Glicoproteínas de Membrana/imunologia , Esquistossomose mansoni/imunologia , Animais , Anticorpos Anti-Helmínticos/sangue , Linfócitos T CD4-Positivos/imunologia , Citocinas/sangue , Feminino , Humanos , Imunização , Imunoglobulina G/sangue , Memória Imunológica , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Endogâmicos C57BL , Schistosoma mansoni/imunologia , Vacinas/imunologiaRESUMO
Aimed to evaluate the lovastatin action on Schistosoma mansoni oviposition, infected mice with 100 plus minus 10 cercariae of the LE strain were used. Thirty days after infection the animals were treated with 100, 200 and 400mg/kg of lovastatin, per os, during five consecutive days and then sacrificed 7, 15, 30 or 60 days after treatment. We analyzed: distribution of worms in mesenteries and liver; mortality of worms in the liver; alteration of the oogram; eggs counting in the jejunum and liver; presence of intrauterine eggs and morphology of the worms from the treated and control groups (infected and not treated animals). Significant statistical differences were found between treated and control groups when the presence of intrauterine eggs was considered and also, alteration on the oogram, eggs at different stages of development in jejunum, liver and in the body length of males and females. The morphological study of the worms showed that the degenerative modifications occurred, mainly in the reproductive system, with reduction and alteration of the viteline follicles and the ovary of the females. Also modifications in the males testicles were observed. The results suggest that the drug under study reduces, considerably, the female S. mansoni, oviposition increases the worms' size, leads to alteration in the reproductive system of males and females. It also may induce death of a significant part of the worm populations at the dose of 400mg/kg.
Assuntos
Antiparasitários/uso terapêutico , Modelos Animais de Doenças , Lovastatina/uso terapêutico , Esquistossomose mansoni/tratamento farmacológico , Animais , CamundongosRESUMO
To investigate whether mice immunization with the recombinant form of a 14.7 KDa Schistosoma mansoni protein (rSm14) confers protection against a S. mansoni lethal challenge infection, rSm14-immunized mice were challenged with different cercarial burdens. A significant protection was detected in immunized mice challenged with 100 or 1,000 S. mansoni cercariae when compared with their controls (p< 0.004 and p< 0.01 respectively). Differently from previous report, none of the mice from the control group (not immunized and infected with 1000 cercariae) died before the 30th day post-infection. A direct correlation between the number of challenge cercariae and the precocity of mice death was found. IgM anti-rSm14 antibodies were significantly produced (p< 0.05) mainly in the groups of immunized mice infected with 500 or 1000 cercariae. IgG and IgA anti-rSm14 antibodies were not significantly detected. In Western immunoblots, all mice sera showed a specific antibody response with a 14.7 KDa antigen being reacted with particular intensity in sera from immunized mice. The results show that immunization with rSm14 reduced mice worm burden independently of the cercariae load of challenge infection. No correlation was found between serum antibodies and worm burden reduction. In relation to cercarial load and the rate and precocity of mice mortality a direct correlation was found.
Assuntos
Proteínas de Transporte , Proteínas de Helminto , Proteínas de Membrana Transportadoras , Proteínas Recombinantes , Schistosoma mansoni , Esquistossomose mansoni/mortalidade , Esquistossomose mansoni/parasitologia , Vacinas , Animais , Proteínas de Transporte de Ácido Graxo , Feminino , Camundongos , Esquistossomose mansoni/prevenção & controleRESUMO
BACKGROUND: Protein kinases are proven targets for drug development with an increasing number of eukaryotic Protein Kinase (ePK) inhibitors now approved as drugs. Mitogen-activated protein kinase (MAPK) family members connect cell-surface receptors to regulatory targets within cells and influence a number of tissue-specific biological activities such as cell proliferation, differentiation and survival. However, the contributions of members of the MAPK pathway to schistosome development and survival are unclear. METHODOLOGY/PRINCIPAL FINDINGS: We employed RNA interference (RNAi) to elucidate the functional roles of five S. mansoni genes (SmCaMK2, SmJNK, SmERK1, SmERK2 and SmRas) involved in MAPK signaling pathway. Mice were injected with post-infective larvae (schistosomula) subsequent to RNAi and the development of adult worms observed. The data demonstrate that SmJNK participates in parasite maturation and survival of the parasites, whereas SmERK are involved in egg production as infected mice had significantly lower egg burdens with female worms presenting underdeveloped ovaries. Furthermore, it was shown that the c-fos transcription factor was overexpressed in parasites submitted to RNAi of SmERK1, SmJNK and SmCaMK2 indicating its putative involvement in gene regulation in this parasite's MAPK signaling cascade. CONCLUSIONS: We conclude that MAPKs proteins play important roles in the parasite in vivo survival, being essential for normal development and successful survival and reproduction of the schistosome parasite. Moreover SmERK and SmJNK are potential targets for drug development.
Assuntos
Proteínas de Helminto/metabolismo , Sistema de Sinalização das MAP Quinases , Proteínas Quinases Ativadas por Mitógeno/metabolismo , Schistosoma mansoni/crescimento & desenvolvimento , Animais , Feminino , Fertilidade , Regulação da Expressão Gênica , Genes de Helmintos , Proteínas de Helminto/genética , Masculino , Camundongos , Proteínas Quinases Ativadas por Mitógeno/genética , Ovário/crescimento & desenvolvimento , Contagem de Ovos de Parasitas , Inibidores de Proteínas Quinases/farmacologia , Interferência de RNA , Reprodução , Schistosoma mansoni/genéticaRESUMO
BACKGROUND: Schistosomiasis has a considerable impact on public health in many tropical and subtropical areas. In the new world, schistosomiasis is caused by the digenetic trematode Schistosoma mansoni. Chemotherapy is the main measure for controlling schistosomiasis, and the current drug of choice for treatment is praziquantel (PZQ). Although PZQ is efficient and safe, its repetitive large-scale use in endemic areas may lead to the selection of resistant strains. Isolates less susceptible to PZQ have been found in the field and selected for in the laboratory. The impact of selecting strains with a decreased susceptibility phenotype on disease dynamics and parasite population genetics is not fully understood. This study addresses the impact of PZQ pressure on the genetics of a laboratory population by analyzing frequency variations of polymorphic genetic markers. METHODOLOGY: Infected mice were treated with increasing PZQ doses until the highest dose of 3 × 300 mg/Kg was reached. The effect of PZQ treatment on the parasite population was assessed using five polymorphic microsatellite markers. Parasitological and genetic data were compared with those of the untreated control. After six parasite generations submitted to treatment, it was possible to obtain a S. mansoni population with decreased susceptibility to PZQ. In our experiments we also observed that female worms were more susceptible to PZQ than male worms. CONCLUSIONS: The selective pressure exerted by PZQ led to decreased genetic variability in S. mansoni and increased endogamy. The understanding of how S. mansoni populations respond to successive drug pressure has important implications on the appearance and maintenance of a PZQ resistance phenotype in endemic regions.
Assuntos
Anti-Helmínticos/uso terapêutico , Variação Genética , Praziquantel/uso terapêutico , Schistosoma mansoni/classificação , Schistosoma mansoni/genética , Esquistossomose mansoni/tratamento farmacológico , Esquistossomose mansoni/parasitologia , Animais , Resistência a Medicamentos , Feminino , Masculino , Camundongos , Repetições de Microssatélites , Schistosoma mansoni/isolamento & purificação , Seleção GenéticaRESUMO
If Schistosoma mansoni infection could be detected in its early stages, especially before the egg deposition in the host tissues, the development of severe pathologic lesions could be efficiently prevented. We therefore developed an indirect enzyme-linked immunosorbent assay based on the detection of specific IgG against schistosomula antigens (ELISA-SmTeg). The assay was applied in sera samples from non-infected and infected mice collected seven and 15 days post-infection. The results were compared to the number of adult worms obtained by perfusion of the murine hepatic system 50 days post-infection. The sensitivity and specificity of the ELISA-SmTeg were 100% (p = 0.0032 and 0.0048 respectively for seven and 15 days of infection) with a cutoff value of 0.15 (p = 0.0002). Our findings show a novel low-cost serological assay using antigens which are easy to obtain, which was able to detect all the infected mice as early as seven days post-infection.
Assuntos
Anticorpos Anti-Helmínticos/sangue , Antígenos de Helmintos/imunologia , Imunoglobulina G/sangue , Schistosoma mansoni/imunologia , Esquistossomose mansoni/diagnóstico , Animais , Anticorpos Anti-Helmínticos/imunologia , Diagnóstico Precoce , Ensaio de Imunoadsorção Enzimática/métodos , Feminino , Imunoglobulina G/imunologia , Camundongos , Contagem de Ovos de Parasitas , Sensibilidade e EspecificidadeRESUMO
In schistosomiasis, the current control strategy does not prevent reinfection, therefore, vaccine strategies are essential to combat the Schistosoma mansoni. The efficacy vaccine depends on parasite stage and effective adjuvant. We have recently demonstrated that S. mansoni schistosomula tegument (Smteg) is able to activate dendritic cells up regulate CD40 and CD86 molecules and induce a partial protection in mice (43-48%) when formulated with Freund's adjuvant. In this study we evaluated the ability of Smteg + alum or Smteg + alum + CpG-ODN to induce protection in mice. Our results demonstrate that Smteg + alum + CpG-ODN induced a partial reduction in worm burden (43.1%), reduction in the number of eggs eliminated in the feces. The protective response was associated with a predominant Th1 type of immune response, with increased production of specific IgG2c, IFN-γ and TNF-α, B cells proliferation and CD4 cells and macrophages activation.