Imunização contra malária: perspectivas e desafios / Malaria immunization: prospects and challenges

O referido trabalho tem como objetivo analisar e avaliar a atual conjuntura das pesquisas científicas na busca da imunização eficaz contra a malária, destacando os principais mecanismos imunológicos e moleculares subjacentes à referida proteção, bem como, as perspectivas a curto e médio prazo. O presente estudo de revisão selecionou pesquisas nas bases de dados da Medical Literature Analysis and Retrieval System Online (Medline), National Library of Medicine (Pubmed), Scientific Electronic Library Online (SciELO), Web of Science e Scopus. Foram combinados os termos Malaria, Immunization, Vaccine and Epidemiology, com seus sinônimos remissivos e outros descritores associados, no período compreendido entre janeiro e julho de 2019. Como fator preponderante dos critérios de inclusão, foram selecionadas revisões sistemáticas com ou sem metanálise, publicadas nos últimos 5 anos, que discorressem detalhadamente sobre o tema, ou que apresentassem informações estatísticas ou históricas relevantes, relacionada ao tema. Como critérios de exclusão foram considerados: materiais literários e científicos, anteriores ao período de 2014 e que não apresentassem informações estatísticas ou histórica relevantes ao tema, ou que, não se adequassem à temática da pesquisa. Após a aplicação dos critérios de inclusão e exclusão, foi realizada a análise e seleção dos artigos. Dos 451 artigos identificados, 44 foram selecionados. As informações extraídas dos referidos trabalhos convergem no sentido de que a erradicação da malária é uma tarefa demasiadamente complexa, a qual não será alcançada com as vacinas atuais, havendo necessidade do desenvolvimento de ferramentas imunizadoras de maior eficácia. Apesar dos esforços, atualmente ainda não existe uma vacina eficaz na prevenção da infecção, mas vários estudos se encontram em andamento nessa vertente, tornando promissor o surgimento de uma vacina eficaz contra o parasita.

This study aims at analyzing and evaluating the current status of scientific research in the search for effective immunization against malaria, highlighting the key immunological and molecular mechanisms of such protection and the short- and medium-term perspectives. The search and selection of studies took place in the databases of the Medical Literature Analysis and Retrieval System Online (Medline); National Library of Medicine (Pubmed); Scientific Electronic Library Online (SciELO); Web of Science; and Scopus. The terms Malaria, Immunization, Vaccine, and Epidemiology were used, with their corresponding cross-referenced synonyms and other associated descriptors, including the period from January to July 2019. As a main factor in the inclusion criteria, systematic reviews with or without meta-analysis published in the last 5 years, presenting a detailed discourse about the topic, or relevant statistical or historical information related to the topic were selected. The following exclusion criteria were considered: literary and scientific materials, prior to 2014, and without statistical or historical information relevant to the theme, or which did not fit the research theme. After applying the inclusion and exclusion criteria, the articles were analyzed and selected. From a total of 451 identified articles, 44 were selected. The information extracted from the referred studies converge in the sense that malaria eradication is an overly complex task, which will not be achieved with the current vaccines, requiring the development of more effective immunizing tools. Despite all the efforts, there is no effective vaccine for preventing infection yet, but several studies are being developed in this area, making the emergence of an effective vaccine against the disease promising.

Identification and Characterization of the ATG8, a Marker of Eimeria tenella Autophagy / Identificação e Caracterização do ATG8, um marcador de autofagia em Eimeria tenella

Abstract Autophagy plays an important role in maintaining cell homeostasis through degradation of denatured proteins and other biological macromolecules. In recent years, many researchers focus on mechanism of autophagy in apicomplexan parasites, but little was known about this process in avian coccidia. In our present study. The cloning, sequencing and characterization of autophagy-related gene (Etatg8) were investigated by quantitative real-time PCR (RT-qPCR), western blotting (WB), indirect immunofluorescence assays (IFAs) and transmission electron microscopy (TEM), respectively. The results have shown 375-bp ORF of Etatg8, encoding a protein of 124 amino acids in E. tenella, the protein structure and properties are similar to other apicomplexan parasites. RT-qPCR revealed Etatg8 gene expression during four developmental stages in E. tenella, but their transcriptional levels were significantly higher at the unsporulated oocysts stage. WB and IFA showed that EtATG8 was lipidated to bind the autophagosome membrane under starvation or rapamycin conditions, and aggregated in the cytoplasm of sporozoites and merozoites, however, the process of autophagosome membrane production can be inhibited by 3-methyladenine. In conclusion, we found that E. tenella has a conserved autophagy mechanism like other apicomplexan parasites, and EtATG8 can be used as a marker for future research on autophagy targeting avian coccidia.

Resumo A autofagia desempenha um papel importante na manutenção da homeostase celular através da degradação de proteínas desnaturadas e outras macromoléculas biológicas. Nos últimos anos, muitos pesquisadores se concentraram no mecanismo da autofagia em parasitas apicomplexos, mas pouco se sabe sobre esse processo na coccidia aviária. No presente estudo, a clonagem, sequenciamento e caracterização de gene relacionado à autofagia Etatg8 foram investigados pela PCR quantitativa em tempo real (RT-qPCR), mancha ocidental (WB), ensaios indiretos de imunofluorescência (IFAs) e microscopia eletrônica de transmissão (TEM), respectivamente. Os resultados mostraram que o gene Etatg8 de E. tenella possui uma ORF de 375 bp, codificando uma proteína de 124 aminoácidos com estrutura e propriedades semelhantes à de outros apicomplexos. RT-qPCR revelou que Etatg8 é expresso durante os quatro estágios de desenvolvimento de E. tenella. Entretanto, seus níveis transcricionais foram significativamente mais elevados na fase de oocisto não esporulados. Os ensaios de manchas ocidental (WB) e de imunofluorescência (IFA) mostraram que a proteína EtATG8 foi lipidada para ligar-se à membrana do autofagossomo sob condições de deficiência nutritiva (em presença de rapamicina) e se agregar no citoplasma de esporozoítas e merozoítas. No entanto, o processo de produção de membrana do autofagossomo pode ser inibido por um inibidor de autofagia (3-meetiladeninatiladenina, 3-MA). Em conclusão, foi demonstrado que E. tenella tem um mecanismo de autofagia conservado, semelhante ao de outros parasitas apicomplexos, e que EtATG8 pode ser usado como um marcador para futuras pesquisas sobre autofagia direcionada à coccidiose aviária.

Potential Vaccine Targets against Rabbit Coccidiosis by Immunoproteomic Analysis

The aim of this study was to identify antigens for a vaccine or drug target to control rabbit coccidiosis. A combination of 2-dimensional electrophoresis, immunoblotting, and mass spectrometric analysis were used to identify novel antigens from the sporozoites of Eimeria stiedae. Protein spots were recognized by the sera of New Zealand rabbits infected artificially with E. stiedae. The proteins were characterized by matrix-assisted laser desorption ionization time of flight mass spectrometry (MALDI-TOF/TOF-MS) analysis in combination with bioinformatics. Approximately 868 protein spots were detected by silver-staining, and a total of 41 immunoreactive protein spots were recognized by anti-E. stiedae sera. Finally, 23 protein spots were successfully identified. The proteins such as heat shock protein 70 and aspartyl protease may have potential as immunodiagnostic or vaccine antigens. The immunoreactive proteins were found to possess a wide range of biological functions. This study is the first to report the proteins recognized by sera of infected rabbits with E. stiedae, which might be helpful in identifying potential targets for vaccine development to control rabbit coccidiosis.

Isolation and Characterization of Vaccine Candidate Genes Including CSP and MSP1 in Plasmodium yoelii

Malaria is an infectious disease affecting humans, which is transmitted by the bite of Anopheles mosquitoes harboring sporozoites of parasitic protozoans belonging to the genus Plasmodium. Despite past achievements to control the protozoan disease, malaria still remains a significant health threat up to now. In this study, we cloned and characterized the full-unit Plasmodium yoelii genes encoding merozoite surface protein 1 (MSP1), circumsporozoite protein (CSP), and Duffy-binding protein (DBP), each of which can be applied for investigations to obtain potent protective vaccines in the rodent malaria model, due to their specific expression patterns during the parasite life cycle. Recombinant fragments corresponding to the middle and C-terminal regions of PyMSP1 and PyCSP, respectively, displayed strong reactivity against P. yoelii-infected mice sera. Specific native antigens invoking strong humoral immune response during the primary and secondary infections of P. yoelii were also abundantly detected in experimental ICR mice. The low or negligible parasitemia observed in the secondary infected mice was likely to result from the neutralizing action of the protective antibodies. Identification of these antigenic proteins might provide the necessary information and means to characterize additional vaccine candidate antigens, selected solely on their ability to produce the protective antibodies.

Molecular characterization, biological forms and sporozoite rate of Anopheles stephensi in southern Iran

<p><b>OBJECTIVE</b>To identify the biological forms, sporozoite rate and molecular characterization of the Anopheles stephensi (An. stephensi) in Hormozgan and Sistan-Baluchistan provinces, the most important malarious areas in Iran.</p><p><b>METHODS</b>Wild live An. stephensi samples were collected from different malarious areas in southern Iran. The biological forms were identified based on number of egg-ridges. Molecular characterization of biological forms was verified by analysis of the mitochondrial cytochrome oxidase subunit I and II (mtDNA-COI/COII). The Plasmodium infection was examined in the wild female specimens by species-specific nested-PCR method.</p><p><b>RESULTS</b>Results showed that all three biological forms including mysorensis, intermediate and type are present in the study areas. Molecular investigations revealed no genetic variation between mtDNA COI/COII sequences of the biological forms and no Plasmodium parasites was detected in the collected mosquito samples.</p><p><b>CONCLUSIONS</b>Presence of three biological forms with identical sequences showed that the known biological forms belong to a single taxon and the various vectorial capacities reported for these forms are more likely corresponded to other epidemiological factors than to the morphotype of the populations. Lack of malaria parasite infection in An. stephensi, the most important vector of malaria, may be partly due to the success and achievement of ongoing active malaria control program in the region.</p>

In vivo antioxidant and biochemical evaluation of Sphenocentrum jollyanum leaf extract in P. berghei infected mice

Recent approach in treatment and drug development suggested that the control of oxidative stress in malarial infected patients may be an added advantage. In this study, effect of methanolic leaf extract of Sphenocentrum jollyanum pier [S. jollyanum] on liver damage, markers of oxidative stress and alteration in lipid profile in P. berghei infected mice was assessed. Oxidative stress was induced by intravenously inoculation of mice with 1 x 107 sporozoites P. berghei. Treatment of parasitized mice with leaf extract of S. jollyanum had a significant [p<0.05] reductions in elevated levels of total protein, globulin, AST, ALT, ALP, GGT and total bilirubin, serum, kidney and liver malondialdehyde [MDA] concentrations, but caused a significant [p<0.05] increased in the activities of serum and liver catalase [CAT], superoxide dismutase [SOD] and glutathione [GSH] level when compared with parasitized non-treated group [PNT]. The extract treated group also showed significant [p<0.05] improvement in the levels of HDLc, total cholesterol, LDL and reduction in triglyceride compared with parasitized non treated group. Our results revealed that the protective capacity and antioxidant activity of the extract is dose dependant. The findings suggest that antioxidant property of Sphenocentrum jollyanum leave extract might be an added advantage to it anti-malarial activity

Sporozoite proteome analysis of Cryptosporidium parvum by one-dimensional SDS-PAGE and liquid chromatography tandem mass spectrometry

Despite the development of new technologies, new challenges still remain for large scale proteomic profiling when dealing with complex biological mixtures. Fractionation prior to liquid chromatography tandem mass spectrometry (LC-MS/MS) analysis is usually the preferred method to reduce the complexity of any biological sample. In this study, a gel LC-MS/MS approach was used to explore the stage specific proteome of Cryptosporidium (C.) parvum. To accomplish this, the sporozoite protein of C. parvum was first fractionated using SDS-PAGE with subsequent LC-MS/MS analysis. A total of 135 protein hits were recorded from 20 gel slices (from same gel lane), with many hits occurring in more than one band. Excluding all non-Cryptosporidium entries and proteins with multiple hits, 33 separate C. parvum entries were identified during the study. The overall goal of this study was to reduce sample complexity by protein fractionation and increase the possibility of detecting proteins present in lower abundance in a complex protein mixture.

Post-challenge hematological evaluation with virulent strain of Eimeria tenella in broilers immunized with attenuated strain or sporozoite proteins from homologous strain / Avaliação hematológica pós-desafio com cepa virulenta de Eimeria tenella em frangos de corte imunizados com cepa atenuada ou proteínas de esporozoítos de cepa homóloga

Hematological parameters were evaluated in broilers immunized and challenged with Eimeria tenella. Broiler chickens of Hubbard strain, females, coccidian-free, were kept in wire cages and inoculated on the third day. The experiment was designed to include five sorts of treatment with three replicates each. T1 was the negative control group, T2 received 500 attenuated sporulated oocysts by gavage, T3 was the positive control, T4 received 50 µg of sporozoite protein + Quil A vaccine, and T5 received Quil A without sporozoite protein + PBS, the last two through nasal route on days 0, 7, and 21. On the 31st day, all treatments were challenged with homologous virulent strain of E. tenella in the dose of 8.0 × 10(4) oocysts, with the exception of T1. One week later, blood sampling, lesion scores, and cecal oocyst count were carried out. The parasitological parameters showed statistical significance (p < 0.05) and there was no damage to the hematological parameters of birds (p > 0.05) by ANOVA test. The correlations suggest that the blood parameters were impaired by effects of the parasite on tissue, showing levels of hemorrhage and/or hydration.

Foram avaliados os parâmetros hematológicos em frangos de corte imunizados e desafiados com Eimeria tenella. Pintos de corte fêmeas da linhagem Hubbard, livres de coccídios, foram mantidos em baterias metálicas e inoculados no terceiro dia. O experimento foi delineado por cinco tratamentos com três repetições cada, sendo: T1 controle negativo, T2 recebeu 500 oocistos esporulados atenuados via oral, T3 controle positivo, T4 recebeu vacina contendo 50 µg de proteínas de esporozoítos + Quil A e T5 recebeu Quil A + PBS, sendo os dois últimos por via nasal nos dias 0, 7 e 21. No dia 31, todos os tratamentos foram desafiados com cepa virulenta homóloga de E. tenella na dose de 8,0 × 10(4) oocistos, exceto T1. Uma semana depois, foi realizada amostragem de sangue, escore de lesão e contagem de oocistos cecais. Os parâmetros parasitológicos apresentaram significância estatística (p < 0,05), sem que causassem prejuízos aos parâmetros hematológicos das aves (p > 0,05), pelo teste ANOVA. As correlações sugerem que os parâmetros sanguíneos foram afetados pelos efeitos do parasita no tecido, apresentando níveis de hemorragia e/ou hidratação.

Eimeria khobahensis sp. n. [apicomplexa: eimeriidae] from guinea fowl, numida meleagris in Saudi Arabia

Eimeria khobahensis sp.n. is described from the intestine of the guinea fowl, Numida meleagris [Galliformes: Phasianidae] collected at and around Khobah area near the Southern borders of Saudi Arabia. Sporulated oocysts are ellipsoid, 25x19.4 [23.3-27.6 x 17.8-20.6] microm, with a smooth, greenish-yellow bi-layered waIl 1.9 [1.5-2.4] microm. Micropyle and polar granule are present. An oocyst residuum is present, consisting of several globules that are irregular in shapes and sizes. Sporocysts are ellipsoid, 13.5 x 7.5 [11.9-14.2 x 6.7-8.8] microm, with a smooth single-layered wall and a prominent Stieda body, but no apparent substieda body. The sporocyst residuum is present, composed of numerous small granules. Sporozoites are comma-shaped, 10 x 3 [8-11 x 2.6-3.8] microm, each contains two refractjle bodies

Choleoeimeria riyadhae sp.n. [apicomplexa: eimeriidae] from the lizard, scincus [Sauria: scincidae] in Saudi Arabia

Choleoeimeria riyadhae species new was described from the gall bladder of the lizard, Scincus scincus [Sauna: Scincidae] collected from east of Riyadh City, Central Region. Sporulated oocysts are broadly ellipsoid, 36.8x30.5 [33.4-39.1 x 28.7-32.5] micro m, with a smooth, brownish-yellow bilayered wall; the shape index [L/W] is 1.21 [1.19-1.23] micro m. Micropyle, polar granule and oocyst residuum are absent. Sporocysts are elongate-ellipsoid, 14.8x9.1 [13.7-15.5 x 8.1-10.4] micro m with shape index [L/W], 1.63 [1.52-1.74] micro m. Sporocyst residuum is present. The sporocysts lack a Stieda body. Sporozoites are banana-shaped blunt at one end and slightly tapered at the other. Sometimes, free sporozoites were seen within oocysts

Incidence and prevalence of Eimeria infection among the hedgehog, Hemiechinus auritus in Yemen

Fecal samples of ten hedgehogs, Hemiechinus auritus from Taiz Governorate, Yemen were examined for coccidian parasites. Four [40%] were infected with Eimeria spp. Comparison of oocyst's criteria with other species of Eimeria indicated a new eimerian, E. yeminii n.sp. besides the previously described species, E. auriti Mirza, 1970 reported in Iraq. Oocysts of E. yeminii n.sp. are ovoidal to ellipsoidal, measuring 30x24.5 micro m [27-36x20-28]. The outer boundary is bilayered with a light reddish colour and perforated by a micro-pyle. Oocyst residuum and polar granules are present. Sporocysts are spherical in shape 10 x7.5 micro m [11-12.2x10-11.2] with granular residuum and Stieda body. Sporozoites are elongate, lying length-wise to the sporocyst long axis. Sporulation takes place within 3-4 days at - 26°C. E. auriti Mirza, 1970 is characterized by subspherical oocysts measuring 20 x 17 [22-26x16-19.5] micro m, a micropyle and oocyst residuum. The oocyst wall is bilayered, smooth and greenish in colour. Sporocysts are subspherical, measuring 9.0x8.3 [8.5-1 x7.5-8] micro m with granular residuum and Stieda body. Fully sporulated oocysts are observed within 48 h at - 26°C

Ultrastructural Localization of Cryptosporidium parvum Antigen Using Human Patients Sera

The antigen location of Cryptosporidium parvum, which stimulates antibody formation in humans and animals, was investigated using infected human sera. Immuno-electron microscopy revealed that antigenicity-inducing humoral immunity was located at various developmental stages of parasites, including asexual, sexual stages, and oocysts. The amount of antigen-stimulating IgG antibodies was particularly high on the oocyst wall. The sporozoite surface was shown to give stimulation on IgG and IgM antibody formation. Trophozoites implicated the lowest antigenicity to humoral immunity, both IgG and IgM, by showing the least amount of gold labeling. Immunogold labeling also provided clues that antigens were presented to the host-cell cytoplasm via feeder organelles and host-parasite junctions.

Observations on sporozoite detection in naturally infected sibling species of the Anopheles culicifacies complex and variant of Anopheles stephensi in India.

Sporozoites were detected in naturally infected sibling species of the primary rural vector Anopheles culicifacies complex in two primary health centres (PHCs) and a variant of the urban vector Anopheles stephensi in Mangalore city, Karnataka, south India while carrying out malaria outbreak investigations from 1998-2006. Sibling species of An. culicifacies were identified based on the banding patterns on ovarian polytene chromosomes, and variants of An. stephensi were identified based on the number of ridges on the egg floats. Sporozoites were detected in the salivary glands by the dissection method. Of the total 334 salivary glands of An. culicifacies dissected, 17 (5.08%) were found to be positive for sporozoites. Of the 17 positive samples, 11 were suitable for sibling species analysis; 10 were species A (an efficient vector) and 1 was species B (a poor vector). Out of 46 An. stephensi dissected, one was sporozoite positive and belonged to the type form (an efficient vector). In malaria epidemiology this observation is useful for planning an effective vector control programme, because each sibling species/variant differs in host specificity, susceptibility to malarial parasites, breeding habitats and response to insecticides.

Age composition of incriminated malaria vector in a rural foothills in West Bengal, India.

Two 1 yr surveys carried out at a gap of 10 yr revealed nine anopheline species from malaria endemic foothills area of Ayodhya - Baghmindi range of West Bengal, India, with 8.4 per cent populations of Anopheles culicifacies. An. culicifacies was incriminated as vector of Plasmodium falciparum with sporozoite rate of 1.23 per cent. Studies on age composition indicated that proportion parous and daily survival rate of An. culicifacies were assessed to be 0.50 and 0.84 respectively. The survival rate per gonotrophic cycle averaged over the two year was 0.61. Rainy season was found to be the favourable period for transmission.

Identification of Anopheles fauna in a hyperendemic falciparum area of Orissa State, India.

BACKGROUND & OBJECTIVE: Keonjhar district of Orissa State has been hyperendemic for falciparum malaria since many years with alarming deaths due to cerebral malaria. Therefore an entomological investigation to know more about the relative prevalence of Anopheles species was done. METHODS: Daytime indoor resting and outdoor resting, light trap and double bed net collections were made. Surveys were also made to collect Anopheles immature in streams and paddy fields. The Anopheles mosquitoes obtained by different catching methods were identified and the known vector species were subjected to gut and salivary gland dissection for vector incrimination. The infected specimens of An. fluviatilis and An. minimus were subjected to polymerase chain reaction assay for identification of sibling species. RESULTS: Of the anophelines collected, the most abundant was An. splendidus (18.2%) and An. fluviatilis (17.7%), followed by An. maculatus (14.0%) and An. minimus (9.0%). The sporozoite rate of An. fluviatilis and An. minimus was 0.9 and 1.4 respectively. The infected specimens have been identified as sibling species S of the An. fluviatilis complex and A of the An. minimus complex. INTERPRETATION & CONCLUSION: An. fluviatilis and An. minimus are the major two species in the transmission of malaria in Keonjhar district in Orissa.

Vector Species Composition and Malaria Infectivity Rates in Mkuzi; Muheza District; North-Eastern Tanzania

Entomological surveys were conducted in Mkuzi village in Muheza District; north-east Tanzania from April to September 2003. The objectives were to determine the species composition and infectivity rates of mosquitoes in Mkuzi village. Mosquito collection was done using CDC light trap and pyrethrum spray catch (PSC) techniques. The light trap: spray catch ratio was 2.2:1. A total of 2157 mosquitoes were collected (light trap= 1483; PSC= 674). Anopheles gambiae s.s. accounted for 56.7(N=1224) of all mosquitoes collected. Other species were An. funestus complex (19.2) and Culex quinquefasciatus (24.1).The mosquito density per room was 74.15 and 33.7 for light trap and PSC techniques; respectively. A total of 1637 Anopheles mosquitoes were tested for circumsporozoite protein by Enzyme linked Immunosobent Assay (ELISA). The overall infectivity rate for circumsporozoite protein for P. falciparum in Anopheles mosquitoes was 21.14(346/1637). Species-specific infectivity rates were 22.7(278/1224) in An. gambiae s.s. and 24.0(68/283) in An. funestus funestus; 0(0/80) for An. rivulorum and 0(0/50) for An.parensis. Blood meal analysis indicated that 92.3of An. gambiae s.s; 88.9of An. funestus s.s.; 64.5of An. rivulorum and 67.7of An. parensis had taken blood meal from human hosts. In conclusion; malaria transmission in Mkuzi area of Muheza district is mainly by the highly anthropophagic An. gambiae s.s. and An. funestus s.s. More studies are needed to identify the seasonal variation of species composition and transmission dynamics in this village

Ocorrência de Eimeria ichiloensis em capivaras (Hydrochaeris hydrochaeris) de criatório / Ocurrencia de Eimeria ichiloensis en capibaras (Hidrochoerus hidrochaeris) de creación / Occurrence of Eimeria ichiloensis in capybaras (Hydrochaeris hydrochaeris) bred in farming

O objetivo deste trabalho foi relatar o parasitismo por Eimeria ichiloensis em capivaras (Hydrochaeris hydrochaeris). Foram analisadas 10 amostras de fezes de capivaras, provenientes de um criatório legalizado, onde eram criadas em ambiente com área de brejo e açude no município de Arroio do Meio, Rio Grande do Sul, Brasil. As fezes foram analisadas através do método de centrífugo-flutuação com sulfato de zinco. Nas amostras, observou-se infecção leve por oocistos de E. ichiloensis, no entanto, os roedores não apresentaram sinais clínicos da enfermidade

This paper reports parasitism by Eimeria ichiloensis in capybaras (Hydrochaeris hydrochaeris). Ten fecal samples of animals from a legal nursery were analyzed. The animals were created in an environment with swamp and dam in the municipality of Arroio do Meio, Rio Grande do Sul state, Brazil. Feces were analyzed by the zinc sulphate centrifugalflotation method. Mild infection by oocytes of E. ichiloensis was observed in the samples, although rodents presented no clinical signs of the disease

El objetivo de esta investigación fue relatar el parasitismo por Eimeria ichiloensis en capibaras (Hydrochoerus hydrochaeris). Fueron analizadas 10 muestras de excrementos de capibaras, provenientes de una creación legalizada, donde eran creadas en pantanos y represa en el municipio de Arroio do Meio, Rio Grande do Sul, Brasil. Los excrementos fueron analizados a través del método centrífugo fluctuación con sulfato de zinc. En las muestras, se observó infección leve por oocistos de E. ichiloensis, sin embargo, los roedores no presentaron señales clínicos de la enfermedad

How reliable are models for malaria vaccine development? Lessons from irradiated sporozoite immunizations.

Models occupy a key position in the development of anti-parasitic vaccines, yet their relevance has been seldom addressed. It is customary to admit that malaria vaccine development requires easy-to-handle, laboratory models. Animal models involving predominantly inbred rodents and primates as parasite hosts are currently the basic tools for the study of host-parasite interactions. Literature however indicates that the induction of host protection is more difficult in natural host-parasite pairs than in experimental models of parasite infection. Moreover different models delineate a wide range of host-pathogen relationship profiles providing a mosaic of contradictory informations, yet there is little incentive to delineate their relevance or to exploit recent advances to develop improved model systems. In this context the analysis of natural host-parasite interactions between Plasmodium berghei and its mammalian host and reservoir, the tree rat Grammomys surdaster could ge of relevance in the study of host-parasite interactions.