Metabolismo intermediario de Blastocystis spp / Intermediate metabolism of Blastocystis spp

Blastocystis es un stramenopile o cromista, pleomórfico no móvil. Se han identificado diecinue-ve subtipos de este organismo (ST1-ST19). Tiene una presencia a nivel mundial. Este microor-ganismo tiene un metabolismo intermediario anaeróbico. Un aspecto interesante de la bioquími-ca de este stramenopile está dado por la presencia de organelas similares a mitocondrias con un conjunto de rutas: cadena de fosforilación oxidativa incompleta, ciclo de Krebs parcial, metabo-lismo de ácidos grasos (anabolismo y catabolismo), metabolismo de aminoácidos y ensamblaje de proteínas con centros hierro/azufre. El tratamiento se ha basado tradicionalmente en metroni-dazol y otros imidazoles. Sin embargo, hay un número creciente de cepas resistentes a esos medicamentos. La reciente obtención del genoma nuclear y los estudios bioquímicos, proteómi-cos, metabolómicos, interactómicos permitirán el desarrollo racional de nuevos fármacos curati-vos. El objetivo de esta revisión es describir el metabolismo de Blastocystis spp

Blastocystis is a stramenopile or chromist, nonmobile pleomorphic. Nineteen subtypes of this organism (ST1-ST19) have been identified worldwide. This microorganism has an intermediate anaerobic metabolism. An interesting aspect of the biochemistry of this stramenopile is given by the presence of mitochondrial-like organelles with a set of pathways: incomplete oxidative phos-phorylation chain, partial Krebs cycle, fatty acid metabolism (anabolism and catabolism), amino acid metabolism and protein assembly with iron / sulfur centers. Treatment has traditionally been based on metronidazole and other imidazoles. However, there are a growing number of strains resistant to these drugs. The recent obtaining of the nuclear genome and the biochemical, proteomic, metabolomic and interactomic studies will allow the rational development of new curative drugs. The objective of this review is to describe the metabolism of Blastocystis spp.

Leishmaniose visceral em um Pastor Belga: relato de caso / Visceral leishmaniasis in a Belgian Pastor: case report

O presente trabalho tem como objetivo relatar um caso de um Pastor Belga, do município de Ponta Porã, Mato Grosso do Sul, positivo para Leishmaniose Visceral, atendido em 2017 em uma clínica veterinária localizada em Pedro Juan Caballero, Paraguai. O diagnóstico foi confirmado através dos sinais clínicos característicos, e dos exames ELISA e PCR positivos. O animal foi submetido ao tratamento clínico para melhora dos sintomas, cujo tratamento antiparasitário inicial foi realizado com a associação de estibogluconato de sódio 75 mg/kg e alopurinol 100 mg seguido de aloputinol 100mg de uso contínuo e uso da coleira antileishmaniose. Tratamento esse considerado eficiente, com melhora clínica do animal. Após 24 meses o animal foi diagnosticado com tumor de mama e lesão da bolsa escrotal, sendo submetido a tratamento clínico e cirúrgico. Com 30 e 36 meses do diagnóstico inicial repetiu-se os exames ELISA (positivo) e PCR (negativo), e então o animal foi considerado curado clinicamente devido à ausência de sinais clínicos. Tendo em vista a complexidade dos fatores no ciclo de transmissão, conclui-se que as medidas em saúde ainda são insuficientes para o controle efetivo da doença. É importante o papel do Médico Veterinário na saúde pública, devido a obrigatoriedade de notificação de casos de Leishmaniose Visceral Canina, sendo necessários esforços nas diferentes áreas da saúde animal, humana e do meio ambiente, visando medidas de vigilância e controle da doença no país.

The present work aims to report a case of a Belgian Shepherd, from the municipality of Ponta Porã, Mato Grosso do Sul, positive for Visceral Leishmaniasis, treated in 2017 in a veterinary clinic located in Pedro Juan Caballero, Paraguay. The diagnosis was confirmed through the characteristic clinical signs, and the positive ELISA and PCR tests. The animal was submitted to clinical treatment for improvement of symptoms, whose initial antiparasitic treatment was performed with the association of sodium stibogluconate 75 mg/kg and allopurinol 100 mg followed by alloputinol 100mg of continuous use and use of the antileishmaniasis collar. This treatment was considered efficient, with clinical improvement of the animal. After 24 months the animal was diagnosed with a breast tumor and scrotum injury, and was submitted to clinical and surgical treatment. At 30 and 36 months from the initial diagnosis, the ELISA tests (positive) and PCR (negative) were repeated, and then the animal was considered clinically cured due to the absence of clinical signs. Considering the complexity of the factors in the transmission cycle, it is concluded that the health measures are still insufficient for the effective control of the disease. The role of the veterinarian in public health is important, due to the obligatory notification of cases of Canine Visceral Leishmaniasis, being necessary efforts in the different areas of animal health, human and environment, aiming at measures of surveillance and control of the disease in the country.

Validation of ELISA with recombinant antigens in serological diagnosis of canine Leishmania infantum infection

BACKGROUND Dogs are the main peridomiciliary reservoir of Leishmania infantum thus the correct diagnosis of infection is essential for the control of the transmission and treatment as well. However, the diagnosis is based on serological assays that are not fully effective. OBJECTIVE We aimed to establish an effective serological assay for the diagnosis of L. infantum infected dogs using Leishmania-derived recombinant antigens. METHODS Leishmania derived rK39-, rK28-, rKR95-based enzyme-linked immunosorbent assay (ELISA) was standardized using symptomatic and asymptomatic L. infantum-infected dogs. Then 2,530 samples from inquiry in endemic areas for VL were evaluated and the results compared with recommended assays by the Brazilian Ministry of Health (MH algorithm). Further samples from a cohort of 30 dogs were searched. FINDINGS For rK39-, rK28- and rKR95-ELISA the sensitivity was around 97% and specificity 100%. The positivity of these three ELISA in the inquiry samples was 27-28%, around 10% higher than the assays currently in use. When cohort samples were searched, we observed likely false-negative results (> 65%) with supposedly negative samples that turned positive six months later with the assays in use (MH algorithm). MAIN CONCLUSIONS For the diagnosis of L. infantum-infected dogs, rK39-based ELISA showed better diagnostic performance than other assays in use in Brazil and worldwide.

Evaluation of different total Leishmania amazonensis antigens for the development of a first-generation vaccine formulated with a Toll-like receptor-3 agonist to prevent cutaneous leishmaniasis

BACKGROUND Unfortunately, no any vaccine against leishmaniasis has been developed for human use. Therefore, a vaccine based on total Leishmania antigens could be a good and economic approach; and there are different methodologies to obtain these antigens. However, it is unknown whether the method to obtain the antigens affects the integrity and immune response caused by them. OBJECTIVES to compare the protein profile and immune response generated by total L. amazonensis antigens (TLA) produced by different methods, as well as to analyse the immune response and protection by a first-generation vaccine formulated with sonicated TLA (sTLA) and polyinosinic:polycytidylic acid [Poly (I:C)]. METHODS TLA were obtained by four different methodologies and their integrity and immune response were evaluated. Finally, sTLA was formulated with Poly (I:C) and their protective immune response was measured. FINDINGS sTLA presented a conserved protein profile and induced a strong immune response. In addition, Poly (I:C) improved the immune response generated by sTLA. Finally, sTLA + Poly (I:C) formulation provided partial protection against L. amazonensis infection. MAIN CONCLUSIONS The protein profile and immune response depend on the methodology used to obtain the antigens. Also, the formulation sTLA + Poly (I:C) provides partial protection against cutaneous leishmaniasis in mice.

Analyzing weight evolution in mice infected by Trypanosoma cruzi

Concerning the specificities of a longitudinal study, the trajectories of a subject's mean responses not always present a linear behavior, which calls for tools that take into account the non-linearity of individual trajectories and that describe them towards associating possible random effects with each individual. Generalized additive mixed models (GAMMs) have come to solve this problem, since, in this class of models, it is possible to assign specific random effects to individuals, in addition to rewriting the linear term by summing unknown smooth functions, not parametrically specified, then using the P-splines smoothing technique. Thus, this article aims to introduce this methodology applied to a dataset referring to an experiment involving 57 Swiss mice infected by Trypanosoma cruzi, which had their weights monitored for 12 weeks. The analyses showed significant differences in the weight trajectory of the individuals by treatment group; besides, the assumptions required to validate the model were met. Therefore, it is possible to conclude that this methodology is satisfactory in modeling data of longitudinal sort, because, with this approach, in addition to the possibility of including fixed and random effects, these models allow adding complex correlation structures to residuals.

O probiótico Saccharomyces boulardii modula a resposta de IgG2a em camundongos expostos aos antígenos de Leishmania infantum / Probiotic Saccharomyces boulardii modulates IgG2a response in miceexposed to Leishmania infantum antigens

O objetivo do presente estudo foi avaliar os efeitos do probiótico Saccharomyces boulardii na modulação da resposta imune humoral de animais expostos a antígenos de Leishmania infantum. Para isso, 16 camundongos BALB/c foram imunizados com antígeno particulado de Leishmania infantum e divididos em dois grupos experimentais, um composto por animais suplementados e outro por animais não suplementados com o probiótico. Amostras de sangue dos animais foram colhidas semanalmente durante o período experimental e submetidas ao Ensaio da Imunoabsorbância Ligado à Enzima indireto para avaliação dos títulos de IgG totais e o perfil dos isotipos de IgG produzidos (IgG1 e IgG2a). A suplementação com o probiótico não exacerbou a produção de IgG total em comparação ao grupo controle, não havendo diferenças significativas entre os dois grupos. Porém, as soroconversões de IgG2a foram mais elevadas no grupo suplementado, no qual registrou-se um aumento de 1,46 vezes no final do experimento. Assim, a suplementação com S. boulardii foi capaz de modular a resposta de IgG2a/IgG1 nos animais expostos aos antígenos de Leishmania infantum.

The aim of the present study was to evaluate the effects of the Saccharomyces boulardii probiotic on the modulation of humoral immune response in animals exposed to Leishmania infantum antigens. For this, 16 BALB/c mice were immunized with Leishmania infantum particulate antigen and divided into two experimental groups, one consisting of supplemented animals and the other not probiotic supplemented animals. Blood samples from the animals were taken weekly during the experimental period and subjected to the Indirect Enzyme-Linked Immunosorbance Assay for evaluation of total IgG titers and the profile of the produced IgG isotypes (IgG1 and IgG2a). Probiotic supplementation did not exacerbate total IgG production compared to the control group, with no significant differences between the two groups. However, IgG2a seroconversions were higher in the supplemented group, which showed a 1.46-fold increase at the end of the experiment. Thus, supplementation with S. boulardii was able to modulate the IgG2a/IgG1 response in animals exposed to Leishmania infantum antigens.

Performance of an immuno-rapid malaria Pf/Pv rapid diagnostic test for malaria diagnosis in the Western Brazilian Amazon

Abstract INTRODUCTION: Rapid diagnostic tests (RDTs) for detecting Plasmodium antigens have become increasingly common worldwide. We aimed to evaluate the accuracy of the Immuno-Rapid Malaria Pf/Pv RDT in detecting Plasmodium vivax infection compared to standard thick blood smear (TBS) under microscopy. METHODS: Hundred and eighty-one febrile patients from the hospital's regular admissions were assessed using TBS and RDT in a blinded experiment. RESULTS: RDT showed a sensitivity of 98.9%, specificity of 100%, and accuracy of 99.5% for P. vivax infection when compared to TBS. CONCLUSIONS: The RDT is highly accurate, making it a valuable diagnostic tool for P. vivax infection.

Asymptomatic plasmodium infection in a residual malaria transmission area in the atlantic forest region: implications for elimination

Abstract INTRODUCTION: Elimination of malaria in areas of interrupted transmission warrants careful case assessment to avoid the reintroduction of this disease. Occasional malaria cases are reported among visitors of the Atlantic Forest area of Brazil, while data on residents of this area are scarce. METHODS: A sectional study was carried out to examine 324 individuals living in a municipality where autochthonous cases were detected. RESULTS: Asymptomatic Plasmodium infections were detected in 2.8% of the individuals by polymerase chain reaction (PCR), with one case of P. falciparum (0.3%), two cases of P. vivax (0.6%), and six cases of P. malariae (1.9%). The thick blood smears were negative in all individuals. Serological tests performed in 314 subjects were reactive in 11.1%, with 3.5% for P. falciparum and 7.7% for P. vivax. A subsample of 42 reactive individuals for any Plasmodium species showed P. malariae in 30.9% of specimens. Individuals who entered the Atlantic Forest region were 2.7 times more likely to exhibit reactive serology for P. vivax compared with individuals who did not enter this region (p<0.05). Children <15 years had a higher chance of reactive serology for P. falciparum and P. vivax than individuals ≥15 years of age (p<0.05). Individuals living in the Paraiso district had a higher chance of reactive serology for P. vivax compared to other districts (p<0.05). No associations were found between sex, past exposure to malaria, or serological response to antibodies of any Plasmodium species. CONCLUSIONS: The implications of these results for the elimination of malaria were discussed.

Perfil antigénico en fase aguda y crónica de toxoplasmosis en embarazadas por la técnica de Western Blot / Antigenic profile in the acute and chronic phase of toxoplasmosis in pregnant women using the Western Blot technique

La toxoplasmosis es una enfermedad endémica con prevalencia mundial variable, cuyo agente causal es el parásito Toxoplasma gondii. Para un diagnóstico certero de la infección por T. gondii son necesarias combinaciones de métodos serológicos. Estudios recientes han reportado que la técnica de Western Blot permite evidenciar proteínas antigénicas como marcadores de la infección, así como ciertos perfiles proteicos como posibles indicadores de las fases de la infección, aguda y crónica. El objetivo del estudio fue identificar el perfil antigénico específico asociado a las diferentes fases de la toxoplasmosis. Fueron incluidos en el estudio 55 sueros de embarazadas con toxoplasmosis, diferenciados en fase aguda y crónica de la enfermedad por medio del método de ELISA de Avidez de IgG. Mediante el método de Western Blot se observó que las proteínas antigénicas p35, p43, p45, p56 y p107 fueron reconocidas por el 20- 60% de los sueros de pacientes en fase aguda, mientras que p65, p95, p98 y p113 fueron reconocidas por el 17-35% de sueros de pacientes en fase crónica. Se observó que seis proteínas antigénicas, p32, p38, p41, p48, p59 y p72, fueron reconocidas por más del 60% de los sueros de pacientes tanto en fase aguda como crónica. Los resultados obtenidos sugieren que estas seis proteínas podrían ser consideradas como marcadores diagnósticos de la enfermedad(AU)

Toxoplasmosis is an endemic disease with variable global prevalence, being the causative agent the parasite Toxoplasma gondii. For an accurate diagnosis of a T. gondii infection, combinations of serological methods are required. Recent studies have reported that the Western Blot technique allows the detection of antigenic proteins as markers of infection, as well as certain protein profiles as possible indicators of acute and chronic phases of infection. The objective of the study was to identify the specific antigenic profile associated with different phases of toxoplasmosis. Fifty five sera from pregnant women with toxoplasmosis were included in the study, differentiated in acute and chronic phase of the disease by an IgG Avidity ELISA. By using the Western Blot method it was observed that antigenic proteins p35, p43, p45, p56 and p107 were recognized by 20-60% of sera from patients in acute phase, while p65, p95, p98 and p113 were recognized by 17-35% of sera from patients in chronic phase. It was observed that six antigenic proteins, p32, p38, p41, p48, p59 and p72, were recognized by more than 60% of sera from patients in both acute and chronic phases. The results obtained in this study suggest that these six proteins could be considered as diagnostic markers of the disease(AU)

Estudio piloto de diagnóstico de parasitosis intestinal y respuesta al uso de Mebendazol en niños de edad escolar en las escuelas Charcas II, El Sillar y la Cascada, gestión 2010 La Paz / Pilot study of intestinal parasitosis diagnostic and response to Mebendazol on school age children at schools in Charcas II, El Sillar and La Cascada, year 2010 La Paz

El proyecto IDH 09: Desparasitación de niños en escuelas rurales", llevo adelante un trabajo piloto experimental de diagnóstico sobre parásitos intestinales en niños en las Escuelas de las Comunidades: Charcas II; La Cascada y El Sillar, Provincia Sud Yungas, Departamento de La Paz, Bolivia. El análisis coproparasitológico fue en 93 muestras tomadas entre Inicial y quinto de primaria, con edades entre 5 y 12 años. En promedio, el 97,9% de las muestras indicaron presencia de Protozoarios y hasta un 54,5% de Helmintos, concomitantemente, con una relación promedio de 2,0 veces más Protozoarios. En las escuelas de Charcas II y La Cascada la relación fue de 1,8 y en El Sillar fue de 2,5. Hasta 12 parásitos fueron identificados entre los Protozoarios: Blatocystis hominis (92,7%); Entamoeba coli (50,3%); Endolimax nana (44,0%); Giardia lamblia (39,3%); Iodamoeba bütschlii (25,0%) y Chilomastix mesnili (8,3%) y entre los Helmintos: Ascaris lumbricoides (30,0%); Uncinaria spp (21,7%), Strongyloides stercoralis (9,0%); Hymenolepis nana (7,0%) y Trichuris trichiura (5,7%), en una muestra se detectó Enterobius vermicularis. En la escuela Charcas II, de acuerdo a sus programas de desparasitación, los niños recibieron tratamiento con Mebendazol y el efecto de la medicación fue evaluado, aleatoriamente, a los 7 días, sobre un total de 21 niños. El Mebendazol (1200mg) elimino 50% de los Helmintos. A. lumbricoides fue eliminado de todas las muestras, Uncinaria spp, S. stercoralisy T. trichiura fueron eliminados en un 50%, mientras que H. nana persistió en todas las muestras, mientras que los Protozoarios fueron eliminados solo en un 19% de las muestras.

The Project Deworming of children in rural schools carried out a pilot experimental field work to determine intestinal parasites levels in kids in rural schools, at Charcas II, La Cascada and El Sillar communities, South Yungas province, Department of La Paz, Bolivia. The coproparasitologic studies were carry out on 93 feces samples, from kids from initial to fifth grade, within ages from 5 to 12 years. An average of 97,9% of the samples showed presence of protozoa parasites and up to 54,5% showed, additionally, presence of Helminthes, with a general ratio of Protozoan to Helminthes of 2,0. At Charcas II School and La Cascada School the ratio was of 1,8; while at El Sillar gave a ratio of 2,5. A total of 12 parasites were identified, among the protozoa: Blatocystishominis (92,7%); Entamoeba coli (50,3%); Endolimax nana (44,0%); Giardia lamblia (39,3%); Iodamoeba bütschlii (25,0%) and Chilomastix mesnili:(8,3%) and among the Helminthes: Ascaris lumbriocoides (30,0%); Uncinaria spp (21,7%), Strongyloides stercoralis (9,0%); Hymenolepis nana (7,0%) and Trichuris trichiura (5,7%) and in one sample we detected Enterobius vermicularis. According to their deworming program, at Charcas II School, kids received treatment with Mebendazol (1200mg) and the effect was evaluated 7 days after treatment. On a total of 21 children. Mebendazol eliminated 50% of Helminthes. A. lumbricoides was eliminated from all samples; Uncinaria spp, S. stercoralis y T. trichiura only from 50% of the samples and H. nana persisted in all samples, while Protozoan parasites were eliminated on nearly 19% of the samples

Vimentin and Anti Vimentin Antibodies in Chagas' Disease / Vimentina e Anticorpos Anti-Vimentina na Doença de Chagas

Abstract Background: Vimentin is a main structural protein of the cell, a component of intermediate cell filaments and immersed in cytoplasm. Vimentin is mimicked by some bacterial proteins and anti-vimentin antibodies occur in autoimmune cardiac disease, as rheumatic fever. In this work we studied vimentin distribution on LLC-MK2 cells infected with T. cruzi and anti-vimentin antibodies in sera from several clinical pictures of Chagas' disease or American Trypanosomiasis, in order to elucidate any vimentin involvement in the humoral response of this pathology. Objective: We standardized an indirect immunofluorescence assay (IFI) to determine sub cellular expression in either parasites and host cells, and ELISA to evaluate anti-vimentin antibodies in sera fron chagasic patients. Methods: We analyzed the distribution of vimentin in culture cells using indirect fluorescent assays, using as external controls anti-T. cruzi sera, derived from chronic infected patients for identification of the parasites in the same model. After infection and growth of T.cruzi amastigotes, those cells express larger amounts of vimentin, with heavy staining of cytoplasm outside the parasitophorous vacuole and some particle shadowing patterns, suggesting that vimentin are associated with cell cytoplasm. Anti-vimentin antibodies were present in most American trypanosomiasis samples, but notably, they are much more present in acute (76, 9%) or clinical defined syndromes, especially cardiac disease (87, 9%). Paradoxically, they were relatively infrequent in asymptomatic (25%) infected patients, which had a clearly positive serological reaction to parasite antigens, but had low frequency of anti-vimentin antibodies, similar to controls (2,5%). Conclusion: Our current data revealed that anti-vimentin antibodies induced during T. cruzi infection could be a marker of active disease in the host and its levels could also justify drug therapy in American Trypanosomiasis chronic infection, as a large group of asymptomatic patients would be submitted to treatment with frequent adverse reactions of the available drugs. Anti-vimentin antibodies could be a marker of cardiac muscle cell damage, appearing in American Trypanosomiasis patients during active muscle cell damage.

Resumo Fundamento: A Vimentina é uma proteína estrutural importante da célula, um componente dos filamentos celulares intermediários e imersa no citoplasma. Algumas proteínas bacterianas imitam a Vimentina e anticorpos anti-vimentina ocorrem em doenças cardíacas auto-imunes, como a febre reumática. Neste trabalho, estudamos a distribuição de vimentina em células LLC-MK2 infectadas com T. Cruzi e anticorpos anti-vimentina em soros de várias imagens clínicas da doença de Chagas ou tripanossomíases americanas, a fim de elucidar qualquer implicação da vimentina na resposta humoral desta patologia. Objetivo: padronizamos um teste de imunofluorescência indireta (IFI) para determinar a expressão subcelular em parasitas e células hospedeiras, e ELISA para testar anticorpos anti-vimentina em soros de pacientes chagásicos. Métodos: analisamos a distribuição de vimentina em células de cultura usando ensaios fluorescentes indiretos, utilizando como controles externos soros anti-T. Cruzi, derivados de pacientes com infecção crônica para a identificação de parasitas no mesmo modelo. Após a infecção e o crescimento de amastigotas de T. Cruzi, essas células expressam grandes quantidades de vimentina, com forte coloração do citoplasma fora da vacuola parasitófora e alguns padrões de sombreamento das partículas, sugerindo que a vimentina está associada ao citoplasma da célula. Os anticorpos anti-vimentina estavam presentes na maioria das amostras americanas de tripanossomíases, mas estão notavelmente mais presentes em síndromes agudas ou clinicamente definidas (76,9%), especialmente em doenças cardíacas (87,9%). Paradoxalmente, eram relativamente infrequentes em pacientes infectados assintomáticos (25%), que apresentavam uma reação sorológica claramente positiva aos antígenos parasitas, mas apresentavam baixa frequência de anticorpos anti-vimentina, semelhante aos controles (2,5%). Conclusão: Nossos dados atuais revelaram que os anticorpos anti-vimentina induzidos durante a infecção por T. Cruzi poderiam ser um marcador de doença ativa no hospedeiro e seus níveis também poderiam justificar o tratamento farmacológico em infecção crônica com tripanossomíase americana, uma vez que um grande grupo de pacientes assintomáticos seria submetido a tratamento com reações adversas frequentes aos medicamentos disponíveis. Os anticorpos anti-vimentina poderiam ser um marcador de danos nas células do músculo cardíaco, que aparece em pacientes com tripanossomíase americana durante o dano das células musculares ativas.

Hemolytic, anticancer and antigiardial activity of Palythoa caribaeorum venom

Background Cnidarian venoms and extracts have shown a broad variety of biological activities including cytotoxic, antibacterial and antitumoral effects. Most of these studied extracts were obtained from sea anemones or jellyfish. The present study aimed to determine the toxic activity and assess the antitumor and antiparasitic potential of Palythoa caribaeorum venom by evaluating its in vitro toxicity on several models including human tumor cell lines and against the parasite Giardia intestinalis. Methods The presence of cytolysins and vasoconstrictor activity of P. caribaeorum venom were determined by hemolysis, PLA2 and isolated rat aortic ring assays, respectively. The cytotoxic effect was tested on HCT-15 (human colorectal adenocarcinoma), MCF-7 (human mammary adenocarcinoma), K562 (human chronic myelogenous leukemia), U251 (human glyoblastoma), PC-3 (human prostatic adenocarcinoma) and SKLU-1 (human lung adenocarcinoma). An in vivo toxicity assay was performed with crickets and the antiparasitic assay was performed against G. intestinalis at 24 h of incubation. Results P. caribaeorum venom produced hemolytic and PLA2 activity and showed specific cytotoxicity against U251 and SKLU-1 cell lines, with approximately 50% growing inhibition. The venom was toxic to insects and showed activity against G. intestinalis in a dose-dependent manner by possibly altering its membrane osmotic equilibrium. Conclusion These results suggest that P. caribaeorum venom contains compounds with potential therapeutic value against microorganisms and cancer.

Complement system contributes to modulate the infectivity of susceptible TcI strains of Trypanosoma cruzi

BACKGROUND Trypanosoma cruzi is a protozoan parasite and an etiological agent of Chagas disease. There is a wide variability in the clinical outcome of its infection, ranging from asymptomatic individuals to those with chronic fatal mega syndromes. Both parasite and host factors, as well as their interplay, are thought to be involved in the process. OBJECTIVES To evaluate the resistance to complement-mediated killing in two T. cruzi TcI strains with differential virulence and the subsequent effect on their infectivity in mammalian cells. METHODS Tissue-culture derived trypomastigotes of both strains were incubated in guinea pig serum and subjected to flow cytometry in order to determine their viability and complement activations. Trypomastigotes were also incubated on host cells monolayers in the presence of serum, and infectivity was evaluated under different conditions of complement pathway inhibition. Relative expression of the main parasite-specific complement receptors between the two strains was assessed by quantitative real-time polymerase chain reaction. FINDINGS In this work, we showed that two TcI strains, one with lower virulence (Ninoa) compared to the other (Qro), differ in their resistance to the lytic activity of complement system, hence causing a compromised ability of Ninoa strain to invade mammalian cells. These results correlate with the three-fold lower messenger RNA (mRNA) levels of complement regulatory protein (CRP), trypomastigote-decay acceleration factor (T-DAF), and complement C2 receptor inhibitor trispanning (CRIT) in Ninoa compared to those in Qro. On the other hand, calreticulin (CRT) mRNA and surface protein levels were higher in Ninoa strain and promoted its infectivity when the lectin pathway of the complement system was inhibited. MAIN CONCLUSIONS This work suggests the complex interplay of CRP, T-DAF, CRIT, and CRT, and the diagnostic value of mRNA levels in the assessment of virulence potential of T. cruzi strains, particularly when dealing with isolates with similar genetic background.

Immunoproteomics of Plasmodium falciparum-infected red blood cell membrane fractions

BACKGROUND The surface of infected red blood cells (iRBCs) has been widely investigated because of the molecular complexity and pathogenesis mechanisms involved. Asymptomatic individuals are important in the field because they can perpetuate transmission as natural reservoirs and present a challenge for diagnosing malaria because of their low levels of circulating parasites. Recent studies of iRBC antibody recognition have shown that responses are quantitatively similar in symptomatic and asymptomatic infections, but no studies have characterised the plasmodial proteins targeted by this response. OBJECTIVES Our main objective was to identify Plasmodium falciparum proteins associated with iRBC ghosts recognised by antibodies in the sera of symptomatic and asymptomatic individuals in the Brazilian Amazon. METHODS We collected symptomatic and asymptomatic sera from patients residing in the Brazilian Amazon and P. falciparum iRBC ghosts to identify the proteins involved in natural antibody recognition by 2D-electrophoresis, western blotting, and high- resolution mass spectrometry. FINDINGS 2D gel-based immunoproteome analysis using symptomatic and asymptomatic sera identified 11 proteins with at least one unique peptide, such as chaperones HSP70-1 and HSP70-x, which likely are components of the secretion machinery/PTEX translocon. PfEMP1 is involved in antigenic variation in symptomatic infections and we found putative membrane proteins whose functions are unknown. MAIN FINDINGS Our results suggest a potential role of old and new proteins, such as antigenic variation proteins, iRBC remodelling, and membrane proteins, with no assigned functions related to the immune response against P. falciparum, providing insights into the pathogenesis, erythrocyte remodelling, and secretion machinery important for alternative diagnosis and/or malaria therapy.

New strategy to improve quality control of Montenegro skin test at the production level

Abstract INTRODUCTION: The production of the Montenegro antigen for skin test poses difficulties regarding quality control. Here, we propose that certain animal models reproducing a similar immune response to humans may be used in the quality control of Montenegro antigen production. METHODS: Fifteen Cavia porcellus (guinea pigs) were immunized with Leishmania amazonensis or Leishmania braziliensis , and, after 30 days, they were skin tested with standard Montenegro antigen. To validate C. porcellus as an animal model for skin tests, eighteen Mesocricetus auratus (hamsters) were infected with L. amazonensis or L. braziliensis , and, after 45 days, they were skin tested with standard Montenegro antigen. RESULTS: Cavia porcellus immunized with L. amazonensis or L. braziliensis , and hamsters infected with the same species presented induration reactions when skin tested with standard Montenegro antigen 48-72h after the test. CONCLUSIONS: The comparison between immunization methods and immune response from the two animal species validated C. porcellus as a good model for Montenegro skin test, and the model showed strong potential as an in vivo model in the quality control of the production of Montenegro antigen.

Scoring clinical signs can help diagnose canine visceral leishmaniasis in a highly endemic area in Brazil

Canine visceral leishmaniasis (CVL) diagnosis is still a challenge in endemic areas with limited diagnostic resources. This study proposes a score with the potential to distinguish positive CVL cases from negative ones. We studied 265 dogs that tested positive for CVL on ELISA and parasitological tests. A score ranging between 0 and 19 was recorded on the basis of clinical signs. Dogs with CVL had an overall higher positivity of the majority of clinical signs than did dogs without CVL or with ehrlichiosis. Clinical signs such as enlarged lymph nodes (83.93%), muzzle/ear lesions (55.36%), nutritional status (51.79%), bristle condition (57.14%), pale mucosal colour (48.21%), onychogryphosis (58.93%), skin lesion (39.28%), bleeding (12.50%), muzzle depigmentation (41.07%), alopecia (39.29%), blepharitis (21.43%), and keratoconjunctivitis (42.86%) were more frequent in dogs with CVL than in dogs with ehrlichiosis or without CVL. Moreover, the clinical score increased according to the positivity of all diagnostic tests (ELISA, p < 0.001; parasite culture, p = 0.0021; and smear, p = 0.0003). Onychogryphosis (long nails) [odds ratio (OR): 3.529; 95% confidence interval (CI): 1.832-6.796; p < 0.001], muzzle depigmentation (OR: 4.651; 95% CI: 2.218-9.750; p < 0.001), and keratoconjunctivitis (OR: 5.400; 95% CI: 2.549-11.441; p < 0.001) were highly associated with CVL. Interestingly, a score cut-off value ≥ 6 had an area under the curve of 0.717 (p < 0.0001), sensitivity of 60.71%, and specificity of 73.64% for CVL diagnosis. The clinical sign-based score for CVL diagnosis suggested herein can help veterinarians reliably identify dogs with CVL in endemic areas with limited diagnostic resources.

Occurrences of antibodies against Toxoplasma gondii, Neospora spp. and Sarcocystis neurona in horses and dogs in the municipality of Pauliceia, São Paulo, Brazil / Ocorrências de anticorpos anti-Toxoplasma gondii, Neospora spp. e Sarcocystis neurona em equinos e cães do município de Pauliceia, São Paulo, Brasil

Serum samples from 116 horses and 47 dogs from the municipality of Paulicéia, in the state of São Paulo, Brazil, were examined for anti-Toxoplasma gondii, -Neospora spp. and -Sarcocystis neurona antibodies by means of the indirect fluorescent antibody test (IFAT). The results showed that only one horse was seropositive for T. gondii (0.9%) and anti-Neospora spp. antibodies were detected in three out of the 116 horses tested (2.6%). However, 27 horses showed antibodies against S. neurona (23.8%). Amongst the serum samples from the dogs, 10 out of the 47 dogs showed antibodies against T. gondii (21.3%) and three dogs showed antibodies against Neospora caninum (6.4%). This study reports that in the municipality of Paulicéia dogs in both the rural and the urban area were exposed to T. gondii and N. caninum, while horses in the rural area were exposed to all three protozoa studied, with high occurrence of anti-S. neurona antibodies.(AU)

Amostras de soro de 116 equinos e 47 cães provenientes do município de Paulicéia, São Paulo, foram testadas para detecção de anticorpos anti-Toxoplasma gondii, -Neospora spp. e -Sarcocystis neurona por meio da reação de imunofluorescência indireta (RIFI). Apenas um equino, entre 116 equinos testados, teve diagnóstico soropositivo para T. gondii (0,9%), e três deles (2,6%) apresentaram anticorpos anti-Neospora spp. Entretanto, 27 equinos apresentaram anticorpos anti-S. neurona (23,8%). Nas amostras de cães, dez dos 47 animais apresentaram anticorpos anti-T. gondii (21,3%) e três tiveram diagnóstico soropositivo para Neospora caninum (6,4%). Este estudo relata que no município de Paulicéia os cães das áreas urbana e rural foram expostos a T. gondii e N. caninum, enquanto os equinos da área rural foram expostos aos três protozoários estudados, com alta ocorrência de anticorpos anti- S. neurona.(AU)

Recent updates and perspectives on approaches for the development of vaccines against visceral leishmaniasis

Abstract: Visceral leishmaniasis (VL) is one of the most important tropical diseases worldwide. Although chemotherapy has been widely used to treat this disease, problems related to the development of parasite resistance and side effects associated with the compounds used have been noted. Hence, alternative approaches for VL control are desirable. Some methods, such as vector control and culling of infected dogs, are insufficiently effective, with the latter not ethically recommended. The development of vaccines to prevent VL is a feasible and desirable measure for disease control; for example, some vaccines designed to protect dogs against VL have recently been brought to market. These vaccines are based on the combination of parasite fractions or recombinant proteins with adjuvants that are able to induce cellular immune responses; however, their partial efficacy and the absence of a vaccine to protect against human leishmaniasis underline the need for characterization of new vaccine candidates. This review presents recent advances in control measures for VL based on vaccine development, describing extensively studied antigens, as well as new antigenic proteins recently identified using immuno-proteomic techniques.