A proposed pathway from D-glucose to D-arabinose in eukaryotes.

In eukaryotes, the D-enantiomer of arabinose (D-Ara) is an intermediate in the biosynthesis of D-erythroascorbate in yeast and fungi and in the biosynthesis of the nucleotide sugar GDP-α-D-arabinopyranose (GDP-D-Arap) and complex α-D-Arap-containing surface glycoconjugates in certain trypanosomatid parasites. Whereas the biosynthesis of D-Ara in prokaryotes is well understood, the route from D-glucose (D-Glc) to D-Ara in eukaryotes is unknown. In this paper, we study the conversion of D-Glc to D-Ara in the trypanosomatid Crithidia fasciculata using positionally labeled [13C]-D-Glc and [13C]-D-ribose ([13C]-D-Rib) precursors and a novel derivatization and gas chromatography-mass spectrometry procedure applied to a terminal metabolite, lipoarabinogalactan. These data implicate the both arms of pentose phosphate pathway and a likely role for D-ribulose-5-phosphate (D-Ru-5P) isomerization to D-Ara-5P. We tested all C. fasciculata putative sugar and polyol phosphate isomerase genes for their ability to complement a D-Ara-5P isomerase-deficient mutant of Escherichia coli and found that one, the glutamine fructose-6-phosphate aminotransferase (GFAT) of glucosamine biosynthesis, was able to rescue the E. coli mutant. We also found that GFAT genes of other trypanosomatid parasites, and those of yeast and human origin, could complement the E. coli mutant. Finally, we demonstrated biochemically that recombinant human GFAT can isomerize D-Ru-5P to D-Ara5P. From these data, we postulate a general eukaryotic pathway from D-Glc to D-Ara and discuss its possible significance. With respect to C. fasciculata, we propose that D-Ara is used not only for the synthesis of GDP-D-Arap and complex surface glycoconjugates but also in the synthesis of D-erythroascorbate.

Infection by Crithidia bombi increases relative abundance of Lactobacillus spp. in the gut of Bombus terrestris.

Gut microbial communities confer protection against natural pathogens in important pollinators from the genera Bombus and Apis. In commercial species B. terrestris and B. impatiens, the microbiota increases their resistance to the common and virulent trypanosomatid parasite Crithidia bombi. However, the mechanisms by which gut microorganisms protect the host are still unknown. Here, we test two hypotheses: microbiota protect the host (1) through stimulation of its immune response or protection of the gut epithelium and (2) by competing for resources with the parasite inside the gut. To test them, we reduced the microbiota of workers and then rescued the microbial community by feeding them with microbiota supplements. We then exposed them to an infectious dose of C. bombi and characterised gene expression and gut microbiota composition. We examined the expression of three antimicrobial peptide genes and Mucin-5AC, a gene with a putative role in gut epithelium protection, using qPCR. Although a protective effect against C. bombi was observed in bumblebees with supplemented microbiota, we did not observe an effect of the microbiota on gene expression that could explain alone the protective effect observed. On the other hand, we found an increased relative abundance of Lactobacillus bacteria within the gut of infected workers and a negative correlation of this genus with Gilliamella and Snodgrassella genera. Therefore, our results point to a displacement of bumblebee endosymbionts by C. bombi that might be caused by competition for space and nutrients between the parasite and the microbiota within the gut.

La microbiota intestinal confiere protección frente a los patógenos naturales en polinizadores importantes de los géneros Bombus y Apis. En concreto, la microbiota de las especies comerciales B. terrestris y B. impatients, incrementa su resistencia frente al parásito tripanosomátido común y virulento Crithidia bombi. Sin embargo, los mecanismos por los cuales los microorganismos protegen al hospedador todavía se desconocen. Aquí probamos dos hipótesis: la microbiota protege al hospedador (1) a través de la estimulación de la respuesta inmunitaria o la protección del epitelio y (2) por competición por los recursos con el parásito dentro del intestino. Para probar estas hipótesis, redujimos la microbiota de obreras y dimos suplementos de microbiota a una parte de ellas. Las expusimos a una dosis infecciosa de C. bombi y caracterizamos la expresión génica y la composición de la microbiota intestinal. Examinamos la expresión de los genes de tres péptidos antimicrobianos (AMPs) y de Mucin­5AC, un gen con un rol putativo en la protección del epitelio intestinal, usando la qPCR. Aunque observamos un efecto protector contra C. bombi en los abejorros suplementados con microbiota, no vimos un efecto en la expresión génica que pudiese explicar por sí solo la protección observada. Por otro lado, encontramos un incremento en la abundancia relativa de bacterias del género Lactobacillus en el intestino de obreras infectadas y una correlación negativa de este género con los géneros Gilliamella y Snodgrassella. Por tanto, nuestros resultados apuntan a un desplazamiento de los endosimbiontes por parte de C. bombi, que podría estar causado por la competición por espacio y nutrientes entre el parásito y la microbiota dentro del intestino.

Genetic modification of the bee parasite Crithidia bombi for improved visualization and protein localization.

Crithidia bombi is a trypanosomatid parasite that infects several species of bumble bees (Bombus spp.), by adhering to their intestinal tract. Crithidia bombi infection impairs learning and reduces survival of workers and the fitness of overwintering queens. Although there is extensive research on the ecology of this host-pathogen system, we understand far less about the mechanisms that mediate internal infection dynamics. Crithidia bombi infects hosts by attaching to the hindgut via the flagellum, and one previous study found that a nectar secondary compound removed the flagellum, preventing attachment. However, approaches that allow more detailed observation of parasite attachment and growth would allow us to better understand factors mediating this host-pathogen relationship. We established techniques for genetic manipulation and visualization of cultured C. bombi. Using constructs established for Crithidia fasciculata, we successfully generated C. bombi cells expressing ectopic fluorescent transgenes using two different selectable markers. To our knowledge, this is the first genetic modification of this species. We also introduced constructs that label the mitochondrion and nucleus of the parasite, showing that subcellular targeting signals can function across parasite species to highlight specific organelles. Finally, we visualized fluorescently tagged parasites in vitro in both their swimming and attached forms, and in vivo in bumble bee (Bombus impatiens) hosts. Expanding our cell and molecular toolkit for C. bombi will help us better understand how factors such as host diet, immune system, and physiology mediate outcomes of infection by these common parasites.

Comparison of quantitative and qualitative anti-dsDNA assays.

OBJECTIVE: In evaluation of systemic lupus erythematosus (SLE), anti-double-stranded DNA antibodies (anti-dsDNA) play a significant role in diagnosis, monitoring SLE activity, and assessing prognosis. However, evaluations of the performance and limitations for recently developed methods for anti-dsDNA assessment are sparse. METHODS: Specimens used for antinuclear antibody testing (n = 129) were evaluated for anti-dsDNA assay comparability across 4 medical centers in the United States. The methods compared were Werfen Quanta Lite dsDNA, Zeus Scientific dsDNA Enzyme Immunoassay, Bio-Rad multiplex immunoassay (MIA) dsDNA, ImmunoConcepts Crithidia, and Bio-Rad Laboratories Crithidia. RESULTS: For quantitative anti-dsDNA measurements, Spearman's correlation coefficient was highest between Zeus and Werfen (ρ = 0.86; CI, 0.81-0.90; P < .0001). Comparison of MIA to Werfen or Zeus yielded similar results to each other (ρ = 0.58; CI, 0.44-0.68; P < .0001; and ρ = 0.59; CI, 0.46-0.69; P < .0001, respectively), but lower than the correlation between Zeus and Werfen. Positive concordance between assays ranged from 31.4% to 97.1%, and negative concordance between assays ranged from 58.5% to 100%. The detection of anti-dsDNA in those with SLE diagnosis ranged from 50.9% to 77.4% for quantitative assays and 15.1% to 24.5% for Crithidia assays. CONCLUSION: Current quantitative anti-dsDNA assays are not interchangeable for patient follow-up. Crithidia-based assays demonstrate high negative concordance and lack positive concordance among the methods.

Winter Hive Debris Analysis Is Significant for Assessing the Health Status of Honeybee Colonies (Apis mellifera).

Honeybee diseases are one of the most significant and most common causes of honeybee colonies' weakness and death. An early diagnosis of subclinical infections is necessary to implement precautionary and control measures. Sampling debris from hive bottom boards is simple, non-invasive, and cheap. In this study, we collected winter debris samples in apiaries located in the continental part of Croatia. We used molecular methods, PCR and qPCR, for the first time to analyze those samples. Laboratory results were compared with the health condition and strength of honeybee colonies at an apiary in spring. Our study successfully identified the presence and quantity of various pathogens, including the presence of Vairimorpha spp. (Nosema spp.), quintefied Paenibacillus larvae, Acute Bee Paralysis Virus (ABPV), Black Queen Cell Virus (BQCV), Deformed Wing Virus (DWV), and Sacbrood Virus (SBV). However, our analysis did not detect Melissococcus plutonius, Crithidia mellificae, Lotmaria passim, and Aethina tumida. Samples of winter debris were also examined for the presence and quantification of the V. destructor mites, and their natural mite fall was observed in spring. Honeybee colonies were simultaneously infected by an average of four to six pathogens. Some observed honeybee colonies developed characteristic symptoms, while others did not survive the winter.

Determinación de anticuerpos anti-dsDNA: evaluación del desempeño de un inmunoensayo quimioluminiscente y correlación con el método de inmunofluorescencia indirecta / Detection of anti-dsDNA antibodies: evaluation of performance of a chemiluminescent immunoassay and correlation to the indirect immunofluorescence assay / Determinação de anticorpos anti-dsDNA: avaliação do desempenho de um imunoensaio quimioluminiscente e correlação com o método de imunoflourescência indireta

Resumen La determinación de anticuerpos anti-dsDNA es de utilidad para el diagnóstico y seguimiento clínico de pacientes con lupus eritematoso sistémico (LES) y es uno de los criterios de clasificación del SLICC-2012. El objetivo del estudio fue verificar el desempeño del inmunoensayo quimioluminiscente (CLIA) QUANTA Flash dsDNA y compararlo con el método en uso de inmunofluorescencia indirecta en Crithidia luciliae (CLIFT). Se analizaron con ambos métodos 195 pacientes con diagnóstico de enfermedades del tejido conectivo y solicitud de anticuerpos anti-dsDNA. Se obtuvieron 38 sueros positivos, 133 negativos y 24 (12,3%) discordantes. Entre estos resultados discordantes, hubo 17 que correspondieron a pacientes con LES y se agruparon en 16 CLIA+/CLIFT- y 1 CLIA-/CLIFT+. Se verificó el desempeño para precisión siguiendo el protocolo EP15-A2 y la linealidad. Se estudió la concordancia mediante el coeficiente Kappa y la correlación con el coeficiente Rho de Spearman. Se observó mayor sensibilidad diagnóstica para CLIA. El grado de acuerdo fue moderado y se obtuvo buena correlación entre los valores cuantitativos de CLIA y los títulos de CLIFT. De acuerdo al buen desempeño encontrado y a los resultados discordantes analizados, la mejor estrategia para la implementación de CLIA sería utilizarla en combinación con CLIFT, lo que aumentaría la sensibilidad diagnóstica sin perder especificidad.

Abstract The detection of anti-dsDNA antibodies is useful for diagnosis and clinical monitoring of patients with systemic lupus erythematosus (SLE) and it is part of the classification criteria according to SLICC 2012. The purpose of this study was to verify the performance of the chemiluminescent immunoassay (CLIA) QUANTA Flash dsDNA and to compare it with the method currently in use, i.e the indirect immunofluorescence in Crithidia luciliae (CLIFT). One hundred and ninety five patients, who presented connective tissue diseases and required the study of anti-dsDNA antibodies, were analyzed. Thirty eight positive serum samples were obtained, 133 were negative and 24 (12.3%) in disagreement. Within the discordant results, there were 17 that corresponded to patients with SLE and they were grouped in 16 CLIA+/CLIFT- and 1 CLIA-/CLIFT+. The accuracy performance was assessed according to the EP15-A2 protocol and linearity. Concordance and correlation were calculated with the Kappa and Spearman's Rho coefficient, respectively. Based on the good performance observed and the discordant results analyzed, the best strategy for CLIA implementation would be to combine it with CLIFT, which would increase the diagnostic sensitivity without losing specificity.

Resumo A determinação dos anticorpos anti-dsDNA é de utilidade para o diagnóstico e seguimento clinico de pacientes com lúpus eritematoso sistêmico (LES) e é um dos critérios de classificação do SLICC 2012. O objetivo do estudo foi verificar o desempenho do imunoensaio quimioluminescente (CLIA) QUANTA Flash dsDNA e compará-lo com o método em uso imunofluorescência indireta em Crithidia luciliae (CLIFT). Foram analisados com os dois métodos, 195 pacientes com diagnóstico de doenças do tecido conjuntivo e solicitude de anticorpos anti-dsDNA. Os resultados foram agrupados em 38 soros positivos, 133 negativos e 24 (12,3%) discordantes. Entre esses resultados discordantes, 17 corresponderam a pacientes com LES e se agruparam em 16 CLIA+/CLIFT- e 1 CLIA-/CLIFT+. Foi verificado o desempenho para precisão seguindo o protocolo EP15-A2 e a linearidade. Foi estudada a concordância mediante o coeficiente Kappa e correlação com o coeficiente Rho de Spearman. Observou-se maior sensibilidade diagnóstica para CLIA. O grau de acordo foi moderado e boa correlação foi observada entre os valores quantitativos de CLIA e os títulos de CLIFT. Com base no bom desempenho encontrado e nos resultados discordantes analisados, a melhor estratégia para implementar o CLIA seria utilizá-lo em combinação com o CLIFT, o que aumentaria a sensibilidade do diagnóstico sem perder a especificidade.

Behavior of alfa-tomatine and tomatidine against several genera of trypanosomatids from insects and plants and Trypanosoma cruzi / Comportamento de alfa-tomatina e tomatidina contra vários gêneros de tripanossomatídeos de insetos e plantas e Trypanosoma cruzi

Glycoalkaloids are important secondary metabolites accumulated by plants as protection against pathogens. One of them, α-tomatine, is found in high concentrations in green tomato fruits, while in the ripe fruits, its aglycone form, tomatidine, does not present a protective effect, and it is usual to find parasites of tomatoes like Phytomonas serpens in these ripe fruits. To investigate the sensitivity of trypanosomatids to the action of α-tomatine, we used logarithmic growth phase culture of 20 trypanosomatids from insects and plants and Trypanosoma cruzi. The lethal dose 50% (LD50) was determined by mixing 107 cells of the different isolates with α-tomatine at concentrations ranging from 10-3 to 10-8 M for 30 min at room temperature. The same tests performed with the tomatidine as a control showed no detectable toxicity against the same trypanosomatid cultures. The tests involved determination of the percentage (%) survival of the protozoan cultures in a Neubauer chamber using optical microscopy. The LD50 values varied from 10-4 to 10-6 M α-tomatine. Slight differences were detected among the LD50 values of the analyzed samples, and none of them showed evidence of resistance to the action of tomatinase, as shown by some pathogenic fungi.

Os glicoalcaloides são metabólitos secundários importantes produzidos pelas plantas e estão envolvidos em sua proteção contra agentes patogênicos. Um deles, α-tomatina, é encontrado em altas concentrações em frutos de tomate verde, enquanto que, nos frutos maduros, sua forma aglicona, tomatidina, não apresenta um efeito protetor, sendo comum encontrar parasitas de tomates como Phytomonas serpens nesses frutos maduros. Para investigar a sensibilidade dos tripanossomatídeos à ação da α-tomatina, utilizamos formas de cultura em fase logarítmica de 20 tripanossomatídeos de plantas e insetos e Trypanosoma cruzi. A dose letal 50% (DL50) foi determinada, misturando 107 células das formas de cultura com concentrações de 10-3 a 10-8 M de α-tomatina durante trinta minutos a temperatura ambiente. Testes realizados com a tomatidina como controle não mostraram toxicidade detectável contra os mesmos tripanossomatídeos. Os testes foram avaliados pela porcentagem (%) de sobrevivência das formas de cultura dos protozoários observados por microscopia óptica em câmara de Neubauer. Os resultados da determinação de DL50 mostraram que esta variou entre 10-4 a 10-6 M de α-tomatina. Pequenas diferenças foram observadas entre os valores de DL50 das amostras analisadas, e nenhuma delas mostrou evidência de resistência pela ação da tomatinidase, como demonstrado em alguns fungos patogênicos.

The role of gallery forests in maintaining Phlebotominae populations: potential Leishmania spp. vectors in the Brazilian savanna

BACKGROUND Knowledge on synanthropic phlebotomines and their natural infection by Leishmania is necessary for the identification of potential areas for leishmaniasis occurrence. OBJECTIVE To analyse the occurrence of Phlebotominae in gallery forests and household units (HUs) in the city of Palmas and to determine the rate of natural infection by trypanosomatids. METHODS Gallery forests and adjacent household areas were sampled on July (dry season) and November (rainy season) in 2014. The total sampling effort was 960 HP light traps and eight Shannon traps. Trypanosomatids were detected in Phlebotominae females through the amplification of the SSU rDNA region, and the positive samples were used in ITS1-PCR. Trypanosomatid species were identified using sequencing. FINDINGS A total of 1,527 sand flies representing 30 species were captured in which 949 (28 spp.) and 578 (22 spp.) were registered in July and November, respectively. In July, more specimens were captured in the gallery forests than in the HUs, and Nyssomyia whitmani was particularly frequent. In November, most of the specimens were found in the HUs, and again, Ny. whitmani was the predominant species. Lutzomyia longipalpis was commonly found in domestic areas, while Bichromomyia flaviscutellata was most frequent in gallery forests. Molecular analysis of 154 pools of females (752 specimens) identified Leishmania amazonensis, L. infantum, and Crithidia fasciculata in Ny. whitmani, as well as L. amazonensis in Lu. longipalpis, Trypanosoma sp. and L. amazonensis in Pintomyia christenseni, and L. amazonensis in both Psathyromyia hermanlenti and Evandromyia walkeri. MAIN CONCLUSIONS These results show the importance of gallery forests in maintaining Phlebotominae populations in the dry month, as well as their frequent occurrence in household units in the rainy month. This is the first study to identify Leishmania, Trypanosoma, and Crithidia species in Phlebotominae collected in Palmas, Tocantins, Brazil.

Combination of the essential oil constituents citral, eugenol and thymol enhance their inhibitory effect on Crithidia fasciculata and Trypanosoma cruzi growth

We analyzed the effect of the combination of citral, eugenol and thymol, respectively the main constituents of essential oils of Cympobogon citratus (DC) Stapf, Poaceae (lemon grass), Syzygium aromaticum (L.) Merr. & L.M. Perry, Myrtaceae (clove) and Thymus vulgaris L., Lamiaceae (thyme), on the proliferation of the trypanosomatids Crithidia fasciculata and Trypanosoma cruzi. The constituents were initially added individually at different concentrations to C. fasciculata cultures to estimate the IC50/24h. Concentrations in a triple combination were about 2 times and 16.5 times lower against C. fasciculata and T. cruzi, respectively, as compared to isolated compounds. Incubation of C. fasciculata with the trypanocydal agent benznidazole did not affect parasite growth at concentrations up to 500 µg/ml, but the IC50 of this drug against T. cruzi was 15.8 µg/ml, a value about 2-5 times higher than that of constituents in the triple combination. Analysis of treated C. fasciculata by scanning electron microscopy showed rounding of the cell body. Our data show that combination of essential oil constituents resulted in increased inhibitory activity on growth of both non-pathogenic and pathogenic trypanosomatid species and indicate that the non-patogenic C. fasciculata may represent a resistant model for drug screening in trypanosomatids.

Anticorpo anti-Trypanosoma cruzi como fator de reatividade cruzada na pesquisa de anticorpos anti-DNA por imunofluorescência indireta / Anti-Trypanosoma cruzi antibodies as a factor of cross-reactivity in the research of anti-DNA antibodies by indirect immunofluorescence

Na pesquisa de anticorpos anti-DNA podem ser utilizadas várias metodologias como a imunofluorescência indireta (IFI), enzimaimunoensaio (ELISA) ou radioimunoensaio (RIE) com DNA marcado com 14C, sendo que a IFI empregando Crithçidia luciliae como substrato é a mais utilizada. Sendo este um parasita flagelado da família dos tripanosomatídeos, apresenta estruturas antigênicas comuns ao Trypanosoma cruzi. Portanto, soros de pacientes com sorologia positiva para Doença de Chagas (DC) podem apresentar uma reatividade cruzada entre estes parasitas, constituindo um fator interferente na reação de IFI para pesquisa de anticorpos anti-DNA. Com o objetivo de verficar a freqüência com que esta inferência ocorre na rotina laboratorial, analisou-se os resultados obtidos na pesquisa de anti-DNA por IFI realizadas no período de junho de 1994 a julho de 1995 no Setor de Imunologia Clínica do Hospital Universitário Regional do Norte do Paraná, Londrina-Paraná. Das 927 reações realizadas, 60 (6,47%) foram reagentes, 832 (89,75%) não reagentes e 35 (3,77%) apresentaram um padrão inespecífico de fluorescência. Suspeitando-se de reatividade cruzada, foram realizadas reações sorológicas para DC (HAI e IFI) nestas amostras, sendo que 100% apresentaram resultados reagentes para ambas as reações. Estes dados confirmam a interferência dos anticorpos anti-Trypanosoma cruzi na pesquisa de anticorpos anti-DNA por IFI e alertam para a necessidade da confirmação de resultados falsos-positivos, principalmente em regiões onde a DC é endêmica.