Etude préliminaire de l’infestation des glossines par les trypanosomes dans le baï de Momba (Nord-Est Gabon)

Une étude préliminaire entomo-parasitologique a été effectuée pendant la grande saison sèche à l’interieur et autour du baï de Momba (nord-est Gabon) pour examiner les espèces de Trypanosomes transmises par les glossines. Ces dernières ont été capturées à l’aide des pièges vavoua et nzi. Les infections par les trypanosomes chez ces glossines ont été recherchées à l’aide d’un microscope au niveau des glandes salivaires, proboscis et intestins moyens des glossines. Ainsi, une infection du proboscis seul correspond à T. vivax, celles des glandes salivaires à T. brucei et celle du proboscis et de l’intestin moyen à T. congolense. Au total six espèces de glossines ont été identifiées : Glossina palpalis palpalis, G. nashi, G. fusca congolensis, G. tachinoides, G. frezili et G. fuscipes fuscipes. Le taux global d’infestation des glossines disséquées et observées au microscope a été estimé à 30 %. L’infestation des glossines par les trypanosomes témoigne de l’existence d’un risque trypanosomien dans le baï de Momba et suggère ainsi l’établissement d’un cycle de transmission Animal-Glossine-Homme dans ce milieu.Mots clés: Glossina, T. vivax, T. congolense, baï de Momba, trypanosomes. Preliminary study of infection of tsetse by trypanosomes in the baï of Momba North East GabonA preliminary study are insect parasitology was carried out during the long dry season in and around the baï of Momba (north-east Gabon) to examine the species of trypanosomes transmitted by tsetse flies. The flies were captured using traps and Vavoua nzi. Infections by trypanosomes were investigated using a microscope in the salivary glands and the proboscis intestines means tsetse. In total six tsetse species were identified : Glossina palpalis palpalis, G. nashi, G. fusca congolensis, G. tachinoides, G. frezili and G. fuscipes fuscipes. The overall rate of infestation of flies dissected and observed under the microscope is estimated at 30 %. The infestation of Bai Momba by flies carrying trypanosomes demonstrates the existence of a trypanosome risk and thus suggests the establishment of a transmission cycle Human-Animal-Glossina in this environment.Keywords: tsetse flies, T. vivax, T. congolense, baï of Momba, trypanosome

Identification et caractérisation de la dynamique de la grande faune dans le baï de Momba (nord-est Gabon)

Les baïs sont des clairières marécageuses localisées généralement au coeur des forêts du Bassin du Congo. Ce sont des écosystèmes particulièrement riches en espèces animales et végétales. Si les connaissances portant sur l’origine de ces milieux sont bien documentées, les espèces de la faune sauvage (éléphants, buffles, sitatungas, etc.) colonisant ces écosystèmes demeurent encore mal connues. Par ailleurs, les informations qui existent sur ces espèces fauniques restent fragmentaires. C’est pour ces raisons qu’une étude basée sur les méthodes d’observation de la faune (scan sampling et animal focal) a été conduite dans le baï de Momba durant 33 jours. Ce travail visait l’identification de la macrofaune présente dans ce type de milieux et l’analyse de la dynamique de cette faune. Au total, 969 animaux ont été observés. Ces animaux ont été représentés majoritairement par les sitatungas (Tragelaphus spekei), les éléphants (Loxodonta africana cyclotis), les buffles (Syncerus caffer nanus) et les colobes (Colobus guereza). En termes de fréquence d’observation, les sitatungas (27%) ont été le groupe le plus abondant, suivis par les éléphants (8%) et les buffles (7%). Les autres animaux ont été faiblement observés avec une fréquence de moins de 2%. La fréquentation du baï de Momba par ces espèces témoigne du rôle crucial que pourrait jouer les zones humides dans la gestion durable de la biodiversité dans le Bassin du Congo. Aussi, il apparaît nécessaire que des mesures de protection et de suivi de la dynamique de ces peuplements soient rapidement entreprises afin de protéger la biodiversité faunique de cemilieu.Mots clés : Loxodonta africana cyclotis, Syncerus caffer nanus, Tragelaphus spekei,Colobus guereza, baï de Momba, Gabon

Expression Analysis of the Ligands for the Natural Killer Cell Receptors NKp30 and NKp44

BACKGROUND: The natural cytotoxicity receptors (NCR) are important to stimulate the activity of Natural Killer (NK) cells against transformed cells. Identification of NCR ligands and their level of expression on normal and neoplastic cells has important implications for the rational design of immunotherapy strategies for cancer. METHODOLOGY/PRINCIPAL FINDINGS: Here we analyze the expression of NKp30 ligand and NKp44 ligand on 30 transformed or non-transformed cell lines of different origin. We find intracellular and surface expression of these two ligands on almost all cell lines tested. Expression of NKp30 and NKp44 ligands was variable and did not correlate with the origin of the cell line. Expression of NKp30 and NKp44 ligand correlated with NKp30 and NKp44-mediated NK cell lysis of tumor cells, respectively. The surface expression of NKp30 ligand and NKp44 ligand was sensitive to trypsin treatment and was reduced in cells arrested in G(2)/M phase. CONCLUSION/SIGNIFICANCE: These data demonstrate the ubiquitous expression of the ligands for NKp30 and NKp44 and give an important insight into the regulation of these ligands

Limited response of NK92 cells to Plasmodium falciparum-infected erythrocytes

<p>Abstract</p> <p>Background</p> <p>Mechanisms by which anti-malarial immune responses occur are still not fully clear. Natural killer (NK) cells are thought to play a pivotal role in innate responses against <it>Plasmodium falciparum</it>. In this study, the suitability of NK92 cells as models for the NK mechanisms involved in the immune response against malaria was investigated.</p> <p>Methods</p> <p>NK92 cells were assessed for several signs of activation and cytotoxicity due to contact to parasites and were as well examined by oligonucleotide microarrays for an insight on the impact <it>P. falciparum</it>-infected erythrocytes have on their transcriptome. To address the parasite side of such interaction, growth inhibition assays were performed including non-NK cells as controls.</p> <p>Results</p> <p>By performing microarrays with NK92 cells, the impact of parasites on a transcriptional level was observed. The findings show that, although not evidently activated by iRBCs, NK92 cells show transcriptional signs of priming and proliferation. In addition, decreased parasitaemia was observed due to co-incubation with NK92 cells. However, such effect might not be NK-specific since irrelevant cells also affected parasite growth <it>in vitro</it>.</p> <p>Conclusions</p> <p>Although NK92 cells are here shown to behave as poor models for the NK immune response against parasites, the results obtained in this study may be of use for future investigations regarding host-parasites interactions in malaria.</p

CD56 is a pathogen recognition receptor on human natural killer cells

Aspergillus (A.) fumigatus is an opportunistic fungal mold inducing invasive aspergillosis (IA) in immunocompromised patients. Although antifungal activity of human natural killer (NK) cells was shown in previous studies, the underlying cellular mechanisms and pathogen recognition receptors (PRRs) are still unknown. Using flow cytometry we were able to show that the fluorescence positivity of the surface receptor CD56 significantly decreased upon fungal contact. To visualize the interaction site of NK cells and A. fumigatus we used SEM, CLSM and dSTORM techniques, which clearly demonstrated that NK cells directly interact with A. fumigatus via CD56 and that CD56 is re-organized and accumulated at this interaction site time-dependently. The inhibition of the cytoskeleton showed that the receptor re-organization was an active process dependent on actin re-arrangements. Furthermore, we could show that CD56 plays a role in the fungus mediated NK cell activation, since blocking of CD56 surface receptor reduced fungal mediated NK cell activation and reduced cytokine secretion. These results confirmed the direct interaction of NK cells and A. fumigatus, leading to the conclusion that CD56 is a pathogen recognition receptor. These findings give new insights into the functional role of CD56 in the pathogen recognition during the innate immune response

Caractéristiques socio-démographiques dans la filière pâte rouie de manioc au Congo-Brazzaville

Socio-Demographic Characteristics in Die Cassava Paste steeped in Congo-Brazzaville. Cassava roots constitute a basic food in Congo. Its consumption in the form of foufou or chikwangue requires the transformation of the roots to steeped paste. Social dynamics related to the activity of production and marketing of the steeped paste, after investigation into 119 producers showed two markets in Brazzaville draining more than 40 % of the producers and retailers, one market in Pointe - Noire with 60 % of the producers and retailers, and the railroad importance for supplying these markets. Important activities are localised in rural zone more particularly in Mindouli and in Bouenza localities. Formerly forsaken with the women, the die of the steeped paste is more and more occupied by the men especially in Pointe - Noire, particularly in the marketing part considered to be less painful and more profitable. Production and marketing activities are carried out by the young people. Illiterates producers proportion is weak in Brazzaville, but stronger in Pointe - Noire. This study does not establish any bond associating the sex, the age, the instruction and the matrimonial statute in this activity

A comprehensive screening platform for aerosolizable protein formulations for intranasal and pulmonary drug delivery.

Aerosolized administration of biopharmaceuticals to the airways is a promising route for nasal and pulmonary drug delivery, but - in contrast to small molecules - little is known about the effects of aerosolization on safety and efficacy of biopharmaceuticals. Proteins are sensitive against aerosolization-associated shear stress. Tailored formulations can shield proteins and enhance permeation, but formulation development requires extensive screening approaches. Thus, the aim of this study was to develop a cell-based in vitro technology platform that includes screening of protein quality after aerosolization and transepithelial permeation. For efficient screening, a previously published aerosolization-surrogate assay was used in a design of experiments approach to screen suitable formulations for an IgG and an antigen-binding fragment (Fab) as exemplary biopharmaceuticals. Efficient, dose-controlled aerosol-cell delivery was performed with the ALICE-CLOUD system containing RPMI 2650 epithelial cells at the air-liquid interface. We could demonstrate that our technology platform allows for rapid and efficient screening of formulations consisting of different excipients (here: arginine, cyclodextrin, polysorbate, sorbitol, and trehalose) to minimize aerosolization-induced protein aggregation and maximize permeation through an in vitro epithelial cell barrier. Formulations reduced aggregation of native Fab and IgG relative to vehicle up to 50% and enhanced transepithelial permeation rate up to 2.8-fold