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SummaryEquine trypanosomosis comprises different parasitic diseases caused by protozoa of the subgenus Trypanozoon: Trypanosoma equiperdum (causative agent of dourine), Trypanosoma brucei (nagana) and Trypanosoma evansi (surra). Due to the absence of a vaccine and the lack of efficacy of the few available drugs, these diseases represent a major health and economic problem for international equine trade. Development of affordable, sensitive and specific diagnostic tests is therefore crucial to ensure the control of these diseases. Recently, it has been shown that a small RNA derived from the 7SL gene (7SL-sRNA) is produced in high concentrations in sera of cattle infected with Trypanosoma congolense, Trypanosoma vivax and Trypanosoma brucei. Our objective was to determine whether 7SL-sRNA could serve as a marker of active infection in equids experimentally infected with Trypanosoma equiperdum by analyzing the sensitivity, specificity and stability of the 7SL-sRNA. Using a two-step RT-qPCR, we were able to detect the presence of 7SL-sRNA between 2 and 7 days post-infection, whereas seroconversion was detected by complement fixation test between 5 and 14 days post-infection. There was a rapid loss of 7SL-sRNA signal from the blood of infected animals one day post-trypanocide treatment. The 7SL-sRNA RT-qPCR allowed an early detection of a treatment failure revealed by glucocorticoid-induced immunosuppression. In addition, the 7SL-sRNA remains detectable in positive sera after 7 days of storage at either 4 °C, room temperature or 30 °C, suggesting that there is no need to refrigerate serum samples before analysis. Our findings demonstrate continual detection of 7SL-sRNA over an extended period of experimental infection, with signals detected more than six weeks after inoculation. The detection of a strong and consistent 7SL-sRNA signal even during sub-patent parasitemia and the early detection of treatment failure highlight the very promising nature of this new diagnostic method.

14 Pág. (This article belongs to the Special Issue Integrating Science on Xanthomonas and Xylella for Integrated Plant Disease Management), Xanthomonas citri pv. citri (Xcc) and X. citri pv. aurantifolii (Xca) are causal agents of Citrus Bacterial Canker (CBC), a devastating disease that severely affects citrus plants. They are harmful organisms not reported in Europe or the Mediterranean Basin. Host plants are in the Rutaceae family, including the genera Citrus, Poncirus, and Fortunella, and their hybrids. In addition, other genera of ornamental interest are reported as susceptible, but results are not uniform and sometimes incongruent. We evaluated the susceptibility of 32 ornamental accessions of the Rutaceae family belonging to the genera Citrus, Fortunella, Atalantia, Clausena, Eremocitrus, Glycosmis, Microcitrus, Murraya, Casimiroa, Calodendrum, and Aegle, and three hybrids to seven strains of Xcc and Xca. Pathotyping evaluation was assessed by scoring the symptomatic reactions on detached leaves. High variability in symptoms and bacterial population was shown among the different strains in the different hosts, indicative of complex host–pathogen interactions. The results are mostly consistent with past findings, with the few discrepancies probably due to our more complete experimental approach using multiple strains of the pathogen and multiple hosts. Our work supports the need to regulate non-citrus Rutaceae plant introductions into areas, like the EU and Mediterranean, that are currently free of this economically important pathogen., This research was funded ORPRAMed Project on “Risk assessment of introduction of Xanthomonas citri subsp. citri through commercial trade of ornamental rutaceous plants in the Mediterranean basin”, ERA-NET ARIMNET 2-Call 2015.C.B., V.C. acknowledge the University of Catania for support under the projects “Investigation of phytopathological problems of the main Sicilian productive contexts and eco-sustainable defense strategies” (PIA.CE.RI. 2020–2022 Linea 2-Research Project MEDIT-ECO.); “Emergent Pests and Pathogens and Relative Sustainable Strategies” (Progetto di ricerca di Ateneo 2018-2020). O.P. and I.R. acknowledge the European Union (ERDF, EAFRD) and Réunion regional council for support

The Supplementary Material for this article can be found online at https://www.frontiersin.org/articles/10.3389/fimmu.2018.01143/full#supplementary-material; International audience; Chitin is a N-acetyl-d-glucosamine biopolymer that can be recognized by chitin-binding proteins. Although mammals lack chitin synthase, they induce proteins responsible for detecting chitin in response to bacterial infections. Our aim was to investigate whether chitinase 3-like 1 (CHI3L1) has a potential role in the innate immunity of the Escherichia coli (E. coli) infected mammary gland. CHI3L1 protein was found to be secreted in whey of naturally coliform-affected quarters compared to whey samples isolated from healthy udders. In addition, gene expression of CHI3L1 was confirmed in udder tissue of cows experimentally infected with a mammary pathogenic E. coli (MPEC) strain. Despite the known anatomical differences, the bovine udders' innate immune response was mimicked by applying an experimental mouse model using MPEC or non-MPEC isolates. The effect of CHI3L1 expression in the murine mammary gland in response to coliform bacteria was investigated through the use of CHI3L1-/- mice as well as through treatment with either a pan-caspase inhibitor or chitin particles in wild-type mice. The local induction of CHI3L1 postinfection with different E. coli strains was demonstrated to be independent of both bacterial growth and mammary interleukin (IL)-8 levels. Indeed, CHI3L1 emerged as a regulator impacting on the transcytosis of Ly6G-positive cells from the interstitial space into the alveolar lumen of the mammary tissue. Furthermore, CHI3L1 was found to be upstream regulated by caspase activity and had a major downstream effect on the local pro-inflammatory cytokine profile, including IL-1beta, IL-6, and RANTES/CCL5. In conclusion, CHI3L1 was demonstrated to play a key role in the cytokine and caspase signaling during E. coli triggered inflammation of the mammary gland.

The Mycobacterium tuberculosis complex (MTBC) is the collective term given to the group of bacteria that cause tuberculosis (TB) in mammals. It has been reported that M. tuberculosis H37Rv, a standard reference MTBC strain, is attenuated in cattle compared to Mycobacterium bovis. However, as M. tuberculosis H37Rv was isolated in the early 1930s, and genetic variants are known to exist, we sought to revisit this question of attenuation of M. tuberculosis for cattle by performing a bovine experimental infection with a recent M. tuberculosis isolate. Here we report infection of cattle using M. bovis AF2122/97, M. tuberculosis H37Rv, and M. tuberculosis BTB1558, the latter isolated in 2008 during a TB surveillance project in Ethiopian cattle. We show that both M. tuberculosis strains caused reduced gross pathology and histopathology in cattle compared to M. bovis. Using M. tuberculosis H37Rv and M. bovis AF2122/97 as the extremes in terms of infection outcome, we used RNA-Seq analysis to explore differences in the peripheral response to infection as a route to identify biomarkers of progressive disease in contrast to a more quiescent, latent infection. Our work shows the attenuation of M. tuberculosis strains for cattle, and emphasizes the potential of the bovine model as a ‘One Health’ approach to inform human TB biomarker development and post-exposure vaccine development.

Cocoa (Theobroma cacao) pod diseases cause tremendous losses, frequently eliminating over 80% of potential yield. Biological control has previously shown promise to supplement cultural control methods practiced by the majority of smallholders. Mixed Clonostachys inocula were most effective against multiple pathogens in Peru, but not in Costa Rica, where Clonostachys spp. seemed to antagonize Trichoderma spp. The objective of our study was to systematically investigate the mycoparasitic interactions between Clonostachys and Trichoderma species, in order to enable the design of mixed inocula in a rational manner. Specifically, we aimed to quantify dominance of one mycoparasite genus over the other using in vitro tests as well as field experiments. The compatibility of Peruvian and Costa Rican isolates of known efficacy was tested by pair-wise confrontations on water agar as well as two host-range assays, one of which mycoparasites were offered another mycoparasite as only host and one where conidia of a Clonostachys and a Trichoderma isolate were mixed at ratios ranging from 1:100 to 100:1 in order to determine dominance on the susceptible host, Phytophthora palmivora. A field study quantified survival and establishment of selected mixtures on surface-sterilized cocoa pods. Hyphal interactions and host-range studies coincided in identifying Clonostachys rosea as the most aggressive mycoparasite, closely followed by C. byssicola. Trichoderma spp. were least aggressive; instead, they were highly susceptible to Clonostachys spp. The outcome of interactions depended on the species used and occasionally even on the isolates confronting each other. The country of origin, however, was irrelevant. Parasitic growth of C. rosea was unaffected by Trichoderma harzianum, even at an inoculum ratio of 1:100. Parasitic growth of Trichoderma spp. progressively slowed as C. rosea concentrations rose, but the effect varied in strength with different isolates. When C. rosea and Trichoderma sp. were applied to cocoa pods in the field either separately or in combination at a ratio of 5:1, C. rosea dominated at the expense of Trichoderma sp., which was suppressed. At equal or ten times higher concentrations of T. harzianum, C. rosea was temporarily suppressed, but from two weeks after application, remained the dominant and persistent pod colonizer. Native Trichoderma spp. were poor pioneer colonizers of surface-sterilized pods and applied populations vanished within less than four weeks. Our results suggest that, although Clonostachys spp. antagonize Trichoderma spp., the incompatibility can be partly overcome by adjusting the inoculum ratio of mixed inocula in favor of Trichoderma spp. Therefore, mycoparasitism among several promising biocontrol candidates do not necessarily rule out their combination into a mixed inoculum, but can be addressed by formulating susceptible isolates at higher inoculum ratios. This, however, will not sustainably improve surface coverage by poorly colonizing Trichoderma spp. Therefore, optimal strains for the habitat and task are needed first.

In pigs, influenza A viruses and Mycoplasma hyopneumoniae (Mhp) are major contributors to the porcine respiratory disease complex. Pre-infection with Mhp was previously shown experimentally to exacerbate the clinical outcomes of H1N1 infection during the first week after virus inoculation. In order to better understand the interactions between these pathogens, this study aimed to assess very early responses (at 5, 24 and 48 hours) after H1N1 infection in pigs pre-infected or not with Mhp. Clinical signs and macroscopic lung lesions were similar in both infected groups at early times post H1N1-infection and Mhp pre-infection affected neither the influenza virus replication nor the IFN-induced antiviral responses in lungs. However, it predisposed the animals to a higher inflammatory response to H1N1 infection, as revealed by the massive infiltration of neutrophils and macrophages into the lungs and the increased production of pro-inflammatory cytokines (IL-6, IL-1 and TNF-). Thus, it seems it is this marked inflammatory state that would play a role in exacerbating the clinical signs subsequent to H1N1 infection.

To aid the development of compatible biocontrol inocula, a prescreening method for the prediction of compatibility of fungal antagonists was developed. Compatibility between 18 Clonostachys isolates with known antagonistic capabilities against Phytophthora palmivora was tested using intra- or interisolate pairings (dual cultures) on water agar plates, a hyphal interaction experiment and a modified double host-range experiment. Almost all inter- or intraisolate pairings of Clonostachys isolates showed growth inhibition zones and did not show free hyphal intermingling. A hyphal interaction experiment on water agar demonstrated that the aggressiveness of a Clonostachys isolate and its susceptibility to mycopar- asitism were unrelated phenomena. However the level of aggressiveness and/or susceptibility of an isolate were largely dependant on the isolate with which it was challenged. The degree of growth-inhibition caused by an isolate was unrelated to the hyphal damaged it caused or received. In the double host-range experi- ment all possible pairs from four Clonostachys isolates were inoculated in different ratios (10 000-fold range) on plates precolonized with one of two P. palmivora isolates. The results showed that antagonistic capabil- ities of certain combinations were affected by the Clonostachys isolates. The primary host, P. palmivora, did not affect antagonistic capabilities; whereas inocu- lum ratio did. Of note, it was not possible to predict the outcome of the double host range on the basis of the results of the hyphal interaction experiment. In conclusion the competitive abilities of Clonostachys isolates depend on the partner with which they are applied and less on resource availability. The double host-range test as developed here might provide the most representative tool to date to test compatibility of fungal antagonists to be used in biocontrol inocula. However the link between the results of the double host-range test and field efficacy of biocontrol inocula remains to be investigated.

To reveal whether bats serve as an amplifying host for Yokose virus (YOKV), we conducted a serological survey and experimentally infected fruit bats with YOKV isolated from microbats in Japan. YOKV belongs to the Entebbe bat virus group of vector unknown group within the genus Flavivirus and family Flaviviridae. To detect antibodies against YOKV, we developed an enzyme-linked immunosorbent assay (ELISA) using biotinylated anti-bat IgG rabbit sera. Serological surveillance was conducted with samples collected in the Philippines and the sera supplied from Malaysia. One of the 36 samples from the Philippines (2.7%) and 5 of the 26 samples from Malaysia (19%) had detectable ELISA antibodies. In the experimental infections, no clinical signs of disease were observed. Moreover, no significant viral genome amplification was detected. These findings revealed that YOKV replicates poorly in the fruit bat, suggesting that fruit bats do not seem to serve as an amplifying host for YOKV.

Ce protocole vise (a) a evaluer la resistance aux maladies de conservation pour differents genotypes de bananiers, (b) a comparer differentes origines de bananes (origine geographique, stade physiologique, etc.) vis-a-vis de leur sensibilite aux maladies de conservation. Le principe, les principaux avantages, le materiel vegetal de depart, le temps necessaire et les resultats attendus de la methode sont presentes. Materiel et methodes. Le materiel necessaire et le detail des douze etapes de realisation du protocole (prelevement de fruits et preparation d'inoculum, etude de resistance a l'anthracnose de blessure, etude de la resistance a l'anthracnose quiescente et etude de resistance a la pourriture de couronne) sont decrits. Resultats. Des symptomes types des differentes maladies sont obtenus apres inoculation artificielle. (Resume d'auteur)

Les techniques presentees permettent une conservation a long terme des souches de Cylindrocladium pour les preserver d'importants changements morphologiques et physiologiques. Le principe des methodes appliquees, leurs principaux avantages, le materiel vegetal necessaire, le temps requis et les resultats attendus sont presentes. Materiel et methodes. Le materiel de laboratoire necessaire, ainsi que le detail des neuf etapes utilisees pour la purification monospore de souches de Cylindrocladium, leur conservation a long terme, et la production de conidies et de microsclerotes sont decrits. Resultats. Une fois reactivees, les souches purifiees produisent des colonies qui s'accroissent activement en 48-72 h. De telles colonies peuvent alors etre aisement utilisees pour la production de conidies ou de microsclerotes. (Resume d'auteur)

As part of a participatory selection programme, promising individual trees were selected in 2004 in cocoa farms of southern and western Cameroon regions for yield and for low incidence of Phytophthora pod rot (Ppr) caused by Phytophthora megakarya. The aim of this study was to compare the levels of resistance to Ppr between farm accessions (FA), introduced and local genebank accessions (GA). In total, 234 FA were grafted in the nursery together with 22 introduced GA and 73 local GA, and tested for resistance to P. megakarya by leaf disc inoculations. The introduced GA, that were reported as resistant to Ppr in other countries, proved to be more resistant than the selected FA and unselected FA and also more resistant than the 3 control clones for Ppr resistance used in the study. However, approximately 10% of the FA were as resistant as the average of the introduced GA, showing the potential of selection for resistance to Ppr in farmers’ fields. The average level of resistance of the FA was relatively higher than that of the local GA. The FA selected for yield and low Ppr incidence in the field were more resistant in the leaf disc test than the unselected FA. The use of FA and of farmers’ knowledge in the participatory selection process is valuable in obtaining Ppr-resistant cultivars.

Applied silicon (Si) can improve resistance of plants to insect attack. We investigated the interactions between soil applied Si, sugarcane cultivar, and three documented feeding/penetration sites (internode, leaf bud, and root primordia), each at three heights (top, middle, and base) on the stalk and their effects on stem borer, Eldana saccharina Walker (Lepidoptera: Pyralidae) performance and the stalk damage it inflicts. Four sugarcane cultivars, treated (Si+) and untreated (Si-) with calcium silicate, were artificially infested with E. saccharina and the larvae were examined 21 days later. Silicon treatment significantly increased stalk Si content in all sugarcane cultivars and, overall, significantly reduced borer growth rate and also reduced stalk damage, particularly at the internode. Borer survival and growth rate and stalk damage were lowest at the internode, particularly in Si+ resistant cultivars. Although the internode had the hardest rind, hardness at each site was not significantly increased by Si+.

Resistance of cacao leaves to Phytophthora palmivora was studied with regard to the time of leaf collection (morning, afternoon) and the degree of exposure of the leaves to light in the field (low, medium and high). The efficiency of leaf disc inoculations in predicting field resistance of nine clones was compared with that of detached and attached pod inoculations. Significant effects were observed, with leaves exposed to high light intensity and collected early in the afternoon showing highest susceptibility. The effect of time of leaf collection was reduced when leaves were stored overnight and leaf discs prepared and inoculated the following day, as compared to inoculations on the day of collection. Interactions between the main factors were significant, though less substantial than the clone effects. The most significant correlations with pod resistance (r = 0.70 to 0.97) were obtained for leaves collected early in the morning and exposed to intermediate shade conditions in the canopy. For other treatments, the correlations with pod resistance were still positive (r = 0.23 to 0.83) but often not significant. Pod inoculations in the laboratory were better correlated with field resistance (r = 0.92) than pod inoculations in the field (r = 0.72). Detached pod inoculations were also better correlated with leaf disc inoculations than those of attached pods. The results confirm the validity of laboratory inoculations of leaves and pods to assess field resistance to Phytophthora. Standardization of the leaf disc test is essential to obtain reliable results. (Resume d'auteur)

South American Leaf Blight (SALB), caused by the ascomycete Pseudocercospora ulei, is responsible for the low productivity of rubber trees in Latin America and is a serious threat to rubber plantations in Asia and Africa, where the rubber trees are derived from highly susceptible clones. Three contrasted genotypes were chosen for their levels of resistance to the pathogen: FX2784 (totally resistant), MDF180 (partially resistant) and PB314 (susceptible). Array analyses were previously performed to identify genes differentially expressed in resistant and susceptible genotypes. Twenty-one genes were selected for further gene expression analysis in non-inoculated and inoculated genotypes from 24 to 216 h post infection (hpi). These genes are involved in ROS production (HbRBOHA, HbRBOHB, HbRBOHC, HbRBOHD), ROS-scavenging systems (cytoplasmic and chloroplastic HbCuZnSOD, HbMnSOD, HbCAT, HbAPX1, HbAPX2, HbMDHAR, HbGCL1, HbGCL2, HbOASTL, HbGPX, HbDHAR), and leaf senescence (HbCASP, HbPCYST, HbWRKY2, HbPLY, HbKAT2). First, a genotype-dependent level of expression was observed. The genes HbRBOHA, HbCuZnSOD cyto, HbCAT, HbGCL and HbWRKY2 were constitutively expressed at lower levels in the MDF180 genotype than in the FX2784 and PB314 genotypes. Conversely, the levels of expression of HbDHAR, HbGPX and HbPCYST were higher in the older, non-inoculated leaves of MDF180. Lower production of ROS and efficient regeneration of reduced ascorbate ensure a balanced redox intracellular state in this genotype. Second, inoculation of the leaves induced few modifications in the expression level of the studied genes. In the MDF180 partially resistant genotype, an increase in the expression level of HbRBOHB, HbRBOHD 48 hpi and a decrease in the expression level of HbDHAR 216 hpi were observed. In the FX2784 totally resistant genotype, an increase in the expression level of HbRBOHD and HbCuZnSOD cyto and a decrease in HbCAT were observed 48 hpi. This transitory variation could be associated with the oxidative burst classically observed in hypersensitive response (HR). The increase in the synthesis of reduced glutathione in this genotype could ensure redox balance and consequently cell homeostasis. In the PB314 susceptible genotype, HbROHC, HbCuZnSOD chloro was up-regulated 216 hpi concomitantly with a decrease in the expression level of HbCAT, consequently causing an accumulation of H2O2 and programmed cell death. The level of expression of a transcription factor, HbWRKY2, was also modulated by the P. ulei infection with early transient up-regulation in the FX2784 totally resistant genotype and permanent up-regulation in the MDF180 partially resistant genotype. These results complement studies on genetic determinism of SALB resistance and a recent publication on Hevea glutathione reductase gene.

Endothelial cells constitute a main target for Cowdria ruminantium (CR) and can potentially play a role as antigen presenting cells (APC). Therefore, we measured, in vitro, the effect of CR infections on the expression of MHC class I and class II molecules on bovine umbilical endothelial cells (BUEC) and on bovine brain endothelial cells (BBEC). A dramatic inhibition of the expression of IFNgamma induced MHC class II molecules was observed on BUEC and to a lesser extent on BBEC upon CR infection. This inhibitory effect was also observed on constitutively expressed MHC class I molecules. Part of the reduction of cell surface MHC molecules could be ascribed to their accumulation in intracellular compartments pinpointing a disruption in the transit of these molecules to the surface of the cells. The exact mechanisms of inhibition are not yet known but, as opposed to what is described in other models, the involvement of prostaglandin E2 can be excluded. The results obtained in this study show that endothelial cells have a decreased capacity to express both MHC class I and class II molecules on their surface upon CR infection, thus favouring the escape of this pathogen from the host immune system.

Des foyers de la peste des petits ruminants (PPR) ont été étudiés en 1993 et 1994 dans des troupeaux de chèvres de race sahélienne au Tchad. Si le virus n'a pu être isolé des premiers foyers de 1993, le sondage sérologique par le test ELISA de compétition ponant sur 475 sérums récoltés dans la zone d'épidémie a montré une prévalence de 34 %. Pour la première fois au Tchad, le virus fut isolé et des cas cliniques caractéristiques de la PPR furent observés sur les chèvres sahéliennes réputées peu sensibles à ce virus. La maladie a été reproduite expérimentalement par inoculation des chèvres avec des broyats de ganglions et de poumons, ces derniers ayant provoqué les symptômes les plus sévères. La réaction d'immunodiffusion en gélose s'est révélée positive vis-à-vis de l'antisérum anti-PPR avec les broyats de poumons et de ganglions mésentériques, métis pas avec ceux de ganglions préscapulaires. La caractérisation du virus isolé, en particulier sur le plan génomique, s'avère nécessaire.

During chronic infection with Mycobacterium tuberculosis (Mtb), bacilli multiplication is constrained within lung granulomas until excessive inflammation destroys the lung. Neutrophils are recruited early and participate in granuloma formation, but excessive neutrophilia exacerbates the tuberculosis disease. Neutrophils thus appear as potential targets for therapeutic interventions, especially in patients for whom no antibiotic treatment is possible. Signals that regulate neutrophil recruitment to the lung during mycobacterial infection need to be better understood. We demonstrated here, in the mouse model, that neutrophils were recruited to the lung in two waves after intranasal infection with virulent Mtb or the live attenuated vaccine strain Bacillus Calmette Guérin (BCG). A first wave of neutrophils was swiftly recruited, followed by a subsequent adaptive wave that reached the lung together with IFN-γ- and IL-17A-producing T cells. Interestingly, the second neutrophil wave did not participate to mycobacteria control in the lung and established contacts with T cells. The adaptive wave was critically dependent on the expression of IL-17RA, the receptor for IL-17A, expressed in non-hematopoietic cells. In absence of this receptor, curtailed CXCL-1 and 5 production in the lung restrained neutrophil recruitment. CXCL-1 and 5 instillation reconstituted lung neutrophil recruitment in BCG-infected IL17RA-/- mice.

Afin de préciser le rôle éventuel des petits ruminants dans l'épidémiologie de la trypanosomose à Trypanosoma evansi dans le Sud mauritanien, on a procédé à l'inoculation expérimentale d'une brebis et d'une chèvre par une souche locale de T. evansi isolée d'une chamelle laitière, et à des enquêtes dans des troupeaux de petits ruminants du Sud Trarza qui côtoient au pâturage des troupeaux de dromadaires souvent très contaminés. L'inoculation expérimentale a permis de confirmer que la brebis et la chèvre (races locales) sont réceptives. Seule la brebis a manifesté une sensibilité (amaigrissement et avortement). Pendant 220 jours après inoculation, le sang de la chèvre est resté infectant pour la souris. Chez la brebis, en revanche, on a pu constater l'alternance de phases infectantes et de phases "silencieuses". Sur le terrain, 207 frottis sanguins de caprins et 174 frottis d'ovins sont négatifs ainsi que 1O9 sérums de caprins et 78 d'ovins. Il semble donc que les petits ruminants ne jouent aucun rôle dans l'épidémiologie de la trypanosomose à T. evansi et ce, en dépit de leur réceptivité à l'inoculation expérimentale.

La dermatophilose est une des maladies les plus importantes des ruminants domestiques des iles caraibes, ou la maladie clinique est associee a la presence de la tique Amblyomma variegatum. Des etudes seroepidemiologiques ont ete effectuees afin d'eclaircir l'epidemiologie de la maladie dans la region, en faisant particulierement attention au role d'A.variegatum. Une banque de 1300 serums de bovins des Petites Antilles a ete examinee par ELISA pour la presence d'anticorps contre Dermatophilus congolensis. II s'est avere que des animaux seropositifs existent dans des iles non infestees par A. variegatum, et ou la dermatophilose n'est jamais ou rarement observee. De plus, il n'y avait pas de difference significative entre la prevalence d'animaux seropositifs des zones infestees par la tique et des zones non infestees de la Martinique et de Sainte-Lucie, deux iles partiellement infestees et ou la dermatophilose n'est observee que dans les parties infestees par la tique. La prevalence etait basse dans les petites iles ayant un climat sec. Ceci confirme les resultats experimentaux indiquant qu'A. variegatum n'est pas indispensable pour la transmission de D. congolensis, qui est tres repandu dans la plupart des iles. Les concentrations elevees de prostaglandine E2 (entre 151 et 377 ng/ml) et de prostacycline (entre 124 et 134 ng/ml) trouvees dans la salive des femelles d'A. variegatum, suggerent fortement que la tique pourrait favoriser le developpement des lesions par une activite immunomodulatrice de sa salive. Neanmoins, malgre un certain succes dans la reproduction de la dermatophilose chez des chevres simultanement infestees avec des adultes d' A. variegatum et scarifiees avec Dermatophilus, on n'a pas observe de difference entre des bovins Creole naturellement resistants et des Brahman hautement sensibles, utilisant le meme modele. Les lesions de la dermatophilose sont restees tres benignes sur les animaux des deux races. Apres cette experience, les Brahman ont developpe une dermatophilose generalisee apres avoir ete mis au pâturage, ce qui indique que le role respectif des facteurs de risque identifies comme etant d'importance majeure pour l'expression de la dermatophilose clinique, n'est pas completement clarifie et demande d'etre etudie davantage. (Resume d'auteur)

We report here the isolation and characterization of three distinct isolates of Cymbidium mosaic virus (CymMV) co-infecting Dendrobium orchid in Hawaii. Isolates 1 and 2 were phylogenetically distinct from previously reported CymMV isolates. However, isolate 3 was highly similar to previously reported CymMV sequences and could be localised to CymMV subgroup A. Isolate 2 localised to CymMV subgroup B. Thus, we report here the first full-length CymMV subgroup B isolate. Isolate 1 represents a recombination event between isolates 2 and 3. Infectivity assays revealed that all three isolates are functional and individually infectious in both Dendrobium and indicator species.

In Africa, trypanosomosis is a tsetse-transmitted disease which represents the most important constraint to livestock production. Several indigenous West African taurine (Bos taurus) breeds, such as the Longhorn (N'Dama) cattle are well known to control trypanosome infections. This genetic ability named "trypanotolerance" results from various biological mechanisms under multigenic control. The methodologies used so far have not succeeded in identifying the complete pool of genes involved in trypanotolerance. New post genomic biotechnologies such as transcriptome analyses are efficient in characterising the pool of genes involved in the expression of specific biological functions. We used the serial analysis of gene expression (SAGE) technique to construct, from Peripheral Blood Mononuclear Cells of an N'Dama cow, 2 total mRNA transcript libraries, at day 0 of a Trypanosoma congolense experimental infection and at day 10 post-infection, corresponding to the peak of parasitaemia. Bioinformatic comparisons in the bovine genomic databases allowed the identification of 187 up- and down- regulated genes, EST and unknown functional genes. Identification of the genes involved in trypanotolerance will allow to set up specific microarray sets for further metabolic and pharmacological studies and to design field marker-assisted selection by introgression programmes.

International audience; Excretory-secretory products (ESP) of myiasis producing agents are involved in nutrition and development of larvae and are often immunogens. This study was carried out in order to define the antigenicity, the immunogenicity of Oestrus ovis ESP and the role of sheep immune response to ESP. Twenty-four six to eight month old female lambs were randomly allocated into two groups. The first one was immunised twice, four weeks apart, with excretory-secretory products of Oestrus ovis third instar larvae (L3ESP) in complete then incomplete Freund adjuvant. The second one served as a control, and received two injections of PBS plus complete and incomplete Freund adjuvant. Fifteen and twenty-eight days after the second immunisation, animals of both groups were experimentally challenged with O. ovis first instar larvae. Twelve days after the second experimental challenge, the twenty-four lambs were necropsied. The total number of O. ovis larvae, their stages of development, weights and sizes were recorded per animal and compared between the two groups. Establishment rates were very similar in both groups: 39% and 35% in control and vaccinated groups respectively but the percentage of developing stages was higher in the control group (13% ) than in the vaccinated group (6% ). It was concluded that the L3ESP immunisation of sheep did not protect against larval establishment but provided an inhibitory effect on larval growth.; Immunisation d'agneaux avec des produits d'excrétion-sécrétion de larves de troisième stade d'Oestrus ovis et infestations expérimentales d'épreuve. Les produits d'excrétion-sécrétion des larves de Diptères myiasigènes interviennent dans la nutrition et le développement de ces larves et sont très souvent immunogènes. Dans le cas de l'œstrose ovine, leurs propriétés antigéniques et immunogéniques n'ont pas encore été étudiées. De plus, le rôle exact de la réponse immune du mouton vis-à-vis des produits d'excrétion-sécrétion n'est pas connu et c'est ce qui a motivé ce travail. Vingt quatre agnelles âgées de six à huit mois ont été réparties de façon aléatoire en deux groupes de douze individus. Le premier groupe a reçu deux injections à quatre semaines d'intervalle d'un mélange de produits d'excrétion-sécrétion de larves de troisième stade d'Oestrus ovis et d'adjuvant complet puis incomplet de Freund. Le deuxième groupe a servi de témoin et a reçu seulement deux injections de PBS avec adjuvant complet puis incomplet de Freund. Quinze et trente jours après la deuxième immunisation, les animaux des deux groupes ont été infestés expérimentalement par des larves de premier stade d'Oestrus ovis. Douze jours après la seconde infestation expérimentale, tous les agneaux ont été abattus. Le nombre total de larves d'Oestrus ovis, leur stade de développement, leur taille ainsi que leur poids ont été comparés entre les deux groupes. Les taux d'installation des larves étaient très comparables dans les deux groupes (39 % chez les témoins et 35 % chez les immunisés) mais le pourcentage de stades larvaires en développement était significativement plus important chez les témoins (13 % ) que chez les immunisés (6 % ). L'immunisation avec des produits d'excrétion-sécrétion de larves de troisième stade, bien que n'ayant pas protégé les agneaux de l'installation des larves, a conduit à une inhibition partielle du développement larvaire.

Skeletal muscle catabolism is a characteristic metabolic response to sepsis. We investigated the ability of physiological insulin (2 nM) or insulin-like growth factor I (IGF-I, 10 nM) concentrations to modify protein metabolism during incubation of epitrochlearis 2, 6, or 15 days after injection of live Escherichia coli. On days 2 and 6 postinfection, skeletal muscle exhibited an exacerbated negative protein balance resulting from both an inhibition in protein synthesis (25%) and an enhanced proteolysis (90%) compared with controls. By day 15 postinfection, protein balance in infected rats was significantly improved compared with either day 2 or 6. At this time, protein synthesis was augmented and protein degradation was decreased in infected rats relative to day 6. Insulin or IGF-I stimulated protein synthesis in muscles from septic and control rats in vitro to the same extent at each time point examined. The ability of insulin or IGF-I to limit protein degradation was severely blunted 48 h after infection. On day 6 postinfection, the effect of insulin or IGF-I to inhibit proteolysis was more pronounced than on day 2. Incubation with IGF-I limited proteolysis to a greater extent than insulin on both days in infected but not control rats. By day 15, insulin diminished proteolysis to the same extent as in controls. The results suggest that injection of bacteria causes fundamental derangements in protein metabolism that persist for days after infection.

The course of immune reactions of the manifold antigens of Mycoplasma mycoides subsp. mycoides small colony type (SC) was analysed in serum and bronchial lavage of cattle experimentally infected with the African strain Afade and the European strain L2 using Western-blots and complement fixation. Western-blot analysis of total antigens of both strains with sera from animals infected with the homologous and heterologous strain revealed the common dominant immunogenic antigens with the molecular masses of 110, 95, 85, 80, 72, 62, 48 and 39 kDa. The sequential sampling of the blood and bronchial lavages before and after contact infections allowed us to identify the antigens of 85, 80, 72, 48 and 39 kDa as particularly early immunogens. The IgA Western blots of the bronchial lavages showed distinct, early and persistent reactions to the 110, 85, 80, 72, 48 and 45 kDa proteins. These proteins were the predominant lipoproteins as determined by [14C]palmitic acid labelling. Only relatively weak reactions of the bronchial lavages were detected with IgG. In general immune responses were significantly stronger in the animals infected with the African strain Afade, which gave positive results two weeks after contact infection. In contrast, the animals infected with the European strain L2 induced much lower reactions with a delay of three months after contact infection. In one animal strain L2 caused no sero-conversion and no infection. The results indicate a difference in virulence between the African strain Afade and the European strain L2.

This study investigated the successive losses in the parasite densities of Plasmodium falciparum stages during the early sporogony in laboratory-reared Anopheles gambiae infected by membrane feeding with blood from naturally infected gametocyte carriers (>50 gametocytes/mm3). The developmental stages of P. falciparum in the mosquito were studied from zygote to oocyst, by immunofluorescent method using monoclonal antibodies against the Pfs25 protein present on the surface of newly formed gametes. This method allows for assessment of the various sporogonic stages before, during and after passage of the midgut wall. Parasite densities were determined within the entire blood meal at 3 h (zygotes and macrogametes) and 24 h (ookinetes) post-infection. At 48 h after the mosquito blood meal, midguts were checked for the presence of early oocysts. For the mid-size oocysts count, classic microscopy examination was used at day 7 postinfection. The parasite efficacy was estimated by following successive losses in parasite densities between different early stages of the sporogonic cycle in A. gambiae. Thirty-seven experimental infections were realized with high gametocyte densities, ranging from 64 to 2392 gametocytes/mm3. All gametocyte carriers showed infection with round forms 100%; ookinetes were found in 91.9%. The prevalences of infections with oocysts were 48.6% at day 2 (young oocyst) and 37.8% at day 7 (mid-size oocyst). The mean densities per mosquito for each parasite stage were 12.6 round forms, 5.5 ookinetes, 1.8 young oocyst and 2 mid-size oocysts. Significant correlations were found between two consecutive parasite stages (round forms/ookinetes, ookinetes/young oocysts, young oocysts/mid-size oocysts) and between round forms and mid-size oocysts. The mean parasite density significantly decreased between round forms and ookinetes (yield Y1 = 41.6%) and between ookinetes and young oocysts (Y2 = 61.4%). By contrast, no significant decrease was observed between young oocysts and mid-size oocysts (Y3 = 91.2%). The overall yield of the early sporogonic cycle (from round form to oocyst at day 7) was equal to 25.7%, indicating that almost 3/4 of the total parasites were lost during the early step of the sporogonic cycle, from 3 h post-infection to day 7.

Factors which could influence the success of experimental infections of Anopheles gambiae with Plasmodium falciparum were investigated in Cameroon. 139 experimental infections with different gametocyte carriers were performed. 86 (62%) gave rise to mosquito infection after dissection of at least 20 mosquitoes. Among succeeding infections, the mean percentage of infected mosquitoes was 18.6% and mean oocyst load per positive midgut was 2.56. Only gametocyte density was identified as a factor which determined the success and the level of mosquito infection. No significant influence was found for sex and age of the gametocyte carrier, body-temperature, presence of asexual erythrocyte stages, rhesus factor, blood group and use of antimalarial drugs (chloroquine and amodiaquine).

L'expérience réalisée a eu pour but de vérifier la réceptivité des chèvres à l'agent de la péripneumonie contagieuse bovine. Quatre voies d'inoculation ont été expérimentées: les voies sous-cutanée, endobronchique, intrapleurale et intrapéritonéale. Une des chèvres inoculées par la voie intrapéritonéale a succombé à une péritonite et l'agent de la péripneumonie a pu être isolé à nouveau du liquide ascitique présent. Les sérologies effectuées ont permis de mettre en évidence des séroconversions chez un certain nombre d'animaux, notamment par la technique d'Elisa de compétition. Ce résultat ouvre la voie à des enquêtes de terrain pour déterminer si des chèvres en contact avec des bovins atteints de la péripneumonie peuvent être naturellement contaminées.

The authors have compared the susceptibility to Histomonas meleagridis infection of two turkey strains : an industrial Heavy Weight strain, (H.W.) and a traditional Light Weight strain, (L.W.), used in Bresse. The aim of the study was to know if the industrial strain is naturally more resistant to histomoniasis than the traditional strain. Intracloacal infections were carried out experimentally using inoculums containing 106 and 3.106 Histomonas per bird according to the different groups. The repercussions on the body weight, mortality and the incidence of lesions were studied. The response to infection of the H.W. was in every way comparable to that of the L.W. with the exception of the mortality : 100% mortality was attained later (seven days) in the H.W. than in the L.W. At necropsy, lesion scores for the liver and caeca were given: there was no difference in the seriousness of the lesions or histological difference between the two strains of turkeys., Les auteurs comparent la réceptivité et la sensibilité des dindes industrielles lourdes, Heavy Weight (H.W.), et des dindes fermières légères, Light Weight (L.W.), à une infection par Histomonas meleagridis, le but de l’étude étant de savoir si les dindes industrielles sont naturellement plus résistantes à l’histomonose que les dindes fermières. Des infections expérimentales intracloacales sont réalisées avec des inoculums de 106 et 3.106 Histomonas par animal. Les répercussions sur la croissance pondérale, la mortalité et les incidences lésionnelles sont étudiées. La réponse des H.W. à l’infection est tout à fait comparable à celle des L.W.. La seule différence observée concerne la mortalité : une mortalité de 100% est atteinte plus tardivement pour les H.W. (sept jours plus tard). A l’autopsie, les scores lésionnels sont déterminés pour le foie et les caeca ; il n’apparaît aucune différence ni dans la gravité des lésions ni dans l’examen histologique.

Les auteurs donnent les resultats d'une enquete comparative du lauryl sulfate de sodium alcalin et du bromure de cetylpyridinium comme agents d'homogeneisation et de decontamination pour l'isolement de mycobacteries sur les milieux a l'oeuf. Ces deux produits sont experimentes sur 25 prelevements d'origine humaine (crachats) et sur 26 prelevements d'origine animale (ganglions a tubercules caseeux ou infectes artificiellement). La technique utilisant le lauryl sulfate alcalin se montre la plus favorable, pour les deux types de prelevements. Ses avantages compensent largement les legers inconvenients qu'entraine la necessite d'une neutralisation. Grâce a sa faible toxicite, le cetylpyridinium conserve tout son interet en Afrique comme agent de transport des prelevements recoltes loin du laboratoire. (Resume d'auteur)