Prevalence and sequence-based identity of rumen fluke in cattle and deer in New Caledonia

An abattoir survey was performed in the French Melanesian archipelago of New Caledonia to determine the prevalence of paramphistomes in cattle and deer and to generate material for molecular typing at species and subspecies level. Prevalence in adult cattle was high at animal level (70% of 387 adult cattle) and batch level (81%). Prevalence was lower in calves at both levels (33% of 484 calves, 51% at batch level). Animals from 2 of 7 deer farms were positive for rumen fluke, with animal-level prevalence of 41.4% (29/70) and 47.1% (33/70), respectively. Using ITS-2 sequencing, 3 species of paramphistomes were identified, i.e. Calicophoron calicophorum, Fischoederius elongatus and Orthocoelium streptocoelium. All three species were detected in cattle as well as deer, suggesting the possibility of rumen fluke transmission between the two host species. Based on heterogeneity in ITS-2 sequences, the C. calicophorum population comprises two clades, both of which occur in cattle as well as deer. The results suggest two distinct routes of rumen fluke introduction into this area. This approach has wider applicability for investigations of the origin of rumen fluke infections and for the possibility of parasite transmission at the livestock-wildlife interface

Cellular expression, trafficking, and function of two isoforms of human ULBP5/RAET1G

Background: The activating immunoreceptor NKG2D is expressed on Natural Killer (NK) cells and subsets of T cells. NKG2D contributes to anti-tumour and anti-viral immune responses in vitro and in vivo. The ligands for NKG2D in humans are diverse proteins of the MIC and ULBP/RAET families that are upregulated on the surface of virally infected cells and tumours. Two splicing variants of ULBP5/RAET1G have been cloned previously, but not extensively characterised. Methodology/Principal Findings: We pursue a number of approaches to characterise the expression, trafficking, and function of the two isoforms of ULBP5/RAET1G. We show that both transcripts are frequently expressed in cell lines derived from epithelial cancers, and in primary breast cancers. The full-length transcript, RAET1G1, is predicted to encode a molecule with transmembrane and cytoplasmic domains that are unique amongst NKG2D ligands. Using specific anti-RAET1G1 antiserum to stain tissue microarrays we show that RAET1G1 expression is highly restricted in normal tissues. RAET1G1 was expressed at a low level in normal gastrointestinal epithelial cells in a similar pattern to MICA. Both RAET1G1 and MICA showed increased expression in the gut of patients with celiac disease. In contrast to healthy tissues the RAET1G1 antiserum stained a wide variety or different primary tumour sections. Both endogenously expressed and transfected RAET1G1 was mainly found inside the cell, with a minority of the protein reaching the cell surface. Conversely the truncated splicing variant of RAET1G2 was shown to encode a soluble molecule that could be secreted from cells. Secreted RAET1G2 was shown to downregulate NKG2D receptor expression on NK cells and hence may represent a novel tumour immune evasion strategy. Conclusions/Significance: We demonstrate that the expression patterns of ULBP5RAET1G are very similar to the well-characterised NKG2D ligand, MICA. However the two isoforms of ULBP5/RAET1G have very different cellular localisations that are likely to reflect unique functionality

Gliadin Peptide P31-43 Localises to Endocytic Vesicles and Interferes with Their Maturation

BACKGROUND: Celiac Disease (CD) is both a frequent disease (1:100) and an interesting model of a disease induced by food. It consists in an immunogenic reaction to wheat gluten and glutenins that has been found to arise in a specific genetic background; however, this reaction is still only partially understood. Activation of innate immunity by gliadin peptides is an important component of the early events of the disease. In particular the so-called "toxic" A-gliadin peptide P31-43 induces several pleiotropic effects including Epidermal Growth Factor Receptor (EGFR)-dependent actin remodelling and proliferation in cultured cell lines and in enterocytes from CD patients. These effects are mediated by delayed EGFR degradation and prolonged EGFR activation in endocytic vesicles. In the present study we investigated the effects of gliadin peptides on the trafficking and maturation of endocytic vesicles. METHODS/PRINCIPAL FINDINGS: Both P31-43 and the control P57-68 peptide labelled with fluorochromes were found to enter CaCo-2 cells and interact with the endocytic compartment in pulse and chase, time-lapse, experiments. P31-43 was localised to vesicles carrying early endocytic markers at time points when P57-68-carrying vesicles mature into late endosomes. In time-lapse experiments the trafficking of P31-43-labelled vesicles was delayed, regardless of the cargo they were carrying. Furthermore in celiac enterocytes, from cultured duodenal biopsies, P31-43 trafficking is delayed in early endocytic vesicles. A sequence similarity search revealed that P31-43 is strikingly similar to Hrs, a key molecule regulating endocytic maturation. A-gliadin peptide P31-43 interfered with Hrs correct localisation to early endosomes as revealed by western blot and immunofluorescence microscopy. CONCLUSIONS: P31-43 and P57-68 enter cells by endocytosis. Only P31-43 localises at the endocytic membranes and delays vesicle trafficking by interfering with Hrs-mediated maturation to late endosomes in cells and intestinal biopsies. Consequently, in P31-43-treated cells, Receptor Tyrosine Kinase (RTK) activation is extended. This finding may explain the role played by gliadin peptides in inducing proliferation and other effects in enterocytes from CD biopsies

Approche intégrée de la lutte contre la tique du bétail, Rhipicephalus (Boophilus) australis, en Nouvelle-Calédonie

Cattle breeding is the 3rd most important agricultural sector in New Caledonia in terms of economic value and covers 96% of the useful agricultural area. Since its accidental introduction in 1942, the cattle tick, Rhipicephalus (Boophilus) australis, has been the main health constraint in cattle farms due to the blood spoliation it causes. To control the parasitic infestations, farmers have regularly used acaricides but their repeated use has led to the development of resistance to these products. In 2014, 23% of tick samples collected from farms showed resistance to amitraz, the acaricide currently used on the Territory. This situation compromises the control of this parasite and, given this observation, it has become crucial to diversify the control methods. The objective of this thesis is to present the control methods that we have developed to assist cattle farmers in managing this tick. Based on the knowledge of the biology and ecology of this tick, we have developed an innovative method of pasture and herd management, combined with targeted acaricide management to reduce parasite populations in pastures and limit contact between the parasite and its host. We have also worked on a vaccine against this tick, originally developed in Australia but which we have adapted using a vaccine protein derived from ticks collected in local farms. The studies we have conducted under controlled conditions have proven its impact on the development and reproduction capacities of the parasite. A trial conducted under farm conditions made it possible to reduce the number of acaricide treatments by 40.2% after two years of vaccination. At the end of this work, cattle breeders now have a real integrated control program to reduce the use of acaricides and ensure the sustainability of their activity.L’élevage bovin représente la 3ème filière agricole en Nouvelle-Calédonie en valeur économique et occupe 96% de la surface agricole utile. Depuis son introduction accidentelle en 1942, la tique du bétail, Rhipicephalus (Boophilus) australis, constitue la principale contrainte sanitaire dans les élevages bovins du territoire par la spoliation sanguine qu’elle engendre. Pour contrôler les infestations parasitaires, les éleveurs ont utilisé régulièrement des acaricides mais leur usage répété a entrainé le développement de résistance à ces produits. En 2014, 23% des échantillons de tiques prélevés dans les élevages présentaient une résistance à l’amitraze, acaricide actuellement utilisé par les éleveurs calédoniens. Cette situation compromet le contrôle de ce parasite et face à ce constat il est devenu crucial de diversifier les méthodes de lutte. L’objectif de cette thèse est de présenter les méthodes de lutte que nous avons développées pour accompagner les éleveurs de bovins dans la gestion de ce parasite. A partir des connaissances sur la biologie et l’écologie de cette tique, nous avons développé une méthode innovante de gestion des pâturages et des troupeaux, combinée à une gestion ciblée des acaricides pour réduire les populations parasitaires dans les pâturages et limiter le contact entre le parasite et son hôte. Nous avons également travaillé sur un vaccin contre cette tique, initialement développé en Australie mais que nous avons adapté en utilisant une protéine vaccinale issue de tiques prélevées dans les élevages calédoniens. Les études que nous avons menées en conditions contrôlées ont prouvé son impact sur les capacités de développement et de reproduction du parasite. Un essai conduit en conditions d’élevage a permis de réduire de 40,2% le nombre de traitements acaricides à l’issue de 2 années de vaccination. A l’issue de ces travaux, les éleveurs bovins du territoire disposent ainsi d’un réel programme de lutte intégrée pour réduire le recours aux acaricides et assurer la pérennité de leur activité

Comparison of tick resistance of crossbred Senepol × Limousin to purebred Limousin cattle

International audienceThe comparison of resistance to natural tick infestation by Rhipicephalus microplus (Canestrini, 1887) of crossbred Senepol × Limousin and purebred Limousin cattle was investigated. The Senepol breed, originated from St Croix Island in the Caribbean is considered as a Bos taurus breed adapted to tropical conditions. Despite its B. taurus genetic background, it is believed to have a good tick resistance, but this resistance has never been assessed previously. Tick counts under natural infestation were carried out to investigate the difference of susceptibility between crossbred Senepol × Limousin and purebred Limousin cattle. Mixed-effect models were used to assess the effect of the breed on the number of ticks. Results show that Senepol × Limousin are five times less infested by ticks than purebred Limousin. These results underline the opportunity to use Senepol cattle for crossing with susceptible B. taurus breeds in tick infested areas, to combine tick resistance with beef production abilities

Acaricidal and insecticidal activities of plants among Reunion Island’s flora

International audienc

First report of autochthonous non-vectorial canine leishmaniasis in New Caledonia, south-western Pacific: implications for new control measures and recommendations on importation of dogs

International audienceBACKGROUND: Canine leishmaniasis (CanL), a parasitic zoonotic disease caused by Leishmania infantum and usually transmitted by phlebotomine sandflies, has rarely been reported in Pacific islands, which have been regarded until now as leishmaniasis-free territory. Here, we report the first autochthonous CanL case in New Caledonia (south-western Pacific) and the investigations carried out 1) to determine how infection was introduced into and transmitted among these dogs and 2) to assess the risks to animal and public health.METHODS: Extensive epidemiological and entomological investigations in and around the focus were carried out. Leishmaniasis infection was confirmed by histopathology, indirect fluorescent antibody test, real-time PCR, and culture. Parasite strain was typed by the isoenzymatic technique.RESULTS: The survey revealed close contacts between the autochthonous dog and two infected bitches imported from Spain, but failed to find any possible vector or disease spreading to other animals or humans. L. infantum zymodeme MON-1, the most frequent type in the Mediterranean basin, was identified. Although transplacental and venereal transmissions could not be excluded, the evidence was in favour of non-vectorial, direct dog-to-dog transmission.CONCLUSIONS: This study corroborates the possibility of non-vectorial routes (transplacental, venereal, and direct dog-to-dog) of canine leishmaniasis transmission in New Caledonia and raises the debate of relevant test requirements and diagnostic sensitivity prior to importation of dogs in Leishmania-free regions. New leishmaniasis control measures and recommendations to avoid future CanL introduction on the island are discussed