Experimental Infections Reveal Acquired Zoonotic Capacity of Human Schistosomiasis Trough Hybridization.

We are currently witnessing the endemization of urogenital schistosomiasis in southern Europe. The incriminated parasite is a hybrid between a human parasite and a livestock parasite. Using an experimental evolutionary protocol, we created hybrid lines from pure strains of both parasite species. We showed that the host spectrum of the human parasite is enlarged to the livestock parasite after genomic introgression. We also evidenced that the tropism of the parasites within the host changes and that some hybrid lines are more virulent than the parental strains. These results engage a paradigm shift from human to zoonotic transmission of urogenital schistosomiasis.

First identification of Cryptosporidium parvum virus 1 (CSpV1) in various subtypes of Cryptosporidium parvum from diarrheic calves, lambs and goat kids from France.

Cryptosporidium spp. remain a major cause of waterborne diarrhea and illness in developing countries and represent a significant burden to farmers worldwide. Cryptosporidium parvum virus 1 (CSpV1), of the genus Cryspovirus, was first reported to be present in the cytoplasm of C. parvum in 1997. Full-length genome sequences have been obtained from C. parvum from Iowa (Iowa), Kansas (KSU) and China. We aimed at characterizing the genome of CSpV1 from France and used sequence analysis from Cryptosporidium isolates to explore whether CSpV1 genome diversity varies over time, with geographical sampling location, C. parvum genetic diversity, or ruminant host species. A total of 123 fecal samples of cattle, sheep and goats were collected from 17 different French departments (57 diseased animal fecal samples and 66 healthy animal fecal samples). Subtyping analysis of the C. parvum isolates revealed the presence of two zoonotic subtype families IIa and IId. Sequence analysis of CSpV1 revealed that all CSpV1 from France, regardless of the subtype of C. parvum (IIaA15G2R1, IIaA17G2R1 and IIdA18G1R1) are more closely related to CSpV1 from Turkey, and cluster on a distinct branch from CSpV1 collected from C. parvum subtype IIaA15G2R1 from Asia and North America. We also found that samples collected on a given year or successive years in a given location are more likely to host the same subtype of C. parvum and the same CSpV1 strain. Yet, there is no distinct clustering of CSpV1 per French department or ruminants, probably due to trade, and transmission of C. parvum among host species. Our results point towards (i) a close association between CSpV1 movement and C. parvum movement, (ii) recent migrations of C. parvum among distantly located departments and (iii) incidental transmission of C. parvum between ruminants. All together, these results provide insightful information regarding CSpV1 evolution and suggest the virus might be used as an epidemiological tracer for C. parvum. Future studies need to investigate CSpV1's role in C. parvum virulence and on subtype ability to infect different species.

A two-step morphology-PCR strategy for the identification of nematode larvae recovered from muscles after artificial digestion at meat inspection.

To ensure that meat from livestock and game is safe for human consumption, European legislation lays down rules for mandatory testing. Helminth larvae are a category of zoonotic foodborne pathogens that can contaminate meat. Among helminths, the only zoonotic nematode regulated in Europe regarding meat inspection is Trichinella spp.. It is precisely during Trichinella testing that other potentially zoonotic larvae can be found. Due to current lack of tools, their identification is often very complicated. Nematode larvae other than Trichinella, recovered from artificial digestions of pig and wild boar muscles from France and Germany, were subjected to a newly developed two-step identification scheme, which includes both morphological examination and molecular assays. The first step is a general orientation towards a broad taxonomic group; the second step consists of targeted identification based on the results of first step. Different parasites were identified, some of which were not zoonotic such as Metastrongylus spp. and Angiostrongylus vasorum, but others are known to be zoonotic such as Toxocara cati, Ascaris suum, and Uncinaria stenocephala. The strategy is efficient for the identification of nematode larvae recovered from muscles but could also be applied for larvae from other sources.

Occurrence and molecular characterization of Giardia duodenalis in lambs in Djelfa, the central steppe of Algeria.

Little is known of the prevalence and genetic identity of Giardia duodenalis in sheep in Algeria. The present study aimed at characterizing G. duodenalis in lambs up to 6 months of age in Djelfa, Algeria. A total of 346 fecal specimens were collected from 28 farms and screened for G. duodenalis cysts by zinc sulfate flotation microscopy, and positive specimens were confirmed using a direct immunofluorescence assay. Microscopy-positive specimens were analyzed by PCR and sequence analysis of the triosephosphate isomerase and glutamate dehydrogenase genes to determine G. duodenalis assemblages. Coprological examination indicated that the overall infection rate was 7.0% (24/346). Lambs under 3 months of age had higher infection rate (18/197, 9.0%) than older (6/149, 4.0%) animals, and animals with diarrhea (7/44, 16.0%) had higher infection rate than animals without diarrhea (17/302, 5.6%). PCR sequence analyses of the 15 G. duodenalis isolates revealed the presence of assemblages A in 6 isolates, assemblage E in 7 isolates, and both in 2 isolates. Assemblage A was only found in pre-weaned lambs with diarrhea, while assemblage E was mostly found in post-weaned lambs without diarrhea. The assemblage E isolates from sheep were genetically related to those from cattle in Algeria, while assemblage A isolates were from a well-known subtype prevalent in humans. Data generated from the study improve our understanding of the transmission of G. duodenalis in Algeria.

Efficacy of chitosan, a natural polysaccharide, against Cryptosporidium parvum in vitro and in vivo in neonatal mice.

Cryptosporidiosis is a zoonotic disease caused by species in the genus Cryptosporidium. In young ruminants, Cryptosporidium parvum causes economically significant disease with mild to severe clinical signs and occasional death. The typical clinical course in animals aged 1-3 weeks old is acute diarrhoea. Currently there are no available treatments that are fully effective against cryptosporidiosis in either humans or animals. Therefore there is a critical need for the development of new therapeutic agents. We adapted two in vitro culture systems (HCT-8 and Caco-2 cell lines) for C. parvum infection to investigate the "anticryptosporidial" activity of two chitosans; Chitosan NAG and Chitosan Mix. Chitosan-a naturally-occurring polysaccharide compound-has been found to be active against a variety of diseases, possessing both antimicrobial and anticancer properties. We investigated both chitosan's toxicity and effects on C. parvum in the two in vitro models. To evaluate chitosan's effects on oocyst shedding in vivo, CD-1 neonate mice were orally inoculated with C. parvum oocysts (Iowa strain), treated with chitosan, and compared to infected non-treated animals. Paromomycin, a classical drug used in veterinary medicine, was used as a reference compound. Immunofluorescence techniques were used to analyse the parasites. Our results showed significant reductions in Cryptosporidium oocyst viability (>95%) after oocyst pre-incubation with either paromomycin (P < 0.001), Chitosan Mix or Chitosan NAG (P < 0.001), for 24 h at 37 °C. Additionally, paromomycin, Chitosan Mix, and Chitosan NAG significantly inhibited C. parvum multiplication in HCT-8 and Caco-2 cell lines (P < 0.005). These effects were dose-dependent. In in vivo studies, treatment with both chitosans (Chitosan NAG, Chitosan Mix) or paromomycin sulfate significantly reduced parasite shedding in infected treated newborn mice (-56%, -34.5% and -58%, respectively). In conclusion, these findings provide the first in vitro and in vivo evidence of the anticryptosporidial activities of this natural polysaccharide.

PrP-associated resistance to scrapie in five highly infected goat herds.

The PrP gene polymorphisms at codons 142 (I/M), 154 (R/H), 211 (R/Q), 222 (Q/K) and 240 (S/P) and their association with susceptibility to classical scrapie infection were investigated in five French goat herds displaying a high disease prevalence (>10%). On the basis of PrP(Sc) detection in the central nervous system and in various lymphoid tissues, 301 of 1343 goats were found to be scrapie infected. The statistical analyses indicated that while P(240) mutation had no direct impact on scrapie infection risk, the H(154), Q(211) and K(222) mutations were associated with high resistance to scrapie. The M(142) mutated allele was associated with a limited protection level against the disease. These results further reinforce the view that, like in sheep, the control and eradication of classical scrapie through the selection of certain PrP alleles could be envisaged in commercial goat population.

Anatomical distribution of Toxoplasma gondii in naturally and experimentally infected lambs.

Consumption of raw or undercooked meat containing Toxoplasma gondii tissue cysts is one of the main sources of infection for humans worldwide. Among the various species intended for human consumption, sheep appear to be a high risk for human infection. The present study focused on the detailed anatomical distribution of Toxoplasma gondii in naturally and experimentally infected lambs using fresh and frozen samples of various pieces of meat, from a public health perspective. The first objective was to rank the edible parts intended for human consumption according to the detectable parasite burden by real-time PCR targeting the 529-bp repeated element. The second objective was to evaluate the impact of freezing by comparing the detection efficiency of the quantitative PCR between fresh and frozen tissues, as imports of lamb carcasses/cuts may arrive frozen or chilled. The highest estimated parasite loads were observed in skeletal muscles, and more particularly in edible portions such as quadriceps femoris muscle, intercostal muscles, deltoid muscle and diaphragm, with a significant difference in detectable parasite burden between fresh and frozen samples (p < 0.0001) or natural and experimental infection (p < 0.0001). Thoracic and pelvic limbs (3278-1048 parasites/g muscle) were ranked at the top of the list. Toxoplasma gondii DNA was detected in all the edible parts of lamb studied. These results suggest that lamb meat represents a risk for consumers. Further investigations are needed in order to confirm these differences in larger numbers of animals and in different breeds.

Title: Distribution anatomique de Toxoplasma gondii chez des agneaux infectés naturellement et expérimentalement. Abstract: La consommation de viande crue ou insuffisamment cuite contenant des kystes tissulaires de Toxoplasma gondii est l'une des principales sources d'infection pour l'homme dans le monde. Parmi les différentes espèces destinées à la consommation humaine, le mouton apparaît à haut risque d'infection humaine. La présente étude s'est concentrée sur une distribution anatomique détaillée de Toxoplasma gondii chez des agneaux infectés naturellement et expérimentalement à l'aide d'échantillons frais et congelés de divers morceaux de viande, du point de vue de la santé publique. Classer les parties comestibles destinées à la consommation humaine, selon la charge parasitaire détectable par une PCR en temps réel ciblant l'élément répété de 529 pb était un premier objectif. Un second objectif était d'évaluer l'impact de la congélation en comparant l'efficacité de détection de la PCR quantitative entre les tissus frais et congelés, car les importations de carcasses/coupes d'agneau peuvent arriver congelées ou réfrigérées. Les charges parasitaires estimées les plus élevées ont été observées dans les muscles squelettiques et plus particulièrement dans les parties comestibles telles que le quadriceps fémoral, les muscles intercostaux, le deltoïde et le diaphragme avec une différence significative de charge parasitaire détectable entre les échantillons frais et congelés (p < 0,0001) ou l'infection naturelle et expérimentale (p < 0,0001). Les membres thoraciques et pelviens (3278 à 1048 parasites/g de muscle) ont été classés en tête de liste. L'ADN de T. gondii a été détecté dans toutes les parties comestibles étudiées de l'agneau. Ces résultats suggèrent que l'agneau représente un risque pour les consommateurs. Des investigations supplémentaires doivent être effectuées afin de confirmer les différences mentionnées ci-dessus chez plus d'animaux et dans différentes races.

Age and Giardia intestinalis Infection Impact Canine Gut Microbiota.

Giardia intestinalis is a flagellated protozoan responsible for giardiosis (also called giardiasis in humans), the most prevalent and widespread parasitic infection in humans and mammals worldwide. The intestinal microbiota is highly diverse and any alteration in its composition may impact on the health of the host. While studies on the mouse model of giardiosis described the role of the gut microbiota in host susceptibility to infection by the parasite, little is known about the gut microbiota during natural infections in dogs and particularly in puppies. In this study, we monitored naturally G. intestinalis-infected puppies for 3 months and quantified cyst excretion every 2 weeks. All puppies remained subclinically infected during the sampling period as confirmed by fecal examination. In parallel, we performed 16S Illumina sequencing of fecal samples from the different time points to assess the impact of G. intestinalis infection on gut microbiota development of the puppies, as well as gut health markers of immunity such as fecal IgA and calprotectin. Sequencing results revealed that the canine fecal microbiota of Giardia-infected puppies becomes more complex and less diverse with increasing age. In addition, significant differences in the structure of the microbiota were observed between puppies with high and low Giardia cyst excretion. Chronic subclinical G. intestinalis infection appears to be associated with some detrimental structural changes in the gut microbiota. G. intestinalis-associated dysbiosis is characterized by an enrichment of facultative anaerobic, mucus-degrading, pro-inflammatory species and opportunistic pathogens, as well as a reduction of Lactobacillus johnsonii at specific time points. Calprotectin levels increased with age, suggesting the establishment of chronic low-grade inflammation in puppies. Further work is needed to demonstrate whether these alterations in the canine gut microbiota could lead to a dysbiosis-related disease, such as irritable bowel syndrome (IBS) or inflammatory bowel disease (IBD).

Cryptosporidium parvum-Infected Neonatal Mice Show Gut Microbiota Remodelling Using High-Throughput Sequencing Analysis: Preliminary Results.

BACKGROUND: During the last decade, the scientific community has begun to investigate the composition and role of gut microbiota in normal health and disease. These studies have provided crucial information on the relationship between gut microflora composition and intestinal parasitic infection, and have demonstrated that many enteric pathogen infections are associated with altered gut microflora composition. In this study, we investigated the effects of Cryptosporidium parvum infection (zoonotic protozoan affecting a large range of vertebrates) on both qualitative and quantitative composition of gut microbiota in a CD-1 neonatal mouse model. METHODS: 5-day-old neonate mice were experimentally infected with 105Cryptosporidium parvum Iowa oocysts by oesophageal gavage. The intestinal microbiota of both infected (Cp+) and uninfected (Cp-) mice groups was examined by high-throughput sequencing of the bacterial 16S rDNA gene V3-V4 hypervariable region. RESULTS: The most consistent change in the microbiota composition of Cp+ mice was the increased proportion of bacterial communities belonging to the Phylum Bacteroidetes. In contrast, the microbiota of Cp- mice was associated with increased proportions of several Firmicutes and Actinobacteria phyla members. CONCLUSION: For the first time, our study provides evidence of an association between cryptosporidial infection and gut dysbiosis, thus contributing valuable knowledge to the as-yet little-explored field of Cryptosporidium-microbiota interactions in a neonatal mouse model.

Molecular characterization of zoonotic Cryptosporidium spp. and Giardia duodenalis pathogens in Algerian sheep.

Little is known about the presence of Cryptosporidium spp. and Giardia duodenalis in Algerian sheep, nor their potential role as zoonotic reservoirs. This study aimed to investigate the occurrence and distribution of these two protists in lambs. A total of 83 fecal samples were collected from lambs (< 40 days old) from 14 different farms. Samples were screened for Cryptosporidium spp. and Giardia duodenalis presence using immunofluorescent techniques (IF). Nested PCR of the small subunit ribosomal RNA (rRNA) gene, followed by restriction fragment length polymorphism (PCR-RFLP) and sequence analyses were used to identify Cryptosporidium species. C. parvum was further subtyped by sequencing the highly polymorphic 60 kDa glycoprotein (gp60) gene. For G. duodenalis, nested PCR of the glutamate dehydrogenase (gdh) and triose phosphate isomerase (tpi) genes was performed and then PCR-RFLP was used to identify G. duodenalis assemblages. Cryptosporidium oocysts and Giardia cysts were detected in 36/83 (43%) and 23/83 (28%) of fecal samples, respectively. Of the 21/36 (58%) Cryptosporidium samples that were positive with IF, 16/21 (76%) were identified as C. parvum, and 5/21 (24%) as C. ubiquitum. From 15C. parvum isolates, 2 subtypes were identified within the IIa subtype family, including IIaA21G2R1 (3/15) and IIaA13G2R1 (1/15), while IIdA16G1 (11/15) was the only subtype identified from the IId subtype family. Of the 16/23 (69%) G. duodenalis IF-positive samples, the most frequent assemblage was ruminant-specific assemblage E (10/16), followed by assemblage D (4/16), and A + E mixed assemblages (2/16). This study is the first to identify and genotype both Cryptosporidium spp. and Giardia duodenalis in Algerian lambs, and is also the first to describe G. duodenalis assemblage D in small ruminants. The presence of zoonotic C. parvum subtype families (IIa, IId), C. ubiquitum, as well as G. duodenalis assemblage A + E, indicates that sheep could play an important role as a potential reservoir for protists.

First identification of Cryptosporidium parvum zoonotic subtype IIaA15G2R1 in diarrheal lambs in France.

To date, no information is available about the presence of Cryptosporidium spp. in French sheep, nor their potential role as zoonotic reservoirs. A total of 23 fecal samples were collected from diarrheic lambs (<11 days old) from seven randomly selected farms. Cryptosporidium-oocysts were detected microscopically with Direct Immunofluorescence Assays (DFA) in 23/23 (100%) of fecal samples. PCR-RFLP of the 18S rRNA gene was used to determine species in all samples, and only Cryptosporidium parvum was identified. Isolates were subtyped by sequencing the 60 kDa glycoprotein (gp60) gene. Two zoonotic subtypes within the IIa subtype family were identified, including IIaA15G2R1 (22/23) and IIaA16G3R1 (1/23). This study reports for the first time the identification and genotyping of zoonotic C. parvum subtypes from lambs in France. Sheep could thus play an important role as potential reservoirs for this zoonotic protist.

Molecular characterization of Cryptosporidium isolates from diarrheal dairy calves in France.

Cryptosporidium is an obligate intracellular protist parasite infecting a wide range of vertebrate hosts and causes significant intestinal disease in both animals and humans, as some species are zoonotic. Cattle and especially calves have been identified as one of the most common reservoirs of this protist. However, little is known about the genetics of Cryptosporidium in calves in some regions of France. The aim of this study was to detect and isolate Cryptosporidium spp. in faecal samples from naturally infected pre-weaned calves (≤45 days-old) in France. A total of 35 diarrhoeic pre-weaned calf faecal samples were collected from 26 dairy cattle farms in six departments (French administrative provinces). Cryptosporidium presence was established by microscopically screening samples for oocystes with an immunofluorescent (DFA) staining method. DFA-positive samples were then analysed by PCR-RFLP and 18S rRNA gene sequencing to determine species. Cryptosporidium parvum-positive samples were subtyped via nested PCR analysis of a partial fragment of the 60 kDa glycoprotein (gp60) gene product. Data were then integrated into phylogenetic tree analysis. DFA revealed the presence of Cryptosporidium oocysts in 31 out of 35 (88%) samples. Combined with 18S rRNA gene analysis results, C. parvum was detected in 30 samples. Subtyping analysis in 27/30 samples (90%) of the C. parvum isolates revealed two zoonotic subtype families, IIa (24/27) and IId (3/27). Four subtypes were recognised within the subtype family IIa, including the hypertransmissible IIaA15G2R1 subtype that is the most frequently reported worldwide (21/27), IIaA17G3R1 (1/27), IIaA17G1R1 (1/27), and IIaA19G1R1 (1/27). Two subtypes were recognised within the IId subtype family including IIdA22G1 (2/27) and IIdA27G1 (1/27). These findings illustrate the high occurrence of Cryptosporidium in calves in dairy herds and increase the diversity of molecularly characterised C. parvum isolates with the first description of IIaA17G3R1, IIaA19G1R1, and IId subtypes in France. The presence of zoonotic C. parvum subtype families (IIa, IId) in this study suggests that pre-weaned calves are likely to be a significant reservoir of zoonotic C. parvum, and highlights the importance of animal to human cryptosporidiosis transmission risk. Further molecular studies in calves and small ruminants from other French regions are required to better understand the epidemiology of cryptosporidiosis in France.

Toxoplasma gondii in beef consumed in France: regional variation in seroprevalence and parasite isolation.

In France, the consumption of cattle and sheep meat appears to be a risk factor for infection of pregnant women with Toxoplasma gondii. Several nation-wide surveys in France have investigated the prevalence of T. gondii in sheep and pig meat, but little is known at present about the prevalence of the parasite in beef. The main objective of the present cross-sectional survey was to estimate the seroprevalence of T. gondii infection in beef consumed in France. A secondary objective was to attempt to isolate T. gondii from cattle tissues and to study the geographical and age variations of this seroprevalence. The overall estimate of seroprevalence of T. gondii in bovine carcasses (n = 2912), for a threshold of 1:6 was 17.38%. A strong age effect was observed (p < 0.0001) with a seroprevalence of 5.34% for calves (<8 months) and 23.12% for adults (>8 months). Seroprevalence estimates given by area of birth and area of slaughtering for adults showed that the areas with the highest seroprevalence were not the same between these two variables. Only two strains, corresponding to genotype II, were isolated from heart samples, indicating that there is a limited risk of human infection with T. gondii, which needs to be correlated with the food habit of consuming raw or undercook (bleu or saignant) beef. However, new questions have emerged, especially concerning the isolation of parasites from beef and the precise role of bovines, generally described as poor hosts for T. gondii, in human infection.

TITLE: Toxoplasma gondii dans la viande bovine consommée en France : variation régionale de la séroprévalence et isolement de parasites. ABSTRACT: En France, la consommation de viande bovine et ovine apparaît comme un facteur de risque pour la contamination des femmes enceintes par Toxoplasma gondii. Plusieurs enquêtes nationales ont été réalisées afin de déterminer le niveau de contamination par T. gondii de la viande ovine et porcine, en France, mais très peu est encore connu quant à la prévalence du parasite dans la viande bovine. La présente enquête transversale avait pour objectif principal d'estimer la séroprévalence de l'infection à T. gondii dans la viande bovine consommée en France, ainsi que d'isoler T. gondii à partir de tissus de bovins et d'étudier, à titre d'objectif secondaire, les variations géographiques et d'âge de cette prévalence. L'estimation globale de la séroprévalence de T. gondii dans les carcasses de bovins (n = 2912) était de 17,38 % (pour un seuil de dilution à 1:6). Un effet significatif de l'âge a été observé (p < 0,0001) avec une séroprévalence de 5,34 % pour les veaux (<8 mois) et de 23,12 % pour les adultes (>8 mois). Les estimations de séroprévalence données par zone de naissance et par zone d'abattage pour les adultes montrent que les zones de séroprévalence les plus élevées n'étaient pas les mêmes pour ces deux variables. Seulement deux souches, de génotype II, ont été isolées à partir d'échantillons de cœurs, soulignant que le risque d'infection humaine est limité, mais doit être corrélé avec les habitudes de consommation alimentaire de la viande bovine peu/pas cuite (bleu ou saignante). Cependant, de nouvelles questions se posent, notamment en ce qui concerne l'isolement du parasite à partir de la viande bovine, ainsi que le rôle précis des bovins, généralement décrits comme des hôtes médiocres pour T. gondii, dans la contamination humaine.

Bile Salt Hydrolase Activities: A Novel Target to Screen Anti-Giardia Lactobacilli?

Giardia duodenalis is a protozoan parasite responsible for giardiasis, a disease characterized by intestinal malabsorption, diarrhea and abdominal pain in a large number of mammal species. Giardiasis is one of the most common intestinal parasitic diseases in the world and thus a high veterinary, and public health concern. It is well-established that some probiotic bacteria may confer protection against this parasite in vitro and in vivo and we recently documented the implication of bile-salt hydrolase (BSH)-like activities from strain La1 of Lactobacillus johnsonii as mediators of these effects in vitro. We showed that these activities were able to generate deconjugated bile salts that were toxic to the parasite. In the present study, a wide collection of lactobacilli strains from different ecological origins was screened to assay their anti-giardial effects. Our results revealed that the anti-parasitic effects of some of the strains tested were well-correlated with the expression of BSH-like activities. The two most active strains in vitro, La1 and Lactobacillus gasseri CNCM I-4884, were then tested for their capacity to influence G. duodenalis infection in a suckling mice model. Strikingly, only L. gasseri CNCM I-4884 strain was able to significantly antagonize parasite growth with a dramatic reduction of the trophozoites load in the small intestine. Moreover, this strain also significantly reduced the fecal excretion of Giardia cysts after 5 days of treatment, which could contribute to blocking the transmission of the parasite, in contrast of La1 where no effect was observed. This study represents a step toward the development of new prophylactic strategies to combat G. duodenalis infection in both humans and animals.

Bile-Salt-Hydrolases from the Probiotic Strain Lactobacillus johnsonii La1 Mediate Anti-giardial Activity in Vitro and in Vivo.

Giardia duodenalis (syn. G. lamblia, G. intestinalis) is the protozoan parasite responsible for giardiasis, the most common and widely spread intestinal parasitic disease worldwide, affecting both humans and animals. After cysts ingestion (through either contaminated food or water), Giardia excysts in the upper intestinal tract to release replicating trophozoites that are responsible for the production of symptoms. In the gut, Giardia cohabits with the host's microbiota, and several studies have revealed the importance of this gut ecosystem and/or some probiotic bacteria in providing protection against G. duodenalis infection through mechanisms that remain incompletely understood. Recent findings suggest that Bile-Salt-Hydrolase (BSH)-like activities from the probiotic strain of Lactobacillus johnsonii La1 may contribute to the anti-giardial activity displayed by this strain. Here, we cloned and expressed each of the three bsh genes present in the L. johnsonii La1 genome to study their enzymatic and biological properties. While BSH47 and BSH56 were expressed as recombinant active enzymes, no significant enzymatic activity was detected with BSH12. In vitro assays allowed determining the substrate specificities of both BSH47 and BSH56, which were different. Modeling of these BSHs indicated a strong conservation of their 3-D structures despite low conservation of their primary structures. Both recombinant enzymes were able to mediate anti-giardial biological activity against Giardia trophozoites in vitro. Moreover, BSH47 exerted significant anti-giardial effects when tested in a murine model of giardiasis. These results shed new light on the mechanism, whereby active BSH derived from the probiotic strain Lactobacillus johnsonii La1 may yield anti-giardial effects in vitro and in vivo. These findings pave the way toward novel approaches for the treatment of this widely spread but neglected infectious disease, both in human and in veterinary medicine.

The limits of test-based scrapie eradication programs in goats.

Small ruminant post-mortem testing programs were initially designed for monitoring the prevalence of prion disease. They are now considered as a potential alternative to genetic selection for eradicating/controlling classical scrapie at population level. If such policy should be implemented, its success would be crucially dependent on the efficiency of the surveillance system used to identify infected flocks. In this study, we first determined the performance of post-mortem classical scrapie detection in eight naturally affected goat herds (total n = 1961 animals) according to the age at culling. These results provided us with necessary parameters to estimate, through a Monte Carlo simulation model, the performance of scrapie detection in a commercial population. According to this model, whatever the number of tests performed, post mortem surveillance will have limited success in identifying infected herds. These data support the contention that scrapie eradication programs relying solely on post mortem testing in goats will probably fail. Considering the epidemiological and pathological similarities of scrapie in sheep and goats, the efficiency of scrapie surveillance in both species is likely to be similar.

New strategy for the survey of Toxoplasma gondii in meat for human consumption.

Monitoring of Toxoplasma infection in animals destined for human consumption is a great challenge for human toxoplasmosis prevention. This study aimed to compare results obtained from a naturally infected population of sheep using different tests and targeting an original matrix: meat samples and muscle fluids collected at the slaughterhouse. A commercial ELISA test was performed on diaphragm fluids from 419 ovine carcasses collected at the slaughterhouse. A MAT (modified agglutination test) was performed on heart fluids obtained from the same animals. In addition, all hearts were bioassayed in mice. Serological test agreement, the relative sensitivity of ELISA MAT and mouse bioassay as well as a correlation between titres and parasite isolation probability were statistically evaluated. The overall agreement (kappa coefficient=0.64) of ELISA on diaphragm fluids and MAT on heart fluids is substantial and subsequently both tests can be used for epidemiological studies. Relative sensitivity was higher for MAT performed on cardiac fluids (90%) than ELISA on diaphragm fluid (61%). For both serological tests, relative sensitivity is lower in lambs younger than 12 months. Relative sensitivity of mouse inoculation was 42%. A significant correlation was obtained between increasing MAT titres and probability to isolate live parasite from the heart. When the fluid titre was higher than 1:16, parasites were isolated in 65% of cases. When it was lower, isolation failed in 95% of the cases. According to our results, cardiac fluids appear to be a relevant matrix for toxoplasmosis survey in meat.

An innovative survey underlining the significant level of contamination by Toxoplasma gondii of ovine meat consumed in France.

Consumption of sheep meat presents a risk of human contamination by Toxoplasma gondii. A nationwide study was conducted in France to evaluate the prevalence of Toxoplasma in fresh ovine meat. A sampling procedure was established to guarantee the representativity of consumption. As is the case for meat consumed, half of the samples were from France and half were imported from other countries. Animals were selected according to their age, as lamb (<12months) represents 90% of the meat consumed. Available data for French samples allowed the selection of 16 districts distributed in seven areas according to their density of production. Diaphragms and hearts from 433 sheep were collected. Diaphragms were collected from 398 imported carcasses. Fluids from hearts and diaphragms were tested serologically. All hearts were bioassayed in mice and parasite isolates were genotyped using PCR-restriction fragment length polymorphism and microsatellite markers. Prevalence estimates were calculated, taking into account uneven distribution of production and age. For French meat, the effect of area, age and their interactions was evaluated. The overall estimate of Toxoplasma seroprevalence was 17.7% (11.6-31.5%) for lambs and 89% (73.5-100%) for adults (P<0.0001). No significant difference was observed between imported and French meat. In France, seroprevalence in lambs showed an increasing North-western to Southern gradient. The proportion of French carcasses carrying live parasites according to bioassay results was estimated at 5.4% (3-7.5%) (45 genotype II; one genotype III). This study offers an accurate drawing of the toxoplasmosis pattern amongst sheep consumed in France and a model for a zoonosis hazard control survey.