Taxonomic and functional dynamics during chytrid epidemics in an aquatic ecosystem.

Fungal parasitism is common in plankton communities and plays a crucial role in the ecosystem by balancing nutrient cycling in the food web. Previous studies of aquatic ecosystems revealed that zoosporic chytrid epidemics represent an important driving factor in phytoplankton seasonal successions. In this study, host-parasite dynamics in Lake Pavin (France) were investigated during the spring diatom bloom while following chytrid epidemics using next generation sequencing (NGS). Metabarcoding analyses were applied to study changes in the eukaryotic microbial community throughout diatom bloom-chytrid epidemics. Relative read abundances of metabarcoding data revealed potential "beneficiaries" and "victims" during the studied period. Subsequently, metatranscriptomic analyses on samples before and during the chytrid epidemic unveiled the active part of the community and functional/metabolic dynamics in association with the progress of chytrid infection. Diatom functions involving lipases, transporters, histones, vacuolar systems, the proteasome, proteases and DNA/RNA polymerases were more abundant during the diatom bloom. Chytrid functions related to a parasitic lifestyle including invasion, colonization and stress tolerance were up-regulated during the chytrid epidemic. In addition, functions related to the degradation/metabolism of proteins, lipids and chitin were in higher proportion in the community during the epidemic event. Results of NGS and bioinformatics analyses offered a panorama of dynamic biodiversity and biological functioning of the community.

Proteogenomic Insights into the Intestinal Parasite Blastocystis sp. Subtype 4 Isolate WR1.

Blastocystis sp. is known for years as a highly prevalent anaerobic eukaryotic parasite of humans and animals. Several monophyletic clades have been delineated based on molecular data, and the occurrence of each subtype in humans and/or animal hosts has been documented. The genome of several representatives has been sequenced revealing specific traits such as an intriguing 3'-end processing of primary transcripts. Here, a first high-throughput proteomics dataset acquired on this difficult-to-cultivate parasite is presented for the zoonotic subtype T4 isolate WR1. Amongst the 2766 detected proteins, we highlighted the role of a small ADP ribosylation factor GTP-binding protein involved in intracellular traffic as major regulator of vesicle biogenesis and a voltage-dependent anion-selective channel protein because both were unexpectedly highly abundant. We show how these data may be used for gaining proteogenomics insights into Blastocystis sp. specific molecular mechanisms. We evidenced for the first time by proteogenomics a functional termination codon derived from transcript polyadenylation for seven different key cellular components.

Prevalence, transmission, and host specificity of Cryptosporidium spp. in various animal groups from two French zoos.

Cryptosporidium represents a major cause of gastrointestinal illness in humans and animals including domestic, wild, and in captivity animals, and more than 30 validated species of Cryptosporidium are recognized as infectious to different hosts such as mammals, birds, reptiles, amphibians, and fish. Therefore, numerous investigations have been conducted worldwide in order to shed light on the epidemiology of this parasite and to explore its potential reservoirs. Few surveys, targeting humans and animals have been carried out regarding the epidemiology of Cryptosporidium spp. in France and no data are available about the circulation of this parasite in French zoological gardens. Herein, we determined the prevalence of Cryptosporidium in animals housed in two French zoos. A total of 307 fecal samples belonging to 161 species were screened by nested PCR. Overall, Cryptosporidium DNA was detected in 1.9% of the 161 species and 1% of the total number of fecal samples tested. Additionally, three Cryptosporidium species were identified: C. galli, C. andersoni, and C. tyzzeri. To our knowledge, this is the first molecular study focused on Cryptosporidium infection in captivity animals in France. This study is of interest considering the exposure of a large number of humans and animals to this waterborne protozoan, found ubiquitously in the environment.

Prevalence, risk factors for infection and subtype distribution of the intestinal parasite Blastocystis sp. from a large-scale multi-center study in France.

BACKGROUND: Blastocystis sp. is the most common intestinal parasite of humans. Despite its potential public health impact, epidemiological data regarding the prevalence and molecular subtype distribution of Blastocystis sp. in Europe are rarely reported. Therefore, the first multi-center epidemiological survey performed in Europe was conducted in France to diagnose and subtype Blastocystis sp. and to identify risk factors for infection. METHODS: Stool samples from 788 patients were collected either in summer or winter in 11 hospitals throughout France together with patient data. All stool samples were tested for the presence of Blastocystis sp. by quantitative PCR targeting the SSU rDNA gene. Positive samples were sequenced to determine the distribution of the subtypes in our cohort. Statistical analyses were performed to identify potential risk factors for infection. RESULTS: Using quantitative PCR, the overall prevalence of Blastocystis sp. was shown to reach 18.1 %. The prevalence was significantly higher in summer (23.2 %) than in winter (13.7 %). Travellers or subjects infected with other enteric parasites were significantly more infected by Blastocystis sp. than non-travellers or subjects free of other enteric parasites, respectively. Different age-related epidemiological patterns were also highlighted from our data. The prevalence of Blastocystis sp. was not significantly higher in patients with digestive symptoms or diagnosed with chronic bowel diseases. Among symptomatic patients, Blastocystis sp. infection was significantly associated with abdominal pain. Gender, socioeconomic status, and immune status were not identified as potential risk factors associated with infection. Among a total of 141 subtyped isolates, subtype 3 was predominant (43.3 %), followed by subtype 1 and subtype 4 (20 %), subtype 2 (12.8 %), subtype 6 and subtype 7 (2.1 %). No association between ST and clinical symptoms was statistically evidenced. CONCLUSIONS: A high prevalence of Blastocystis sp. infection was found in our French patient population. Seasonal impact on the prevalence of Blastocystis sp. was highlighted and recent travels and age were identified as main risk factors for infection. Most cases were caused by subtypes 1 to 4, with a predominance of subtype 3. Large variations in both prevalence and ST distribution between hospitals were also observed, suggesting distinct reservoirs and transmission sources of the parasite.

Acute blastocystis-associated appendicular peritonitis in a child, Casablanca, Morocco.

Despite increasing reports that Blastocystis infection is associated with digestive symptoms, its pathogenicity remains controversial. We report appendicular peritonitis in a 9-year-old girl returning to France from Morocco. Only Blastocystis parasites were detected in stools, appendix, peritoneal liquid, and recto-uterine pouch. Simultaneous gastroenteritis in 26 members of the child's family suggested an outbreak.

Winter-summer succession of unicellular eukaryotes in a meso-eutrophic coastal system.

The objective of this study was to explore the succession of planktonic unicellular eukaryotes by means of 18S rRNA gene tag pyrosequencing in the eastern English Channel (EEC) during the winter to summer transition. The 59 most representative (>0.1%, representing altogether 95% of total reads), unique operational taxonomic units (OTUs) from all samples belonged to 18 known high-level taxonomic groups and 1 unaffiliated clade. The five most abundant OTUs (69.2% of total reads) belonged to Dinophyceae, Cercozoa, Haptophyceae, marine alveolate group I, and Fungi. Cluster and network analysis between samples distinguished the winter, the pre-bloom, the Phaeocystis globosa bloom and the post-bloom early summer conditions. The OTUs-based network revealed that P. globosa showed a relatively low number of connections-most of them negative-with all other OTUs. Fungi were linked to all major taxonomic groups, except Dinophyceae. Cercozoa mostly co-occurred with the Fungi, the Bacillariophyceae and several of the miscellaneous OTUs. This study provided a more detailed exploration into the planktonic succession pattern of the EEC due to its increased depth of taxonomic sampling over previous efforts based on classical monitoring observations. Data analysis implied that the food web concept in a coastal system based on predator-prey (e.g. grazer-phytoplankton) relationships is just a part of the ecological picture; and those organisms exploiting a variety of strategies, such as saprotrophy and parasitism, are persistent and abundant members of the community.

Children of Senegal River Basin show the highest prevalence of Blastocystis sp. ever observed worldwide.

BACKGROUND: Blastocystis sp. is currently the most common intestinal protist found in human feces and considered an emerging parasite with a worldwide distribution. Because of its potential impact in public health, we reinforced the picture of Blastocystis sp. prevalence and molecular subtype distribution in Africa by performing the first survey of this parasite in Senegal. METHODS: Stool samples from 93 symptomatic presenting with various gastrointestinal disorders or asymptomatic children living in three villages of the Senegal River Basin were tested for the presence of Blastocystis sp. by non-quantitative and quantitative PCR using primer pairs targeting the SSU rDNA gene. Positive samples were subtyped to investigate the frequency of Blastocystis sp. subtypes in our cohort and the distribution of subtypes in the symptomatic and asymptomatic groups of children. RESULTS: By the use of molecular tools, all 93 samples were found to be positive for Blastocystis sp. indicating a striking parasite prevalence of 100%. Mixed infections by two or three subtypes were identified in eight individuals. Among a total of 103 subtyped isolates, subtype 3 was most abundant (49.5%) followed by subtype 1 (28.2%), subtype 2 (20.4%) and subtype 4 (1.9%). Subtype 3 was dominant in the symptomatic group while subtypes 1 and 2 were detected with equal frequency in both symptomatic and asymptomatic groups. The distribution of subtypes was compared with those available in other African countries and worldwide. Comparison confirmed that subtype 4 is much less frequently detected or absent in Africa while it is commonly found in Europe. Potential sources of Blastocystis sp. infection including human-to-human, zoonotic, and waterborne transmissions were also discussed. CONCLUSIONS: The prevalence of Blastocystis sp. in our Senegalese population was the highest prevalence ever recovered worldwide for this parasite by reaching 100%. All cases were caused by subtypes 1, 2, 3 and 4 with a predominance of subtype 3. More than half of the children infected by Blastocystis sp. presented various gastrointestinal disorders. Such high prevalence of blastocystosis in developing countries makes its control a real challenge for public health authorities.

Frequency and Molecular Identification of Cryptosporidium in Adult Prim'Holstein Dairy Cattle Farms in the North of France.

Cryptosporidium apicomplexan protozoa are ubiquitous intracellular agents affecting humans and animals. In particular, bovine cryptosporidiosis is recognized as endemic worldwide. However, epidemiological investigations remain limited in France regarding the burden of these parasites in cattle. To improve our understanding of the epidemiology of cryptosporidiosis, the main aim of this study was to determine the frequency and the genetic diversity of Cryptosporidium in adult Prim'Holstein dairy cattle farms in the north of France. Fecal specimens were collected from 1454 non-diarrheic and non-pregnant animals (nulli-, primi-, or multiparous) throughout 20 farms in an area of 110 km around Lille. For Cryptosporidium species identification, nested PCR followed by sequence and phylogenetic analyses were used. The overall frequency of Cryptosporidium spp. in-fection was 30.00% (C.I. 95%: 12.83-54.33) in farms and 0.89% (C.I. 95%: 0.498-1.57) at the individual level. In primi- or multiparous cows, only C. andersoni was found. C. ryanae, C. bovis/xiaoi and C. andersoni were detected in heifers. The phylogenetic tree confirmed that analyzed sequences were grouped with known reference sequences reported in dairy cattle. Further studies on the cumulative prevalence, risks factors and pathogenicity are needed to give a more accurate assessment of the impact of Cryptosporidium infection in dairy cattle in France.

Molecular Identification and Subtype Analysis of Blastocystis sp. Isolates from Wild Mussels (Mytilus edulis) in Northern France.

Blastocystis sp. is the most common single-celled eukaryote colonizing the human gastrointestinal tract worldwide. Because of the proven zoonotic potential of this protozoan, sustained research is therefore focused on identifying various reservoirs of transmission to humans, and in particular animal sources. Numerous groups of animals are considered to be such reservoirs due to their handling or consumption. However, some of them, including mollusks, remain underexplored. Therefore, a molecular epidemiological survey conducted in wild mussels was carried out in Northern France (Hauts-de-France region) to evaluate the frequency and subtypes (STs) distribution of Blastocystis sp. in these bivalve mollusks. For this purpose, 100 mussels (Mytilus edulis) were randomly collected in two sampling sites (Wimereux and Dannes) located in the vicinity of Boulogne-sur-Mer. The gills and gastrointestinal tract of each mussel were screened for the presence of Blastocystis sp. by real-time polymerase chain reaction (qPCR) assay followed by direct sequencing of positive PCR products and subtyping through phylogenetic analysis. In parallel, sequences of potential representative Blastocystis sp. isolates that were previously obtained from temporal surveys of seawater samples at marine stations offshore of Wimereux were integrated in the present analysis. By taking into account the qPCR results from all mussels, the overall prevalence of the parasite was shown to reach 62.0%. In total, more than 55% of the positive samples presented mixed infections. In the remaining mussel samples with a single sequence, various STs including ST3, ST7, ST14, ST23, ST26 and ST44 were reported with varying frequencies. Such distribution of STs coupled with the absence of a predominant ST specific to these bivalves strongly suggested that mussels might not be natural hosts of Blastocystis sp. and might rather be carriers of parasite isolates from both human and animal (bovid and birds) waste. These data from mussels together with the molecular identification of isolates from marine stations were subsequently discussed along with the local geographical context in order to clarify the circulation of this protozoan in this area. The identification of human and animal STs of Blastocystis sp. in mussels emphasized the active circulation of this protozoan in mollusks and suggested a significant environmental contamination of fecal origin. This study has provided new insights into the host/carrier range and transmission of Blastocystis sp. and emphasized its potential as an effective sentinel species for water quality and environmental contamination.

Prevalence of Intestinal Parasitosis in Guinea: Systematic Review of the Literature and Meta-Analysis.

BACKGROUND: Intestinal parasitosis constitute a major public health issue, particularly in sub-tropical and tropical areas. Even though they are classified as neglected tropical diseases, no national study has been carried out recently in Guinea to estimate the prevalence of intestinal parasitosis. OBJECTIVE: A systematic review and meta-analysis aimed to determine the overall prevalence of intestinal parasitosis in Guinea. METHOD: The PRISMA method was used to perform a systematic review and meta-analysis. The studies carried out in order to study intestinal parasitosis in Guinea and published between 2010 and 2020 were searched in online public databases. The prevalence of parasitosis was calculated by a random-effects meta-analysis. Subgroup comparisons were performed using Q-tests. Statistical analyses were performed with the R software. This review was registered with PROSPERO under the identification number CRD42022349743. RESULTS: 69 studies were selected out of 1230 studies identified in online public databases. The meta-analysis involved 44,186 people with an overall prevalence of intestinal parasitic infections of 52%. CONCLUSIONS: This is the first study in Guinea to assess the prevalence of intestinal parasitic infections in different regions of the country. It was found that intestinal parasitosis are a real health problem in Guinea, hence, the need to put in place national strategies for regular control.

Prevalence and Association of Campylobacter spp., Salmonella spp., and Blastocystis sp. in Poultry.

Poultry and poultry meat are considered the most important sources of human campylobacteriosis and salmonellosis. However, data about the occurrence of Campylobacter and Salmonella concomitantly with intestinal protozoa such as Blastocystis sp. in poultry remain very scarce. Therefore, this study aimed to investigate the presence and possible interactions between these three microorganisms in fecal samples from 214 chickens collected either on farms or from live bird markets in Egypt. The results obtained showed that Campylobacter spp., Salmonella spp., and Blastocystis sp. were present in 91.6% (196/214), 44.4% (95/214), and 18.2% (39/214) of tested samples, respectively, highlighting an active circulation of these microorganisms. Moreover, a significant positive correlation was reported between the occurrence of Campylobacter spp. and Blastocystis sp. together with a significant negative correlation between Blastocystis sp. and Salmonella spp. This study confirms the association reported previously between Blastocystis sp. and Campylobacter spp. while disclosing an association between Blastocystis sp. and Salmonella spp.; it also highlights the need to improve studies on the interactions between bacteria and eukaryotes in the gut microbiota of poultry.

First Epidemiological Survey on the Prevalence and Subtypes Distribution of the Enteric Parasite Blastocystis sp. in Vietnam.

Although Blastocystis sp. is the most common enteric protozoan in human stools worldwide, various geographical areas remain to be investigated regarding the frequency and circulation of this parasite. Such is the case of some developing countries in Southeast Asia that exhibit a higher risk for parasitic infections due to unsanitary conditions. While several epidemiological surveys have been conducted, for instance, in Thailand, little or no data are available from neighboring countries, such as Vietnam. Therefore, in order to determine the prevalence and subtype (ST) distribution of Blastocystis sp. and to clarify the transmission of the parasite, the first molecular epidemiological survey ever conducted in this country was performed. For this purpose, a total of 310 stool specimens were collected from patients enrolled at the Family Hospital of Da Nang and then tested for the presence of Blastocystis sp. by real-time Polymerase Chain Reaction (qPCR), followed by subtyping of the isolates. The overall prevalence of the parasite reached 34.5% in this Vietnamese cohort. No significant association was found between parasite infection and gender, age, symptomatic status, contact with animals or source of drinking water. Out of the 107 positive patients, nearly half presented mixed infections. Therefore, some of the corresponding samples were reanalyzed by end-point PCR, followed by PCR products cloning and sequencing. Of the 88 total subtyped isolates, ST3 was predominant, followed by ST10, ST14, ST7, ST1, ST4, ST6 and ST8. Our study was, thus, the first to report ST8, ST10 and ST14 in the Southeast Asian population. The predominance of ST3 within this Vietnamese cohort, coupled with its low intra-ST genetic variability, reflected a large inter-human transmission, while ST1 transmission was suggested to be not only anthroponotic, but also likely correlated to animal or environmental sources. Strikingly, isolates considered of animal origin (ST6-ST8, ST10 and ST14) accounted for more than 50% of the subtyped isolates. These findings improved our knowledge of the epidemiology and circulation of Blastocystis sp. in Southeast Asia, and in particular, in Vietnam, and highlighted both a major burden of the parasite in this country and a high risk of zoonotic transmission, mainly from poultry and livestock.

Molecular Epidemiology and Genetic Diversity of the Enteric Protozoan Parasite Blastocystis sp. in the Northern Egypt Population.

Blastocystis sp. is currently reported as the most frequent single-celled eukaryote inhabiting the intestinal tract of humans and a wide range of animal groups. Its prevalence is especially higher in developing countries linked with fecal peril. Despite a growing interest in this enteric protozoan, certain geographical regions potentially at high risk of infection, such as North Africa, remain under-investigated. Therefore, a large-scale molecular epidemiological survey, including 825 participants presenting digestive disorders or not, was conducted in five governorates located in Northern Egypt. A real-time polymerase chain reaction (qPCR) assay was performed to identify the parasite in stool samples, followed by direct sequencing of the positive PCR products for subtyping and genotyping of the corresponding isolates. The overall prevalence was shown to reach 72.4% in the Egyptian cohort, coupled with a variable frequency depending on the governorate (41.3 to 100%). Among the 597 positive participants, a large proportion of them (39.4%) presented mixed infections, as determined by sequencing. The remaining individuals with single infection were predominantly colonized by subtype 3 (ST3) (48.3%) followed by ST1 (39.5%), ST2 (10.8%), ST14 (1.1%), and ST10 (0.3%). This was the first report of ST10 and ST14 in North Africa. Age, sex, digestive symptoms, and health status of the participants or contact with animals were not identified as significant risk factors for Blastocystis sp. occurrence or affecting the ST distribution. In contrast, substantial variations in the prevalence and ST distribution of the parasite were reported according to the governorate. Genotyping of isolates revealed the lower intra-ST diversity for ST3, followed by ST1 and then ST2. By combining subtyping and genotyping data, a widespread inter-human transmission was strongly suggested for ST3 within the Egyptian cohort. Regarding ST1 and ST2, additional animal or environmental sources of infection by these STs have been proposed, whereas the few cases of colonization by ST10 and ST14 were likely the result of zoonotic transmission from bovid. These investigations clearly emphasized the active circulation of Blastocystis sp. in Northern Egypt and the necessity for health authorities to implement prevention campaigns towards the population and quality control of drinking water, with the aim of reducing the burden of this enteric protozoan in this endemic country.

Prevalence, Subtype Distribution and Zoonotic Significance of Blastocystis sp. Isolates from Poultry, Cattle and Pets in Northern Egypt.

Blastocystis sp. is a widespread enteric protozoan that frequently infects human and animal groups. Despite its burden and zoonotic potential worldwide, epidemiological investigations remain limited in animal groups that come in contact with humans. Therefore, the largest survey ever conducted in North Africa was performed in Egypt with the aim to investigate the prevalence and subtype (ST) distribution of Blastocystis sp. in animals. For this purpose, a total of 889 fecal specimens were collected from chickens (217), cattle (373), dogs (144) and cats (155) from six governorates of northern Egypt. These specimens were then screened for the presence of Blastocystis sp. using a quantitative real-time PCR, followed by subtyping the isolates. The overall prevalence of Blastocystis sp. reached 9.2% (82/889), with the highest infection rates reported in chickens (17.0%) and domestic cattle (11.0%), highlighting an active circulation of the parasite in both animal groups. In contrast, the low prevalence in cats (2.6%) and the absence of the parasite in dogs suggested that pets are not natural hosts of Blastocystis sp. ST10 and ST14 were largely predominant in cattle, confirming that both STs represented cattle-adapted STs. The report of one ST3 and one ST4 isolate in this animal group could be explained by an accidental zoonosis from humans to animals. All but one of the subtyped isolates in poultry belonged to ST7, which was considered as an avian ST. The presence of a remaining isolate of ST14 likely reflected a transient infection from contact between birds and cattle feces. The same environmental contamination was also likely the source of the ST14 infection in three of the four positive cats, with the remaining animals infected by ST3 as the result of human-to-animal transmission. These occurrences and subtyping data, combined with those previously collected in the Egyptian population, implies that poultry could play a significant role as reservoir for zoonotic transmission, which would not be the case for cattle and pets.

Detection, Molecular Identification and Transmission of the Intestinal Protozoa Blastocystis sp. in Guinea from a Large-Scale Epidemiological Study Conducted in the Conakry Area.

Blastocystis sp. is a single-celled parasite estimated to colonize the digestive tract of 1 to 2 billion people worldwide. Although it represents the most frequent intestinal protozoa in human stools, it remains still under-investigated in countries with a high risk of infection due to poor sanitary and hygiene conditions, such as in Africa. Therefore, the present study was carried out to determine the prevalence and subtype (ST) distribution of Blastocystis sp. in the Guinean population. For this purpose, fecal samples were collected from 500 individuals presenting or not digestive disorders in two hospitals of Conakry. Search for the parasite in stools was performed by real-time PCR targeting the small subunit rDNA gene followed by sequencing of the PCR products for subtyping of the isolates. A total of 390 participants (78.0%) was positive for Blastocystis sp. Five STs were identified in the Guinean cohort (ST1, ST2, ST3, ST4 and ST14) with varying frequency, ST3 being predominant. Among them, ST4 was found in only two patients confirming its global rarity in Africa whereas infections by ST14 were likely the result of zoonotic transmission from bovid. No significant association was detected between Blastocystis sp. colonization or ST distribution and the symptomatic status of Guinean subjects or the presence of digestive symptoms. In contrast, drilling water consumption represented a significant risk factor for infection by Blastocystis sp. Predominance of ST3 coupled with its low intra-ST diversity strongly suggested large-scale human-to-human transmission of this ST within this cohort. In parallel, the highest intra-ST diversity of ST1 and ST2 was likely correlated with various potential sources of infection in addition to anthroponotic transmission. These findings highlighted the active circulation of the parasite in Guinea as reported in some low-income African countries and the necessity to implement prevention and control measures in order to limit the circulation of this parasite in this endemic geographical area.

A national study through a 'Farm-to-fork' Approach to determine Salmonella dissemination along with the Lebanese poultry production chain.

This cross-sectional study was conducted to determine the prevalence of Salmonella at different stages of the broiler production chain and layer flocks in addition to their antibiotic resistance profile and molecular patterns. Over a period of 3 years, different sample matrices were collected from Lebanese farms, slaughterhouses and retail markets. Out of 672 Salmonella serotyped, 514 were analysed for antimicrobial resistance and 214 for clonality using Pulsed-field gel electrophoresis (PFGE). The results highlighted an important prevalence of Salmonella, 30% in farms, 35.8% in slaughterhouses and 22.4% at retail level. A large diversity of serotypes was identified with predominance among Salmonella Infantis (32.9%), Salmonella Enteritidis (28.4%) and Salmonella Kentucky (21.4%). High resistance to nalidixic acid was revealed in all the isolates. The most prominent resistance was exhibited in S. Kentucky and S. Infantis. The latter was resistant to tetracycline (99%), streptomycin (88.2%) and remarkable multi-drug resistance (MDR) (89.7%). All S. Kentucky isolates were resistant to ciprofloxacin, MDR (62.4%) and 6% were resistant to extended-spectrum cephalosporin (ESCs). One persistent clone of S. Enteritidis was found common between poultry and humans. Similar genomic profiles were detected between farms, slaughterhouses and retail suggesting the dissemination of identical clones throughout the food chain possibly due to weak barriers preventing such transmission.

Putative SET-domain methyltransferases in Cryptosporidium parvum and histone methylation during infection.

Cryptosporidium parvum is a leading cause of diarrhoeal illness worldwide being a significant threat to young children and immunocompromised patients, but the pathogenesis caused by this parasite remains poorly understood. C. parvum was recently linked with oncogenesis. Notably, the mechanisms of gene expression regulation are unexplored in Cryptosporidium and little is known about how the parasite impact host genome regulation. Here, we investigated potential histone lysine methylation, a dynamic epigenetic modification, during the life cycle of the parasite. We identified SET-domain containing proteins, putative lysine methyltransferases (KMTs), in the C. parvum genome and classified them phylogenetically into distinct subfamilies (namely CpSET1, CpSET2, CpSET8, CpKMTox and CpAKMT). Our structural analysis further characterized CpSET1, CpSET2 and CpSET8 as histone lysine methyltransferases (HKMTs). The expression of the CpSET genes varies considerably during the parasite life cycle and specific methyl-lysine antibodies showed dynamic changes in parasite histone methylation during development (CpSET1:H3K4; CpSET2:H3K36; CpSET8:H4K20). We investigated the impact of C. parvum infection on the host histone lysine methylation. Remarkably, parasite infection led to a considerable decrease in host H3K36me3 and H3K27me3 levels, highlighting the potential of the parasite to exploit the host epigenetic regulation to its advantage. This is the first study to describe epigenetic mechanisms occurring throughout the parasite life cycle and during the host-parasite interaction. A better understanding of histone methylation in both parasite and host genomes may highlight novel infection control strategies.

Exploring and quantifying fungal diversity in freshwater lake ecosystems using rDNA cloning/sequencing and SSU tag pyrosequencing.

Water samples were collected along transects from the shore to the centre of two French lakes: the deep, volcanic, oligomesotrophic and low allochthonic-impacted Lake Pavin, and the productive and higher allochthonic-impacted Lake Aydat. The biodiversity was analysed using two approaches: the classical approach consisting of cloning/sequencing of the 18S, ITS1, 5.8S, ITS2 and partial 28S region using primers designed for fungus sequences, and the pyrosequencing of 18S rRNA hypervariable V2, V3 and V5 regions using two primer sets (one universal for eukaryotes and one for fungi). The classical approach yielded 146 (Lake Pavin) and 143 (Lake Aydat) sequences, corresponding to 46 and 63 operational taxonomic units (OTUs) respectively. Fungi represented half of the OTUs identified in Lake Pavin and 30% in Lake Aydat, and were dominated by sequences from Chytridiomycota found throughout Lake Pavin but mostly in the central pelagic zone of Lake Aydat. The pyrosequencing approach yielded 42,064 (Pavin) and 61,371 (Aydat) reads, of which 12-15% and 9-19% reads were assigned to fungi in Lakes Pavin and Aydat respectively. Chytridiomycota members were also dominant among these reads, with OTUs displaying up to > 33-fold overrepresentation in the centre compared with the riparian areas of Lake Aydat. Besides fungi, both approaches revealed other major eukaryote groups, with the highest diversity in the central areas of lakes. One of the major findings of our study was that the two lakes displayed contrasting spatial distributions, homogenous for Lake Pavin and heterogeneous for Lake Aydat, which may be related to their peculiarities. This study represents the first unveiling of microbial eukaryote and fungus diversity assessed with two complementary molecular methods, and is considered a major milestone towards understanding the dynamics and ecology of fungi in freshwater lake ecosystems, which are directly link to the abundance and distribution of taxa.

Pneumocystis: from a doubtful unique entity to a group of highly diversified fungal species.

At the end of the 20th century the unique taxonomically enigmatic entity called Pneumocystis carinii was identified as a heterogeneous group of microscopic Fungi, constituted of multiple stenoxenic biological entities largely spread across ecosystems, closely adapted to, and coevolving in parallel with, mammal species. The discoveries and reasoning that led to the current conceptions about the taxonomy of Pneumocystis at the species level are examined here. The present review also focuses on the biological, morphological and phylogenetical features of Pneumocystis jirovecii, Pneumocystis oryctolagi, Pneumocystis murina, P. carinii and Pneumocystis wakefieldiae, the five Pneumocystis species described until now, mainly on the basis of the phylogenetic species concept. Interestingly, Pneumocystis organisms exhibit a successful adaptation enabling them to dwell and replicate in the lungs of both immunocompromised and healthy mammals, which can act as infection reservoirs. The role of healthy carriers in aerial disease transmission is nowadays recognized as a major contribution to Pneumocystis circulation, and Pneumocystis infection of nonimmunosuppressed hosts has emerged as a public health issue. More studies need to be undertaken both on the clinical consequences of the presence of Pneumocystis in healthy carriers and on the intricate Pneumocystis life cycle to better define its epidemiology, to adapt existing therapies to each clinical context and to discover new drug targets.

Molecular subtyping of Blastocystis sp. isolates from symptomatic patients in Italy.

Blastocystis sp. is the most common eukaryotic parasite in the intestinal tract of humans. Due to its potential impact in public health, we determined the Blastocystis sp. subtypes (STs) and their relative frequency in symptomatic patients living in or in the vicinity of two Italian cities (Rome and Sassari). A total of 34 Blastocystis sp. isolates corresponding to 26 single and 4 mixed infections were subtyped using partial small subunit ribosomal RNA gene sequencing. From this molecular approach, the ST distribution in the present Italian population was as follows: ST3 (47.1%), ST2 (20.6%), ST4 (17.7%), ST1 (8.8%), and ST7, and ST8 (2.9%). As in almost all countries worldwide, ST3 was the most common ST reinforcing the hypothesis of its human origin. Together with a previous preliminary report, a total of seven STs (with the addition of ST5) have been found in Italian symptomatic patients. The wide range of STs identified in the Italian population suggest that Blastocystis sp. infection is not associated with specific STs even if some STs (ST1-ST4) are predominant as reported in all other countries. Since most of the STs identified in Italian patients are zoonotic, our data raise crucial questions concerning the identification of animal reservoirs for Blastocystis sp. and the potential risks of transmission to humans.