A Shift from Cellular to Humoral Responses Contributes to Innate Immune Memory in the Vector Snail Biomphalaria glabrata.

Discoveries made over the past ten years have provided evidence that invertebrate antiparasitic responses may be primed in a sustainable manner, leading to the failure of a secondary encounter with the same pathogen. This phenomenon called "immune priming" or "innate immune memory" was mainly phenomenological. The demonstration of this process remains to be obtained and the underlying mechanisms remain to be discovered and exhaustively tested with rigorous functional and molecular methods, to eliminate all alternative explanations. In order to achieve this ambitious aim, the present study focuses on the Lophotrochozoan snail, Biomphalaria glabrata, in which innate immune memory was recently reported. We provide herein the first evidence that a shift from a cellular immune response (encapsulation) to a humoral immune response (biomphalysin) occurs during the development of innate memory. The molecular characterisation of this process in Biomphalaria/Schistosoma system was undertaken to reconcile mechanisms with phenomena, opening the way to a better comprehension of innate immune memory in invertebrates. This prompted us to revisit the artificial dichotomy between innate and memory immunity in invertebrate systems.

Hyperdiverse gene cluster in snail host conveys resistance to human schistosome parasites.

Schistosomiasis, a neglected global pandemic, may be curtailed by blocking transmission of the parasite via its intermediate hosts, aquatic snails. Elucidating the genetic basis of snail-schistosome interaction is a key to this strategy. Here we map a natural parasite-resistance polymorphism from a Caribbean population of the snail Biomphalaria glabrata. In independent experimental evolution lines, RAD genotyping shows that the same genomic region responds to selection for resistance to the parasite Schistosoma mansoni. A dominant allele in this region conveys an 8-fold decrease in the odds of infection. Fine-mapping and RNA-Seq characterization reveal a <1Mb region, the Guadeloupe Resistance Complex (GRC), with 15 coding genes. Seven genes are single-pass transmembrane proteins with putative immunological roles, most of which show strikingly high nonsynonymous divergence (5-10%) among alleles. High linkage disequilibrium among three intermediate-frequency (>25%) haplotypes across the GRC, a significantly non-neutral pattern, suggests that balancing selection maintains diversity at the GRC. Thus, the GRC resembles immune gene complexes seen in other taxa and is likely involved in parasite recognition. The GRC is a potential target for controlling transmission of schistosomiasis, including via genetic manipulation of snails.

Comparison in the incidence of anorectal malformations between a first- and third-world referral center.

PURPOSE: Aim of study was to evaluate the differences in incidence and presentation of anorectal malformations (ARMs) between selected Pediatric Surgery Divisions in the Republic of South Africa (ZAR) and Italy. METHODS: A retrospective cohort study involved analysis of clinical records of patients with ARM born between 2005 and 2012. Type of ARM, maternal age, birth weight, gestational age, presence of associated anomalies and delayed diagnosis were analyzed. RESULTS: 335 patients were included in this study. Of note, statistically significant differences between the African and European patient groups were observed in a male predominance in the ZAR patient population. In addition, female recto-perineal fistulas were diagnosed in significantly more Italian patients than in ZAR. Furthermore, a more advanced maternal age and a lower gestational age was noted in the European cohort with a minimal delay in initial diagnosis as opposed to the African counterpart. Both centers reported recto-perineal fistula as the most common malformation in male patients. CONCLUSION: With the exception of perineal fistulas in females, the incidence of specific subtypes of ARMs was similar in the two groups. This may be of importance when extrapolating European study conclusion to the South African setting.

A new chronotype of Schistosoma mansoni: adaptive significance.

OBJECTIVES: To optimise host-to-host transmission, digenean trematodes (parasites) synchronize their cercarial emission patterns with the aquatic activities of their vertebrate hosts. Schistosoma mansoni has a strictly diurnal shedding pattern involving two circadian chronotypes: an early shedding pattern with a mean peak occurring at 11:00 h and a late pattern with a mean peak occurring at 16:00 h. We analysed the cercarial emergence pattern of three schistosome populations from Oman where S. mansoni is resurgent. METHODS: For each schistosome population, the cercarial emergence pattern was assessed hourly over several days. Because we identified a new chronotype hitherto unknown in S. mansoni, we undertook taxonomic characterisation based on egg morphology and mitochondrial DNA sequence (COX1). RESULTS: Taxonomic characterisation revealed that the three schistosome populations belong to the species S. mansoni. Hence, this is the first report of this species exhibiting a nocturnal chronotype, with the mean peak occurring at 20:00 h. We interpreted the new chronotype as being the result of a lateral transfer of S. mansoni from humans to Rattus rattus. CONCLUSION: The cercarial emergence pattern of S. mansoni from Oman is circadian, exhibiting either a diurnal or a nocturnal phenotype.

Recovery of primary sporocysts in vivo in the Schistosoma mansoni/Biomphalaria glabrata model using a simple fixation method suitable for extraction of genomic DNA and RNA.

Detailed studies of host/parasite interactions are currently limited because in situ gene sequencing or monitoring of parasite gene expression is so far limited to genes presenting a high loci copy number in the Schistosome genome or a high level of expression. Indeed, how to investigate the host parasite molecular interplay when parasites are not directly accessible in vivo? Here we describe a method to circumvent this problem and to analyze DNA and RNA of Schistosoma mansoni during the interaction with its intermediate snail host Biomphalaria glabrata. We propose a technique for improved DNA and RNA extraction from the intra-molluscan stage of the parasite recovered after fixation of infected snails in Raillet-Henry solution. The extractions can be used for genetic analysis, transcription studies and microsatellite genotyping.

Visceral versus somatic pain: an educational review of anatomy and clinical implications.

Somatic and visceral nociceptive signals travel via different pathways to reach the spinal cord. Additionally, signals regulating visceral blood flow and gastrointestinal tract (GIT) motility travel via efferent sympathetic nerves. To offer optimal pain relief and increase GIT motility and blood flow, we should interfere with all these pathways. These include the afferent nerves that travel with the sympathetic trunks, the somatic fibers that innervate the abdominal wall and part of the parietal peritoneum, and the sympathetic efferent fibers. All somatic and visceral afferent neural and sympathetic efferent pathways are effectively blocked by appropriately placed segmental thoracic epidural blocks (TEBs), whereas well-placed truncal fascial plane blocks evidently do not consistently block the afferent visceral neural pathways nor the sympathetic efferent nerves. It is generally accepted that it would be beneficial to counter the effects of the stress response on the GIT, therefore most enhanced recovery after surgery protocols involve TEB. The TEB failure rate, however, can be high, enticing practitioners to resort to truncal fascial plane blocks. In this educational article, we discuss the differences between visceral and somatic pain, their management and the clinical implications of these differences.

Immunoblot analysis of membrane antigens of Schistosoma mansoni, Schistosoma intercalatum, and Schistosoma haematobium against Schistosoma-infected patient sera.

Antigens present in aqueous n-butanolic extracts (BE) of Schistosoma mansoni (Venezuelan JL strain), Schistosoma intercalatum (Cameroon EDEA strain), and Schistosoma haematobium (Yemen strain) adult worm membranes were compared in immunoblot against sera of patients infected with S. mansoni, S. intercalatum, S. haematobium, Schistosoma japonicum, or Schistosoma mekongi looking for similarities (common antigens) and differences (species-specific antigens). About 17 S. mansoni BE polypeptides (M (r) approximately 8 to >80 kDa) were commonly recognized by S. mansoni-infected patient sera from Venezuela, Senegal, and Ethiopia. S. intercalatum-, S. haematobium-, or S. japonicum-infected sera were almost unreactive with S. mansoni BE. Nonetheless, S. mekongi-infected sera weakly cross-reacted with a approximately 10-15-kDa subset of S. mansoni BE. About 72.7% of S. intercalatum-infected patient sera reacted with a approximately 19-21-kDa complex in S. intercalatum BE and cross-reacted with a similar complex in S. haematobium BE. Conversely, all S. haematobium-infected patient sera reacted with a approximately 19-21-kDa complex in S. haematobium BE and cross-reacted with the approximately 19-21-kDa complex in S. intercalatum BE; S. mansoni- and S. japonicum-infected patient sera did not react with S. intercalatum or S. haematobium BE. Results showed the presence of a common membrane antigen between African schistosome species and species-specific antigens in S. mansoni BE that could be useful to discriminate between species and/or to detect Schistosoma infections.

Excretory-secretory products of larval Fasciola hepatica investigated using a two-dimensional proteomic approach.

So far, very few secreted proteins from trematodes have been characterized, although their role in the mechanisms that allow the parasite to escape host's immune response have been largely documented. Here we performed a proteomic analysis of excretory-secretory proteins from the intra-molluscan larval stages of Fasciola hepatica. We identified two antioxidative enzymes: a Cu/Zn-superoxide dismutase (Cu/Zn SOD) and a thioredoxin (TRX) previously characterized in ES products from adult stages. These results support the importance of parasite detoxication of reactive oxygen species in invertebrate hosts, and raise the question of the possible conservation of major immune evasion effectors across trematode developmental life-stages.

Molecular determinants of compatibility polymorphism in the Biomphalaria glabrata/Schistosoma mansoni model: new candidates identified by a global comparative proteomics approach.

The co-evolutionary dynamics that exist in host-parasite interactions sometimes lead to compatibility polymorphisms, the molecular bases of which are rarely investigated. To identify key molecules that are involved in this phenomenon in the Schistosoma mansoni/Biomphalaria glabrata model, we developed a comparative proteomics approach using the larval stages that interact with the invertebrate host. We used qualitative and quantitative analyses to compare the total proteomes of primary sporocysts from compatible and incompatible parasite strains. The differentially expressed proteins thus detected belong to three main functional groups: (i) scavengers of reactive oxygen species, (ii) components of primary metabolism, and (iii) mucin-like proteins. We discuss the putative roles played by these protein families as determinants of compatibility polymorphism. Since mucins are known to play key roles in the host-parasite interplay, we consider the newly discovered S. mansoni mucin-like proteins (SmMucin-like) as the most promising candidates for influencing the fate of host-parasite interactions. An analysis of their expression is presented in a paper published in the same journal issue.

Excretory-secretory proteome of larval Schistosoma mansoni and Echinostoma caproni, two parasites of Biomphalaria glabrata.

Schistosoma mansoni and Echinostoma caproni are two trematode species that use different strategies (mimicry and immunosuppression, respectively) to interfere with the snail innate immune system. Parasites excretory-secretory (ES) products have been shown to play a key role in these host-parasite immune interactions. However, they remain largely uncharacterized in larval trematodes. We developed a global proteomic approach to characterize the ES proteome of S. mansoni and E. caproni primary sporocysts. In ES products of both parasites, we found proteins involved in reactive oxygen species scavenging, glycolysis, signalling or calcium binding (superoxide dismutase Cu/Zn; glutathione S-transferase; aldo-keto-reductase; triose-phosphate isomerase; glyceraldehyde-3-phosphate dehydrogenase; aldolase, enolase, MICAL-like, calreticulin). According to their predicted functions, we propose a model in which these proteins (i) are involved in antioxidant activity, (ii) prevent hemocyte encapsulation process or (iii) favor invasion and migration of sporocysts in host tissues. These results suggest that S. mansoni and E. caproni sporocysts develope a strong immune protection during the first hours of infection giving them enough time to build up a long lasting immune evasion strategy relying on molecular mimicry or immunosuppression, respectively.

Birth Prevalence of Anorectal Malformations for the Western Cape Province, South Africa, 2005 to 2012.

Introduction Anorectal malformations (ARMs) are a major birth anomaly worldwide. South Africa has ethnically and geologically diverse populations. A recent publication indicated an increased birth prevalence of ARMs in the Witwatersrand referral area between 2005 and 2010. The purpose of this study was to determine the birth prevalence of ARM and its various subtypes in the Western Cape referral district over an 8-year period. Methods For an 8-year period from January 1, 2005, to December 31, 2012; retrospective data were collected from the Pediatric Surgical Departments of Red Cross War Memorial Children's Hospital, Tygerberg Children's Hospital, as well as the private sector health registries. The number of live births per year for a specific municipal district was obtained from the National Department of Health. The chi-square for trend test was used to determine statistical significance. Results The birth prevalence for ARM in the Western Cape Province (WCP) in 2012 was shown to be 1:5,572 live births (1.79/10,000 live births). The West Coast municipality district had the highest average birth prevalence rate of 1:3,063 (3.26/10,000) live births for years studied. There was a male predominance (1.6:1), the most common ARM was the vestibular fistula (19.2%) and in 26% of the patients, there was an initial delay in the diagnosis. Conclusion This study has provided some recent data for ARMs for the WCP. There was no statistical significant change in the prevalence of ARMs over the 8-year period for the WCP as well as in any of the individual six municipal health districts (χ2 for trend, p = 0.52). The number of delayed diagnosis of ARM is of concern.

A multistrain approach to studying the mechanisms underlying compatibility in the interaction between Biomphalaria glabrata and Schistosoma mansoni.

In recent decades, numerous studies have sought to better understand the mechanisms underlying the compatibility between Biomphalaria glabrata and Schistosoma mansoni. The developments of comparative transcriptomics, comparative genomics, interactomics and more targeted approaches have enabled researchers to identify a series of candidate genes. However, no molecular comparative work has yet been performed on multiple populations displaying different levels of compatibility. Here, we seek to fill this gap in the literature. We focused on B. glabrata FREPs and S. mansoni SmPoMucs, which were previously demonstrated to be involved in snail/schistosome compatibility. We studied the expression and polymorphisms of these factors in combinations of snail and schistosome isolates that display different levels of compatibility. We found that the polymorphism and expression levels of FREPs and SmPoMucs could be linked to the compatibility level of S. mansoni. These data and our complementary results obtained by RNA-seq of samples from various snail strains indicate that the mechanism of compatibility is much more complex than previously thought, and that it is likely to be highly variable within and between populations. This complexity must be taken into account if we hope to identify the molecular pathways that are most likely to be good targets for strategies aimed at blocking transmission of the parasite through the snail intermediate host.

Host sex and parasite genetic diversity.

Is the genetic diversity of parasites infecting male and female hosts equal or different? This is the question we address in this paper by studying the neutral genetic variability of the plathyhelminth trematode Schistosoma mansoni within males and females of its natural murine host Rattus rattus in the marshy forest focus of Guadeloupe (French West Indies). Using seven microsatellite markers, we demonstrate that parasites from male hosts are genetically more diversified than parasites from female hosts. Three hypotheses are discussed that could explain this pattern: 1) a host sex-specific duration of cercariae recruitment; 2) a difference in the behaviour of male and female hosts that would lead to the exposure of males to a greater diversity of parasites; and 3) a host sex-biased immunocompetence that would lead to the selection of more genetically diversified individuals in male than in female rats. This finding is the first empirical evidence that each host sex may play different roles in the maintenance of parasite genetic diversity and so in their evolutionary dynamics and epidemiology.

Biofilms associated with bowel necrosis: A newly recognised phenomenon in infants.

BACKGROUND: A biofilm is defined as a collection of organisms attached to a surface and surrounded by a matrix. OBJECTIVE: To present three cases in which bowel necrosis coexisted with biofilm. METHODS: The medical records, bacteriological findings and tissue biopsies from three infants with bowel necrosis who subsequently died from sepsis were analysed. Tissue sent for histological evaluation was prepared for light microscopy. Haematoxylin and eosin (H&E), Sandiford and Alcian blue/periodic acid Schiff (ABPAS) stains were performed. Tissue samples were ex-waxed for electron microscopy in one case. RESULTS: The three patients described all had necrotic bowel at laparotomy, all cultured Klebsiella pneumoniae from peritoneal pus swabs, and all died despite appropriate antibiotics. All specimens showed varying degrees of bowel necrosis and an organising acute peritoneal reaction. In addition, all showed colonies of Gram-negative bacteria within a mucopolysaccharide matrix. CONCLUSIONS: The identification of biofilms in necrotic bowel has raised questions regarding their clinical implications. Further studies are needed to evaluate all resected necrotic bowel for biofilms and the clinical implications of this finding.

Epigenetic origin of adaptive phenotypic variants in the human blood fluke Schistosoma mansoni.

BACKGROUND: Adaptive evolution is not possible without the generation of phenotypic variants. The origin of these variations has been a central topic in evolutionary biology. Up to now, it was commonly accepted that standing genetic variation is the only cause of phenotypic variants. However, epigenetic information is emerging as a complementary source of heritable phenotypic variation that contributes to evolution. The relative importance of genetics and epigenetics in generating heritable phenotypic variation is nevertheless a matter of debate. RESULTS: We used a host-parasite system to address this question. The human blood fluke Schistosoma mansoni can adapt rapidly to new intermediate snail hosts. The interaction between parasite and mollusk is characterized by a compatibility polymorphism illustrating the evolutionary dynamics in this system. The principal molecular marker for compatibility (infection success) is the expression pattern of a group of polymorphic mucins (SmPoMuc) in the parasite. We show here that chromatin structure changes as the SmPoMuc promoters are the cause for SmPoMuc transcription polymorphism leading to phenotypic novelty and increase in infection success, i.e., fitness. CONCLUSION: We establish that epigenetic changes can be the major if not only cause of adaptive phenotypic variants in Schistosoma mansoni, suggesting that epimutations can provide material for adaptive evolution in the absence of genetic variation in other systems. In addition, our results indicate that epidrugs can be used to control parasite development but also parasite evolution.

Speciation in parasites: a population genetics approach.

Parasite speciation and host-parasite coevolution should be studied at both macroevolutionary and microevolutionary levels. Studies on a macroevolutionary scale provide an essential framework for understanding the origins of parasite lineages and the patterns of diversification. However, because coevolutionary interactions can be highly divergent across time and space, it is important to quantify and compare the phylogeographic variation in both the host and the parasite throughout their geographical range. Furthermore, to evaluate demographic parameters that are relevant to population genetics structure, such as effective population size and parasite transmission, parasite populations must be studied using neutral genetic markers. Previous emphasis on larger-scale studies means that the connection between microevolutionary and macroevolutionary events is poorly explored. In this article, we focus on the spatial fragmentation of parasites and the population genetics processes behind their diversification in an effort to bridge the micro- and macro-scales.

Dispersal in a parasitic worm and its two hosts: consequence for local adaptation.

Characterizing host and parasite population genetic structure and estimating gene flow among populations is essential for understanding coevolutionary interactions between hosts and parasites. We examined the population genetic structure of the trematode Schistosoma mansoni and its two host species (the definitive host Rattus rattus and the intermediate host Biomphalaria glabrata) using microsatellite markers. Parasites were sampled from rats. The study was conducted in five sites of the Guadeloupe Island, Lesser Antilles. Mollusks display a pattern of isolation by distance whereas such a pattern is not found neither in schistosomes nor in rats. The comparison of the distribution of genetic variability in S. mansoni and its two host species strongly suggests that migration of parasites is principally determined by that of the vertebrate host in the marshy focus of Guadeloupe. However, the comparison between genetic differentiation values in schistosomes and rats suggests that the efficacy of the schistosome rat-mediated dispersal between transmission sites is lower than expected given the prevalence, parasitic load and migration rate of rats among sites. This could notably suggest that rat migration rate could be negatively correlated to the age or the infection status of individuals. Models made about the evolution of local adaptation in function of the dispersal rates of hosts and parasites suggest that rats and mollusks should be locally adapted to their parasites.

Chronobiology of trematode cercarial emergence: from data recovery to epidemiological, ecological and evolutionary implications.

One major challenge for parasites with complex cycles consists to succeed in the transmission from one host to the next host. To maximize the probability of encountering the right host, numerous trematode species have selected various emergence rhythms occurring during the escape of the short-lived cercariae from the mollusc host. Cercarial shedding patterns are beautiful examples of adaptation of the parasite for a successful rendezvous with its subsequent host. In this review, after an analysis of the technical and statistical aspects specific to such studies, we compile the knowledge and unresolved issues we have about the synchronization of these rhythms, their genetic support and the role of the host physiology or activity. We are also interested on how cercarial rhythmicity influences cercarial densities in waters of transmission sites and then the risk of host infection in case of schistosomiasis. Ecological significance of the inter- and intra-specific diversity of these rhythms is emphasized as well as the evolutionary implication of new chronotypes resulting from the capture of new host species and promoting reproductive isolation and alloxenic speciation. Currently, genome sequence data now available for some trematodes such as the schistosomes provide an unprecedented resource for new research approaches that should contribute identification of the genes and mechanisms involved in determining the cercarial shedding rhythms observed.

Birth prevalence of anorectal malformation in the referral area for the University of the Witwatersrand tertiary hospitals, South Africa.

BACKGROUND: Anorectal malformations (ARMs) are a major congenital anomaly in neonates. There is significant geographical variation in the birth prevalence varying from 1:1,500 to 1:5,000 live births. There is no published literature on the birth prevalence of ARM occurring within the referral area for The University of Witwatersrand tertiary hospitals in South Africa. METHODS: Retrospective data were collected from the Pediatric Surgical Department, University of the Witwatersrand. Patient records for a 6-year period from January 2005 to December 2010 were obtained from Chris Hani Baragwanath Academic Hospital and Charlotte Maxeke Johannesburg Academic Hospital. The number of live births per year for a specific municipal district was obtained from the National Department of Health. The χ(2) test for trend test was used to determine statistically significance. RESULTS: The birth prevalence for ARM in 2010 was shown to be 1:3,989 live births (2.5/10,000 live births) for the University of Witwatersrand tertiary hospital referral area. A statistically significant overall increase in the birth prevalence of ARM from January 2005 till December 2010 was demonstrated (p < 0.0001). The municipal districts of Johannesburg (p = 0.0015) and Ekurhuleni (p = 0.0066) revealed the greatest increase in birth prevalence. CONCLUSION: This study has provided current statistics on the birth prevalence of ARM in the University of Witwatersrand tertiary hospital referral area, as well as demonstrating a positive incremental trend in the occurrence of this condition over a 6-year period. Future studies will examine the birth prevalence in several other provinces of South Africa. Results from the collective data will then be used to form conclusions regarding any regional or national changes in the birth prevalence of ARM as well as to identify any epidemiological trends.