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Schistosoma mansoni, a snail‐borne, blood fluke that infects humans, was introduced into the Americas from Africa during the Trans‐Atlantic slave trade. As this parasite shows strong specificity to the snail intermediate host, we expected that adaptation to South American Biomphalaria spp. snails would result in population bottlenecks and strong signatures of selection. We scored 475,081 single nucleotide variants in 143 S. mansoni from the Americas (Brazil, Guadeloupe and Puerto Rico) and Africa (Cameroon, Niger, Senegal, Tanzania, and Uganda), and used these data to ask: (i) Was there a population bottleneck during colonization? (ii) Can we identify signatures of selection associated with colonization? (iii) What were the source populations for colonizing parasites? We found a 2.4‐ to 2.9‐fold reduction in diversity and much slower decay in linkage disequilibrium (LD) in parasites from East to West Africa. However, we observed similar nuclear diversity and LD in West Africa and Brazil, suggesting no strong bottlenecks and limited barriers to colonization. We identified five genome regions showing selection in the Americas, compared with three in West Africa and none in East Africa, which we speculate may reflect adaptation during colonization. Finally, we infer that unsampled populations from central African regions between Benin and Angola, with contributions from Niger, are probably the major source(s) for Brazilian S. mansoni. The absence of a bottleneck suggests that this is a rare case of a serendipitous invasion, where S. mansoni parasites were pre‐adapted to the Americas and able to establish with relative ease. [ABSTRACT FROM AUTHOR]

BACKGROUND Key genes control the infectivity of the Schistosoma haematobium causing schistosomiasis. A method for understanding the regulation of these genes might help in developing new disease strategies to control schistosomiasis, such as the silencing mediated by microRNAs (miRNAs). The miRNAs have been studied in schistosome species and they play important roles in the post-transcriptional regulation of genes, and in parasite-host interactions. However, genome-wide identification and characterisation of novel miRNAs and their pathway genes and their gene expression have not been explored deeply in the genome and transcriptome of S. haematobium. OBJECTIVES Identify and characterise mature and precursor miRNAs and their pathway genes in the S. haematobium genome. METHODS Computational prediction and characterisation of miRNAs and genes involved in miRNA pathway from S. haematobium genome on SchistoDB. Conserved domain analysis was performed using PFAM and CDD databases. A robust algorithm was applied to identify mature miRNAs and their precursors. The characterisation of the precursor miRNAs was performed using RNAfold, RNAalifold and Perl scripts. FINDINGS We identified and characterised 14 putative proteins involved in miRNA pathway including ARGONAUTE and DICER in S. haematobium. Besides that, 149 mature miRNAs and 131 precursor miRNAs were identified in the genome including novel miRNAs. MAIN CONCLUSIONS miRNA pathway occurs in the S. haematobium, including endogenous miRNAs and miRNA pathway components, suggesting a role of this type of non-coding RNAs in gene regulation in the parasite. The results found in this work will open up a new avenue for studying miRNAs in the S. haematobium biology in helping to understand the mechanism of gene silencing in the human parasite Schistosome.

Recently, DNA barcoding based on the mitochondrial gene cytochrome c oxidase subunit 1 (COI) has become a widespread tool to identify animals. Its use with parasites of humans has been limited with some groups of nematodes where the amplification of this gene has been difficult. In this study, we present the first COI barcode sequence of a rare parasite from tropical regions, Lagochilascaris minor, which parasitized a human host from Quintana Roo, southern Yucata´n Peninsula, Mexico. Destruction of the mastoid apophysis in the lateral sinus and cerebellar involvement were observed at the site of infection. After a radical mastoidectomy and a treatment with 200 mg oral albendazole for 63 days, the patient completely recovered. Lagochilascaris minor was identified based on the ratio between length of spicules and ejaculatory duct, shape of eggs, and host, as well as comparison with its congeners. The mode of infection is unknown, although it could be after direct exposure to eggs or consumption of uncooked wild meat. Morphology of adults is demonstrated using scanning electron microscopy, and high-quality sequences of COI barcode are presented from amplifications using semi-degenerate primers designed for micro-crustaceans. DNA barcoding proved to be a reliable identification method for L. minor. A comparison of the sequences for this species with 81 ascaridoids obtained from the Barcode of Life Database places it in a unique clade most closely related to Baylisascaris procyonis. Future diagnosis of larval and adult stages of L. minor using DNA barcoding will allow the recognition of its infection parameters, transmission, and precise epidemiology. Reports of lagochilascarosis in the Yucata´n Peninsula have been occurred over the last decade, suggesting it is an emerging zoonotic disease in the region. [ABSTRACT FROM AUTHOR]

Syf1 is a tetratricopeptide repeat (TPR) protein implicated in transcription elongation, spliceosome conformation, mRNA nuclear-cytoplasmic export and transcription-coupled DNA repair. Recently, we identified the spliceosomal components of the human parasite Entamoeba histolytica, among them is EhSyf. Molecular predictions confirmed that EhSyf contains 15 type 1 TPR tandem α-antiparallel array motifs. Amoeba transformants carrying plasmids overexpressing HA-tagged or EhSyf silencing plasmids were established to monitor the impact of EhSyf on the splicing of several test Entamoeba transcripts. EhSyf Entamoeba transformants efficiently silenced or overexpressed the proteins in the nucleus. The overexpression or absence of EhSyf notably enhanced or blocked splicing of transcripts irrespective of the strength of their 3′ splice site. Finally, the absence of EhSyf negatively affected the transcription of an intron-less transcript. Altogether our data suggest that EhSyf is a bona fide Syf1 ortholog involved in transcription and splicing. [ABSTRACT FROM AUTHOR]

Introduction:Genetics combined with proteomics allows for a better understanding of parasite-host interactions and host immune responses. Immunomics elucidates that antigens are targets of induced or naturally acquired immunity (NAI), a promising solution to the challenge of eradicating human infections. High-throughput protein microarrays enhance rapid antigen discovery for the development of serodiagnostic tests/vaccines. Areas covered:This review systematically analyzes the emergence of protein microarrays as a powerful technology for parasite antigen discovery and subsequently summarizes some of the attributes and disadvantages of these approaches. Major insights on novel/validated serological biomarkers or vaccine candidates against malaria and Neglected Tropical Diseases (NTDs) are highlighted. We conclude with a brief description of the processes involved in immunomic protein microarrays. Expert commentary:Interesting discoveries have been made using protein microarrays. However, there is a need to evaluate targets that elicit strong immunogenicity and correlates of protective efficacy to aid prioritization and guide further clinical development. The goal of parasitic disease elimination will be best achieved through an integrated strategy that will incorporate and implement the different control components. [ABSTRACT FROM PUBLISHER]

Genomic and transcriptomics analyses have revealed human head and body lice to be almost genetically identical; although con-specific, they nevertheless occupy distinct ecological niches and have differing feeding patterns. Most importantly, while head lice are not known to be vector competent, body lice can transmit three serious bacterial diseases; epidemictyphus, trench fever, and relapsing fever. In order to gain insights into the molecular bases for these differences, we analyzed alternative splicing (AS) using next-generation sequencing data for one strain of head lice and one strain of body lice. We identified a total of 3,598 AS events which were head or body lice specific. Exon skipping AS events were overrepresented among both head and body lice, whereas intron retention events were underrepresented in both. However, both the enrichment of exon skipping and the underrepresentation of intron retention are significantly stronger in body lice compared with head lice. Genes containing body louse-specific AS events were found to be significantly enriched for functions associated with development of the nervous system, salivary gland, trachea, and ovarian follicle cells, as well as regulation of transcription. In contrast, no functional categories were overrepresented among genes with head louse-specific AS events. Together, our results constitute the first evidence for transcript pool differences in head and body lice, providing insights into molecular adaptations that enabled human lice to adapt to clothing, and representing a powerful illustration of the pivotal role AS can play in functional adaptation. [ABSTRACT FROM AUTHOR]

Leishmania are protozoan pathogens of humans that exist as extracellular promastigotes in the gut of their sand fly vectors and as obligate intracellular amastigotes within phagolysosomes of infected macrophages. Between infectious blood meal feeds, sand flies take plant juice meals that contain sucrose and store these sugars in their crop. Such sugars are regurgitated into the sand fly anterior midgut where they impact the developing promastigote parasite population. In this report we showed that promastigotes of all Leishmania species secreted an invertase/sucrase enzyme during their growth in vitro. In contrast, neither L. donovani nor L. mexicana amastigotes possessed any detectable invertase activity. Importantly, no released/secreted invertase activity was detected in culture supernatants from either Trypanosoma brucei or Trypanosoma cruzi. Using HPLC, the L. donovani secretory invertase was isolated and subjected to amino acid sequencing. Subsequently, we used a molecular approach to identify the LdINV and LmexINV genes encoding the ~72 kDa invertases produced by these organisms. Interestingly, we identified high fidelity LdINV-like homologs in the genomes of all Leishmania sp. but none were present in either T. brucei or T. cruzi. Northern blot and RT-PCR analyses showed that these genes were developmentally/differentially expressed in promastigotes but not amastigotes of these parasites. Homologous transfection studies demonstrated that these genes in fact encoded the functional secretory invertases produced by these parasites. Cumulatively, our results suggest that these secretory enzymes play critical roles in the survival/growth/development and transmission of all Leishmania parasites within their sand fly vector hosts. [ABSTRACT FROM AUTHOR]

Previously, we characterized a gene encoding the unique nuclease ( LdNuc) from a Sudanese isolate of the human pathogen Leishmania donovani. This parasite secretory enzyme is involved in the salvage of host-derived purines and is constitutively expressed by both developmental forms of the parasite . Currently, we assessed whether an LdNuc-like nuclease was conserved among other geographically disparate isolates of L. donovani and whether this enzyme was produced by intracellular amastigotes during human infections. Using RT-PCR and Southern blotting, we showed that LdNuc gene homologs were present in each of the viscerotropic Leishmania tested (i.e ., L. donovani isolates from the Sudan , Ethiopia and India as well as L. infantum). Further results of in situ enzyme activity gel analyses showed that each of these parasite isolates also expressed a released/secreted LdNuc-like nuclease activity. In Western blots, our anti- LdNuc (Sudan) peptide-specific antibody reacted with only a single ~35 kDa protein in each of the viscerotropic Leishmania isolates. Further, the ~35 kDa nuclease secreted by each of these isolates was specifically immunoprecipitated by the anti- LdNuc antibody above. In situ gel analyses showed that each of these immunoprecipitates had LdNuc-like nuclease activity. Moreover, sera from acute visceral leishmaniasis patients from India, Sudan and Brazil all immunoprecipitated an LdNuc-HA expressed nuclease demonstrating, that these patients possessed antibodies against this parasite secretory enzyme. Cumulatively, these results showed that the LdNuc homologs were functionally conserved among geographically disparate visceral Leishmania spp. and that amastigotes of these parasites must produce this nuclease enzyme during the course of human disease. [ABSTRACT FROM AUTHOR]

Lipases have been implicated to be of importance in the life cycle development, virulence, and transmission of a variety of parasitic organisms. Potential functions include the acquisition of host resources for energy metabolism and as simple building blocks for the synthesis of complex parasite lipids important for membrane remodeling and structural purposes. Using a molecular approach, we identified and characterized the structure of an LdLip3-lipase gene from the primitive trypanosomatid pathogen of humans , Leishmania donovani. The LdLip3 encodes a ~33 kDa protein, with a well-conserved substrate-binding and catalytic domains characteristic of members of the serine lipase-protein family. Further, we showed that LdLip3 mRNA is constitutively expressed by both the insect vector (i.e., promastigote) and mammalian (i.e., amastigote) life cycle developmental forms of this protozoan parasite. Moreover, a homologous episomal expression system was used to express an HA epitope-tagged LdLip3 chimeric construct ( LdLip3::HA) in these parasites. Expression of the LdLip3 chimera was verified in these transfectants by Western blots and indirect immuno-fluorescence analyses. Results of coupled immuno-affinity purification and enzyme activity experiments demonstrated that the LdLip3::HA chimeric protein was secreted/released by transfected L. donovani parasites and that it possessed functional lipase enzyme activity. Taken together these observations suggest that this novel secretory lipase might play essential role(s) in the survival, growth, and development of this important group of human pathogens. [ABSTRACT FROM AUTHOR]

Abstract: In addition to its classic glycolytic role, glyceraldehyde-3-phosphate dehydrogenase (GAPDH) has been implicated in many activities unrelated to glycolysis, such as membrane fusion, binding to host proteins and signal transduction. GAPDH can be the target of several modifications that allow incorporation to membranes and possible regulation of its activity; among these modifications is mono-ADP-ribosylation. This post-translational modification is important for the regulation of many cellular processes and is the mechanism of action of several bacterial toxins. In a previous study, we observed the extracellular ADP-ribosylation of a 37-kDa ameba protein. We report here that GAPDH and cysteine synthase A are the main ADP-ribosylated proteins in Entamoeba histolytica extracellular medium, GAPDH is secreted from ameba at 37°C in a time-dependent manner, and its enzymatic activity is not inhibited by ADP-ribosylation. Extracellular GAPDH from ameba may play an important role in the survival of this human pathogen or in interaction with host molecules, as occurs in other organisms. [Copyright &y& Elsevier]

• E. histolytica contains two genes that codify for LMW-PTPs, EhLMW-PTP1 and EhLMW-PTP2. • Differential expression of EhLMW-PTPs is shown in trophozoites in asynchronous culture. • Overexpression of EhLMW-PTP2 impairs erythrophagocytosis, phagocytic cup formation, adherence to FN, and cytopathic effect. The Entamoeba histolytica parasite is the causative agent of amebiasis, infecting approximately 1% of the world population and causing 100,000 deaths per year. It binds to Fibronectin (FN), activating signaling pathways regulated by kinases and phosphatases. EhLMW-PTPs genes from E. histolytica encode for Low Molecular Weight Tyrosine Phosphatases expressed in trophozoites and amoebic cysts. The role of these phosphatases in the virulence of the parasite has not yet been well characterized. Our results showed a differential expression of the EhLMW-PTPs, at the mRNA and protein levels, in an asynchronous trophozoites culture. Furthermore, we observed that trophozoites transfected that overexpressed EhLMW-PTP2 phagocytized fewer erythrocytes, possibly due to decreased phagocytic cups, and showed deficiencies in adherence to FN and less cytopathic effect. These analyzes suggest that the parasite's EhLMW-PTPs have an essential role in the mechanisms of proliferation, adhesion, and phagocytosis, regulating its pathogenicity. [ABSTRACT FROM AUTHOR]

The genome length of the Ascaris lumbricoides, human parasitic roundworm, is 14,281 bp with a nucleotide composition of 22.1% A, 49.8% T, 7.8% C, and 20.3% G. The genome consists of 12 protein-coding genes, 2 rRNA genes, 22 tRNA genes, and 1 control region. [ABSTRACT FROM AUTHOR]

All 100+ bedbug species (Cimicidae) are obligate blood-sucking parasites [ 1, 2 ]. In general, blood sucking (hematophagy) is thought to have evolved in generalist feeders adventitiously taking blood meals [ 3, 4 ], but those cimicid taxa currently considered ancestral are putative host specialists [ 1, 5 ]. Bats are believed to be the ancestral hosts of cimicids [ 1 ], but a cimicid fossil [ 6 ] predates the oldest known bat fossil [ 7 ] by >30 million years (Ma). The bedbugs that parasitize humans [ 1, 8 ] are host generalists, so their evolution from specialist ancestors is incompatible with the "resource efficiency" hypothesis and only partially consistent with the "oscillation" hypothesis [ 9–16 ]. Because quantifying host shift frequencies of hematophagous specialists and generalists may help to predict host associations when vertebrate ranges expand by climate change [ 17 ], livestock, and pet trade in general and because of the previously proposed role of human pre-history in parasite speciation [ 18–20 ], we constructed a fossil-dated, molecular phylogeny of the Cimicidae. This phylogeny places ancestral Cimicidae to 115 mya as hematophagous specialists with lineages that later frequently populated bat and bird lineages. We also found that the clades, including the two major current urban pests, Cimex lectularius and C. hemipterus , separated 47 mya, rejecting the notion that the evolutionary trajectories of Homo caused their divergence [ 18–21 ]. • Bedbugs arose 115 mya, 30+ Ma before their assumed host, bats • From unknown ancestral hosts, several bat and bird host lineages evolved • Humans became hosts three times by host extension of specialists, not host switching • Two urban pests, common and tropical bedbug, split ca. 40 Ma before Homo speciation Using a fossil-dated phylogeny, Roth et al. show the bedbug family evolved 30+ Ma before bats, their previously assumed hosts. Bats, birds, and humans were each colonized several times. The tropical and common bedbug split 47 mya, rejecting Ashford's hypothesis of their independent evolution on Homo erectus and H. sapiens. [ABSTRACT FROM AUTHOR]