Host Skin Research Articles

Venestatin from parasitic helminths interferes with receptor for advanced glycation end products (RAGE)-mediated immune responses to promote larval migration.

Parasitic helminths can reside in humans owing to their ability to disrupt host protective immunity. Receptor for advanced glycation end products (RAGE), which is highly expressed in host skin, mediates inflammatory responses by regulating the expression of pro-inflammatory cytokines and endothelial adhesion molecules. In this study, we evaluated the effects of venestatin, an EF-hand Ca2+-binding protein secreted by the parasitic helminth Strongyloides venezuelensis, on RAGE activity and immune responses. Our results demonstrated that venestatin bound to RAGE and downregulated the host immune response. Recombinant venestatin predominantly bound to the RAGE C1 domain in a Ca2+-dependent manner. Recombinant venestatin effectively alleviated RAGE-mediated inflammation, including footpad edema in mice, and pneumonia induced by an exogenous RAGE ligand. Infection experiments using S. venezuelensis larvae and venestatin silencing via RNA interference revealed that endogenous venestatin promoted larval migration from the skin to the lungs in a RAGE-dependent manner. Moreover, endogenous venestatin suppressed macrophage and neutrophil accumulation around larvae. Although the invasion of larvae upregulated the abundance of RAGE ligands in host skin tissues, mRNA expression levels of tumor necrosis factor-α, cyclooxygenase-2, endothelial adhesion molecules vascular cell adhesion protein-1, intracellular adhesion molecule-1, and E-selectin were suppressed by endogenous venestatin. Taken together, our results indicate that venestatin suppressed RAGE-mediated immune responses in host skin induced by helminthic infection, thereby promoting larval migration. The anti-inflammatory mechanism of venestatin may be targeted for the development of anthelminthics and immunosuppressive agents for the treatment of RAGE-mediated inflammatory diseases.

Abnormal\ufeff composition of microbiota in the gut and skin of imiquimod-treated mice

Psoriasis is a chronic, inflammatory skin disease. Although the precise etiology of psoriasis remains unclear, gut–microbiota axis might play a role in the pathogenesis of the disease. Here we investigated whether the composition of microbiota in the intestine and skin is altered in the imiquimod (IMQ)-treated mouse model of psoriasis. Topical application of IMQ to back skin caused significant changes in the composition of microbiota in the intestine and skin of IMQ-treated mice compared to control mice. The LEfSe algorithm identified the species Staphylococcus lentus as potential skin microbial marker for IMQ group. Furthermore, there were correlations for several microbes between the intestine and skin, suggesting a role of skin–gut–microbiota in IMQ-treated mice. Levels of succinic acid and lactic acid in feces from IMQ-treated mice were significantly higher than control mice. Moreover, the predictive functional analysis of the microbiota in the intestine and skin showed that IMQ caused alterations in several KEGG pathways. In conclusion, the current data indicated that topical application with IMQ to skin alters the composition of the microbiota in the gut and skin of host. It is likely that skin–gut microbiota axis plays a role in pathogenesis of psoriasis.

Molecular characterization of four novel serpins in Psoroptes ovis var. cuniculi and their implications in the host-parasite interaction

Psoroptes ovis var. cuniculi infestation rapidly causes skin lesion, cutaneous inflammatory and subsequent adaptive immune response in rabbits. To success feeding and survive on the host skin, this mite should product bioactive molecules to confront host tissue repair and immune defense, but these molecules of this mite remains mostly unknown. Serpins have been proved to involve in diverse biological functions including parasite reproduction, survival and modulating host defense. Limited information is currently available on serpins from Psoroptes mites. Herein, we identified four novel serpins (PsoSP3-PsoSP6) in P. ovis var. cuniculi using bioinformatics and molecular biology techniques. Sequence analysis revealed that PsoSP3-PsoSP6 comprised the common features of typical serpins superfamily including serpin domains, signature or the reactive centre loop (RCL) domain. The recombinant PsoSP4-PsoSP6 (rPsoSP4-rPsoSP6) revealed variable potency inhibition on trypsin, chymotrypsin and elastase except for rPsoSP3 in inhibitory activity assays. By quantitative RT-PCR, the expressions of PsoSP3 and PsoSP4 were higher in juvenile mites (larva and nymph) than in adult mites, however, PsoSP5 and PsoSP6 appeared near-exclusive expression in adult female mites. Immunolocalization showed that native PsoSP4 protein was localized in uterus, whilst native PsoSP3, PsoSP5 and PsoSP6 were specifically localized in the ovarian nutritive cell (ONC) in ovary. Our findings indicated that PsoSP3-PsoSP6 might play critical roles in development and reproduction physiologies. rPsoSP4-rPsoSP6 might participate in modulating host inflammation, immune response and tissue repair.

Stylostome of the trombiculid mite larvae Neotrombicula talmiensis (Schluger, 1955) (Acariformes, Trombiculidae) feeding on two host species in the Russian Far East

Stylostome and skin inflammatory reaction during feeding of Neotrombicula talmiensis (Schluger, 1955) (Acariformes, Trombiculidae) larvae on the naturally infected host animals – voles Myodes rufocanus Sundevall, 1846 and Asian chipmunk Tamias sibiricus (Laxmann, 1769) were studied by histological methods. In addition, larvae were studied in scanning electron microscope (SEM). The apical hypostomal portions form a temporal sucker, which applies to the host skin during feeding. Larval feeding on both naturally infected voles and chipmunks causes an epidermal hyperkeratosis and a permanent delayed inflammation with predominance of neutrophil leukocytes, dilation of dermal capillaries and local hemorrhages. Larvae tend to feed in tight groups and may attach themselves to both ‘living’ epidermis and hypertrophic stratum corneum. The stylostome is organized nearly identically in the two host species, which points to the species-specific character of the feeding tube in trombiculid larvae. The stylostome does not penetrate the epidermis through, so it may be classified as belonging to the epidermal type. The stylostome is produced by a solidifying larval secretion and composed of the proximal eosinophil cone and the main stylostome tube, both pale-pink in azure-II-eosin with a greyish peripheral portion more pronounced in voles. No longitudinal and transverse stratification is found in the stylostome composition. In contrast with other trombiculid larvae studied so far, larvae of N. talmiensis also ingest, besides liquefied nutrients, a pure blood that reveals a possibility for trombiculid larvae to be natural bloodsuckers.

Assessment of the microbiome during bacteriophage therapy in combination with systemic antibiotics to treat a case of staphylococcal device infection

BackgroundInfectious bacterial diseases exhibiting increasing resistance to antibiotics are a serious global health issue. Bacteriophage therapy is an anti-microbial alternative to treat patients with serious bacterial infections. However, the impacts to the host microbiome in response to clinical use of phage therapy are not well understood.ResultsOur paper demonstrates a largely unchanged microbiota profile during 4 weeks of phage therapy when added to systemic antibiotics in a single patient with Staphylococcus aureus device infection. Metabolomic analyses suggest potential indirect cascading ecological impacts to the host (skin) microbiome. We did not detect genomes of the three phages used to treat the patient in metagenomic samples taken from saliva, stool, and skin; however, phages were detected using endpoint-PCR in patient serum.ConclusionResults from our proof-of-principal study supports the use of bacteriophages as a microbiome-sparing approach to treat bacterial infections.E21QRb1nrJpVFpfB3nSJ8UVideo abstract

Bedbug salivation patterns during hematophagy in the skin of a mammalian host

Cimex lectularius (Hemiptera:Cimicidae) infestations have increased over the past decades in several parts of the world, constituting a major urban pest with no reversion signs. The impact on human health caused by these insects, commonly known as bedbugs, is associated with their obligatory hematophagous habit. Allergies induced by hematophagous arthropod bites are related to the deposition of salivary molecules in the host tissues. Many reports of humans developing severe allergic reactions due to bedbug bites have been recorded, however, there is limited information on the salivation of bedbugs on the host, which was the objective of this study. C. lectularius females were fed on blood containing acridine orange fluorochrome, which labeled the principal salivary glands content. The salivation pattern of bedbugs was investigated using intravital microscopy during its blood meal on the ear skin of hairless mice. Saliva deposition occurred during all insect blood-feeding phases, beginning as soon as the mouthpart touched the host skin. During the probing phase, saliva was deposited in large quantities in the host dermis. In contrast, during the engorgement phase (which represents the largest blood meal of the insects), saliva was released at a much slower rate. The apparent release of saliva into the cannulated vessel and/or adjacent tissue occurs only sporadically during insect blood ingestion. However, a small area (spot) of fluorescence was detected around the proboscis tip during this feeding phase. An interesting feature of bedbugs is that they release saliva inside and outside the vessels without removing their mouthparts from the vessel lumen. This is an effective feeding strategy because it does not interrupt blood ingestion and decreases the mouthparts movements on the host’s skin, minimizing the damage to tissues and contact time with the host (feeding time).

Herpesvirus-Associated Proliferative Skin Disease in Frogs and Toads: Proposed Pathogenesis.

A comparative study was carried out on common and agile frogs (Rana temporaria and R. dalmatina) naturally infected with ranid herpesvirus 3 (RaHV3) and common toads (Bufo bufo) naturally infected with bufonid herpesvirus 1 (BfHV1) to investigate common pathogenetic pathways and molecular mechanisms based on macroscopic, microscopic, and ultrastructural pathology as well as evaluation of gene expression. Careful examination of the tissue changes, supported by in situ hybridization, at different stages of development in 6 frogs and 14 toads revealed that the skin lesions are likely transient, and part of a tissue cycle necessary for viral replication in the infected hosts. Transcriptomic analysis, carried out on 2 naturally infected and 2 naïve common frogs (Rana temporaria) and 2 naturally infected and 2 naïve common toads (Bufo bufo), revealed altered expression of genes involved in signaling and cell remodeling in diseased animals. Finally, virus transcriptomics revealed that both RaHV3 and BfHV1 had relatively high expression of a putative immunomodulating gene predicted to encode a decoy receptor for tumor necrosis factor in the skin of the infected hosts. Thus, the comparable lesions in infected frogs and toads appear to reflect a concerted epidermal and viral cycle, with presumptive involvement of signaling and gene remodeling host and immunomodulatory viral genes.

The Leishmania donovani LDBPK_220120.1 Gene Encodes for an Atypical Dual Specificity Lipid-Like Phosphatase Expressed in Promastigotes and Amastigotes; Substrate Specificity, Intracellular Localizations, and Putative Role(s).

The intracellular protozoan parasites of the Leishmania genus are responsible for Leishmaniases, vector borne diseases with a wide range of clinical manifestations. Leishmania (L.) donovani causes visceral leishmaniasis (kala azar), the most severe of these diseases. Along their biological cycle, Leishmania parasites undergo distinct developmental transitions including metacyclogenesis and differentiation of metacyclic promastigotes (MPs) to amastigotes. Metacyclogenesis inside the phlebotomine sandfly host’s midgut converts the procyclic dividing promastigotes to non-dividing infective MPs eventually injected into the skin of mammalian hosts and phagocytosed by macrophages where the MPs are converted inside modified phagolysosomes to the intracellular amastigotes. These developmental transitions involve dramatic changes in cell size and shape and reformatting of the flagellum requiring thus membrane and cytoskeleton remodeling in which phosphoinositide (PI) signaling and metabolism must play central roles. This study reports on the LDBPK_220120.1 gene, the L. donovani ortholog of LmjF.22.0250 from L. major that encodes a phosphatase from the “Atypical Lipid Phosphatases” (ALPs) enzyme family. We confirmed the expression of the LDBPK_220120.1 gene product in both L. donovani promastigotes and axenic amastigotes and showed that it behaves in vitro as a Dual Specificity P-Tyr and monophosphorylated [PI(3)P and PI(4)P] PI phosphatase and therefore named it LdTyrPIP_22 (Leishmaniad onovani Tyrosine PI Phosphatase, gene locus at chromosome 22). By immunofluorescence confocal microscopy we localized the LdTyrPIP_22 in several intracellular sites in the cell body of L. donovani promastigotes and amastigotes and in the flagellum. A temperature and pH shift from 25°C to 37°C and from pH 7 to 5.5, induced a pronounced recruitment of LdTyrPIP_22 epitopes to the flagellar pocket and a redistribution around the nucleus. These results suggest possible role(s) for this P-Tyr/PI phosphatase in the regulation of processes initiated or upregulated by this temperature/pH shift that contribute to the developmental transition from MPs to amastigotes inside the mammalian host macrophages.

Living in Your Skin: Microbes, Molecules, and Mechanisms.

Human skin functions as a physical, chemical, and immune barrier against the external environment while also providing a protective niche for its resident microbiota, known as the skin microbiome. Cooperation between the microbiota, host skin cells, and the immune system is responsible for maintenance of skin health, and a disruption to this delicate balance, such as by pathogen invasion or a breach in the skin barrier, may lead to impaired skin function. In this minireview, we describe the role of the microbiome in microbe, host, and immune interactions under distinct skin states, including homeostasis, tissue repair, and wound infection. Furthermore, we highlight the growing number of diverse microbial metabolites and products that have been identified to mediate these interactions, particularly those involved in host-microbe communication and defensive symbiosis. We also address the contextual pathogenicity exhibited by many skin commensals and provide insight into future directions in the skin microbiome field.

Characterization of the human skin resistome and identification of two microbiota cutotypes

BackgroundThe human skin microbiota is considered to be essential for skin homeostasis and barrier function. Comprehensive analyses of its function would substantially benefit from a catalog of reference genes derived from metagenomic sequencing. The existing catalog for the human skin microbiome is based on samples from limited individuals from a single cohort on reference genomes, which limits the coverage of global skin microbiome diversity.ResultsIn the present study, we have used shotgun metagenomics to newly sequence 822 skin samples from Han Chinese, which were subsequently combined with 538 previously sequenced North American samples to construct an integrated Human Skin Microbial Gene Catalog (iHSMGC). The iHSMGC comprised 10,930,638 genes with the detection of 4,879,024 new genes. Characterization of the human skin resistome based on iHSMGC confirmed that skin commensals, such as Staphylococcus spp, are an important reservoir of antibiotic resistance genes (ARGs). Further analyses of skin microbial ARGs detected microbe-specific and skin site-specific ARG signatures. Of note, the abundance of ARGs was significantly higher in Chinese than Americans, while multidrug-resistant bacteria (“superbugs”) existed on the skin of both Americans and Chinese. A detailed analysis of microbial signatures identified Moraxella osloensis as a species specific for Chinese skin. Importantly, Moraxella osloensis proved to be a signature species for one of two robust patterns of microbial networks present on Chinese skin, with Cutibacterium acnes indicating the second one. Each of such “cutotypes” was associated with distinct patterns of data-driven marker genes, functional modules, and host skin properties. The two cutotypes markedly differed in functional modules related to their metabolic characteristics, indicating that host-dependent trophic chains might underlie their development.ConclusionsThe development of the iHSMGC will facilitate further studies on the human skin microbiome. In the present study, it was used to further characterize the human skin resistome. It also allowed to discover the existence of two cutotypes on the human skin. The latter finding will contribute to a better understanding of the interpersonal complexity of the skin microbiome.7R3iiahnQ7D7AnHo8QeRebVideo abstract

Vector saliva controlled inflammatory response of the host may represent the Achilles heel during pathogen transmission.

Infection with vector-borne pathogens starts with the inoculation of these pathogens during blood feeding. In endemic regions, the population is regularly bitten by naive vectors, implicating a permanent stimulation of the immune system by the vector saliva itself (pre-immune context). Comparatively, the number of bites received by exposed individuals from non-infected vectors is much higher than the bites from infected ones. Therefore, vector saliva and the immunological response in the skin may play an important role, so far underestimated, in the establishment of anti-pathogen immunity in endemic areas. Hence, the parasite biology and the disease pathogenesis in “saliva-primed” and “saliva-unprimed” individuals must be different. This integrated view on how the pathogen evolves within the host together with vector salivary components, which are known to be endowed with a variety of pharmacological and immunological properties, must remain the focus of any investigational study dealing with vector-borne diseases.Considering this three-way partnership, the host skin (immune system), the pathogen, and the vector saliva, the approach that consists in the validation of vector saliva as a source of molecular entities with anti-disease vaccine potential has been recently a subject of active and fruitful investigation. As an example, the vaccination with maxadilan, a potent vasodilator peptide extracted from the saliva of the sand fly Lutzomyia longipalpis, was able to protect against infection with various leishmanial parasites. More interestingly, a universal mosquito saliva vaccine that may potentially protect against a range of mosquito-borne infections including malaria, dengue, Zika, chikungunya and yellow fever. In this review, we highlight the key role played by the immunobiology of vector saliva in shaping the outcome of vector-borne diseases and discuss the value of studying diseases in the light of intimate cross talk among the pathogen, the vector saliva, and the host immune mechanisms.

Skin pH varies among bat species and seasons and between wild and captive bats

Skin is a key aspect of the immune system in the defence against pathogens. Skin pH regulates the activity of enzymes produced both by hosts and by microbes on host skin, thus implicating pH in disease susceptibility. Skin pH varies inter- and intra-specifically and is influenced by a variety of intrinsic and extrinsic variables. Increased skin alkalinity is associated with a predisposition to cutaneous infections in humans and dogs, and inter-specific and inter-individual variation in skin pH is implicated in differential susceptibility to some skin diseases. The cutaneous pH of bats has not been characterized but is postulated to play a role in susceptibility to white-nose syndrome (WNS), a fungal infection that has decimated several Nearctic bat species. We used non-invasive probes to measure the pH of bat flight membranes in five species with differing susceptibility to WNS. Skin pH ranged from 4.67 to 8.59 and varied among bat species, geographic locations, body parts, age classes, sexes and seasons. Wild Eptesicus fuscus were consistently more acidic than wild Myotis lucifugus, Myotis leibii and Perimyotis subflavus. Juvenile bats had more acidic skin than adults during maternity season but did not differ during swarming. Male M. lucifugus were more acidic than females during maternity season, yet this trend reversed during swarming. Bat skin was more acidic in summer compared to winter, a pattern also reported in humans. Skin pH was more acidic in captive than wild E. fuscus, suggesting environmental impacts on skin pH. The pH of roosting substrates affects skin pH in captive bats and may partially explain seasonal patterns in wild bats that use different roost types across seasons. Future research on the influence of pH on microbial pathogenic factors and skin barrier function may provide valuable insights on new therapeutic targets for treating bat skin conditions.

Immune Sensing and Potential Immunotherapeutic Approaches to Control Chromoblastomycosis.

Chromoblastomycosis (CBM) is a neglected, chronic, and progressive subcutaneous mycosis caused by different species of fungi from the Herpotrichiellaceae family. CBM disease is usually associated with agricultural activities, and its infection is characterized by verrucous, erythematous papules, and atrophic lesions on the upper and lower limbs, leading to social stigma and impacts on patients’ welfare. The economic aspect of disease treatment is another relevant issue. There is no specific treatment for CBM, and different anti-fungal drug associations are used to treat the patients. However, the long period of the disease and the high cost of the treatment lead to treatment interruption and, consequently, relapse of the disease. In previous years, great progress had been made in the comprehension of the CBM pathophysiology. In this review, we discuss the differences in the cell wall composition of conidia, hyphae, and muriform cells, with a particular focus on the activation of the host immune response. We also highlight the importance of studies about the host skin immunology in CBM. Finally, we explore different immunotherapeutic studies, highlighting the importance of these approaches for future treatment strategies for CBM.

The Effects of A Mosquito Salivary Protein on Sporozoite Traversal of Host Cells.

Malaria begins when Plasmodium-infected Anopheles mosquitoes take a blood meal on a vertebrate. During the initial probing process, mosquitoes inject saliva and sporozoites into the host skin. Components of mosquito saliva have the potential to influence sporozoite functionality. Sporozoite-associated mosquito saliva protein 1 (SAMSP1; AGAP013726) was among several proteins identified when sporozoites were isolated from saliva, suggesting it may have an effect on Plasmodium. Recombinant SAMSP1 enhanced sporozoite gliding and cell traversal activity in vitro. Moreover, SAMSP1 decreased neutrophil chemotaxis in vivo and in vitro, thereby also exerting an influence on the host environment in which the sporozoites reside. Active or passive immunization of mice with SAMSP1 or SAMSP1 antiserum diminished the initial Plasmodium burden after infection. Passive immunization of mice with SAMSP1 antiserum also added to the protective effect of a circumsporozoite protein monoclonal antibody. SAMSP1 is, therefore, a mosquito saliva protein that can influence sporozoite infectivity in the vertebrate host.

Mosquito Behavior and Vertebrate Microbiota Interaction: Implications for Pathogen Transmission.

The microbiota is increasingly recognized for its ability to influence host health and individual fitness through multiple pathways, such as nutrient synthesis, immune system development, and even behavioral processes. Most of these studies though focus on the direct effects microbiota has on its host, but they do not consider possible interactions with other individuals. However, host microbiota can change not only host behavior but also the behavior of other individuals or species toward the host. For example, microbes can have an effect on animal chemistry, influencing animal behaviors mediated by chemical communication, such as mosquito attraction. We know that host skin microbes play a major role in odor production and thus can affect the behavior of mosquitoes leading to differences in attraction to their hosts. Ultimately, the vector feeding preference of mosquitoes conditions the risk of vertebrates of coming into contact with a vector-borne pathogen, affecting its transmission, and thus epidemiology of vector-borne diseases. In this mini review, I provide an overview of the current status of research on the interaction between mosquito behavior and host skin microbiota, both in humans and other vertebrates. I consider as well the factors that influence vertebrate skin microbiota composition, such as sex, genetic makeup, and infection status, and discuss the implications for pathogen transmission.

Plasmodium sporozoites on the move: Switching from cell traversal to productive invasion of hepatocytes.

Parasites of the genus Plasmodium, the etiological agent of malaria, are transmitted through the bite of anopheline mosquitoes, which deposit sporozoites into the host skin. Sporozoites migrate through the dermis, enter the bloodstream, and rapidly traffic to the liver. They cross the liver sinusoidal barrier and traverse several hepatocytes before switching to productive invasion of a final one for replication inside a parasitophorous vacuole. Cell traversal and productive invasion are functionally independent processes that require proteins secreted from specialized secretory organelles known as micronemes. In this review, we summarize the current understanding of how sporozoites traverse through cells and productively invade hepatocytes, and discuss the role of environmental sensing in switching from a migratory to an invasive state. We propose that timely controlled secretion of distinct microneme subsets could play a key role in successful migration and infection of hepatocytes. A better understanding of these essential biological features of the Plasmodium sporozoite may contribute to the development of new strategies to fight against the very first and asymptomatic stage of malaria.

Development and validation of a high-throughput whole cell assay to investigate Staphylococcus aureus adhesion to host ligands

Staphylococcus aureus adhesion to the host's skin and mucosae enables asymptomatic colonization and the establishment of infection. This process is facilitated by cell wall-anchored adhesins that bind to host ligands. Therapeutics targeting this process could provide significant clinical benefits; however, the development of anti-adhesives requires an in-depth knowledge of adhesion-associated factors and an assay amenable to high-throughput applications. Here, we describe the development of a sensitive and robust whole cell assay to enable the large-scale profiling of S. aureus adhesion to host ligands. To validate the assay, and to gain insight into cellular factors contributing to adhesion, we profiled a sequence-defined S. aureus transposon mutant library, identifying mutants with attenuated adhesion to human-derived fibronectin, keratin, and fibrinogen. Our screening approach was validated by the identification of known adhesion-related proteins, such as the housekeeping sortase responsible for covalently linking adhesins to the cell wall. In addition, we also identified genetic loci that could represent undescribed anti-adhesive targets. To compare and contrast the genetic requirements of adhesion to each host ligand, we generated a S. aureus Genetic Adhesion Network, which identified a core gene set involved in adhesion to all three host ligands, and unique genetic signatures. In summary, this assay will enable high-throughput chemical screens to identify anti-adhesives and our findings provide insight into the target space of such an approach.

16502 Effect of pH on growth of skin commensals and pathogens

Background: Several studies have demonstrated that skin pH can play an important role in regulation of enzyme activity primarily in keratinization and barrier function. The skin microbiome is influenced by the condition of the host skin, such as moisture and sebum content, presence of skin antimicrobial peptides, skin pH, etc. It has been previously shown that skin pH increases with skin dryness or when skin is washed with a harsh soap. The skin pH is also shown to be higher in patients with atopic eczema, where there is a dysbiosis in the microbiome balance, in particular the relative abundance of Staphylococcus aureus and Staphylococcus epidermidis.

Setaria labiatopapillosa (Filarioidea, Nematoda) in Moroccan cattle: atypical localization and morphological characterization of females and microfilariae by light and scanning electron microscopy.

Filarioid nematodes are parasites of the tissues and tissue spaces of all vertebrates except fish. Females produce microfilariae that enter the host's blood circulation or skin and may cause ocular and neurological pathology, leading to important implications in veterinary and public health. The present work is the first investigation on Setaria labiatopapillosa conducted in Morocco to characterize the morphological features of both adult and microfilaria forms. Two adult female nematodes were found free in the thoracic cavity of a slaughtered 3.5-year-old (6 teeth) Moroccan enhanced cross-breed bull which was born and raised in Morocco. The worms were identified as S. labiatopapillosa by light microscope (LM) and scanning electron microscopy (SEM) on the basis of their characteristic features of the anterior and posterior parts of the worms. The two S. labiatopapillosa worms measured 90mm and 105mm in length and 0.55 and 0.64mm in width, respectively. Microfilariae were detected in the fully developed eggs contained in the uterus of both nematodes. A detailed morphology of both the adult females and larvae of S. labiatopapillosa is described using LM and SEM. Although the origin of S. labiatopapillosa analyzed in the present study is unknown and there is currently no evidence that Setaria spp. have invaded Morocco, further surveillance is warranted to determine the incidence of setariasis, identify its vectors, and take appropriate measures to protect the livestock and cattle industry of the country.

Engineering a vector-based pan-Leishmania vaccine for humans: proof of principle

Leishmaniasis is a spectrum of diseases transmitted by sand fly vectors that deposit Leishmania spp. parasites in the host skin during blood feeding. Currently, available treatment options are limited, associated with high toxicity and emerging resistance. Even though a vaccine for human leishmaniasis is considered an achievable goal, to date we still do not have one available, a consequence (amongst other factors) of a lack of pre-clinical to clinical translatability. Pre-exposure to uninfected sand fly bites or immunization with defined sand fly salivary proteins was shown to negatively impact infection. Still, cross-protection reports are rare and dependent on the phylogenetic proximity of the sand fly species, meaning that the applicability of a sand fly saliva-based vaccine will be limited to a defined geography, one parasite species and one form of leishmaniasis. As a proof of principle of a future vector saliva-based pan-Leishmania vaccine, we engineered through a reverse vaccinology approach that maximizes translation to humans, a fusion protein consisting of immunogenic portions of PdSP15 and LJL143, sand fly salivary proteins demonstrated as potential vaccine candidates against cutaneous and visceral leishmaniasis, respectively. The in silico analysis was validated ex vivo, through T cell proliferation experiments, proving that the fusion protein (administered as a DNA vaccine) maintained the immunogenicity of both PdSP15 and LJL143. Additionally, while no significant effect was detected in the context of L. major transmission by P. duboscqi, this DNA vaccine was defined as partially protective, in the context of L. major transmission by L. longipalpis sand flies. Importantly, a high IFNγ response alone was not enough to confer protection, that mainly correlated with low T cell mediated Leishmania-specific IL-4 and IL-10 responses, and consequently with high pro/anti-inflammatory cytokine ratios. Overall our immunogenicity data suggests that to design a potentially safe vector-based pan-Leishmania vaccine, without geographic restrictions and against all forms of leishmaniasis is an achievable goal. This is why we propose our approach as a proof-of principle, perhaps not only applicable to the anti-Leishmania vector-based vaccines’ field, but also to other branches of knowledge that require the design of multi-epitope T cell vaccines with a higher potential for translation.