Shaping the Microbial Landscape: Parasitoid-Driven Modifications of Bactrocera dorsalis Microbiota.

Koinobiont endoparasitoids regulate the physiology of their hosts through altering host immuno-metabolic responses, processes which function in tandem to shape the composition of the microbiota of these hosts. Here, we employed 16S rRNA and ITS amplicon sequencing to investigate whether parasitization by the parasitoid wasps, Diachasmimorpha longicaudata (Ashmaed) (Hymenoptera: Braconidae) and Psyttalia cosyrae (Wilkinson) (Hymenoptera: Braconidae), induces gut dysbiosis and differentially alter the gut microbial (bacteria and fungi) communities of an important horticultural pest, Bactrocera dorsalis (Hendel) (Diptera: Tephritidae). We further investigated the composition of bacterial communities of adult D. longicaudata and P. cosyrae to ascertain whether the adult parasitoids and parasitized host larvae share microbial taxa through transmission. We demonstrated that parasitism by D. longicaudata induced significant gut perturbations, resulting in the colonization and increased relative abundance of pathogenic gut bacteria. Some pathogenic bacteria like Stenotrophomonas and Morganella were detected in both the guts of D. longicaudata-parasitized B. dorsalis larvae and adult D. longicaudata wasps, suggesting a horizontal transfer of microbes from the parasitoid to the host. The bacterial community of P. cosyrae adult wasps was dominated by Arsenophonus nasoniae, whereas that of D. longicaudata adults was dominated by Paucibater spp. and Pseudomonas spp. Parasitization by either parasitoid wasp was associated with an overall reduction in fungal diversity and evenness. These findings indicate that unlike P. cosyrae which is avirulent to B. dorsalis, parasitization by D. longicaudata induces shifts in the gut bacteriome of B. dorsalis larvae to a pathobiont-dominated community. This mechanism possibly enhances its virulence against the pest, further supporting its candidacy as an effective biocontrol agent of this frugivorous tephritid fruit fly pest.

SOD3 suppresses early cellular immune responses to parasite infection.

Host immune responses are tightly controlled by various immune factors during infection, and protozoan parasites also manipulate the immune system to evade surveillance, leading to an evolutionary arms race in host‒pathogen interactions; however, the underlying mechanisms are not fully understood. We observed that the level of superoxide dismutase 3 (SOD3) was significantly elevated in both Plasmodium falciparum malaria patients and mice infected with four parasite species. SOD3-deficient mice had a substantially longer survival time and lower parasitemia than control mice after infection, whereas SOD3-overexpressing mice were much more vulnerable to parasite infection. We revealed that SOD3, secreted from activated neutrophils, bound to T cells, suppressed the interleukin-2 expression and concomitant interferon-gamma responses crucial for parasite clearance. Overall, our findings expose active fronts in the arms race between the parasites and host immune system and provide insights into the roles of SOD3 in shaping host innate immune responses to parasite infection.

Parasite infection in a cell population: role of the partitioning kernel.

We consider a cell population subject to a parasite infection. Cells divide at a constant rate and, at division, share the parasites they contain between their two daughter cells. The sharing may be asymmetric, and its law may depend on the number of parasites in the mother. Cells die at a rate which may depend on the number of parasites they carry, and are also killed when this number explodes. We study the survival of the cell population as well as the mean number of parasites in the cells, and focus on the role of the parasites partitioning kernel at division.

Alterations of plasma circulating microRNAs in BALB/c mice with Toxocara canis visceral and cerebral larva migrans.

BACKGROUND: Human toxocariasis is a neglected parasitic disease characterised by the syndromes visceral, cerebral, and ocular larva migrans. This disease is caused by the migrating larvae of Toxocara roundworms from dogs and cats, affecting 1.4 billion people globally. Via extracellular vesicles (EVs), microRNAs have been demonstrated to play roles in host-parasite interactions and proposed as circulating biomarkers for the diagnosis and follow-up of parasitic diseases. METHODS: Small RNA-seq was conducted to identify miRNAs in the infective larvae of T. canis and plasma EV-containing preparations of infected BALB/c mice. Differential expression analysis and target prediction were performed to indicate miRNAs involved in host-parasite interactions and miRNAs associated with visceral and/or cerebral larva migrans in the infected mice. Quantitative real-time polymerase chain reaction (PCR) was used to amplify circulating miRNAs from the infected mice. RESULTS: This study reports host and parasite miRNAs in the plasma of BALB/c mice with visceral and cerebral larva migrans and demonstrates the alterations of these miRNAs during the migration of larvae from the livers through the lungs and to the brains of infected mice. After filtering unspecific changes in an irrelevant control, T. canis-derived miRNAs and T. canis infection-induced differential miRNAs are predicted to modulate genes consistently involved in mitogen-activated protein kinase (MAPK) signalling and pathways regulating axon guidance and pluripotency of stem in the infected mice with visceral and cerebral larva migrans. For these plasma circulating miRNAs predicted to be involved in host-parasite crosstalk, two murine miRNAs (miR-26b-5p and miR-122-5p) are experimentally verified to be responsive to larva migrans and represent circulating biomarker candidates for visceral and cerebral toxocariasis in BALB/c mice. CONCLUSIONS: Our findings provide novel insights into the crosstalk of T. canis and the mammalian host via plasma circulating miRNAs, and prime agents and indicators for visceral and cerebral larva migrans. A deep understanding of these aspects will underpin the diagnosis and control of toxocariasis in humans and animals.

Occurrence of parasitism promoted by Myzobdella lugubris Leidy, 1851 (Annelida: Piscicolidae) in Callinectes bocourti (Crustacea: Portunidae): A report of invasive leech in Brazilian Amazon province.

This study reports the presence of high parasitic load by Myzobdella lugubris Leidy, 1851 in the swimming crab Callinectes bocourti A. Milne-Edwards, 1879 from Amazon mangrove. We sampled the swimming crabs using a baited trap, between January and June 2023, in Santa Maria River, located in the municipality of Curuçá, state of Pará, Brazil (geographical coordinates 0°40'3.705"S, 047°54'43.405"W). After sampling, each swimming crab was individually placed in plastic containers for the count of leeches per individual. In the laboratory, the specimens were sexed, measured (parasite and host) and fixed in 70% alcohol. For the leech species identification, macroscopic techniques were combined with light microscopy (LM) and scanning electron microscopy (SEM). We examined 86 specimens of C. bocourti (75 males and 11 females) in a ratio of 1 M:0.14 F, all infested with leeches. In total, 186 leech specimens were collected, ranging from 1 to 21 leeches per host. Leeches oviposited the cocoons in greater quantities in ventral area of swimming crab carapace (32%), followed by dorsal area of carapace (29.09%), chelipeds (24.34%) and ambulatory legs (14.57%). The presence of M. lugubris is a risk to the health of the host, once it may transmit a range of diseases to aquatic organisms, and subsequently risk to human health.

Pleiotropy alleviates the fitness costs associated with resource allocation trade-offs in immune signalling networks.

Many genes and signalling pathways within plant and animal taxa drive the expression of multiple organismal traits. This form of genetic pleiotropy instigates trade-offs among life-history traits if a mutation in the pleiotropic gene improves the fitness contribution of one trait at the expense of another. Whether or not pleiotropy gives rise to conflict among traits, however, likely depends on the resource costs and timing of trait deployment during organismal development. To investigate factors that could influence the evolutionary maintenance of pleiotropy in gene networks, we developed an agent-based model of co-evolution between parasites and hosts. Hosts comprise signalling networks that must faithfully complete a developmental programme while also defending against parasites, and trait signalling networks could be independent or share a pleiotropic component as they evolved to improve host fitness. We found that hosts with independent developmental and immune networks were significantly more fit than hosts with pleiotropic networks when traits were deployed asynchronously during development. When host genotypes directly competed against each other, however, pleiotropic hosts were victorious regardless of trait synchrony because the pleiotropic networks were more robust to parasite manipulation, potentially explaining the abundance of pleiotropy in immune systems despite its contribution to life history trade-offs.

Intraspecific variation in Gyrodactylus mediotorus and G. crysoleucas (Gyrodactylidae) from Nearctic shiners (Leuciscidae): evidence for ongoing speciation, host-switching, and parasite translocation.

A parasitological investigation of Cyprinella venusta and Notropis cf. stramineus sampled in Texas, USA, in the Guadalupe River, revealed the presence of Gyrodactylus crysoleucas Mizelle and Kritsky, 1967 on C. venusta, and Gyrodactylus mediotorus King, Marcogliese, Forest, McLaughlin & Bentzen, 2013 on both fish species. This represents new leuscicid fish hosts and locality records for these two gyrodactylids. Gyrodactylus crysoleucas previously identified from both non-native Californian Notemigonus crysoleucas and from farmed stocks in Minnesota demonstrated intraspecific variability in terms of morphology and genetics as a local adaptation associated with isolation by distance. Results further confirmed G. crysoleucas as alien in the western USA and suggested host-switching involving C. venusta and N. crysoleucas. Conservative morphology and genetics on the part of G. mediotorus from C. venusta and N. cf. stramineus (Guadalupe River) was observed, while higher genetic divergence in the ITS sequences associated with morphological discrepancy was found between the studied G. mediotorus specimens and those of Notropis hudsonius than when considering the parasites of Notropis texanus. The separation of G. mediotorus into geographical subgroups may indicate ongoing speciation linked to the Pleistocene glaciations in North America, and to hydrographic barriers that facilitated separate evolutionary paths leading to speciation. We suggest that deep investigations of Gyrodactylus populations will help to understand the speciation of these parasites and their adaptation to Nearctic fish hosts.

Title: Variation intraspécifique chez Gyrodactylus mediotorus et G. crysoleucas (Gyrodactylidae), parasites de ménés néarctiques (Leuciscidae) : preuves d'une spéciation en cours, d'un changement d'hôte et d'une translocation de parasites. Abstract: Une enquête parasitologique sur Cyprinella venusta et Notropis cf. stramineus échantillonnés au Texas, États-Unis, dans la rivière Guadalupe, a révélé la présence de Gyrodactylus crysoleucas Mizelle et Kritsky, 1967 sur C. venusta, et de Gyrodactylus mediotorus King, Marcogliese, Forest, McLaughlin & Bentzen, 2013 sur les deux espèces de poissons. Ceci représente de nouveaux poissons Leuciscidae hôtes et des nouvelles localités pour ces deux Gyrodactylidae. Gyrodactylus crysoleucas, identifié précédemment à partir de Notemigonus crysoleucas californiens non indigènes et de stocks d'élevage du Minnesota a démontré une variabilité intraspécifique en termes de morphologie et de génétique en tant qu'adaptation locale associée à l'isolement par la distance. Les résultats ont en outre confirmé que G. crysoleucas était exotique dans l'ouest des États-Unis et ont suggéré un changement d'hôte impliquant C. venusta et N. crysoleucas. Une morphologie et une génétique conservatrices pour G. mediotorus de C. venusta et N. cf. stramineus (rivière Guadalupe) ont été observées, tandis qu'une divergence génétique plus élevée dans les séquences ITS, associée à une divergence morphologique, a été trouvée chez les spécimens étudiés de G. mediotorus et de Notropis hudsonius lorsque l'on considère les parasites de Notropis texanus. La séparation de G. mediotorus en sous-groupes géographiques peut indiquer une spéciation continue liée aux glaciations du Pléistocène en Amérique du Nord et à des barrières hydrographiques qui ont facilité des chemins évolutifs séparés menant à la spéciation. Nous suggérons que des études approfondies sur les populations de Gyrodactylus aideront à comprendre la spéciation de ces parasites et leur adaptation aux poissons hôtes néarctiques.

Trichomonas vaginalis extracellular vesicles up-regulate and directly transfer adherence factors promoting host cell colonization.

Trichomonas vaginalis, a common sexually transmitted parasite that colonizes the human urogenital tract, secretes extracellular vesicles (TvEVs) that are taken up by human cells and are speculated to be taken up by parasites as well. While the crosstalk between TvEVs and human cells has led to insight into host:parasite interactions, roles for TvEVs in infection have largely been one-sided, with little known about the effect of TvEV uptake by T. vaginalis. Approximately 11% of infections are found to be coinfections of multiple T. vaginalis strains. Clinical isolates often differ in their adherence to and cytolysis of host cells, underscoring the importance of understanding the effects of TvEV uptake within the parasite population. To address this question, our lab tested the ability of a less adherent strain of T. vaginalis, G3, to take up fluorescently labeled TvEVs derived from both itself (G3-EVs) and TvEVs from a more adherent strain of the parasite (B7RC2-EVs). Here, we showed that TvEVs generated from the more adherent strain are internalized more efficiently compared to the less adherent strain. Additionally, preincubation of G3 parasites with B7RC2-EVs increases parasite aggregation and adherence to host cells. Transcriptomics revealed that TvEVs up-regulate expression of predicted parasite membrane proteins and identified an adherence factor, heteropolysaccharide binding protein (HPB2). Finally, using comparative proteomics and superresolution microscopy, we demonstrated direct transfer of an adherence factor, cadherin-like protein, from TvEVs to the recipient parasite's surface. This work identifies TvEVs as a mediator of parasite:parasite communication that may impact pathogenesis during mixed infections.

Plasmodium vivax spleen-dependent protein 1 and its role in extracellular vesicles-mediated intrasplenic infections.

Recent studies indicate that human spleen contains over 95% of the total parasite biomass during chronic asymptomatic infections caused by Plasmodium vivax. Previous studies have demonstrated that extracellular vesicles (EVs) secreted from infected reticulocytes facilitate binding to human spleen fibroblasts (hSFs) and identified parasite genes whose expression was dependent on an intact spleen. Here, we characterize the P. vivax spleen-dependent hypothetical gene (PVX_114580). Using CRISPR/Cas9, PVX_114580 was integrated into P. falciparum 3D7 genome and expressed during asexual stages. Immunofluorescence analysis demonstrated that the protein, which we named P. vivax Spleen-Dependent Protein 1 (PvSDP1), was located at the surface of infected red blood cells in the transgenic line and this localization was later confirmed in natural infections. Plasma-derived EVs from P. vivax-infected individuals (PvEVs) significantly increased cytoadherence of 3D7_PvSDP1 transgenic line to hSFs and this binding was inhibited by anti-PvSDP1 antibodies. Single-cell RNAseq of PvEVs-treated hSFs revealed increased expression of adhesion-related genes. These findings demonstrate the importance of parasite spleen-dependent genes and EVs from natural infections in the formation of intrasplenic niches in P. vivax, a major challenge for malaria elimination.

Pathogenicity associated with an infestation of the marine leech parasite Pterobdella arugamensis in farmed fish.

The marine leech Pterobdella arugamensis is a hematophagous parasite, and the extent of injury to the host largely depends on the number of attached leeches. This study aimed to assess the pathogenicity of marine leeches in Asian seabass (Lates calcarifer) and tiger grouper (Epinephelus fuscoguttatus) fingerlings under laboratory conditions. Five groups of healthy Asian seabass and tiger grouper were exposed to varying numbers of marine leeches (0, 1, 10, 30, or 70 per fish) for 7 d. Infested Asian seabass and tiger grouper both showed pathological changes even with only 1 leech, manifesting as clinical signs like haemorrhages. The cumulative mortality at 7 d post-exposure (dpe) was 11 or 33% for Asian seabass infested with 1 or 10 marine leeches, respectively. Fish with 30 or 70 marine leeches showed higher rates of mortality (56%). A similar trend was seen in tiger grouper, with mortality rates reaching 78% in fish with 30 or 70 marine leeches, and 56 or 33% in fish with 10 leeches or 1 leech, respectively. Factorial analysis of mortality after 7 dpe between both species showed significant differences (2-way ANOVA p = 0.001) when exposed to varying numbers of marine leeches. The haematocrit values differed significantly between Asian seabass or tiger grouper infested with either 0 or 1 marine leech and those infested with 10, 30, or 70 marine leeches (1-way ANOVA, p = 0.0001). This suggests that marine leech infestation has a measurable impact on both species. Consequently, fish farmers should promptly address leech infestation upon discovery in their cages.

Does the body size, sex, and reproductive modes of leaf litter anurans affect the diversity of parasites?

We describe the composition of endoparasites associated with leaf litter anurans from an Atlantic Forest area, in southeastern Brazil. We tested if body size, sex, and reproductive modes of anuran hosts influence endoparasite abundance and richness. We sampled 583 individuals from 11 anuran species and recorded 1,600 helminths from 14 taxa. The helminths that infected the greatest number of anuran host species were the nematodes Cosmocerca parva (8 spp.), Physaloptera sp. (8 spp.), and Cosmocerca brasiliense (7 spp.), and the most abundant helminth species were Physaloptera sp. (14.6%), Cosmocerca brasiliense (13.7%) and Cosmocerca parva (12.6%). Both helminth abundance and richness were positively affected by anuran body size and dependence on water for reproduction. Larger hosts can contain a higher abundance of parasites because they may provide more physical space than smaller ones, or it can simply be a function of age. Besides, parasite species richness can be highly correlated with the amount of time a host spends in association with aquatic habitats, a conservative aspect of both parasite and host natural history. Within host species, there was a positive and significant influence of body size on helminth abundance. Haddadus binotatus females had greater helminth abundance than males, probably due to sex-related differences in behavior and/or in physiology. Our data suggest that reproductive modes could also influence helminth infection parameters in other anuran communities and should be considered in detail in future analyses.

Expression of IL-10 and TGF-ß1 in horses experimentally infected with T. equi merozoites is associated with antibody production but not modulation of pro-inflammatory responses.

Theileria equi (T. equi) is an apicomplexan parasite that causes severe hemolytic anemia in equids. Presently, there is inadequate knowledge of the immune responses induced by T. equi in equid hosts impeding understanding of the host parasite relationship and development of potent vaccines for control of T. equi infections. The objective of this study was to evaluate the host-parasite dynamics between T. equi merozoites and infected horses by assessing cytokine expression during primary and secondary parasite exposure, and to determine whether the pattern of expression correlated with clinical indicators of disease. Our findings showed that the expression of pro-inflammatory cytokines was very low and inconsistent during both primary and secondary infection. There was also no correlation between the symptoms observed during primary infection and expression of the cytokines. This suggests that the symptoms might have occurred primarily due to hemolysis and likely not the undesirable effects of pro-inflammatory responses. However, IL-10 and TGF-ß1 were highly expressed in both phases of infection, and their expression was linked to antibody production but not moderation of pro-inflammatory cytokine responses.

Host weight, seasonality and anthropogenic factors contribute to parasite community differences between urban and rural foxes.

Pathogens often occur at different prevalence along environmental gradients. This is of particular importance for gradients of anthropogenic impact such as rural-urban transitions presenting a changing interface between humans and wildlife. The assembly of parasite communities is affected by both the external environmental conditions and individual host characteristics. Hosts with low body weight (smaller individuals or animals with poor body condition) might be more susceptible to infection. Furthermore, parasites' mode of transmission might affect their occurrence: rural environments with better availability of intermediate hosts might favour trophic transmission, while urban environments, typically with dense definitive host populations, might favour direct transmission. We here study helminth communities (141 intestinal samples) within the red fox (Vulpes vulpes), a synanthropic host, using DNA metabarcoding of multiple marker genes. We analysed the effect of urbanisation, seasonality and host-intrinsic (weight, sex) variables on helminth communities. Helminth species richness increased in foxes with lower body weight and in winter and spring. Season and urbanisation, however, had strong effects on the community composition, i.e., on the identity of the detected species. Surprisingly, transmission in two-host life cycles (trophic transmission) was more pronounced in urban Berlin than in rural Brandenburg. This disagrees with the prevailing hypothesis that trophically transmitted helminths are less prevalent in urban areas than in rural areas. Generally, co-infestations with multiple helminths and high infection intensity are associated with lighter (younger, smaller or low body condition) animals. Both host-intrinsic traits and environmental drivers together shape parasite community composition and turnover along urban-rural gradients.

Accelerating snail vector genomics.

The three most important genera of snails for the transmission of schistosomes are Bulinus, Biomphalaria and Oncomelania. Each of these genera, found in two distantly related families, includes species that act as the intermediate host for one of the three most widespread schistosome species infecting humans, Schistosoma haematobium, S. mansoni and S. japonicum, respectively. An important step in the fight against schistosomiasis in Asia has been taken with the publication of the article "Chromosome-level genome assembly of Oncomelania hupensis: the intermediate snail host of Schistosoma japonicum", which means that genomes for all three major genera, including species across three continents, are now available in the public domain. This includes the first genomes of African snail vectors, namely Biomphalaria sudanica, Bi. pfeifferi and Bulinus truncatus, as well as high-quality chromosome level assemblies for South American Bi. glabrata. Most importantly, the wealth of new genomic and transcriptomic data is helping to establish the specific molecular mechanisms that underly compatibility between snails and their schistosomes, which although diverse and complex, may help to identify potential targets dictating host parasite interactions that can be utilised in future transmission control strategies. This new work on Oncomelania hupensis and indeed studies on other snail vectors, which provide deep insights into the genome, will stimulate research that may well lead to new and much needed control interventions.

Leishmania donovani mitogen-activated protein kinases as a host-parasite interaction interface.

Leishmaniasis, a major globally re-emerging neglected tropical disease, has a restricted repertoire of chemotherapeutic options due to a narrow therapeutic index, drug resistance, or patient non-compliance due to toxicity. The disease is caused by the parasite Leishmania that resides in two different forms in two different environments: as sessile intracellular amastigotes within mammalian macrophages and as motile promastigotes in sandfly gut. As mitogen-activated protein kinases (MAPKs) play important roles in cellular differentiation and survival, we studied the expression of Leishmania donovani MAPKs (LdMAPKs). The homology studies by multiple sequence alignment show that excepting LdMAPK1 and LdMAPK2, all thirteen other LdMAPKs share homology with human ERK and p38 isoforms. Expression of LdMAPK4 and LdMAPK5 is less in avirulent promastigotes and amastigotes. Compared to miltefosine-sensitive L. donovani parasites, miltefosine-resistant parasites have higher LdMAPK1, LdMAPK3-5, LdMAPK7-11, LdMAPK13, and LdMAPK14 expression. IL-4-treatment of macrophages down-regulated LdMAPK11, in virulent amastigotes whereas up-regulated LdMAPK5, but down-regulated LdMAPK6, LdMAPK12-15, expression in avirulent amastigotes. IL-4 up-regulated LdMAPK1 expression in both virulent and avirulent amastigotes. IFN-γ-treatment down-regulated LdMAPK6, LdMAPK13, and LdMAPK15 in avirulent amastigotes but up-regulated in virulent amastigotes. This complex profile of LdMAPKs expression among virulent and avirulent parasites, drug-resistant parasites, and in amastigotes within IL-4 or IFN-γ-treated macrophages suggests that LdMAPKs are differentially controlled at the host-parasite interface regulating parasite survival and differentiation, and in the course of IL-4 or IFN-γ dominated immune response.

Functional similarity affects similarity in partner composition in flea-mammal networks.

Functional signal in an interaction network is a phenomenon in which species resembling each other in their traits interact with similar partners. We tested the functional signal concept in realm-specific and regional flea-host networks from four biogeographic realms and asked whether the species composition of (a) host spectra and (b) flea assemblages is similar between functionally similar flea and host species, respectively. Analogously to testing for phylogenetic signal, we applied Mantel tests to investigate the correlation between flea or host functional distances calculated from functional dendrograms and dissimilarities in sets of interacting partners. In all realm-specific networks, functionally similar fleas tended to exploit similar hosts often belonging to the same genus, whereas functionally similar hosts tended to harbour similar fleas, again often belonging to the same genus. The strength of realm-specific functional signals and the frequency of detecting a significant functional signal in the regional networks differed between realms. The frequency of detecting a significant functional signal in the regional networks correlated positively with the network size for fleas and with the number of hosts in a network for hosts. A functional signal in the regional networks was more frequently found for hosts than for fleas. We discuss the mechanisms behind the functional signal in both fleas and their hosts, relate geographic functional signal patterns to the historic biogeography of fleas and conclude that functional signals in the species composition of host spectra for fleas and of flea assemblages for hosts result from the interplay of evolutionary and ecological processes.

Understanding the host response of farmed fish to blood flukes (Trematoda: Aporocotylidae) for developing new treatment strategies.

Aporocotylids (Trematoda: Digenea), also known as fish blood flukes infect the circulatory system of fish leading to serious health problems and mortality. Aporocotylids are a particular concern for farmed fish as infection intensity can increase within the farming environment and lead to mortalities. In the context of managing these infections, one of the most crucial aspects to consider is the host response of the infected fish against these blood flukes. Understanding the response is essential to improving current treatment strategies that are largely based on the use of anthelmintic praziquantel to manage infections in aquaculture. This review focuses on the current knowledge of farmed fish host responses against the different life stages of aporocotylids. New treatment strategies that are able to provide protection against reinfections should be a long-term goal and is not possible without understanding the fish response to infection and the interactions between host and parasite.

Performance and preference of larval parasitoid, Microplitis pallidipes (Hymenoptera: Braconidae), on 2 Spodoptera pest species.

Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae) and Spodoptera litura (Fabricius) are the main pests on corn (Poaceae: Gramineae). The performance of the larval wasp, Microplitis pallidipes Szépligeti (Hymenoptera: Braconidae), was reported on S. frugiperda and S. litura. In this study, we evaluated host selectivity, constructed an age-stage, 2-sex life table, and assessed the pest control potential of M. pallidipes against these 2 pests under laboratory conditions. In a 2-choice host preference experiment, M. pallidipes exhibited a stronger preference for S. frugiperda over S. litura and a distinct preference for second instars. We also investigated the parasitism of females that were either unfed or fed with 10% honey-water solution under different host densities and found that the highest parasitism rate was observed when M. pallidipes were fed with honey-water solution on the first day after mating and a presented female wasp:host ratio of 1:90. In a nonselective assay, M. pallidipes successfully completed a full generation on both hosts. However, the parasitoids exhibited higher fitness and population growth potential when reared on S. frugiperda, with a net reproductive rate (R0) of 24.24, an intrinsic rate of increase (r) of 0.20 per day, a finite rate of increase (λ) of 1.23 per day, and a mean generation time (T) of 15.69 days. This study elucidates the performance of M. pallidipes on 2 Spodoptera host species and offers insights into its biological control potential on lepidopteran pests.

TurboID mapping reveals the exportome of secreted intrinsically disordered proteins in the transforming parasite Theileria annulata.

Theileria annulata is a tick-transmitted apicomplexan parasite that gained the unique ability among parasitic eukaryotes to transform its host cell, inducing a fatal cancer-like disease in cattle. Understanding the mechanistic interplay between the host cell and malignant Theileria species that drives this transformation requires the identification of responsible parasite effector proteins. In this study, we used TurboID-based proximity labeling, which unbiasedly identified secreted parasite proteins within host cell compartments. By fusing TurboID to nuclear export or localization signals, we biotinylated proteins in the vicinity of the ligase enzyme in the nucleus or cytoplasm of infected macrophages, followed by mass spectrometry analysis. Our approach revealed with high confidence nine nuclear and four cytosolic candidate parasite proteins within the host cell compartments, eight of which had no orthologs in non-transforming T. orientalis. Strikingly, all eight of these proteins are predicted to be highly intrinsically disordered proteins. We discovered a novel tandem arrayed protein family, nuclear intrinsically disordered proteins (NIDP) 1-4, featuring diverse functions predicted by conserved protein domains. Particularly, NIDP2 exhibited a biphasic host cell-cycle-dependent localization, interacting with the EB1/CD2AP/CLASP1 parasite membrane complex at the schizont surface and the tumor suppressor stromal antigen 2 (STAG2), a cohesion complex subunit, in the host nucleus. In addition to STAG2, numerous NIDP2-associated host nuclear proteins implicated in various cancers were identified, shedding light on the potential role of the T. annulata exported protein family NIDP in host cell transformation and cancer-related pathways.IMPORTANCETurboID proximity labeling was used to identify secreted proteins of Theileria annulata, an apicomplexan parasite responsible for a fatal, proliferative disorder in cattle that represents a significant socio-economic burden in North Africa, central Asia, and India. Our investigation has provided important insights into the unique host-parasite interaction, revealing secreted parasite proteins characterized by intrinsically disordered protein structures. Remarkably, these proteins are conspicuously absent in non-transforming Theileria species, strongly suggesting their central role in the transformative processes within host cells. Our study identified a novel tandem arrayed protein family, with nuclear intrinsically disordered protein 2 emerging as a central player interacting with established tumor genes. Significantly, this work represents the first unbiased screening for exported proteins in Theileria and contributes essential insights into the molecular intricacies behind the malignant transformation of immune cells.

Contribution of parasite and host genotype to immunopathology of schistosome infections.

BACKGROUND: The role of pathogen genotype in determining disease severity and immunopathology has been studied intensively in microbial pathogens including bacteria, fungi, protozoa and viruses but is poorly understood in parasitic helminths. The medically important blood fluke Schistosoma mansoni is an excellent model system to study the impact of helminth genetic variation on immunopathology. Our laboratory has demonstrated that laboratory schistosome populations differ in sporocyst growth and cercarial production in the intermediate snail host and worm establishment and fecundity in the vertebrate host. Here, we (i) investigate the hypothesis that schistosome genotype plays a significant role in immunopathology and related parasite life history traits in the vertebrate mouse host and (ii) quantify the relative impact of parasite and host genetics on infection outcomes. METHODS: We infected BALB/c and C57BL/6 mice with four different laboratory schistosome populations from Africa and the Americas. We quantified disease progression in the vertebrate host by measuring body weight and complete blood count (CBC) with differential over a 12-week infection period. On sacrifice, we assessed parasitological (egg and worm counts, fecundity), immunopathological (organ measurements and histopathology) and immunological (CBC with differential and cytokine profiles) characteristics to determine the impact of parasite and host genetics. RESULTS: We found significant variation between parasite populations in worm numbers, fecundity, liver and intestine egg counts, liver and spleen weight, and fibrotic area but not in granuloma size. Variation in organ weight was explained by egg burden and intrinsic parasite factors independent of egg burden. We found significant variation between infected mouse lines in cytokine levels (IFN-γ, TNF-α), eosinophils, lymphocytes and monocyte counts. CONCLUSIONS: This study showed that both parasite and host genotype impact the outcome of infection. While host genotype explains most of the variation in immunological traits, parasite genotype explains most of the variation in parasitological traits, and both host and parasite genotypes impact immunopathology outcomes.