Recombinant antigen 5 from Polybia paulista wasp venom (Hymenoptera, Vespidae): Antigen-specific antibody production and functional profile of CD4+ T cells in the immune response.

Polybia paulista is a neotropical social wasp related to severe accidents and allergic reactions cases, including anaphylaxis, in southeastern Brazil. Antigen 5 (Poly p 5) is a major allergenic protein from its venom with potential use for component-resolved diagnostic. Therefore, the previous characterization of the immune response profile triggered by Poly p 5 should be evaluated. Recombinant Poly p 5 (rPoly p 5) was used to sensitize BALB/c mice with six weekly intradermal doses, and the specific antibody production and the functional profile of CD4+ T cells were assessed. rPoly p 5 induced the production of specific immunoglobulins (sIg) sIgE, sIgG1 and sIgG2a, which could recognize natural Poly p 5 presented in the venom of four different wasp species. rPoly p 5 stimulated in vitro the CD4+ T cells from immunized mice, which showed a significant proliferative response. These antigen-specific CD4+T cells produced IFN-γ and IL-17A cytokines and increased ROR-γT transcription factor expression. No differences between the control group and sensitized mice were found in IL-4 production and GATA-3 and T-bet expression. Interestingly, increased CD25+FoxP3+ regulatory T cells (Tregs) frequency was observed in the splenocyte cell cultures from rPoly p 5 immunized mice after the in vitro stimulation with both P. paulista venom extract and rPoly p 5. Here we showed that rPoly p 5 induces antigen-specific antibodies capable of recognizing Antigen 5 in the venom of four wasp species and modulates antigen-specific CD4+ T cells to IFN-γ production response associated with a Th17 profile in sensitized mice. These findings emphasize the potential use of rPoly p 5 as an essential source of a major wasp allergen with significant immunological properties.

STING deficiency protects against wasp venom-induced acute kidney injury.

OBJECTIVE: Recent evidence suggests a key role of the inflammatory responses in wasp venom-induced acute kidney injury (AKI). However, the potential regulatory mechanisms underlying the inflammatory responses in wasp venom-induced AKI remain unclear. STING reportedly plays a critical role in other AKI types and is associated with inflammatory responses and diseases. We aimed to investigate the involvement of STING in inflammatory responses associated with wasp venom-induced AKI. METHODS: The role of the STING signaling pathway in wasp venom-induced AKI was studied in vivo using a mouse model of wasp venom-induced AKI with STING knockout or pharmacological inhibition and in vitro using human HK2 cells with STING knockdown. RESULTS: STING deficiency or pharmacological inhibition markedly ameliorated renal dysfunction, inflammatory responses, necroptosis, and apoptosis in wasp venom-induced AKI in mice. Moreover, STING knockdown in cultured HK2 cells attenuated the inflammatory response, necroptosis, and apoptosis induced by myoglobin, the major pathogenic factor in wasp venom-induced AKI. Urinary mitochondrial DNA upregulation has also been observed in patients with wasp venom-induced AKI. CONCLUSIONS: STING activation mediates the inflammatory response in wasp venom-induced AKI. This may offer a potential therapeutic target for the management of wasp venom-induced AKI.

The therapeutic effect of wasp venom (Vespa magnifica, Smith) and its effective part on rheumatoid arthritis fibroblast-like synoviocytes through modulating inflammation, redox homeostasis and ferroptosis.

ETHNOPHARMACOLOGICAL RELEVANCE: Rheumatoid arthritis (RA) is a chronic inflammatory disease that is related to the aberrant proliferation of fibroblast-like synoviocytes (FLS). Wasp venom (WV, Vespa magnifica, Smith), an insect secretion, has been used to treat RA in Chinese Jingpo national minority's ancient prescription. However, the potential mechanisms haven't been clarified. AIM OF THE STUDY: The purposes of this paper were two-fold. First, to investigate which was the best anti-RA effective part of WV-I (molecular weight less than 3 kDa), WV-II (molecular weight 3-10 kDa) and WV-III (molecular weight more than 10 kDa) that were separated from WV. Second, to explore the underlying molecular mechanism of WV and WV-II that was best effective part in RA. MATERIALS AND METHODS: The wasps were electrically stimulated and the secretions were collected. WV-I, WV-II and WV-III were acquired by ultracentrifuge method according to molecular weight. Next, WV, WV-I, WV-II and WV-III were identified by HPLC. Functional annotation and pathway analysis of WV used to bioinformatics analysis. RNA-seq analyses were constructed to identify differentially expressed genes (DEGs). GO and KEGG pathway analyses were performed by Metascape database. STRING was used to analyze the PPI network from DEGs. Next, PPI network was visualized using Cytoscape that based on MCODE. The pivotal genes of PPI network and MCODE analysis were verified by qRT-PCR. Subsequently, MH7A cells were performed by MTT assay to evaluate the ability of inhibiting cell proliferation. Luciferase activity assay was conducted in HepG2/STAT1 or HepG2/STAT3 cells to assess STAT1/3 sensitivity of WV, WV-I, WV-II and WV-III. Additionally, interleukin (IL)-1ß and IL-6 expression levels were detected by ELISA kits. Intracellular thioredoxin reductase (TrxR) enzyme was evaluated by TrxR activity assay kit. ROS levels, lipid ROS levels and Mitochondrial membrane potential (MMP) were assessed by fluorescence probe. Cell apoptosis and MMP were measured by using flow cytometry. Furthermore, the key proteins of JAK/STAT signaling pathway, protein levels of TrxR and glutathione peroxidase 4 axis (GPX4) were examined by Western blotting assay. RESULTS: RNA-sequencing analysis of WV displayed be related to oxidation-reduction, inflammation and apoptosis. The data displayed that WV, WV-II and WV-III inhibited significantly cells proliferation in human MH7A cell line compared to WV-I treatment group, but WV-III had no significant suppressive effect on luciferase activity of STAT3 compared with IL-6-induced group. Combined with earlier reports that WV-III contained major allergens, we selected WV and WV-II further to study the mechanism of anti-RA. In addition, WV and WV-II decreased the level of IL-1ß and IL-6 in TNF-α-induced MH7A cells via inactivating of JAK/STAT signaling pathway. On the other hand, WV and WV-II down-regulated the TrxR activity to produce ROS and induce cell apoptosis. Furthermore, WV and WV-II could accumulate lipid ROS to induce GPX4-mediated ferroptosis. CONCLUSIONS: Taken together, the experimental results revealed that WV and WV-II were potential therapeutic agents for RA through modulating JAK/STAT signaling pathways, redox homeostasis and ferroptosis in MH7A cells. Of note, WV-II was an effective part and the predominant active monomer in WV-II will be further explored in the future.

Two venom serpins from the parasitoid wasp Microplitis mediator inhibit the host prophenoloxidase activation and antimicrobial peptide synthesis.

Endoparasitoid wasps inject venom proteins into the hemocoel of host insects to ensure survival, growth, and development of their progenies by blocking host immunity. We previously identified ten serine protease inhibitors of the serpin superfamily in venom of the endoparasitoid wasp, Microplitis mediator, but it is unclear how these inhibitors may interact with host immune serine proteases. In this study, we investigated the functions of two serpins, MmvSPN-1 and MmvSPN-2, in the regulation of humoral immune responses in two hosts, the oriental armyworm Pseudaletia separate and the cotton bollworm Helicoverpa armigera, by dsRNA knockdown and biochemical assays using recombinant proteins. Knockdown of the two serpins resulted in increases in prophenoloxidase (PPO) activation and antimicrobial peptide (AMP) production in the hosts. After injection into the host hemocoel, the recombinant serpins inhibited PPO activation and AMP transcription. Mass spectrometry analysis of the pull-downs and in vitro reconstitution experiments revealed that HacSP29, a clip-domain serine protease in H. armigera, is the target of these two serpins. Therefore, these two inhibitors in the wasp venom may protect eggs from attacks by melanization and AMPs in the host insects.

Rho 1 participates in parasitoid wasp eggs maturation and host cellular immunity inhibition.

Endoparasitoid wasps introduce venom into their host insects during the egg-laying stage. Venom proteins play various roles in the host physiology, development, immunity, and behavior manipulation and regulation. In this study, we identified a venom protein, MmRho1, a small guanine nucleotide-binding protein derived from ovary in the endoparasitoid wasp Microplitis mediator and found that knockdown of its expression by RNA interference caused down-regulation of vitellogenin and juvenile hormone, egg production, and cocoons formation in the female wasps. We demonstrated that MmRho1 entered the cotton bollworm's (host) hemocytes and suppressed cellular immune responses after parasitism using immunofluorescence staining. Furthermore, wasp MmRho1 interacted with the cotton bollworm's actin cytoskeleton rearrangement regulator diaphanous by yeast 2-hybrid and glutathione s-transferase pull-down. In conclusion, this study indicates that MmRho1 plays dual roles in wasp development and the suppression of the host insect cellular immune responses.

Overexpression of FcεRI on Bone Marrow Mast Cells, but Not MRGPRX2, in Clonal Mast Cell Disorders With Wasp Venom Anaphylaxis.

Background: Uncertainties remain about the molecular mechanisms governing clonal mast cell disorders (CMCD) and anaphylaxis. Objective: This study aims at comparing the burden, phenotype and behavior of mast cells (MCs) and basophils in patients with CMCD with wasp venom anaphylaxis (CMCD/WVA+), CMCD patients without anaphylaxis (CMCD/ANA-), patients with an elevated baseline serum tryptase (EBST), patients with wasp venom anaphylaxis without CMCD (WVA+) and patients with a non-mast cell haematological pathology (NMHP). Methods: This study included 20 patients with CMCD/WVA+, 24 with CMCD/ANA-, 19 with WVA+, 6 with EBST and 5 with NMHP. We immunophenotyped MCs and basophils and compared baseline serum tryptase (bST) and both total and venom specific IgE in the different groups. For basophil studies, 13 healthy controls were also included. Results: Higher levels of bST were found in CMCD patients with wasp venom anaphylaxis, CMCD patients without anaphylaxis and EBST patients. Total IgE levels were highest in patients with wasp venom anaphylaxis with and without CMCD. Bone marrow MCs of patients with CMCD showed lower CD117 expression and higher expression of CD45, CD203c, CD63, CD300a and FcεRI. Within the CMCD population, patients with wasp venom anaphylaxis showed a higher expression of FcεRI as compared to patients without anaphylaxis. Expression of MRGPRX2 on MCs did not differ between the study populations. Basophils are phenotypically and functionally comparable between the different patient populations. Conclusion: Patients with CMCD show an elevated burden of aberrant activated MCs with a significant overexpression of FcεRI in patients with a wasp venom anaphylaxis.

A venom protein of ectoparasitoid Pachycrepoideus vindemiae, PvG6PDH, contributes to parasitism by inhibiting host glucose-6-phosphate metabolism.

To achieve successful development, female parasitoids, while laying eggs, introduce various virulence factors, mainly venoms, into host insects to manipulate their physiology. Although numerous studies have been conducted to characterize the components of venoms that regulate host immune responses, few systematic investigations have been conducted on the roles of venom proteins in host metabolic regulation. In this investigation, we characterized a novel venom protein in Pachycrepoideus vindemiae called glucose-6-phosphate dehydrogenase (PvG6PDH) and showed it has a vital role in regulating host carbohydrate metabolism. PvG6PDH encodes 510 amino acids and features a signal peptide and two conserved "G6PDH" domains. Multiple sequence alignment showed it has high amino acid identity with G6PDH from other pteromalids, and quantitative polymerase chain reaction analysis and immunofluorescent staining demonstrated a significantly higher expression of PvG6PDH in the venom apparatus compared with the carcass. We report that PvG6PDH contributes to parasitism by inhibiting the glucose-6-phosphate (G6P) metabolism of host Drosophila melanogaster, as demonstrated by PvG6PDH injection and RNA interference analysis. Further tests revealed that the accumulation of host G6P was caused by the transcriptional inhibition of G6P-metabolism-related genes. These findings greatly contribute to our understanding of venom-mediated host metabolic regulation, further laying the foundation for the development of venom proteins as biological agents for pest control.

Expression profiles of venom components in some social hymenopteran species over different post-capture periods.

To explore and compare the expression patterns of venom components depending on post-capture periods, venom gland-specific transcriptome and proteome analyses were conducted for five model hymenopteran species at a series of time points after capture. Venom gland-specific genes with signal sequences were considered as putative venom component genes. Expression patterns of venom gland-specific genes in all the social wasps and bees examined varied considerably depending on the post-capture period. Higher numbers of venom genes exhibited a decreasing expression pattern than an increasing pattern as the capture period increased. For example, genes encoding most of the allergens (dipeptidyl peptidase 4, endocuticle structural glycoprotein, odorant-binding protein, phospholipase A1, A2, B1, serine protease, serine protease inhibitor and venom allergen 5), pain-producing factor (mast cell degranulating peptide), and paralyzing factor (neprilysin) commonly exhibited decreasing expression patterns in all of the hymenopteran species tested, except for some of the major venom genes in Apis mellifera and Bombus ignitus, which showed an increasing pattern. These findings indicate species- or group-specific variations in the expression patterns of major venom genes. Taken together, flash freezing in liquid nitrogen immediately after capture was determined to be the best way to obtain the most natural expression profiles of venom components in social wasp species, thus, enabling a better understanding of the toxic potential of venom in wasp sting accidents. This study provides guidance for establishing optimal protocols for venom gland isolation and venom extraction from wasps and bees that can ensure the most naturally represented venom composition.

Assessment of the In Vivo and In Vitro Release of Chemical Compounds from Vespa velutina.

Vespa velutina has been rapidly expanding throughout Galicia since 2012. It is causing human health risks and well-known losses in the beekeeping sector. Control methods are scarce, unspecific, and ineffective. Semiochemicals are insect-derived chemicals that play a role in communication and they could be used an integrated pest management tool alternative to conventional pesticides. A previous determination of the organic chemical profile should be the first step in the study of these semiochemicals. HS-SPME in living individuals and the sting apparatus extraction followed by GC-MS spectrometry were combined to extract a possible profile of these compounds in 43 hornets from Galicia. The identified compounds were hydrocarbons, ketones, terpenes, and fatty acid, and fatty acid esters. Nonanal aldehyde appeared in important concentrations in living individuals. While pentadecane, 8-hexyl- and ethyl oleate were mainly extracted from the venom apparatus. Ketones 2-nonanone, 2-undecanone and 7-nonen-2-one, 4,8-dimethyl- were identified by both procedures, as was 1,7-Nonadiene, 4,8-dimethyl-. Some compounds were detected for the first time in V. velutina such as naphthalene, 1,6-dimethyl-4-(1-methylethyl). The chemical profile by caste was also characterized.

A Short Review of the Venoms and Toxins of Spider Wasps (Hymenoptera: Pompilidae).

Parasitoid wasps represent the plurality of venomous animals, but have received extremely little research in proportion to this taxonomic diversity. The lion's share of investigation into insect venoms has focused on eusocial hymenopterans, but even this small sampling shows great promise for the development of new active substances. The family Pompilidae is known as the spider wasps because of their reproductive habits which include hunting for spiders, delivering a paralyzing sting, and entombing them in burrows with one of the wasp's eggs to serve as food for the developing larva. The largest members of this family, especially the tarantula hawks of the genus Pepsis, have attained notoriety for their large size, dramatic coloration, long-term paralysis of their prey, and incredibly painful defensive stings. In this paper we review the existing research regarding the composition and function of pompilid venoms, discuss parallels from other venom literatures, identify possible avenues for the adaptation of pompilid toxins towards human purposes, and future directions of inquiry for the field.

Proteo-Trancriptomic Analyses Reveal a Large Expansion of Metalloprotease-Like Proteins in Atypical Venom Vesicles of the Wasp Meteorus pulchricornis (Braconidae).

Meteorus pulchricornis (Ichneumonoidea, Braconidae) is an endoparasitoid wasp of lepidopteran caterpillars. Its parasitic success relies on vesicles (named M. pulchricornis Virus-Like Particles or MpVLPs) that are synthesized in the venom gland and injected into the parasitoid host along with the venom during oviposition. In order to define the content and understand the biogenesis of these atypical vesicles, we performed a transcriptome analysis of the venom gland and a proteomic analysis of the venom and purified MpVLPs. About half of the MpVLPs and soluble venom proteins identified were unknown and no similarity with any known viral sequence was found. However, MpVLPs contained a large number of proteins labelled as metalloproteinases while the most abundant protein family in the soluble venom was that of proteins containing the Domain of Unknown Function DUF-4803. The high number of these proteins identified suggests that a large expansion of these two protein families occurred in M. pulchricornis. Therefore, although the exact mechanism of MpVLPs formation remains to be elucidated, these vesicles appear to be "metalloproteinase bombs" that may have several physiological roles in the host including modifying the functions of its immune cells. The role of DUF4803 proteins, also present in the venom of other braconids, remains to be clarified.

Stapled Wasp Venom-Derived Oncolytic Peptides with Side Chains Induce Rapid Membrane Lysis and Prolonged Immune Responses in Melanoma.

Peptide stapling chemistry represents an attractive strategy to promote the clinical translation of protein epitope mimetics, but its use has not been applied to natural cytotoxic peptides (NCPs) to produce new oncolytic peptides. Based on a wasp venom peptide, a series of stapled anoplin peptides (StAnos) were prepared. The optimized stapled Ano-3/3s were shown to be protease-resistant and exerted superior tumor cell-selective cytotoxicity by rapid membrane disruption. In addition, Ano-3/3s induced tumor ablation in mice through the direct oncolytic effect and subsequent stimulation of immunogenic cell death. This synergistic oncolytic-immunotherapy effect is more remarkable on melanoma than on triple-negative breast cancer in vivo. The efficacies exerted by Ano-3/3s on melanoma were further characterized by CD8+ T cell infiltration, and the addition of anti-CD8 antibodies diminished the long-term antitumor effects. In summary, these results support stapled peptide chemistry as an advantageous method to enhance the NCP potency for oncolytic therapy.

Parasitoid wasp venom vesicles (venosomes) enter Drosophila melanogaster lamellocytes through a flotillin/lipid raft-dependent endocytic pathway.

Venosomes are extracellular vesicles found in the venom of Leptopilina endoparasitoids wasps, which transport and target virulence factors to impair the parasitoid egg encapsulation by the lamellocytes of their Drosophila melanogaster host larva. Using the co-immunolocalization of fluorescent L. boulardi venosomes and one of the putative-transported virulence factors, LbGAP, with known markers of cellular endocytosis, we show that venosomes endocytosis by lamellocytes is not a process dependent on clathrin or macropinocytosis and internalization seems to bypass the early endosomal compartment Rab5. After internalization, LbGAP colocalizes strongly with flotillin-1 and the GPI-anchored protein Atilla/L1 (a lamellocyte surface marker) suggesting that entry occurs via a flotillin/lipid raft-dependent pathway. Once internalized, venosomes reach all intracellular compartments, including late and recycling endosomes, lysosomes, and the endoplasmic reticulum network. Venosomes therefore enter their target cells by a specific mechanism and the virulence factors are widely distributed in the lamellocytes' compartments to impair their functions.

Neuropolybin: A new antiseizure peptide obtained from wasp venom.

Epilepsy accounts for one of the most serious neurological disorders, and its treatment remains a challenge, due to high cost and harmful side effects. Bioactive molecules extracted from arthropod venoms are considered a promising therapy since these compounds are known for their highly selective and potent profiles. The purpose of this study was to identify and characterize the potential antiseizure effect of the peptide Ppnp7, extracted from the venom of the social wasp Polybia paulista, and also the effect of the bioinspired peptide, named Neuropolybin, in the same parameters. Additionally, we also evaluated the electroencephalographic (EEG) profile in the PTZ-induced acute seizures in animals treated with Neuropolybin, and potential adverse effects of both peptides in general spontaneous activity (Open Field analysis). Interestingly, Ppnp7 and Neuropolybin showed a noteworthy antiseizure effect in rats and mice, respectively. Curves of protection against the maximum seizure were obtained for both peptides, and EEG records demonstrated that Neuropolybin protected 80% of animals from tonic-clonic seizures when applied with a dose of 3 nmol (an approximate Ppnp7 ED50 found in rats). Neuropolybin and Ppnp7 did not cause changes in the general spontaneous activity of the animals in any of the doses evaluated. Therefore, this study demonstrated how compounds isolated from wasps' venom may be essential resources in the search for new drugs, and can also be considered valuable therapeutic and biotechnological tools for the study and future treatment of epileptic disorders.

Purification and molecular characterization of phospholipase, antigen 5 and hyaluronidases from the venom of the Asian hornet (Vespa velutina).

The aim of this study was to purify potential allergenic components of Vespa velutina venom, the yellow legged Asian Hornet, and perform a preliminary characterization of the purified proteins. Starting from the whole venom of V.velutina, several chromatographic steps allowed to purify the phospholipase (named Vesp v 1), as well as the antigen 5 (Vesp v 5, the only allergenic component described as such so far). The two hyaluronidase isoforms found (Vesp v 2A and Vesp v 2B) cannot be separated from each other, but they are partially purified and characterized. Purity of the isolated proteins in shown by SDSPAGE, as well as by the results of the N-terminal sequencing. This characterization and nLC-MS/MS data provide most of the sequence for Vesp v 1 and Vesp v 5 (72 and 84% coverage, respectively), confirming that the whole sequences of the isolated natural components match with the data available in public transcriptomic databases. It is of particular interest that Vesp v 1 is a glycosylated phospholipase, a fact that had only described so far for the corresponding allergen components of Dolichovespula maculata and Solenopsis invicta. The availability of the complete sequences of Vespa velutina components permits comparison with homologous sequences from other Hymenoptera. These data demonstrate the higher similarity among the species of the genera Vespa and Vespula, in comparison to Polistes species, as it is especially observed with the hyaluronidases isoforms: the isoform Vesp v 2A only exists in the former genera, and not in Polistes; in addition, the most abundant isoform (Vesp v 2B) exhibits 93% sequence identity with the Ves v 2 isoform of Vespula vulgaris. Finally, the isolated components might be useful for improving the diagnosis of patients that could be allergic to stings of this invasive Asian hornet, as it has been the case of an improved diagnosis and treatment of other Hymenoptera-sensitized patients.

Venomics of the ectoparasitoid wasp Bracon nigricans.

BACKGROUND: Venom is one of the most important sources of regulation factors used by parasitic Hymenoptera to redirect host physiology in favour of the developing offspring. This has stimulated a number of studies, both at functional and "omics" level, which, however, are still quite limited for ectophagous parasitoids that permanently paralyze and suppress their victims (i.e., idiobiont parasitoids). RESULTS: Here we present a combined transcriptomic and proteomic study of the venom of the generalist idiobiont wasp Bracon nigricans, an ectophagous larval parasitoid of different lepidopteran species, for which we recently described the host regulation strategy and the functional role of the venom in the induction of physiological changes in parasitized hosts. The experimental approach used led to the identification of the main components of B. nigricans venom involved in host regulation. Enzymes degrading lipids, proteins and carbohydrates are likely involved in the mobilization of storage nutrients from the fat body and may concurrently be responsible for the release of neurotoxic fatty acids inducing paralysis, and for the modulation of host immune responses. CONCLUSION: The present work contributes to fill the gap of knowledge on venom composition in ectoparasitoid wasps, and, along with our previous physiological study on this species, provides the foundation on which to develop a functional model of host regulation, based both on physiological and molecular data. This paves the way towards a better understanding of parasitism evolution in the basal lineages of Hymenoptera and to the possible exploitation of venom as source of bioinsecticidal molecules.

The endoparasitoid Psyllaephagus arenarius benefits from ectoparasitic venom via multiparasitism with the ectoparasitoid Tamarixia lyciumi.

As solitary nymphal parasitoids of Paratrioza sinica, the ectoparasitoid Tamarixia lyciumi and the endoparasitoid Psyllaephagus arenarius act as effective biocontrol agents. Thus, it is necessary to facilitate mass productions of both species. Despite showing an excellent parasitic ability, Ps. arenarius is often trapped fatally inside 5th-instar nymphs of Pa. sinica due to strong host immunity. To improve the emergence rate of Ps. arenarius, we evaluated whether Ps. arenarius could utilize T. lyciumi venom via multiparasitism, so the parasitism characteristics of both species were examined between separate-existence (monoparasitism only) and co-existence (mono- and multiparasitism) systems. Further, the parasitism characteristics of Ps. arenarius on venom-injected hosts with/without T. lyciumi eggs were tested to further identify the facilitator. The results showed the parasitism rate of T. lyciumi was increased while that of Ps. arenarius did not change from separate-existence to co-existence systems. The intrinsic performances of two species in monoparasitism did not differ between separate- and co-existence systems. From monoparasitism (separate-existence) to multiparasitism (co-existence), no differences were detected in the intrinsic performances of T. lyciumi, but those of Ps. arenarius were greatly improved. After T. lyciumi venom injection, the parasitism characteristics of Ps. arenarius did not differ between venom-injected hosts with T. lyciumi eggs and those without, further indicating Ps. arenarius benefited from the venom of T. lyciumi females rather than T. lyciumi egg/larval secretions. Instead of negative effects, multiparasitism with ectoparasitoids improves endoparasitoids due to ectoparasitic venom. The study increases host resource utilization and provides creative ways for mass production of endoparasitoids.

Immune Suppressive Extracellular Vesicle Proteins of Leptopilina heterotoma Are Encoded in the Wasp Genome.

Leptopilina heterotoma are obligate parasitoid wasps that develop in the body of their Drosophila hosts. During oviposition, female wasps introduce venom into the larval hosts' body cavity. The venom contains discrete, 300 nm-wide, mixed-strategy extracellular vesicles (MSEVs), until recently referred to as virus-like particles. While the crucial immune suppressive functions of L. heterotoma MSEVs have remained undisputed, their biotic nature and origin still remain controversial. In recent proteomics analyses of L. heterotoma MSEVs, we identified 161 proteins in three classes: conserved eukaryotic proteins, infection and immunity related proteins, and proteins without clear annotation. Here we report 246 additional proteins from the L. heterotoma MSEV proteome. An enrichment analysis of the entire proteome supports vesicular nature of these structures. Sequences for more than 90% of these proteins are present in the whole-body transcriptome. Sequencing and de novo assembly of the 460 Mb-sized L. heterotoma genome revealed 90% of MSEV proteins have coding regions within the genomic scaffolds. Altogether, these results explain the stable association of MSEVs with their wasps, and like other wasp structures, their vertical inheritance. While our results do not rule out a viral origin of MSEVs, they suggest that a similar strategy for co-opting cellular machinery for immune suppression may be shared by other wasps to gain advantage over their hosts. These results are relevant to our understanding of the evolution of figitid and related wasp species.

Study on the effects of different dimerization positions on biological activity of partial d-Amino acid substitution analogues of Anoplin.

Antimicrobial peptides have recently attracted much attention due to their broad-spectrum antimicrobial activity, rapid microbial effects, and minimal tendency toward resistance development. In this study, a series of new C-C terminals and C-N terminals dimer peptides were designed and synthesized by intermolecular dimerization of the partial d-amino acid substitution analogues of Anoplin, and the effects of different dimerization positions on biological activity were researched. The antimicrobial activity and stability of the new C-C terminals and C-N terminals dimer peptides were significantly improved compared with their parent peptide Anoplin. They displayed no obvious hemolytic activity and lower cytotoxicity, with a higher therapeutic index. Furthermore, the new dimer peptides not only enabled to rapidly disrupt bacterial membrane and damage its integrity which was different from conventional antibiotics but also penetrated bacterial membrane into binding to intracellular genomic DNA. More importantly, the new dimer peptides showed excellent antimicrobial activity against multidrug-resistant strains isolated from clinics in contrast to conventional antibiotics with low tendency to develop the bacterial resistance, besides they exhibited better anti-biofilm activity than antibiotic Rifampicin. Interestingly, the C-N terminals dimer peptides were superior to C-C terminals ones in antimicrobial and anti-biofilm activity, therapeutic index, outer membrane permeability, and DNA binding ability, whereas there were no noteworthy effects in different dimerization positions on stability. Thus, these data suggested that dimerization in different positions represented a potent strategy to develop novel antimicrobial agents for fighting against increasing bacterial resistance.

Preferential infectivity of entomopathogenic nematodes in an envenomed host.

Entomopathogenic nematodes and parasitoid wasps are used as biological control agents for management of insect pests such as the Indian meal moth, Plodia interpunctella. The parasitoid wasp Habrobracon hebetor injects a paralytic venom into P. interpunctella larvae before laying eggs. A previous study reported that the entomopathogenic nematode Heterorhabditis indica preferentially infects P. interpunctella that have been envenomed by H. hebetor while results in this study showed a similar preference by the entomopathogenic nematode, Steinernema glaseri. We therefore tested four hypotheses for why nematode infection rates are higher in envenomed hosts: (1) elevated CO2 emission from envenomed hosts attracts nematodes, (2) paralysis prevents hosts from escaping nematodes, (3) volatile chemicals emitted from envenomed hosts attract nematodes and increase infection, and (4) reduced immune defenses in envenomed hosts increase nematode survival. Results showed that envenomed P. interpunctella larvae emitted lower amounts of CO2 than non-envenomed larvae. Physical immobilization of P. interpunctella larvae did not increase infection rates by S. glaseri but did increase infection rates by H. indica. Emissions from envenomed hosts were collected and analyzed by thermal desorption gas chromatography/mass spectrometry. The most abundant compound, 3-methyl-3-buten-1-ol, was found to be an effective cue for S. glaseri attraction and infection but was not an effective stimulus for H. indica. Envenomed P. interpunctella exhibited a stronger immune response toward nematodes than non-envenomed hosts. Altogether, we conclude that different mechanisms underlie preferential infection in the two nematode species: host immobilization for H. indica and chemical cues for S. glaseri.