The venoms of ants (Formicidae) are a promising source of novel bioactive molecules with potential for clinical and agricultural applications. However, despite the rich diversity of ant species, only a fraction of this vast resource has been thoroughly examined in bioprospecting programs. Previous studies focusing on the venom of Central European ants (subfamily Myrmicinae) identified a number of short linear decapeptides and nonapeptides resembling antimicrobial peptides (AMPs). Here, we describe the in silico approach and bioactivity profiling of 10 novel AMP-like peptides from the fellow Central European myrmicine ants Myrmica rubra and Myrmica ruginodis. Using the sequences of known ant venom peptides as queries, we screened the venom gland transcriptomes of both species. We found transcripts of nine novel decapeptides and one novel nonapeptide. The corresponding peptides were synthesized for bioactivity profiling in a broad panel of assays consisting of tests for cytotoxicity as well as antiviral, insecticidal, and antimicrobial activity. U-MYRTX-Mrug5a showed moderately potent antimicrobial effects against several bacteria, including clinically relevant pathogens such as Listeria monocytogenes and Staphylococcus epidermidis, but high concentrations showed negligible cytotoxicity. U-MYRTX-Mrug5a is, therefore, a probable lead for the development of novel peptide-based antibiotics.

The venoms of spiders from the RTA (retro-lateral tibia apophysis) clade contain diverse short linear peptides (SLPs) that offer a rich source of therapeutic candidates. Many of these peptides have insecticidal, antimicrobial and/or cytolytic activities, but their biological functions are unclear. Here, we explore the bioactivity of all known members of the A-family of SLPs previously identified in the venom of the Chinese wolf spider (Lycosa shansia). Our broad approach included an in silico analysis of physicochemical properties and bioactivity profiling for cytotoxic, antiviral, insecticidal and antibacterial activities. We found that most members of the A-family can form α-helices and resemble the antibacterial peptides found in frog poison. The peptides we tested showed no cytotoxic, antiviral or insecticidal activities but were able to reduce the growth of bacteria, including clinically relevant strains of Staphylococcus epidermidis and Listeria monocytogenes. The absence of insecticidal activity may suggest that these peptides have no role in prey capture, but their antibacterial activity may help to defend the venom gland against infection.

Spider-derived peptides with insecticidal, antimicrobial and/or cytolytic activities, also known as spider venom antimicrobial peptides (AMPs), can be found in the venoms of RTA-clade spiders. They show translational potential as therapeutic leads. A set of 52 AMPs has been described in the Chinese wolf spider (Lycosa shansia), and many have been shown to exhibit antibacterial effects. Here we explored the potential to enhance their antimicrobial activity using bioengineering. We generated a panel of artificial derivatives of an A-family peptide and screened their activity against selected microbial pathogens, vertebrate cells and insects. In several cases, we increased the antimicrobial activity of the derivatives while retaining the low cytotoxicity of the parental molecule. Furthermore, we injected the peptides into adult Drosophila suzukii and found no evidence of insecticidal effects, confirming the low levels of toxicity. Our data therefore suggest that spider venom linear peptides naturally defend the venom gland against microbial colonization and can be modified into more potent antimicrobial agents that could help to battle infectious diseases in the future.

Mosquitoes are vectors of deadly diseases and pose a global health threat. Particularly, the Asian tiger mosquito Aedes albopictus can transmit several pathogens, and is expanding into temperate regions. During blood feeding, mosquitoes inject chemically complex saliva, here referred to as venom, which modulates hemostasis, inflammation, immune response and pathogen transmission. In-depth knowledge of mosquito venom is crucial for understanding disease biology and enabling biodiscovery. We present a venomics study of Ae. albopictus and identify 119 distinct proteins validated by mass spectrometry and transcriptomics. The venom is rich in enzymes (e.g., hydrolases and Apyrases) and non-enzymatic components (e.g., odorant binding proteins and protease inhibitors). Additionally, we identified six novel cecropin family antimicrobial peptides. Structural analyses indicate an amphipathic N-terminus, hinge region, and hydrophobic C-terminus consistent with type II channel formation. Functional assays revealed that these cecropins exert potent effects on E. coli while leaving mammalian epithelial cells and erythrocytes unaffected. Overall, our study reveals that mosquito venom is a source of diverse biomacromolecules, deepening our understanding of its physiology, vector biology, and biochemical ecology. This opens paths for new mosquito-control strategies and drug discovery.

Venoms are complex cocktails containing novel biomolecules. Many venomous animal groups are understudied, including Horseflies of the family Tabanidae. Their larvae utilize venom to overpower prey and to defend against predators. Recent studies uncovered short linear peptides in their venoms but their bioactivity spectrum and biological function remain unknown. Here, we employ a bioactivity profiling of eight synthesized toxins of the large marsh horsefly (Tabanus autumnalis) larval venom via in silico, in vitro, and in vivo experiments. Bioinformatic analysis suggest, that the selected peptides fold into cationic and amphipathic alpha-helices. Assays against microbes reveal antimicrobial activity potentially via membrane interaction caused by some of the linear Tabanus toxins, while tests on vertebrate cells reveal cytotoxic and hemolytic effects. Lastly, injections of the peptides in Drosophila melanogaster flies recovered insecticidal and paralytic activity. Based on our analysis, we propose that some of the linear T. autumnalis peptides facilitate prey capture via their rapid paralytic activity in insects. A second line of functional utilization may be present in defense against predators and microbial colonization. From a translational perspective, it appears unlikely that the tested peptides could efficiently be translated into anti-infectives, while an evaluation for agricultural exploitation demands further research. Our study provides functional insights into the toxin repertoire of one of the least studied venom systems on earth and serves as starting point to further investigate dipteran venom biology.

Peptides with insecticidal, antimicrobial and/or cytolytic activities, also known as spider venom antimicrobial peptides (AMPs), can be found in the venoms of RTA-clade spiders. They show translational potential as therapeutic leads. A set of 52 AMPs has been described in the Chinese wolf spider ( Lycosa shansia ), and many have been shown to exhibit antibacterial effects. Here we explored the potential to enhance their antimicrobial activity using bioengineering. We generated a panel of artificial derivatives of an A-family peptide and screened their activity against selected microbial pathogens, vertebrate cells and insects. In several cases, we increased the antimicrobial activity of the derivatives while retaining the low cytotoxicity of the parental molecule. Furthermore, we injected the peptides into adult Drosophila suzukii and found no evidence of insecticidal effects, confirming the low levels of toxicity. Our data therefore suggest that spider venom linear peptides can be modified into more potent antimicrobial agents that could help to battle infectious diseases in the future.