Killer bee molecules: antimicrobial peptides as effector molecules to target sporogonic stages of Plasmodium

Gene drives: an alternative approach to malaria control?

Genetic modification for the control of mosquitoes is frequently touted as a solution for a variety of vector-borne diseases. There has been some success using non-insecticidal methods like sterile or incompatible insect techniques to control arbovirus diseases. However, control by genetic modifications to reduce mosquito populations or create mosquitoes that are refractory to infection with pathogens are less developed. The advent of CRISPR-Cas9-mediated gene drives may advance this mechanism of control. In this review, use and progress of gene drives for vector control, particularly for malaria, is discussed. A brief history of population suppression and replacement gene drives in mosquitoes, rapid advancement of the field over the last decade and how genetic modification fits into the current scope of vector control are described. Mechanisms of alternative vector control by genetic modification to modulate mosquitoes' immune responses and anti-parasite effector molecules as part of a combinational strategy to combat malaria are considered. Finally, the limitations and ethics of using gene drives for mosquito control are discussed.

Curing mosquitoes with genetic approaches for malaria control

Malaria remains a persistent global public health challenge because of the limitations of current prevention tools. The use of transgenic mosquitoes incapable of transmitting malaria, in conjunction with existing methods, holds promise for achieving elimination of malaria and preventing its reintroduction. In this context, population modification involves the spread of engineered genetic elements through mosquito populations that render them incapable of malaria transmission. Significant progress has been made in this field over the past decade in revealing promising targets, optimizing genetic tools, and facilitating the transition from the laboratory to successful field deployments, which are subject to regulatory scrutiny. This review summarizes recent advances and ongoing challenges in 'curing' Anopheles vectors of the malaria parasite.

Structure modification of anoplin for fighting resistant bacteria

The emergence of bacterial resistance has posed a significant challenge to clinical antimicrobial treatment, rendering commonly used antibiotics ineffective. The development of novel antimicrobial agents and strategies is imperative for the treatment of resistant bacterial infections. Antimicrobial peptides (AMPs) are considered a promising class of antimicrobial agents due to their low propensity for resistance and broad-spectrum activity. Anoplin is a small linear α-helical natural antimicrobial peptide that was isolated from the venom of the solitary wasp Anplius samariensis. It exhibits rich biological activity, particularly broad-spectrum antimicrobial activity and low hemolytic activity. Over the past three decades, more than 40 research publications on anoplin have been made available online. This review focuses on the advancements of anoplin in antimicrobial research, encompassing its sources, characterization, antimicrobial activity, influencing factors and structural modifications. The aim is to provide assistances for the development of new antimicrobial agents that can combat bacterial resistance.

Cell Penetrating Peptides: Classification, Mechanisms, Methods of Study, and Applications

Cell-penetrating peptides (CPPs) encompass a class of peptides that possess the remarkable ability to cross cell membranes and deliver various types of cargoes, including drugs, nucleic acids, and proteins, into cells. For this reason, CPPs are largely investigated in drug delivery applications in the context of many diseases, such as cancer, diabetes, and genetic disorders. While sharing this functionality and some common structural features, such as a high content of positively charged amino acids, CPPs represent an extremely diverse group of elements, which can differentiate under many aspects. In this review, we summarize the most common characteristics of CPPs, introduce their main distinctive features, mechanistic aspects that drive their function, and outline the most widely used techniques for their structural and functional studies. We highlight current gaps and future perspectives in this field, which have the potential to significantly impact the future field of drug delivery and therapeutics.

Impact of transgenerational host switch on gut bacterial assemblage in generalist pest, Spodoptera littoralis (Lepidoptera: Noctuidae)

Diet composition is vital in shaping gut microbial assemblage in many insects. Minimal knowledge is available about the influence of transgenerational diet transition on gut microbial community structure and function in polyphagous pests. This study investigated transgenerational diet-induced changes in Spodoptera littoralis larval gut bacteriome using 16S ribosomal sequencing. Our data revealed that 88% of bacterial populations in the S. littoralis larval gut comprise Proteobacteria, Firmicutes, Actinobacteria, and Bacteroidetes. The first diet transition experiment from an artificial diet (F0) to a plant diet (F1), cabbage and cotton, caused an alteration of bacterial communities in the S. littoralis larval gut. The second transgenerational diet switch, where F1 larvae feed on the same plant in the F2 generation, displayed a significant variation suggesting further restructuring of the microbial communities in the Spodoptera larval gut. F1 larvae were also challenged with the plant diet transition at the F2 generation (cabbage to cotton or cotton to cabbage). After feeding on different plant diets, the microbial assemblage of F2 larvae pointed to considerable differences from other F2 larvae that continued on the same diet. Our results showed that S. littoralis larval gut bacteriome responds rapidly and inexplicably to different diet changes. Further experiments must be conducted to determine the developmental and ecological consequences of such changes. Nevertheless, this study improves our perception of the impact of transgenerational diet switches on the resident gut bacteriome in S. littoralis larvae and could facilitate future research to understand the importance of symbiosis in lepidopteran generalists better.

Toxins from Animal Venoms as a Potential Source of Antimalarials: A Comprehensive Review

Malaria is an infectious disease caused by Plasmodium spp. and it is mainly transmitted to humans by female mosquitoes of the genus Anopheles. Malaria is an important global public health problem due to its high rates of morbidity and mortality. At present, drug therapies and vector control with insecticides are respectively the most commonly used methods for the treatment and control of malaria. However, several studies have shown the resistance of Plasmodium to drugs that are recommended for the treatment of malaria. In view of this, it is necessary to carry out studies to discover new antimalarial molecules as lead compounds for the development of new medicines. In this sense, in the last few decades, animal venoms have attracted attention as a potential source for new antimalarial molecules. Therefore, the aim of this review was to summarize animal venom toxins with antimalarial activity found in the literature. From this research, 50 isolated substances, 4 venom fractions and 7 venom extracts from animals such as anurans, spiders, scorpions, snakes, and bees were identified. These toxins act as inhibitors at different key points in the biological cycle of Plasmodium and may be important in the context of the resistance of Plasmodium to currently available antimalarial drugs.

Gene drive mosquitoes can aid malaria elimination by retarding Plasmodium sporogonic development

Gene drives hold promise for the genetic control of malaria vectors. The development of vector population modification strategies hinges on the availability of effector mechanisms impeding parasite development in transgenic mosquitoes. We augmented a midgut gene of the malaria mosquito Anopheles gambiae to secrete two exogenous antimicrobial peptides, magainin 2 and melittin. This small genetic modification, capable of efficient nonautonomous gene drive, hampers oocyst development in both Plasmodium falciparum and Plasmodium berghei. It delays the release of infectious sporozoites, while it simultaneously reduces the life span of homozygous female transgenic mosquitoes. Modeling the spread of this modification using a large-scale agent-based model of malaria epidemiology reveals that it can break the cycle of disease transmission across a range of transmission intensities.

Contemporary exploitation of natural products for arthropod-borne pathogen transmission-blocking interventions

An integrated approach to innovatively counter the transmission of various arthropod-borne diseases to humans would benefit from strategies that sustainably limit onward passage of infective life cycle stages of pathogens and parasites to the insect vectors and vice versa. Aiming to accelerate the impetus towards a disease-free world amid the challenges posed by climate change, discovery, mindful exploitation and integration of active natural products in design of pathogen transmission-blocking interventions is of high priority. Herein, we provide a review of natural compounds endowed with blockade potential against transmissible forms of human pathogens reported in the last 2 decades from 2000 to 2021. Finally, we propose various translational strategies that can exploit these pathogen transmission-blocking natural products into design of novel and sustainable disease control interventions. In summary, tapping these compounds will potentially aid in integrated combat mission to reduce disease transmission trends.

Mastoparans: A Group of Multifunctional α-Helical Peptides With Promising Therapeutic Properties

Biologically active peptides have been attracting increasing attention, whether to improve the understanding of their mechanisms of action or in the search for new therapeutic drugs. Wasp venoms have been explored as a remarkable source for these molecules. In this review, the main findings on the group of wasp linear cationic α-helical peptides called mastoparans were discussed. These compounds have a wide variety of biological effects, including mast cell degranulation, activation of protein G, phospholipase A₂, C, and D activation, serotonin and insulin release, and antimicrobial, hemolytic, and anticancer activities, which could lead to the development of new therapeutic agents.

Bio-nano scale modifications of melittin for improving therapeutic efficacy

INTRODUCTION

Melittin (MLT), a natural membrane-active component, is the most prominent cytolytic peptide from bee venom. Remarkable biological properties of MLT, including anti-inflammatory, antimicrobial, anticancer, anti-protozoan, and antiarthritic activities, make it an up-and-coming therapeutic candidate for a wide variety of human diseases. Therapeutic applications of MLT may be hindered due to low stability, high toxicity, and weak tissue penetration. Different bio-nano scale modifications hold promise for improving its functionality and therapeutic efficacy.

AREAS COVERED

In the current review, we aimed to provide a comprehensive insight into strategies used for MLT conjugations and modifications, cellular delivery of modified forms, and their clinical perspectives by reviewing the published literature on PubMed, Scopus, and Google Scholar databases. We also emphasized the MLT structure modifications, mechanism of action, and cellular toxicity.

EXPERT OPINION

Developing new analogs and conjugates of MLT as a natural drug with improved functions and fewer side effects is crucial for the clinical translation of this approach worldwide, especially where the chemicals and synthetic drugs are more expensive or unavailable in the healthcare system. MLT-nanoconjugation may be one of the best-optimized strategies for improving peptide delivery, increasing its therapeutic efficacy, and providing minimal nonspecific cellular lytic activity. [Figure: see text].

Isolation of Potato Endophytes and Screening of Chaetomium globosum Antimicrobial Genes

Antimicrobial peptides (AMPs) have natural antibacterial activities that pathogens find difficult to overcome. As a result of this occurrence, AMPs can act as an important substitute against the microbial resistance. In this study, we used plate confrontation tests to screen out 20 potential endophytes from potato tubers. Among them, endophyte F5 was found to significantly inhibit the growth of five different pathogenic fungi. Following that, phylogenetic analysis revealed that the internal transcribed spacer (ITS) sequences were 99% identical to Chaetomium globosum corresponding sequences. Thereafter, the Bacillus subtilis expression system was used to create a C. globosum cDNA library in order to isolate the resistance genes. Using this approach, the resistance gene screening technology in the indicator bacteria built-in library was used to identify two antimicrobial peptides, CgR2150 and CgR3101, with broad-spectrum antibacterial activities. Furthermore, the results showed that CgR2150 and CgR3101 have excellent UV, thermal, and enzyme stabilities. Also, these two peptides can significantly inhibit the growth of various bacteria (Xanthomonas oryzae pv. oryzae, Xanthomonas oryzae pv. oryzicola, Clavibacter michiganensis, and Clavibacter fangii) and fungi (Fusarium graminearum, Rhizoctonia solani, and Botrytis cinerea). Scanning electron microscopy (SEM) observations revealed that CgR2150 and CgR3101 peptides act against bacteria by disrupting bacterial cell membranes. Moreover, hemolytic activity assay showed that neither of the two peptides exhibited significant hemolytic activity. To conclude, the antimicrobial peptides CgR2150 and CgR3101 are promising in the development of a new antibacterial agent and for application in plant production.

Overview of paratransgenesis as a strategy to control pathogen transmission by insect vectors

This article presents an overview of paratransgenesis as a strategy to control pathogen transmission by insect vectors. It first briefly summarises some of the disease-causing pathogens vectored by insects and emphasises the need for innovative control methods to counter the threat of resistance by both the vector insect to pesticides and the pathogens to therapeutic drugs. Subsequently, the state of art of paratransgenesis is described, which is a particularly ingenious method currently under development in many important vector insects that could provide an additional powerful tool for use in integrated pest control programmes. The requirements and recent advances of the paratransgenesis technique are detailed and an overview is given of the microorganisms selected for genetic modification, the effector molecules to be expressed and the environmental spread of the transgenic bacteria into wild insect populations. The results of experimental models of paratransgenesis developed with triatomines, mosquitoes, sandflies and tsetse flies are analysed. Finally, the regulatory and safety rules to be satisfied for the successful environmental release of the genetically engineered organisms produced in paratransgenesis are considered.

Applications and evolution of melittin, the quintessential membrane active peptide

Melittin, the main venom component of the European Honeybee, is a cationic linear peptide-amide of 26 amino acid residues with the sequence: GIGAVLKVLTTGLPALISWIKRKRQQ-NH₂. Melittin binds to lipid bilayer membranes, folds into amphipathic α-helical secondary structure and disrupts the permeability barrier. Since melittin was first described, a remarkable array of activities and potential applications in biology and medicine have been described. Melittin is also a favorite model system for biophysicists to study the structure, folding and function of peptides and proteins in membranes. Melittin has also been used as a template for the evolution of new activities in membranes. Here we overview the rich history of scientific research into the many activities of melittin and outline exciting future applications.

Mosquito transgenesis for malaria control

Malaria is one of the deadliest diseases. Because of the ineffectiveness of current malaria-control methods, several novel mosquito vector-based control strategies have been proposed to supplement existing control strategies. Mosquito transgenesis and gene drive have emerged as promising tools for preventing the spread of malaria by either suppressing mosquito populations by self-destructing mosquitoes or replacing mosquito populations with disease-refractory populations. Here we review the development of mosquito transgenesis and its application for malaria control, highlighting the transgenic expression of antiparasitic effector genes, inactivation of host factor genes, and manipulation of miRNAs and lncRNAs. Overall, from a malaria-control perspective, mosquito transgenesis is not envisioned as a stand-alone approach; rather, its use is proposed as a complement to existing vector-control strategies.

Activity of Anti-Microbial Peptides (AMPs) against Leishmania and Other Parasites: An Overview

Anti-microbial peptides (AMPs), small biologically active molecules, produced by different organisms through their innate immune system, have become a considerable subject of interest in the request of novel therapeutics. Most of these peptides are cationic-amphipathic, exhibiting two main mechanisms of action, direct lysis and by modulating the immunity. The most commonly reported activity of AMPs is their anti-bacterial effects, although other effects, such as anti-fungal, anti-viral, and anti-parasitic, as well as anti-tumor mechanisms of action have also been described. Their anti-parasitic effect against leishmaniasis has been studied. Leishmaniasis is a neglected tropical disease. Currently among parasitic diseases, it is the second most threating illness after malaria. Clinical treatments, mainly antimonial derivatives, are related to drug resistance and some undesirable effects. Therefore, the development of new therapeutic agents has become a priority, and AMPs constitute a promising alternative. In this work, we describe the principal families of AMPs (melittin, cecropin, cathelicidin, defensin, magainin, temporin, dermaseptin, eumenitin, and histatin) exhibiting a potential anti-leishmanial activity, as well as their effectiveness against other microorganisms.

Melittin as a promising anti-protozoan peptide: current knowledge and future prospects

Protozoan diseases such as malaria, leishmaniasis, Chagas disease, and sleeping sickness still levy a heavy toll on human lives. Deplorably, only few classes of anti-protozoan drugs have thus far been developed. The problem is further compounded by their intrinsic toxicity, emergence of drug resistance, and the lack of licensed vaccines. Thus, there is a genuine exigency to develop novel anti-protozoan medications. Over the past years, melittin, the major constituent in the venom of European honeybee Apis mellifera, has gathered the attention of researchers due to its potential therapeutic applications. Insofar as we are aware, there has been no review pertinent to anti-protozoan properties of melittin. The present review outlines the current knowledge about anti-protozoan effects of melittin and its underlying mechanisms. The peptide has proven to be efficacious in killing different protozoan parasites such as Leishmania, Plasmodium, Toxoplasma, and Trypanosoma in vitro. Apart from direct membrane-disruptive activity, melittin is capable of destabilizing calcium homeostasis, reducing mitochondrial membrane potential, disorganizing kinetoplast DNA, instigating apoptotic cell death, and induction of autophagy in protozoan pathogens. Emerging evidence suggests that melittin is a promising candidate for future vaccine adjuvants. Transmission-blocking activity of melittin against vector-borne pathogens underscores its potential utility for both transgenic and paratransgenic manipulations. Nevertheless, future research should focus upon investigating anti-microbial activities of melittin, alone or in combination with the current anti-protozoan medications, against a far broader spectrum of protozoan parasites as well as pre-clinical testing of the peptide in animal models.

Venom peptides in association with standard drugs: a novel strategy for combating antibiotic resistance - an overview

Development of antibiotic resistance that leads to resurgence of bacterial infections poses a threat to disease-free existence for humankind and is a challenge for the welfare of the society at large. Despite research efforts directed towards treatment of pathogens, antibiotics within new improved classes have not emerged for years, a fact largely attributable to the pharmacological necessities compelling drug development. Recent reversion to the use of natural products alone or in combination with standard drugs has opened up new vistas for alternative therapeutics. The success of this strategy is evident in the sudden interest in plant extracts as additives/synergists for treatment of maladies caused by drug-resistant bacterial strains. Animal venoms have long fascinated scientists as sources of pharmacologically active components that can be exploited for the treatment of specific ailments and should be promoted further to clinical trials. In the present review, we outline the scope and possible methods for the applications of animal venoms in combination with commercial antibiotics to offer a better treatment approach against antibiotic-resistant infections.

Advances in the Study of Structural Modification and Biological Activities of Anoplin

Anoplin is an amphipathic, α-helical bioactive peptide from wasp venom. In recent years, pharmaceutical and organic chemists discovered that anoplin and its derivatives showed multiple pharmacological activities in antibacterial, antitumor, antifungal, and antimalarial activities. Owing to the simple and unique structure and diverse biological activities, anoplin has attracted considerable research interests. This review highlights the advances in structural modification, biological activities, and the outlook of anoplin in order to provide a basis for new drug design and delivery.

Versatile transgenic multistage effector-gene combinations for Plasmodium falciparum suppression in Anopheles

The malaria parasite's complex journey through the Anopheles mosquito vector provides multiple opportunities for targeting Plasmodium with recombinant effectors at different developmental stages and different host tissues. We have designed and expressed transgenes that efficiently suppress Plasmodium infection by targeting the parasite with multiple independent endogenous and exogenous effectors at multiple infection stages to potentiate suppression and minimize the probability for development of resistance to develop. We have also addressed the fitness impact of transgene expression on the mosquito. We show that highly potent suppression can be achieved by targeting both pre-oocyst stages by transgenically overexpressing either the endogenous immune deficiency immune pathway transcription factor Rel2 or a polycistronic mRNA encoding multiple antiparasitic effectors and simultaneously targeting the sporozoite stages with an anti-sporozoite single-chain antibody fused to the antiparasitic protein Scorpine. Expression of the selected endogenous effector systems appears to pose a lower fitness cost than does the use of foreign genes.

The antimicrobial peptide MPX kills Actinobacillus pleuropneumoniae and reduces its pathogenicity in mice

Actinobacillus pleuropneumoniae is the causative agent of highly contagious and fatal respiratory infections, causing substantial economic losses to the global pig industry. Due to increased antibiotic resistance, there is an urgent need to find new antibiotic alternatives for treating A. pleuropneumoniae infections. MPX is obtained from wasp venom and has a killing effect on various bacteria. This study found that MPX had a good killing effect on A. pleuropneumoniae and that the minimum inhibitory concentration (MIC) was 16 μg/mL. The bacterial density of A. pleuropneumoniae decreased 1000 times after MPX (1 × MIC) treatment for 1 h, and the antibacterial activity was not affected by pH or temperature. Fluorescence microscopy showed that MPX (1 × MIC) destroyed the bacterial cell membrane after treatment for 0.5 h, increasing membrane permeability and releasing bacterial proteins and Ca²⁺, Na⁺ and other cations. In addition, MPX (1 × MIC) treatment significantly reduced the formation of bacterial biofilms. Quantitative RT-PCR results showed that MPX treatment significantly upregulated the expression of the PurC virulence gene and downregulated that of ApxI, ApxII, and Apa1. In addition, the Sap A gene was found to play an important role in the tolerance of A. pleuropneumoniae to antimicrobial peptides. Therapeutic evaluation in a murine model showed that MPX protects mice from a lethal dose of A. pleuropneumoniae and relieves lung inflammation. This study reports the use of MPX to treat A. pleuropneumonia infections, laying the foundation for the development of new drugs for bacterial infections.

Biocompatible Polymer Materials with Antimicrobial Properties for Preparation of Stents

Biodegradable polymers are promising materials for use in medical applications such as stents. Their properties are comparable to commercially available resistant metal and polymeric stents, which have several major problems, such as stent migration and stent clogging due to microbial biofilm. Consequently, conventional stents have to be removed operatively from the patient's body, which presents a number of complications and can also endanger the patient's life. Biodegradable stents disintegrate into basic substances that decompose in the human body, and no surgery is required. This review focuses on the specific use of stents in the human body, the problems of microbial biofilm, and possibilities of preventing microbial growth by modifying polymers with antimicrobial agents.

Current Therapeutic Strategies in Diabetic Foot Ulcers

Diabetic foot ulcers (DFUs) are the fastest growing chronic complication of diabetes mellitus, with more than 400 million people diagnosed globally, and the condition is responsible for lower extremity amputation in 85% of people affected, leading to high-cost hospital care and increased mortality risk. Neuropathy and peripheral arterial disease trigger deformities or trauma, and aggravating factors such as infection and edema are the etiological factors for the development of DFUs. DFUs require identifying the etiology and assessing the co-morbidities to provide the correct therapeutic approach, essential to reducing lower-extremity amputation risk. This review focuses on the current treatment strategies for DFUs with a special emphasis on tissue engineering techniques and regenerative medicine that collectively target all components of chronic wound pathology.

Natural Occurrence in Venomous Arthropods of Antimicrobial Peptides Active against Protozoan Parasites

Arthropoda is a phylum of invertebrates that has undergone remarkable evolutionary radiation, with a wide range of venomous animals. Arthropod venom is a complex mixture of molecules and a source of new compounds, including antimicrobial peptides (AMPs). Most AMPs affect membrane integrity and produce lethal pores in microorganisms, including protozoan pathogens, whereas others act on internal targets or by modulation of the host immune system. Protozoan parasites cause some serious life-threatening diseases among millions of people worldwide, mostly affecting the poorest in developing tropical regions. Humans can be infected with protozoan parasites belonging to the genera Trypanosoma, Leishmania, Plasmodium, and Toxoplasma, responsible for Chagas disease, human African trypanosomiasis, leishmaniasis, malaria, and toxoplasmosis. There is not yet any cure or vaccine for these illnesses, and the current antiprotozoal chemotherapeutic compounds are inefficient and toxic and have been in clinical use for decades, which increases drug resistance. In this review, we will present an overview of AMPs, the diverse modes of action of AMPs on protozoan targets, and the prospection of novel AMPs isolated from venomous arthropods with the potential to become novel clinical agents to treat protozoan-borne diseases.

Streamlined SMFA and mosquito dark-feeding regime significantly improve malaria transmission-blocking assay robustness and sensitivity

Background

The development of malaria transmission-blocking strategies including the generation of malaria refractory mosquitoes to replace the wild populations through means of gene drives hold great promise. The standard membrane feeding assay (SMFA) that involves mosquito feeding on parasitized blood through an artificial membrane system is a vital tool for evaluating the efficacy of transmission-blocking interventions. However, despite the availability of several published protocols, the SMFA remains highly variable and broadly insensitive.

Methods

The SMFA protocol was optimized through coordinated culturing of Anopheles coluzzii mosquitoes and Plasmodium falciparum parasite coupled with placing mosquitoes under a strict dark regime before, during, and after the gametocyte feed.

Results

A detailed description of essential steps is provided toward synchronized generation of highly fit An. coluzzii mosquitoes and P. falciparum gametocytes in preparation for an SMFA. A dark-infection regime that emulates the natural vector-parasite interaction system is described, which results in a significant increase in the infection intensity and prevalence. Using this optimal SMFA pipeline, a series of putative transmission-blocking antimicrobial peptides (AMPs) were screened, confirming that melittin and magainin can interfere with P. falciparum development in the vector.

Conclusion

A robust SMFA protocol that enhances the evaluation of interventions targeting human malaria transmission in laboratory setting is reported. Melittin and magainin are identified as highly potent antiparasitic AMPs that can be used for the generation of refractory Anopheles gambiae mosquitoes.

Bioinspired Designs, Molecular Premise and Tools for Evaluating the Ecological Importance of Antimicrobial Peptides

This review article provides an overview of recent developments in antimicrobial peptides (AMPs), summarizing structural diversity, potential new applications, activity targets and microbial killing responses in general. The use of artificial and natural AMPs as templates for rational design of peptidomimetics are also discussed and some strategies are put forward to curtail cytotoxic effects against eukaryotic cells. Considering the heat-resistant nature, chemical and proteolytic stability of AMPs, we attempt to summarize their molecular targets, examine how these macromolecules may contribute to potential environmental risks vis-à-vis the activities of the peptides. We further point out the evolutional characteristics of the macromolecules and indicate how they can be useful in designing target-specific peptides. Methods are suggested that may help to assess toxic mechanisms of AMPs and possible solutions are discussed to promote the development and application of AMPs in medicine. Even if there is wide exposure to the environment like in the hospital settings, AMPs may instead contribute to prevent healthcare-associated infections so long as ecotoxicological aspects are considered.

Antimicrobial Activity of Bee Venom and Melittin against Borrelia burgdorferi

Lyme disease is a tick-borne, multi-systemic disease, caused by the bacterium Borrelia burgdorferi. Though antibiotics are used as a primary treatment, relapse often occurs after the discontinuation of antimicrobial agents. The reason for relapse remains unknown, however previous studies suggest the possible presence of antibiotic resistant Borrelia round bodies, persisters and attached biofilm forms. Thus, there is an urgent need to find antimicrobial agents suitable to eliminate all known forms of B. burgdorferi. In this study, natural antimicrobial agents such as Apis mellifera venom and a known component, melittin, were tested using SYBR Green I/PI, direct cell counting, biofilm assays combined with LIVE/DEAD and atomic force microscopy methods. The obtained results were compared to standalone and combinations of antibiotics such as Doxycycline, Cefoperazone, Daptomycin, which were recently found to be effective against Borrelia persisters. Our findings showed that both bee venom and melittin had significant effects on all the tested forms of B. burgdorferi. In contrast, the control antibiotics when used individually or even in combinations had limited effects on the attached biofilm form. These findings strongly suggest that whole bee venom or melittin could be effective antimicrobial agents for B. burgdorferi; however, further research is necessary to evaluate their effectiveness in vivo, as well as their safe and effective delivery method for their therapeutic use.

Trypanocidal activity of mastoparan from Polybia paulista wasp venom by interaction with TcGAPDH

Chagas disease, considered a neglected disease, is a parasitic infection caused by Trypanosoma cruzi, which is endemic throughout the world. Previously, the antimicrobial effect of Mastoparan (MP) from Polybia paulista wasp venom against bacteria was described. To continue the study, we report in this short communication the antimicrobial effect of MP against Trypanosoma cruzi. MP inhibits all T. cruzi developmental forms through the inhibition of TcGAPDH suggested by the molecular docking. In conclusion, we suggest there is an antimicrobial effect also on T. cruzi.

Anti-parasitic Peptides from Arthropods and their Application in Drug Therapy

Africa, Asia, and Latin America are regions highly affected by endemic diseases, such as Leishmaniasis, Malaria, and Chagas' disease. They are responsible for the death of 1000s of patients every year, as there is not yet a cure for them and the drugs used are inefficient against the pathogenic parasites. During the life cycle of some parasitic protozoa, insects become the most important host and disseminator of the diseases triggered by these microorganisms. As infected insects do not develop nocive symptoms, they can carry the parasites for long time inside their body, enabling their multiplication and life cycle completion. Eventually, parasites infect human beings after insect's transmission through their saliva and/or feces. Hence, host insects and general arthropods, which developed a way to coexist with such parasites, are a promising source for the prospection of anti-parasitic compounds, as alternative methods for the treatment of protozoa-related diseases. Among the molecules already isolated and investigated, there are proteins and peptides with high activity against parasites, able to inhibit parasite activity in different stages of development. Although, studies are still taking their first steps, initial results show new perspectives on the treatment of parasitic diseases. Therefore, in this report, we describe about peptides from host insect sources with activity against the three most endemic parasites: Leishmania sp., Plasmodium sp., and Trypanosomes. Moreover, we discuss the future application insect peptides as anti-parasitic drugs and the use of non-hosts insect transcriptomes on the prospection of novel molecules for the treatment of parasitic neglected diseases.

Melittin induces in vitro death of Leishmania (Leishmania) infantum by triggering the cellular innate immune response

BACKGROUND

Apis mellifera venom, which has already been recommended as an alternative anti-inflammatory treatment, may be also considered an important source of candidate molecules for biotechnological and biomedical uses, such as the treatment of parasitic diseases.

METHODS

Africanized honeybee venom from Apis mellifera was fractionated by RP-C18-HPLC and the obtained melittin was incubated with promastigotes and intracellular amastigotes of Leishmania (L.) infantum. Cytotoxicity to mice peritoneal macrophages was evaluated through mitochondrial oxidative activity. The production of anti- and pro-inflammatory cytokines, NO and H2O2 by macrophages was determined.

RESULTS

Promastigotes and intracellular amastigotes were susceptible to melittin (IC50 28.3 μg.mL(-1) and 1.4 μg.mL(-1), respectively), but also showed mammalian cell cytotoxicity with an IC50 value of 5.7 μg.mL(-1). Uninfected macrophages treated with melittin increased the production of IL-10, TNF-α, NO and H2O2. Infected melittin-treated macrophages increased IL-12 production, but decreased the levels of IL-10, TNF-α, NO and H2O2.

CONCLUSIONS

The results showed that melittin acts in vitro against promastigotes and intracellular amastigotes of Leishmania (L.) infantum. Furthermore, they can act indirectly on intracellular amastigotes through a macrophage immunomodulatory effect.

Tannic acid anchored layer-by-layer covalent deposition of parasin I peptide for antifouling and antimicrobial coatings

Tannic acid and parasin I were deposited alternatively on stainless steel surface by Michael addition/Schiff base reaction-enabled layer-by-layer deposition technique.

The Potential Use of Natural and Structural Analogues of Antimicrobial Peptides in the Fight against Neglected Tropical Diseases

Recently, research into the development of new antimicrobial agents has been driven by the increase in resistance to traditional antibiotics and Emerging Infectious Diseases. Antimicrobial peptides (AMPs) are promising candidates as alternatives to current antibiotics in the treatment and prevention of microbial infections. AMPs are produced by all known living species, displaying direct antimicrobial killing activity and playing an important role in innate immunity. To date, more than 2000 AMPs have been discovered and many of these exhibit broad-spectrum antibacterial, antiviral and anti-parasitic activity. Neglected tropical diseases (NTDs) are caused by a variety of pathogens and are particularly wide-spread in low-income and developing regions of the world. Alternative, cost effective treatments are desperately needed to effectively battle these medically diverse diseases. AMPs have been shown to be effective against a variety of NTDs, including African trypanosomes, leishmaniosis and Chagas disease, trachoma and leprosy. In this review, the potential of selected AMPs to successfully treat a variety of NTD infections will be critically evaluated.

Assessment of SYBR green I dye-based fluorescence assay for screening antimalarial activity of cationic peptides and DNA intercalating agents

The SYBR green I (SG) dye-based fluorescence assay for screening antimalarial compounds is based on direct quantitation of parasite DNA. We show that DNA-interacting cationic cell-penetrating peptides (CPPs) and intercalating agents compete with SG dye to bind to DNA. Therefore, readouts of this assay, unlike those of the [(3)H]hypoxanthine incorporation assay, for the antimalarial activity of the above DNA binding agents may be erroneous. In the case of CPPs, false readouts can be improved by the removal of excess peptides.

Antimicrobial peptides: an alternative for innovative medicines?

Antimicrobial peptides are small molecules with activity against bacteria, yeasts, fungi, viruses, bacteria, and even tumor cells that make these molecules attractive as therapeutic agents. Due to the alarming increase of antimicrobial resistance, interest in alternative antimicrobial agents has led to the exploitation of antimicrobial peptides, both synthetic and from natural sources. Thus, many peptide-based drugs are currently commercially available for the treatment of numerous ailments, such as hepatitis C, myeloma, skin infections, and diabetes. Initial barriers are being increasingly overcome with the development of cost-effective, more stable peptides. Herein, we review the available strategies for their synthesis, bioinformatics tools for the rational design of antimicrobial peptides with enhanced therapeutic indices, hurdles and shortcomings limiting the large-scale production of AMPs, as well as the challenges that the pharmaceutical industry faces on their use as therapeutic agents.

Antimicrobial peptides: a new class of antimalarial drugs?

A range of antimicrobial peptides (AMP) exhibit activity on malaria parasites, Plasmodium spp., in their blood or mosquito stages, or both. These peptides include a diverse array of both natural and synthetic molecules varying greatly in size, charge, hydrophobicity, and secondary structure features. Along with an overview of relevant literature reports regarding AMP that display antiplasmodial activity, this review makes a few considerations about those molecules as a potential new class of antimalarial drugs.

Heritable strategies for controlling insect vectors of disease

Mosquito-borne diseases are causing a substantial burden of mortality, morbidity and economic loss in many parts of the world, despite current control efforts, and new complementary approaches to controlling these diseases are needed. One promising class of new interventions under development involves the heritable modification of the mosquito by insertion of novel genes into the nucleus or of Wolbachia endosymbionts into the cytoplasm. Once released into a target population, these modifications can act to reduce one or more components of the mosquito population's vectorial capacity (e.g. the number of female mosquitoes, their longevity or their ability to support development and transmission of the pathogen). Some of the modifications under development are designed to be self-limiting, in that they will tend to disappear over time in the absence of recurrent releases (and hence are similar to the sterile insect technique, SIT), whereas other modifications are designed to be self-sustaining, spreading through populations even after releases stop (and hence are similar to traditional biological control). Several successful field trials have now been performed with Aedes mosquitoes, and such trials are helping to define the appropriate developmental pathway for this new class of intervention.