Identification and Characterization of Three New Antimicrobial Peptides from the Marine Mollusk Nerita versicolor (Gmelin, 1791).

Mollusks have been widely investigated for antimicrobial peptides because their humoral defense against pathogens is mainly based on these small biomolecules. In this report, we describe the identification of three novel antimicrobial peptides from the marine mollusk Nerita versicolor. A pool of N. versicolor peptides was analyzed with nanoLC-ESI-MS-MS technology, and three potential antimicrobial peptides (Nv-p1, Nv-p2 and Nv-p3) were identified with bioinformatical predictions and selected for chemical synthesis and evaluation of their biological activity. Database searches showed that two of them show partial identity to histone H4 peptide fragments from other invertebrate species. Structural predictions revealed that they all adopt a random coil structure even when placed near a lipid bilayer patch. Nv-p1, Nv-p2 and Nv-p3 exhibited activity against Pseudomonas aeruginosa. The most active peptide was Nv-p3 with an inhibitory activity starting at 1.5 µg/mL in the radial diffusion assays. The peptides were ineffective against Klebsiella pneumoniae, Listeria monocytogenes and Mycobacterium tuberculosis. On the other hand, these peptides demonstrated effective antibiofilm action against Candida albicans, Candida parapsilosis and Candida auris but not against the planktonic cells. None of the peptides had significant toxicity on primary human macrophages and fetal lung fibroblasts at effective antimicrobial concentrations. Our results indicate that N. versicolor-derived peptides represent new AMP sequences and have the potential to be optimized and developed into antibiotic alternatives against bacterial and fungal infections.

The clubroot pathogen Plasmodiophora brassicae: A profile update.

BACKGROUND: Plasmodiophora brassicae is the causal agent of clubroot disease of cruciferous plants and one of the biggest threats to the rapeseed (Brassica napus) and brassica vegetable industry worldwide. DISEASE SYMPTOMS: In the advanced stages of clubroot disease wilting, stunting, yellowing, and redness are visible in the shoots. However, the typical symptoms of the disease are the presence of club-shaped galls in the roots of susceptible hosts that block the absorption of water and nutrients. HOST RANGE: Members of the family Brassicaceae are the primary host of the pathogen, although some members of the family, such as Bunias orientalis, Coronopus squamatus, and Raphanus sativus, have been identified as being consistently resistant to P. brassicae isolates with variable virulence profile. TAXONOMY: Class: Phytomyxea; Order: Plasmodiophorales; Family: Plasmodiophoraceae; Genus: Plasmodiophora; Species: Plasmodiophora brassicae (Woronin, 1877). DISTRIBUTION: Clubroot disease is spread worldwide, with reports from all continents except Antarctica. To date, clubroot disease has been reported in more than 80 countries. PATHOTYPING: Based on its virulence on different hosts, P. brassicae is classified into pathotypes or races. Five main pathotyping systems have been developed to understand the relationship between P. brassicae and its hosts. Nowadays, the Canadian clubroot differential is extensively used in Canada and has so far identified 36 different pathotypes based on the response of a set of 13 hosts. EFFECTORS AND RESISTANCE: After the identification and characterization of the clubroot pathogen SABATH-type methyltransferase PbBSMT, several other effectors have been characterized. However, no avirulence gene is known, hindering the functional characterization of the five intercellular nucleotide-binding (NB) site leucine-rich-repeat (LRR) receptors (NLRs) clubroot resistance genes validated to date. IMPORTANT LINK: Canola Council of Canada is constantly updating information about clubroot and P. brassicae as part of their Canola Encyclopedia: https://www.canolacouncil.org/canola-encyclopedia/diseases/clubroot/. PHYTOSANITARY CATEGORIZATION: PLADBR: EPPO A2 list; Annex designation 9E.

Host defense peptides as immunomodulators: The other side of the coin.

Host defense peptides (HDPs) exhibit a broad range of antimicrobial and immunomodulatory activities. In this sense, both functions are like different sides of the same coin. The direct antimicrobial side was discovered first, and widely studied for the development of anti-infective therapies. In contrast, the immunomodulatory side was recognized later and in the last 20 years the interest in this field has been continuously growing. Different to their antimicrobial activities, the immunomodulatory activities of host defense peptides are more effective in vivo. They offer a great opportunity for new therapeutic applications in the fields of anti-infective therapy, chronic inflammatory diseases treatment, novel vaccine adjuvants development and anticancer immunotherapy. These immune related functions of HDPs includes chemoattraction of leukocytes, modulation of inflammation, enhancement of antigen presentation and polarization of adaptive immune responses. Our attempt with this review is to make a careful evaluation of different aspects of the less explored, but attractive immunomodulatory side of the HDP functional coin.

Antimicrobial Activity of Cyclic-Monomeric and Dimeric Derivatives of the Snail-Derived Peptide Cm-p5 against Viral and Multidrug-Resistant Bacterial Strains.

Cm-p5 is a snail-derived antimicrobial peptide, which demonstrated antifungal activity against the pathogenic strains of Candida albicans. Previously we synthetized a cyclic monomer as well as a parallel and an antiparallel dimer of Cm-p5 with improved antifungal activity. Considering the alarming increase of microbial resistance to conventional antibiotics, here we evaluated the antimicrobial activity of these derivatives against multiresistant and problematic bacteria and against important viral agents. The three peptides showed a moderate activity against Pseudomonas aeruginosa, Klebsiella pneumoniae Extended Spectrum ß-Lactamase (ESBL), and Streptococcus agalactiae, with MIC values > 100 µg/mL. They exerted a considerable activity with MIC values between 25-50 µg/mL against Acinetobacter baumanii and Enterococcus faecium. In addition, the two dimers showed a moderate activity against Pseudomonas aeruginosa PA14. The three Cm-p5 derivatives inhibited a virulent extracellular strain of Mycobacterium tuberculosis, in a dose-dependent manner. Moreover, they inhibited Herpes Simplex Virus 2 (HSV-2) infection in a concentration-dependent manner, but had no effect on infection by the Zika Virus (ZIKV) or pseudoparticles of Severe Acute Respiratory Syndrome Corona Virus 2 (SARS-CoV-2). At concentrations of >100 µg/mL, the three new Cm-p5 derivatives showed toxicity on different eukaryotic cells tested. Considering a certain cell toxicity but a potential interesting activity against the multiresistant strains of bacteria and HSV-2, our compounds require future structural optimization.

Antimicrobial Peptides Pom-1 and Pom-2 from Pomacea poeyana Are Active against Candidaauris, C. parapsilosis and C. albicans Biofilms.

Recently two peptides isolated from the Cuban freshwater snail Pomacea poeyana (Pilsbry, 1927) were described to have antimicrobial activity against bacterial pathogens. Here we show considerable activities of Pom-1 and Pom-2 to reduce the viability of C. albicans, C. parapsilosis and the less common species C. auris measured as the decrease of metabolic activity in the resazurin reduction assay for planktonic cells. Although these activities were low, Pom-1 and Pom-2 turned out to be highly potent inhibitors of biofilm formation for the three Candida species tested. Whereas Pom-1 was slightly more active against C. albicans and C. parapsilosis as representatives of the more common Candida species Pom-2 showed no preference and was fully active also against biofilms of the more uncommon species C. auris. Pom-1 and Pom-2 may represent promising lead structures for the development of a classical peptide optimization strategy with the realistic aim to further increase antibiofilm properties and other pharmacologic parameters and to generate finally the first antifungal drug with a pronounced dedication against Candida biofilms.

New Antibacterial Peptides from the Freshwater Mollusk Pomacea poeyana (Pilsbry, 1927).

Antimicrobial peptides (AMPs) are biomolecules with antimicrobial activity against a broad group of pathogens. In the past few decades, AMPs have represented an important alternative for the treatment of infectious diseases. Their isolation from natural sources has been widely investigated. In this sense, mollusks are promising organisms for the identification of AMPs given that their immune system mainly relies on innate response. In this report, we characterized the peptide fraction of the Cuban freshwater snail Pomacea poeyana (Pilsbry, 1927) and identified 37 different peptides by nanoLC-ESI-MS-MS technology. From these peptide sequences, using bioinformatic prediction tools, we discovered two potential antimicrobial peptides named Pom-1 (KCAGSIAWAIGSGLFGGAKLIKIKKYIAELGGLQ) and Pom-2 (KEIERAGQRIRDAIISAAPAVETLAQAQKIIKGG). Database search revealed that Pom-1 is a fragment of Closticin 574 previously isolated from the bacteria Clostridium tyrobutyrium, and Pom-2 is a fragment of cecropin D-like peptide first isolated from Galleria mellonella hemolymph. These sequences were chemically synthesized and evaluated against different human pathogens. Interestingly, structural predictions of both peptides in the presence of micelles showed models that comprise two alpha helices joined by a short loop. The CD spectra analysis of Pom-1 and Pom-2 in water showed for both structures a high random coil content, a certain content of α-helix and a low ß-sheet content. Like other described AMPs displaying a disordered structure in water, the peptides may adopt a helical conformation in presence of bacterial membranes. In antimicrobial assays, Pom-1 demonstrated high activity against the Gram-negative bacteria Pseudomonas aeruginosa and moderate activity against Klebsiella pneumoniae and Listeria monocytogenes. Neither of the two peptides showed antifungal action. Pom-1 moderately inhibits Zika Virus infection but slightly enhances HIV-1 infectivion in vitro. The evaluation of cell toxicity on primary human macrophages did not show toxicity on THP-1 cells, although slight overall toxicity was observed in high concentrations of Pom-1. We assume that both peptides may play a key role in innate defense of P. poeyana and represent promising antimicrobial candidates for humans.

Derivates of the Antifungal Peptide Cm-p5 Inhibit Development of Candida auris Biofilms In Vitro.

Growth in biofilms as a fascinating and complex microbial lifestyle has become widely accepted as one of the key features of pathogenic microbes, to successfully express their full virulence potential and environmental persistence. This also increases the threat posed by Candida auris, which has a high intrinsic ability to persist on abiotic surfaces including those of surgical instruments and medical tubing. In a previous study, cyclic and helical-stabilized analogues of the antifungal peptide Cm-p5 were designed and synthetized, and proved to have increased activities against C. albicans and C. parapsilosis, but not against planktonic C. auris cells cultivated in suspension cultures. Here, we demonstrate, initially, that these derivatives, however, exhibited semi-inhibitory concentrations between 10-21 µg/mL toward C. auris biofilms. Maturated biofilms were also arrested between 71-97%. These novel biofilm inhibitors may open urgently needed new routes for the development of novel drugs and treatments for the next stage of fight against C. auris.

A Cerberus-Inspired Anti-Infective Multicomponent Gatekeeper Hydrogel against Infections with the Emerging "Superbug" Yeast Candida auris.

The pathogenic yeast Candida auris has received increasing attention due to its ability to cause fatal infections, its resistance toward important fungicides, and its ability to persist on surfaces including medical devices in hospitals. To brace health care systems for this considerable risk, alternative therapeutic approaches such as antifungal peptides are urgently needed. In clinical wound care, a significant focus has been directed toward novel surgical (wound) dressings as first defense lines against C. auris. Inspired by Cerberus the Greek mythological "hound of Hades" that prevents the living from entering and the dead from leaving hell, the preparation of a gatekeeper hybrid hydrogel is reported featuring lectin-mediated high-affinity immobilization of C. auris cells from a collagen gel as a model substratum in combination with a release of an antifungal peptide drug to kill the trapped cells. The vision is an efficient and safe two-layer medical composite hydrogel for the treatment of severe wound infections that typically occur in hospitals. Providing this new armament to the repertoire of possibilities for wound care in critical (intensive care) units may open new routes to shield and defend patients from infections and clinical facilities from spreading and invasion of C. auris and probably other fungal pathogens.

Design of a Helical-Stabilized, Cyclic, and Nontoxic Analogue of the Peptide Cm-p5 with Improved Antifungal Activity.

Following the information obtained by a rational design study, a cyclic and helical-stabilized analogue of the peptide Cm-p5 was synthetized. The cyclic monomer showed an increased activity in vitro against Candida albicans and Candida parapsilosis, compared to Cm-p5. Initially, 14 mutants of Cm-p5 were synthesized following a rational design to improve the antifungal activity and pharmacological properties. Antimicrobial testing showed that the activity was lost in each of these 14 analogues, suggesting, as a main conclusion, that a Glu-His salt bridge could stabilize Cm-p5 helical conformation during the interaction with the plasma membrane. A derivative, obtained by substitution of Glu and His for Cys, was synthesized and oxidized with the generation of a cyclic monomer with improved antifungal activity. In addition, two dimers were generated during the oxidation procedure, a parallel and antiparallel one. The dimers showed a helical secondary structure in water, whereas the cyclic monomer only showed this conformation in SDS. Molecular dynamic simulations confirmed the helical stabilizations for all of them, therefore indicating the possible essential role of the Glu-His salt bridge. In addition, the antiparallel dimer showed a moderate activity against Pseudomonas aeruginosa and a significant activity against Listeria monocytogenes. Neither the cyclic monomer nor the dimers were toxic against macrophages or THP-1 human cells. Due to its increased capacity for fungal control compared to fluconazole, its low cytotoxicity, together with a stabilized α-helix and disulfide bridges, that may advance its metabolic stability, and in vivo activity, the new cyclic Cm-p5 monomer represents a potential systemic antifungal therapeutic candidate.

Antimicrobial peptides in multiresistant respiratory infections / Péptidos antimicrobianos en infecciones respiratorias multiresistentes

Antimicrobial peptides are small cationic molecules present in almost all living organisms. They show direct or indirect (immunomodulation) activity in a wide range of pathogenic microorganisms as members of the humoral arsenal of innate immunity. In mammals they play a significant role in respiratory airways. The most abundant antimicrobial peptides in the respiratory tract of mammals are lysozymes, lactoferrin, histatins, defensins and cathelicidins. Respiratory and pulmonary infections are combated, primarily, by antimicrobial peptides like LL-37 against Gram-negative bacteria, histatin 5 against Candida albicans and human peptides from neutrophils against adenovirus, influenza and parainfluenza. This paper provides a review of the most important antimicrobial peptides in the respiratory tract and their use in the search for new effective agents against microorganisms that cause respiratory infections based on information published in MedLine, the Web of Science and Scopus in recent years(AU)

Los péptidos antimicrobianos son pequeñas moléculas catiónicas presentes en casi todos los organismos vivos. Muestran actividad directa o indirecta (inmunomodulación) en una amplia gama de microorganismos patógenos como miembros del arsenal humoral de la inmunidad innata. En los mamíferos juegan un papel importante en las vías respiratorias. Los péptidos antimicrobianos más abundantes en el tracto respiratorio son lisozima, lactoferrina, histatinas, defensinas y catelicidinas. Las infecciones respiratorias y pulmonares son combatidas, principalmente, por péptidos antimicrobianos como LL-37 contra bacterias gramnegativas, histatina 5 contra Candida albicans y péptidos humanos de neutrófilos contra adenovirus, influenza y parainfluenza. Este artículo proporciona una revisión sobre los péptidos antimicrobianos más importantes en el tracto respiratorio y su empleo en la búsqueda de nuevos agentes eficaces contra microorganismos causantes de infecciones respiratorias teniendo en cuenta la información publicada al respecto en MedLine, Web of Science y Scopus en los últimos años(AU)

Péptidos antimicrobianos: potencialidades terapéuticas / Antimicrobial peptides: their therapeutic potential

El aumento en la incidencia de las enfermedades infecciosas en los últimos años se ha favorecido por diferentes causas. Entre estas se destacan las inmunodeficiencias adquiridas (sida, trasplantes de órganos, quimioterapia oncológica), la migración de personas que trae consigo la posibilidad de importar enfermedades hacia poblaciones susceptibles, así como el excesivo empleo de antibióticos. Debido a esta situación se ha incrementado la búsqueda de nuevos candidatos terapéuticos para el desarrollo de terapias más efectivas. En este sentido los péptidos antimicrobianos constituyen una opción promisoria, pues presentan un amplio espectro de actividad frente a varios microorganismos patógenos. Además, se encuentran ampliamente distribuidos en la naturaleza, desde organismos unicelulares hasta mamíferos. Algunos péptidos antimicrobianos ya están siendo evaluados en estudios clínicos aunque muchos de ellos no han tenido resultados favorables in vivo debido a su poca estabilidad metabólica y toxicidad, entre otros. Con el fin de optimizar estas propiedades de los péptidos antimicrobianos se han trazado diferentes estrategias como la modificación química de su estructura y la conjugación con nanopartículas magnéticas. Es por eso que este artículo tiene el objetivo de revisar las potenciales aplicaciones terapéuticas de estas moléculas, teniendo en cuenta la información publicada al respecto en MedLine, Web of Science y Scopus en los últimos años

The growing incidence of infectious disease in recent years may be attributed to several causes, among them acquired immunodeficiencies (AIDS, organ transplant, oncological chemotherapy), human migration and the consequent import of diseases into susceptible populations, and the excessive use of antibiotics. This situation has fostered the search for new therapeutic candidates for the development of more effective treatments. Antimicrobial peptides are a promising alternative in this respect, due to their broad spectrum of activity against several pathogenic microorganisms. Moreover, they are widely distributed in nature, from unicellular organisms to mammals. Some antimicrobial peptides are already being evaluated in clinical studies, though many of them have not produced any favorable results in vivo due to their low metabolic stability and their toxicity, among other factors. Several strategies have been developed to overcome the above mentioned drawbacks, among them conjugation of microbial peptides with magnetic nanoparticles and chemical modification of their structure. The present study is aimed at reviewing the potential therapeutic applications of these molecules based on information published in MedLine, the Web of Science and Scopus in recent years.