The Variability of the Salivary Antimicrobial Peptide Profile: Impact of Lifestyle.

Saliva is crucial in maintaining oral health; its composition reflects the body's physiological and diseased state. Among salivary components, antimicrobial peptides (AMPs) stand out for their broad antimicrobial activities and role in modulating the oral microbiota and innate immune response. Local and systemic diseases can affect the levels of AMPs in saliva, making them attractive biomarkers.

Anti-Herpetic Activity of Killer Peptide (KP): An In Vitro Study.

Antimicrobial peptides represent a promising alternative to traditional drugs in relation to cost, toxicity, and, primarily, the growing problem of drug resistance. Here, we report on the activity against HSV-1 and HSV-2 of a previously described wide-spectrum synthetic decapeptide, Killer Peptide (KP). As determined by plaque reduction assays, treatment with KP at 100 μg/mL resulted in a reduction in the viral yield titer of 3.

Activity of Synthetic Peptide KP and Its Derivatives against Biofilm-Producing Strains Resistant to Cephalosporins.

Bacterial resistance to β-lactam antibiotics, particularly new generation cephalosporins, is a major public health concern. In , resistance to these antibiotics is mainly mediated by extended-spectrum β-lactamases (ESBL), which complicates a range of health-threatening infections. These infections may also be biofilm-related, making them more difficult to treat because of the higher tolerance to conventional antibiotics and the host immune response.

Novel Arginine- and Proline-Rich Candidacidal Peptides Obtained through a Bioinformatic Approach.

Antimicrobial resistance is a major public health concern worldwide. Albeit to a lesser extent than bacteria, fungi are also becoming increasingly resistant to antifungal drugs. Moreover, due to the small number of antifungal classes, therapy options are limited, complicating the clinical management of mycoses.

SARS-CoV-2-The Role of Natural Immunity: A Narrative Review.

Background: Both natural immunity and vaccine-induced immunity to COVID-19 may be useful to reduce the mortality/morbidity of this disease, but still a lot of controversy exists.

Aims: This narrative review analyzes the literature regarding these two immunitary processes and more specifically: (a) the duration of natural immunity; (b) cellular immunity; (c) cross-reactivity; (d) the duration of post-vaccination immune protection; (e) the probability of reinfection and its clinical manifestations in the recovered patients; (f) the comparisons between vaccinated and unvaccinated as to the possible reinfections; (g) the role of hybrid immunity; (h) the effectiveness of natural and vaccine-induced immunity against Omicron variant; (i) the comparative incidence of adverse effects after vaccination in recovered individuals vs. COVID-19-naïve subjects.

Guideline for the analysis of the microbial communities of the human upper airways.

The recent COVID-19 pandemic prompted a rapid-growing interest in the investigation of the human microbiota of the upper airways. In fact, the resident microbial community of this body district may have an influence on the onset of SARS-CoV-2 infection and its clinical course in terms of presence, symptom severity, and outcomes. However, several microbiological methodologies are available to study the human microbiota, reflecting the extensive fragmentation of methodological approaches.

Metabolic Plasticity of in Response to Different Environmental Conditions.

The ubiquitous commensal , part of the human microbiota, is an opportunistic pathogen able to cause a wide range of diseases, from cutaneous mycoses to life-threatening infections in immunocompromised patients. adapts to different environments and survives long-time starvation. The ability to switch from yeast to hyphal morphology under specific environmental conditions is associated with its virulence.

Therapeutic Effect of an Antibody-Derived Peptide in a Model of Systemic Candidiasis.

The synthetic peptide T11F (TCRVDHRGLTF), with sequence identical to a fragment of the constant region of human IgM, and most of its alanine-substituted derivatives proved to possess a significant candidacidal activity in vitro. In this study, the therapeutic efficacy of T11F, D5A, the derivative most active in vitro, and F11A, characterized by a different conformation, was investigated in larvae infected with . A single injection of F11A and D5A derivatives, in contrast with T11F, led to a significant increase in survival of larvae injected with a lethal inoculum of cells, in comparison with infected animals treated with saline.

Activity of Two Antimicrobial Peptides against in a Model of Biofilm-Mediated Endodontic Infection.

is a common cause of biofilm-associated opportunistic infections, which are often difficult to treat. The formation of biofilms on the dentinal walls of the root canal is frequently the cause of endodontic treatment failure and secondary apical periodontitis. In a preliminary work, two recognized antifungal peptides, KP and L18R, showed antibacterial activity against planktonic cells at micromolar concentrations.

Yeast Killer Toxins' Medical Applications.

Possible implications and applications of the yeast killer phenomenon in the fight against infectious diseases are reviewed, with particular reference to some wide-spectrum killer toxins (KTs) produced by and other related species. A perspective on the applications of these KTs in the medical field is provided considering (1) a direct use of killer strains, in particular in the symbiotic control of arthropod-borne diseases; (2) a direct use of KTs as experimental therapeutic agents; (3) the production, through the idiotypic network, of immunological derivatives of KTs and their use as potential anti-infective therapeutics. Studies on immunological derivatives of KTs in the context of vaccine development are also described.

Antimicrobial Peptide L18R Displays a Modulating Action against Inter-Kingdom Biofilms in the Lubbock Chronic Wound Biofilm Model.

Chronic wound infections represent an important health problem due to the reduced response to antimicrobial treatment of the pathogens organized in structured biofilms. This study investigated the effects of the previously described antifungal peptide L18R against three representative wound pathogens: , and The antimicrobial activity of L18R was evaluated (i) against single planktonic microbial populations; (ii) on single, dual, and triadic species of biofilms in both the early stage and mature stage; and (iii) in the polymicrobial Lubbock chronic wound biofilm (LCWB) model, mimicking spatial microbial colonization. This study used the evaluation of CFUs, biofilm biomass detection, and confocal and scanning electron microscopy analysis.

In Silico Predicted Antifungal Peptides: In Vitro and In Vivo Anti- Activity.

It has been previously demonstrated that synthetic antibody-derived peptides could exert a significant activity in vitro, ex vivo, and/or in vivo against microorganisms and viruses, as well as immunomodulatory effects through the activation of immune cells. Based on the sequence of previously described antibody-derived peptides with recognized antifungal activity, an in silico analysis was conducted to identify novel antifungal candidates. The present study analyzed the candidacidal and structural properties of in silico designed peptides (ISDPs) derived by amino acid substitutions of the parent peptide KKVTMTCSAS.

In Vitro and In Vivo Anti- Activity and Structural Analysis of Killer Peptide (KP)-Derivatives.

The previously described decapeptide AKVTMTCSAS (killer peptide, KP), derived from the variable region of a recombinant yeast killer toxin-like anti-idiotypic antibody, proved to exert a variety of antimicrobial, antiviral, and immunomodulatory activities. It also showed a peculiar self-assembly ability, likely responsible for the therapeutic effect in animal models of systemic and mucosal candidiasis. The present study analyzed the biological and structural properties of peptides derived from KP by substitution or deletion of the first residue, leaving unchanged the remaining amino acids.

Anti-Infective Antibody-Derived Peptides Active against Endogenous and Exogenous Fungi.

Mycoses still represent relevant opportunistic infections worldwide, although overshadowed in recent years by other severe and more widespread infections. Moreover, deep-seated mycoses are often accompanied by unacceptably high mortality rates. Etiologic agents include endogenous components of the mycobiota, and species above all, and exogenous species, both yeasts and filamentous fungi.

A Peptide Found in Human Serum, Derived from the C-Terminus of Albumin, Shows Antifungal Activity In Vitro and In Vivo.

The growing problem of antimicrobial resistance highlights the need for alternative strategies to combat infections. From this perspective, there is a considerable interest in natural molecules obtained from different sources, which are shown to be active against microorganisms, either alone or in association with conventional drugs. In this paper, peptides with the same sequence of fragments, found in human serum, derived from physiological proteins, were evaluated for their antifungal activity.

Antimicrobial effect on biofilm by application of different wavelengths and dyes and the synthetic killer decapeptide KP.

The aim of this study was to test the application of different laser wavelengths at a low fluence in combination or not with proper photosensitizing dyes on biofilm with or without a synthetic killer decapeptide (KP). SC5314 was grown on Sabouraud dextrose agar plates at 37°C for 24 h. Cells were suspended in RPMI 1640 buffered with MOPS and cultured directly on the flat bottom of 96-wells plates.

Antimicrobial Photodynamic Therapy Protocols on with Different Combinations of Wavelengths and Photosensitizing Dyes.

The aim of the study is to test the application of different laser wavelengths, with and without different photosensitizing dyes on different types of cultures. Laser irradiation was realized on in both solid and liquid culture media in continuous mode at three different fluences (10, 20, and 30 J/cm) with a red diode (650 nm) with toluidine blue dye, a blue-violet diode (405 nm) with curcumin dye, and a green diode (532 nm) with erythrosine dye. Without a photosensitizer, no growth inhibition was obtained with the red diode at any fluence value.

Antiviral Activity of Synthetic Peptides Derived from Physiological Proteins.

Background/aims: New antivirals are needed to supplement or replace currently used drugs. The aim of this study was to evaluate the antiviral activity of synthetic peptides derived from physiological proteins.

Methods: Vero cell monolayers were infected with herpes simplex virus 1, vesicular stomatitis virus, adenovirus, and coxsackievirus B5 strains in the presence of different concentrations of the selected peptides and viral yield was determined by plaque reduction assays to evaluate the antiviral activity of the peptides.

Dissection of the Structural Features of a Fungicidal Antibody-Derived Peptide.

The synthetic peptide T11F (TCRVDHRGLTF), derived from the constant region of human IgM antibodies, proved to exert a significant activity in vitro against yeast strains, including multidrug resistant isolates. Alanine substitution of positively charged residues led to a decrease in candidacidal activity. A more dramatic reduction in activity resulted from cysteine replacement.

Discovering a new class of antifungal agents that selectively inhibits microbial carbonic anhydrases.

Infections caused by pathogens resistant to the available antimicrobial treatments represent nowadays a threat to global public health. Recently, it has been demonstrated that carbonic anhydrases (CAs) are essential for the growth of many pathogens and their inhibition leads to growth defects. Principal drawbacks in using CA inhibitors (CAIs) as antimicrobial agents are the side effects due to the lack of selectivity toward human CA isoforms.

The activity of a mammalian proline-rich peptide against Gram-negative bacteria, including drug-resistant strains, relies on a nonmembranolytic mode of action.

Background: A peptide of 2,733 Da named SP-E, previously isolated from pig saliva and already described for its antifungal activity and absence of toxicity against mammalian cells, is characterized by a high content of proline residues (70% of entire sequence), that confer structural features probably related to peptide activity.

Purpose: The aim of this study was to evaluate the activity of SP-E against Gram-negative bacteria, including drug-resistant clinical isolates.

Methods: SP-E and shorter fragments of the same peptide were tested in vitro against the selected bacteria by colony forming unit assays.

Novel Activity of a Synthetic Decapeptide Against Tachyzoites.

The killer peptide KP is a synthetic decapeptide derived from the sequence of the variable region of a recombinant yeast killer toxin-like microbicidal single-chain antibody. KP proved to exert significant activities against diverse microbial and viral pathogens through different mechanisms of action, but little is known of its effect on apicomplexan protozoa. The aim of the present study was to evaluate the activity of KP against , a globally widespread protozoan parasite of great medical interest.

Candidacidal Activity of a Novel Killer Toxin from Wickerhamomyces anomalus against Fluconazole-Susceptible and -Resistant Strains.

The isolation and characterization from the sand fly of a yeast strain (1F1) displaying the killer phenotype was recently reported. In the present work, the killer toxin (KT) produced by 1F1 was purified and characterized, and its antimicrobial activity in vitro was investigated against fluconazole- susceptible and -resistant clinical isolates and laboratory strains of and displaying known mutations. 1F1-KT showed a differential killing ability against different mutant strains of the same species.

Fungicidal activity of peptides encoded by immunoglobulin genes.

Evidence from previous works disclosed the antimicrobial, antiviral, anti-tumour and/or immunomodulatory activity exerted, through different mechanisms of action, by peptides expressed in the complementarity-determining regions or even in the constant region of antibodies, independently from their specificity and isotype. Presently, we report the selection, from available databases, of peptide sequences encoded by immunoglobulin genes for the evaluation of their potential biological activities. Synthetic peptides representing the translated products of J lambda and J heavy genes proved to act in vitro against pathogenic fungi, entering yeast cells and causing their death, and exerted a therapeutic effect in a Galleria mellonella model of infection by Candida albicans.