ABSTRACT
Bovine mastitis caused by S. aureus has a major economic impact on the dairy sector. With the crucial need for new therapies, anti-virulence strategies have gained attention as alternatives to antibiotics. Here we aimed to identify novel compounds that inhibit the production/activity of hemolysins, a virulence factor of S. aureus associated with mastitis severity. We screened Bacillus strains obtained from diverse sources for compounds showing anti-hemolytic activity. Our results demonstrate that lipopeptides produced by Bacillus spp. completely prevented the hemolytic activity of S. aureus at certain concentrations. Following purification, both iturins, fengycins, and surfactins were able to reduce hemolysis caused by S. aureus, with iturins showing the highest anti-hemolytic activity (up to 76% reduction). The lipopeptides showed an effect at the post-translational level. Molecular docking simulations demonstrated that these compounds can bind to hemolysin, possibly interfering with enzyme action. Lastly, molecular dynamics analysis indicated general stability of important residues for hemolysin activity as well as the presence of hydrogen bonds between iturins and these residues, with longevous interactions. Our data reveals, for the first time, an anti-hemolytic activity of lipopeptides and highlights the potential application of iturins as an anti-virulence therapy to control bovine mastitis caused by S. aureus.
Subject(s)
Bacillus , Hemolysin Proteins , Hemolysis , Lipopeptides , Molecular Docking Simulation , Staphylococcus aureus , Bacillus/metabolism , Bacillus/chemistry , Staphylococcus aureus/drug effects , Hemolysis/drug effects , Animals , Cattle , Lipopeptides/pharmacology , Lipopeptides/chemistry , Hemolysin Proteins/antagonists & inhibitors , Hemolysin Proteins/metabolism , Anti-Bacterial Agents/pharmacology , Anti-Bacterial Agents/chemistry , Mastitis, Bovine/microbiology , Mastitis, Bovine/drug therapy , Female , Peptides, Cyclic/pharmacology , Peptides, Cyclic/chemistry , Staphylococcal Infections/drug therapy , Staphylococcal Infections/microbiology , Molecular Dynamics SimulationABSTRACT
Vibriosis and cholera are serious diseases distributed worldwide and caused by six marine bacteria of the Vibrio genus. Thousands of deaths occur each year due to these illnesses, necessitating the development of new preventive measures. Presently, the existing cholera vaccine demonstrates an effectiveness of approximately 60%. Here we describe a new multi-epitope vaccine, 'vme-VAC/MST-1' based on vaccine targets identified by reverse vaccinology and epitopes predicted by immunoinformatics, two currently effective tools for predicting new vaccines for bacterial pathogens. The vaccine was designed to combat vibriosis and cholera by incorporating epitopes predicted for CTL, HTL, and B cells. These epitopes were identified from six vaccine targets revealed through subtractive genomics, combined with reverse vaccinology, and were further filtered using immunoinformatics approaches based on their predicted immunogenicity. To construct the vaccine, 28 epitopes (24 CTL/B and 4 HTL/B) were linked to the sequence of the cholera toxin B subunit adjuvant. In silico analyses indicate that the resulting immunogen is stable, soluble, non-toxic, and non-allergenic. Furthermore, it exhibits no homology to the host and demonstrates a strong capacity to elicit innate, B-cell, and T-cell immune responses. Our analysis suggests that it is likely to elicit immune reactions mediated through the TLR5 pathway, as evidenced by the molecular docking of the vaccine with the receptor, which revealed high affinity and a favorable reaction. Thus, vme-VAC/MST-1 is predicted to be a safe and effective solution against pathogenic Vibrio spp. However, further experimental analyses are required to measure the vaccine's effects In vivo.Communicated by Ramaswamy H. Sarma.
ABSTRACT
The phytotelmata is a water-filled tank on a terrestrial plant, and it plays an important role in bromeliad growth and ecosystem functioning. Even though previous studies have contributed to elucidate the composition of the prokaryotic component of this aquatic ecosystem, its mycobiota (fungal community) is still poorly known. In the present work, ITS2 amplicon deep sequencing was used to examine the fungal communities inhabiting the phytotelmata of two bromeliads species that coexist in a sun-exposed rupestrian field of Southeastern Brazil, namely Aechmea nudicaulis (AN) and Vriesea minarum (VM). Ascomycota was the most abundant phylum in both bromeliads (57.1 and 89.1% in AN and VM respectively, on average), while the others were present in low abundance (< 2%). Mortierellomycota and Glomeromycota were exclusively observed in AN. Beta-diversity analysis showed that samples from each bromeliad significantly clustered together. In conclusion, despite the considerable within-group variation, the results suggested that each bromeliad harbor a distinct fungi community, what could be associated with the physicochemical characteristics of the phytotelmata (mainly total nitrogen, total organic carbon, and total carbon) and plant morphological features.
