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Abstract Background Aspergillus flavus, a seed-borne fungal pathogen, colonizes host plants and exploits nutrients, hindering the growth of seedlings such as peanut and maize. This study investigates the effectiveness of cell-free supernatants (CFSs) from the plant growth-promoting rhizobacteria (PGPR) Bacillus albus strains NNK24 and NDP61, which belong to the Bacillus cereus group, in suppressing A. flavus AF1. Results The antifungal activity of these CFSs was attributed to their surfactant properties and chemical composition. These were characterized using rapid chemical assays and ultra-high-performance liquid chromatography-electrospray ionization-quadrupole time-of-flight/mass spectrometry (UHPLC-ESI-QTOF/MS), combined with bioinformatic tools such as Global Natural Product Social Molecular Networking (GNPS) and Natural Products Atlas (NPAtlas). Identified putative antifungal compounds included two diketopiperazines (cyclo(Pro-Leu) and cyclo(2-hydroxy-Pro-Leu)), four macrolactins (7-O-succinyl macrolactin A, 7-O-methyl-5′-hydroxy-3′-heptenoate-macrolactin, macrolactin B, and macrolactin C), two siderophores (petrobactin and bacillibactin), and three cyclic lipopeptides (kurstakin 1, 2 or 3, and 4). These compounds are hypothesized to act synergistically via multiple mechanisms, including disruption of fungal membranes, iron capture, direct antibiosis, and triggering plant immunity. Both CFSs strongly suppressed the harmful effects of A. flavus AF1 and seed-borne A. flavus on peanut and maize seedlings, reducing disease incidence (DI) and disease severity index (DSI) compared to controls. The disease control efficacy (DCE) of the CFSs was comparable to that of the commercial fungicide. Additionally, the CFSs enhanced seed germination, vigor, seedling length, and weight in both peanut and maize. Vigor index (VI) values increased by 222.4–286.0% in peanuts and 181.7–216.4% in maize at 7 days after treatment (DAT). Conclusion CFSs of B. albus NNK24 and NDP61 show significant potential as bioprotective agents for sustainable agriculture. Importantly, their use eliminates the need for live bacterial cells from the B. cereus group, addressing biosafety concerns. Graphical abstract

Background: The COVID-19 pandemic in Bulgaria was characterized by a high mortality rate and vaccination efforts yielded suboptimal results. Understanding population immunity is important as new SARS-CoV-2 variants continue to emerge. This study aimed to assess the seroprevalence of SARS-CoV-2 antibodies in the general population of Bulgaria and examine demographic variations in antibody presence. Materials and methods: In December 2023, 1895 serum samples were randomly collected from healthy individuals across all 28 provinces. Samples were tested for SARS-CoV-2 spike protein-specific IgG antibodies using ELISA method. A subset of the positive samples was subsequently tested for neutralizing antibodies. Seroprevalence was analyzed by sex, age group, and geographic region. Statistical analyses were conducted using SPSS v.26. Results: Overall seroprevalence was 91.9%, with similar rates between males (91.6%) and females (92.0%). Seroprevalence was highest in the 18-39 age group (95.1%) and lowest in those over 65 (89.3%). Regional seroprevalence ranged from 80.0% to 98.3%. Among samples tested for presence of neutralizing antibodies, 90.5% were positive, indicating effective immune response. Conclusions: The high seroprevalence suggests widespread prior exposure to SARS-CoV-2 and/or vaccination among the Bulgarian population. The strong presence of neutralizing antibodies might provide potential protection against severe disease. Targeted interventions towards older age groups could be appropriate in order to sustain immunity as COVID-19 remains a public health concern.

As modeling of atherosclerosis requires recapitulating complex interactions with vasculature and immune cells, previous in vitro models have limitations due to their insufficient 3D vascular structures. However, induced pluripotent stem cell-derived blood vessel organoids (BVOs) are applicable for modeling vascular diseases, containing multiple cell types, including endothelial and vascular smooth muscle cells self-assembled into a blood vessel structure. Atherosclerotic BVOs with a microenvironment associated with atherogenesis, such as shear stress, low-density lipoprotein, pro-inflammatory cytokine, and monocyte co-culture are successfully developed. In atherosclerotic BVOs, representative atherosclerotic phenotypes, including endothelial dysfunction, inflammatory responses, formation of foam cells and fibrous plaque, and moreover, calcification of the plaques are observed. To verify the drug response in this model, it is treated with clinically used lovastatin and confirm phenotype attenuation. Furthermore, the therapeutic efficacy of nano-sized graphene oxides (NGOs) is evaluated on atherosclerosis. Due to their anti-inflammatory effects, NGOs effectively alleviate the pathologic lesions in atherosclerotic BVOs by promoting macrophage polarization toward M2. These results suggest that atherosclerotic BVOs are advanced in vitro models suitable for drug discovery and elucidation of therapeutic mechanisms. From the perspective of precision medicine, this platform using patient-derived BVOs can be further employed for personalized drug screening in the future., (© 2024 Wiley‐VCH GmbH.)