Search Results (170)

Lipid raft-associated gangliosides facilitate the early stages of SARS-CoV-2 entry by triggering the exposure of the receptor-binding domain (RBD) within the trimeric spike protein, which is initially sequestered. A broad range of in silico, cryoelectron microscopy and physicochemical approaches indicate that the RBD becomes accessible after a ganglioside-induced conformational rearrangement originating in the N-terminal domain (NTD) of one protomer and propagating to the neighboring RBD. We previously identified a triad of amino acids, Q134-F135-N137, as a strictly conserved element on the NTD. In the present review, we integrate a series of structural and experimental data revealing that this triad may act as a conformational transducer connected to a chain of residues that are capable of transmitting an internal conformational wave within the NTD. This wave is generated at the triad level after physical interactions with lipid raft gangliosides of the host cell membrane. It propagates inside the NTD and collides with the RBD of a neighboring protomer, triggering its unmasking. We also identify a chain of aromatic residues that are capable of controlling electron transfer through the NTD, leading us to hypothesize the existence of a dual conformational/quantum wave. In conclusion, the complete conservation of the Q134-F135-N137 triad despite six years of extensive NTD remodeling underscores its critical role in the viral life cycle. This triad represents a potential Achilles’ heel within the hyper-variable NTD, offering a stable target for therapeutic or vaccinal interventions to disrupt the conformational wave and prevent infection. These possibilities are discussed. Full article

The present study was carried out to analyze the complete genome sequences of infectious bursal disease virus (IBDV) isolates obtained from field outbreaks in the southern regions of India. Bursal tissue samples were collected and screened by RT-PCR, targeting the VP2 gene. Positive samples were subjected to serological identification via AGID. Following this, eight samples (BGE14, BGE15, MDI14, THI14, EDE14, RPM14, VCN14, and NKL14) were subjected to virus isolation in 9 to 11-day-old embryonated chicken eggs, and their complete genomes were sequenced. Analysis of the VP2 hypervariable region (HVR) revealed that all eight isolates had five unique and highly conserved amino acids (A222, I242, Q249, I256, and S299). However, all the isolates reveal a substitution of Isoleucine by Valine at residue 294 (I294V). Furthermore, analysis of segment B from all Indian IBDV sequences revealed that the triplet amino acid pattern was NEG (residues 145–147) and the amino acid at position 242 was consistently D across all isolates. These findings suggest that segment B of the isolates in this study resembled that of vaccine strains and non-vvIBDV strains. Additionally, the presence of the signature D242 in all Indian isolates, characteristic of non-vvIBDV strains, implies a potential attenuation. Moreover, in the phylogenetic analysis of VP2-HVR, all isolates clustered with very virulent reference strains, while segment B clustered with classical attenuated strains. Notably, the phylogenetic analysis of VP2-HVR and VP1 of these viruses demonstrated genetic variances, suggesting evolutionary changes in segment B across all eight Indian isolates, likely indicative of natural genome reassortment resulting in these specific outbreaks in the flocks. Full article

Background/Objectives: Human Respiratory Syncytial Virus (HRSV) is a major global cause of acute lower respiratory infections in children. With recent approval of pre-fusion F protein-based vaccines and monoclonal antibodies, ongoing molecular surveillance is critical. This study examined HRSV molecular epidemiology and evolution in Riyadh, focusing on mutations in the attachment (G) and fusion (F) glycoproteins and their potential impact on vaccine efficacy. Methods: Nasopharyngeal aspirates (NPAs) (200 samples) were collected from pediatric patients. HRSV-positive samples were typed, and the G gene hypervariable region and F gene were sequenced. Sequence and phylogenetic analyses were performed to identify circulating genotypes and amino acid substitutions. Results: HRSV was detected in 15% of samples, with HRSV-B slightly predominant over HRSV-A. Infants aged 2–5 months had the highest incidence rate of infection. The ON1 subgenotype remained dominant. The duplicated region of the G gene showed constrained evolution, with 18 variable and 6 conserved residues over 13 years. In the F protein, HRSV-A isolates exhibited high conservation, with only three amino acid substitutions in antigenic sites (Ø and II). Sites III, IV, and V remained fully conserved. In contrast, HRSV-B isolates displayed eight substitutions in antigenic sites, including six in site II (palivizumab-binding epitope). Conclusions: Given the highly effective HRSV prophylactics, including the approved vaccines and monoclonal antibodies, these mutations raise critical concerns regarding vaccine efficacy against HRSV-B. These findings underscore the necessity of sustained, seasonal molecular surveillance to monitor the emergence of variants and provide a molecular basis for further clinical studies. Full article

In order to clarify the changes and correlations among microbial community structure and soil environmental factors in the rhizosphere soil of peppers under healthy and diseased conditions, Illumina MiSeq technology was used to perform high-throughput sequencing of the V3-V4 region of the bacterial 16S rRNA gene and the ITS hypervariable region of fungi in the rhizosphere soil of peppers. The dominant species and key environmental factors affecting the occurrence of pepper Phytophthora blight were analyzed and screened, and the functions of bacteria and fungi in the samples were predicted by PICRUSt2 and FUNGuild. The results showed that except for soil pH, the contents of microbial biomass carbon, magnesium, zinc, and iron in the rhizosphere soil of healthy peppers were significantly higher than those in the diseased soil. Alpha diversity analysis showed that the diversity index of the bacterial community in healthy soil was higher than that in diseased soil, while the diversity index of the fungal community was significantly lower than that in diseased soil. The relative abundance of beneficial bacteria such as Proteobacteria, Actinobacteriota, Burkholderiales, and Rhodanobacteraceae in the rhizosphere soil of healthy peppers was higher. Pathogens such as Penicillium and Fusarium were significantly enriched in the rhizosphere soil of diseased pepper plants. The functional prediction results showed that soil bacteria were mainly metabolized, including the biosynthesis of ansamycin, the biosynthesis of vancomycin antibiotics, the biosynthesis of valine, leucine, and isoleucine, the metabolism of C5-branched dicarboxylic acid, and the biosynthesis of fatty acids. The main nutritional strategies of the fungal community are disease prototype and saprophytic. Combined with the key environmental factors, microbial composition, and correlation analysis of pepper rhizosphere soil, it is speculated that the occurrence of pepper Phytophthora blight may be related to the synergistic effect of soil nutrients and microbial flora, which provides a theoretical basis for the biological control of pepper Phytophthora blight in the future. Full article

Forage scarcity in semi-arid regions necessitates the identification of optimal sorghum cultivars for high-quality silage production. This study systematically evaluated varietal differences in agronomic characteristics, nutritive value, fermentation quality, and bacterial community structure of whole-plant sorghum silage. A completely randomized design was implemented with four sorghum cultivars representative of semi-arid northwestern China: Liaotian1 (LT1), Jinnuo3 (JN3), Jinza2001 (JZ2001), and Jinza1531 (JZ1531). Five quadrats per cultivar in experimental fields were randomly designated as biological replicates for silage production. The plants were harvested at the dough stage, chopped, and ensiled in laboratory-scale silos (n = 20, 4 cultivars × 5 replicates) for 120 days. Analyses included agronomic measurements, chemical composition, fermentation parameters, microbial plate enumeration, and bacterial community profiling via 16S rRNA gene amplicon sequencing of the V3–V4 hypervariable region. The results showed that cultivar significantly influenced (p < 0.01) all agronomic traits and most nutritional parameters. The forage-type cultivar LT1 showed the highest biomass yield but the lowest nutritional quality, with higher neutral detergent fiber (47.77% vs. 29.21–32.35%; p < 0.05) and lower starch (10.94% vs. 18.10–24.30%; p < 0.05) contents as well as higher dry matter losses (1.39% vs. 0.91–1.23%; p < 0.05) than grain-type cultivars. In contrast, the grain-type cultivar JN3 exhibited balanced yield-quality traits with the highest (p < 0.05) starch (24.30%) and crude protein (7.50%) contents. Most fermentation parameters differed significantly (p < 0.01) among cultivars, with JN3 showing elevated ammonia-nitrogen (0.24 g/kg) but within acceptable ranges. Microbial diversity analysis revealed cultivar-driven differences in bacterial communities, with JN3 enriched in Leuconostoc and early-colonizing taxa (p < 0.05 and LDA Score > 4). It is concluded that the grain-type cultivar JN3 is the most suitable cultivar for whole-plant sorghum silage production in water-limited regions due to its optimal yield-quality balance. The findings underscore the importance of integrated cultivar evaluation and suggest the potential of targeted microbial inoculants for enhancing silage quality. Full article

Sapindus mukorrosi (Sm) seeds have been used in Chinese medicine for treating gingival disease, suggesting that Sm may modulate oral bacteria and alleviate gingival inflammation. However, the hydrophobicity of seed oil limits its use in the aqueous oral environment. Therefore, the artificial saliva-infused Sm seed aqueous extract (SMa) was developed and applied to our ex vivo model to test its anti-bacterial effect. Unstimulated whole saliva from seven patients with Stage III/IV, Grade C periodontitis was cultured for 8 h with or without SMa. The bacterial count was measured based on the optical density and bacterial DNA concentration. The salivary microbiome was sequenced via next-generation sequencing over the 16S rRNA gene V3-V4 hypervariable regions. The bacterial DNA concentration in the SMa group was significantly lower than the Without-SMa group after 6 to 8 h of culture. No significant difference in alpha and beta diversity was observed between the two groups. The relative abundance of Porphyromonas was reduced, while that of Veillonella was elevated in the SMa group compared to the Without-SMa group. The findings indicated that the antibacterial effects of SMa are manifested primarily through bacterial growth inhibition, with the minor modulation of specific taxa. Full article

Increased seawater temperatures and nutrient loading are stressors that affect coral reefs and their microbiomes. In this study, filamentous algae were collected and exposed to different temperatures and nutrient concentrations through a laboratory experiment. Microbial DNA was extracted and analyzed using amplicon sequencing of the V3-V4 hypervariable region of the 16S rRNA gene. In total, 1 domain, 51 phyla, 131 classes, 335 orders, 549 families, and 1905 species were identified. Proteobacteria and Bacteroidota were the dominant taxa reported. Elevated seawater temperatures and nutrient enrichment impacted microbial communities associated with turf algae under laboratory culture. Bacterial species diversity and abundance differed under different temperature and nutrient conditions. Proteobacteria and Actinobacteria were abundant in lower-temperature conditions, while Desulfobacterota, Spirochaetota, and Firmicutes were abundant in higher-temperature conditions. Ruegeria was abundant in low-temperature conditions, whereas Vibrio abundance was low. Regarding nutrient conditions, Proteobacteria and Cyanobacteria were abundant under high-nutrient conditions, while Firmicutes and Desulfobacterota were abundant under ambient-nutrient conditions. The higher nutrient concentration increased the abundance of pathogenic bacteria, such as Vibrio and Photobacterium, while Pseudoalteromonas, which is beneficial for reefs, was present under ambient nutrient conditions. This study demonstrates that temperature and nutrient enrichment can shape microbial communities under laboratory conditions, providing an experimental setting for further studies of bacterial functions and metabolic processes in natural conditions under thermal and nutrient stresses. Full article

Objectives: The aim of this study is to assess the influence of diabetes mellitus on the microbial flora involved in root canal infections through a comparative analysis with that of systemically healthy individuals. Methods: A total of 39 participants, including 21 patients with diabetes mellitus and 18 systemically healthy individuals (controls), were enrolled in the study. In the diabetic group, 12 teeth were diagnosed with secondary/persistent endodontic infections (SEIs) and 9 with primary endodontic infections (PEIs). In the healthy group, 12 teeth presented with SEIs and 6 with PEIs. Root canal samples were obtained using sterile paper points. The V3–V4 hypervariable regions of 16S rDNA from both sample types were amplified and sequenced using the Illumina MiSeq platform. Microbial richness and diversity were assessed using alpha diversity indices and beta diversity metrics. Results: Faith’s Phylogenetic Diversity showed a significant difference between diabetic patients with SEIs and healthy individuals with PEIs (p = 0.02). Both weighted and unweighted UniFrac beta diversity analyses indicated significant differences in microbial composition and phylogenetic structure between diabetic patients with SEIs and healthy individuals with PEIs (p = 0.01 and p = 0.02, respectively). Within the diabetic patient group, significant differences were observed between SEI and PEI groups based on alpha (Fisher’s alpha, p = 0.04) and beta diversity analyses (Bray–Curtis and Weighted UniFrac p = 0.02 and p = 0.01, respectively). Conclusions: Diabetic patients showed different microbial profiles compared to healthy individuals. Full article

Background/Objectives: The effects of geographical origin, alongside age, diet, and drug treatments, on the gut microbiota have not been thoroughly analyzed in African countries. Furthermore, eukaryotic components, including Blastocystis, the most common intestinal protozoan worldwide, require further investigation. This study compares the gut microbiota of Italian subjects with that of two African groups to examine the influence of dietary patterns and the effects of Blastocystis presence and subtypes. Methods: Three cohorts of healthy subjects (Italians residing in Rome, Africans residing in the Côte d’Ivoire, and Africans living in Italy) were compared by sequencing the V3-V4 hypervariable regions of the 16S rDNA gene. Taxa abundance and associations with typical West African and Italian foods were determined using DESeq2. Co-abundant genera were identified with a weighted correlation network analysis (WGCNA). Blastocystis subtypes were determined and correlated with the microbial composition in the three groups. Results: Distinct microbial taxa were associated with specific foods, including palm oil, Cube Maggi, sunflower oil, and olive oil. A Mediterranean diet consumed for over two years did not alter the abundance of Faecalibacterium and Dorea in the Africans living in Italy compared with Africans living in Côte d’Ivoire, whereas differences were observed in the abundance of some Prevotella-9, Bacteroides, and Lachnospiraceae OTUs. Significant associations were identified between palm oil and Subdoligranulum, Cube Maggi and Dorea, sunflower oil and the Ruminococcus torques group, and olive oil and Faecalibacterium. Concerning Blastocystis, alpha and beta diversity analysis showed a significant separation between carriers and non-carriers. Conclusions: This study provides the first comparative analysis of gut microbiota composition between individuals from Côte d’Ivoire and Italians focusing on the influence of distinct dietary patterns. Full article

16S rRNA next-generation sequencing (NGS) has significantly advanced cervicovaginal microbiome profiling, offering insights into the relationship between vaginal dysbiosis and HPV-associated carcinogenesis. However, reliance on a limited set of 16S hypervariable regions introduces inherent biases that impact results. This study developed standardized workflows for 16S/ITS NGS, with a focus on identifying methodological biases that influence microbial abundance and taxonomic specificity. Commercial NGS tools were employed, including the 16S/ITS QIAseq V1–V9 screening panel, ATCC vaginal microbial standard, and CLC Genomics Workbench integrated with a customized database (VAGIBIOTA) for analysis. The microbial communities of 66 cervical cytology samples were characterized. Among the regions tested, V3V4 exhibited the least quantitative bias, while V1V2 offered the highest specificity. Microbial profiles and Community State Types (CST) (I–V) were broadly consistent with prior studies, with Lactobacillus abundance clustering into three states: L.-dominant (CST I–III, V), L.-diminished (CST IV-A), and L.-depleted (CST IV-B). Differential abundance analysis revealed that anaerobic opportunistic pathogens dominant in CST IV-B (dysbiosis) were also enriched in HSIL and HPV-16 positive samples. Our findings revealed distinct differences in species identification across 16S rRNA hypervariable regions, emphasizing the importance of region selection in clarifying microbial contributions to HPV-associated carcinogenesis. Full article

The purpose of this work was to obtain specialized enrichment cultures from an original extreme acidophilic consortium of extremely acidophilic microorganisms and to study their microbial community composition and biotechnological potential. At temperatures of 25, 35, 40 and 50 °C, distinct enrichments of extremely acidophilic microorganisms used in the processes of bioleaching sulfide ores were obtained using nutrient media containing ferrous sulfate, elemental sulfur and a copper sulfide concentrate as nutrient inorganic substrates, with and without the addition of 0.02% yeast extract. The microbial community composition was studied using the sequencing of the V3–V4 hypervariable region of the 16S rRNA genes. The different growth conditions led to changes in the microbial composition and relative abundance of mesophilic and moderately thermophilic, strict autotrophic and mixotrophic microorganisms in members of the genera Acidithiobacillus, Sulfobacillus, Leptospirillum, Acidibacillus, Ferroplasma and Cuniculiplasma. The dynamics of the oxidation of ferrous iron, sulfur, and sulfide minerals (pyrite and chalcopyrite) by the enrichments was also studied in the temperature range of 25 to 50 °C. The study of enrichment cultures using the molecular biological method using the metabarcoding method of variable V3–24 V4 fragments of 16S rRNA genes showed that enrichment cultures obtained under different conditions differed in composition, which can be explained by differences in the physiological properties of the identified microorganisms. Regarding the dynamics of the oxidation of ferrous ions, sulfur, and sulfide minerals (pyrite and chalcopyrite), each enrichment culture was studied at a temperature range of 25 to 50 °C and indicated that all obtained enrichments were capable of oxidizing ferrous iron, sulfur and minerals at different rates. The obtained enrichment cultures may be used in further work to increase bioleaching by using the suitable inoculum for the temperature and process conditions. Full article

The long-term monocropping of red kidney beans in agricultural fields can lead to the occurrence of soil-borne diseases. Alterations in the composition of the soil microbial community are a primary cause of soil-borne diseases and a key factor in continuous cropping obstacles. Research exploring how different cultivation modes can modify the diversity and composition of the rhizosphere microbial community in red kidney beans, and thus mitigate the effects of continuous cropping obstacles, is ongoing. This study employed three cultivation modes: the continuous monocropping of red kidney beans, continuous monocropping of soybeans, and red kidney bean–soybean intercropping. To elucidate the composition and diversity of rhizosphere microbial communities, we conducted amplicon sequencing targeting the V3-V4 hypervariable regions of the bacterial 16S rRNA gene and the ITS1 region of fungal ribosomal DNA across distinct growth stages. The obtained sequencing data provide a robust basis for estimating soil microbial diversity. We observed that, under the intercropping mode, the composition of both bacteria and fungi more closely resembled that of soybean monocropping. The monocropping of red kidney beans increased the richness of rhizosphere bacteria and fungi and promoted the accumulation of pathogenic microorganisms. In contrast, intercropping cultivation and soybean monocropping favored the accumulation of beneficial bacteria such as Bacillus and Streptomyce, reduced pathogenic fungi including Alternaria and Mortierell, and exhibited less microbial variation across different growth stages. Compared to the monocropping of red kidney beans, these systems demonstrated more stable microbial structure and composition. The findings of this study will inform sustainable agricultural practices and soil management strategies. Full article

Beta-thalassemia major is an inherited disorder that requires lifelong blood transfusions, with the risk of complications including poor oral health and dental caries. The objective of this study was to compare the oral microbiome diversity and composition in transfusion-dependent thalassemia patients and relate it to oral hygiene and dental caries. A cross-sectional analysis of 35 patients of beta-thalassemia major aged 6–18 years was performed. The status of oral hygiene was examined through the Oral Hygiene Index—Simplified (OHI-S) and Decayed, Missing, and Filled Teeth (DMFT) index. Saliva was taken for DNA extraction, followed by the 16S rRNA sequencing of V3-V4 hypervariable regions. The bioinformatics pipeline in QIIME2 was utilized for analyzing the comparison of microbial composition and diversity in groups of varying oral hygiene status and severity of caries. Metagenomic analysis revealed 3334 Amplicon Sequence Variants (ASVs), of which the most prevalent genera were Streptococcus, Haemophilus, Veillonella, Rothia, and Prevotella. High-oral-hygiene groups presented increased levels of cariogenic bacteria, while moderate-oral-hygiene groups presented an equilibrated microbiome. No statistically significant differences in microbial diversity were found between the study groups (p > 0.05). This study sheds light on the critical importance of oral hygiene in microbiome diversity in patients with beta-thalassemia major. Full article

In Mexico, hospital wastewater (HWW) is a source of chemical and microbiological contamination, and it is released into the municipal sewage system without prior treatment. This water may contain pathogenic bacteria and antimicrobial resistance genes, which represent a risk to Public Health and the environment. So far, there are no studies that analyse this problem comprehensively, relating bacterial population structures, chemical contaminants, and seasonality. The aim of this work was to seasonally characterise the bacterial communities of HWW, including clinically relevant bacteria and resistance genes in Hospital Juárez de México (HJM), and to evaluate the impact of physicochemical factors on their composition. A one-year observational, cross-sectional study was conducted at five HWW discharge points of HJM. Fourteen physicochemical parameters were determined by using standard methodologies, and statistical differences between discharges and seasons were evaluated. Bacterial communities were analysed by targeted amplicon sequencing of the V3-V4 region of the 16S rRNA gene. In addition, the presence of eight antimicrobial resistance genes of local epidemiological importance was assessed. Data were analysed using alpha and beta diversity indices, principal component analysis, and multivariate statistical tests. HWW showed high taxonomic diversity, with Proteobacteria, Firmicutes, and Bacteroidetes standing out. Clinically relevant bacteria were identified in 73.3% of the analyses, with Enterobacter and Escherichia-Shigella predominating. Total and dissolved solids, temperature, nitrate, and pH significantly influenced the bacterial composition of HWW. Seven out of the eight genes evaluated were identified, with bla_KPC, bla_OXA-40, and mcr-1 being the most frequent, showing significant seasonal differences. This study underlines the microbiological and chemical complexity of HWW, highlighting the impact of clinically relevant bacteria and antimicrobial resistance genes on Public Health. The findings emphasise the need to implement hospital waste management programmes and ideally specific treatment plants to minimise the associated risks and protect the environment and human health. Full article

Background/Objectives: The evidence regarding the efficacy of probiotics in chronic rhinosinusitis (CRS) is very limited, prompting the EPOS2020 steering group to advise against their use in CRS treatment. Therefore, further research to evaluate the impact of probiotics on microbial communities is particularly important. This study aimed to assess the influence of probiotic nasal rinses on nasal microbiota profiles in patients with primary CRS, granulomatosis with polyangiitis (GPA), and nasal septal perforation (NSP) using 16S rRNA sequencing. Methods: Thirty-six patients with nasal mucosal diseases, including sixteen with primary CRS, eleven with GPA, and nine with NSP, were randomly assigned to either a study group receiving nasal rinses with probiotics containing Lactobacillus plantarum and Bifidobacterium animalis, or a control group using nasal rinses with saline. Metagenomic analysis targeting the V3–V4 hypervariable region of the 16S rRNA gene was performed to characterize bacterial and archaeal populations. Results: At the genus level, the most abundant co-colonizers included Staphylococcus, Streptococcus, and Haemophilus. After one month of probiotic rinsing, a decrease in abundance of the genera Finegoldia (p = 0.010), Haemophilus (p = 0.020), Streptococcus (p = 0.027), Staphylococcus (p = 0.033), Micrococcus (p = 0.035), Corynebacterium (p = 0.049), Gemella (p = 0.055), Rubrobacter (p = 0.055), and Pseudonocardia (p = 0.058) was observed. Conversely, the abundance of probiotic species Lactobacillus plantarum and Bifidobacterium animalis increased. Moreover, increases in the genera Dolosigranulum and Stenotrophomonas were observed, although they did not reach statistical significance. Conclusions: Probiotic nasal rinses may contribute to restoring microbial homeostasis by reducing genera associated with inflammatory dysbiosis in nasal inflammatory diseases, warranting further research on their clinical benefits. Full article