Novel Drexlerviridae bacteriophage KMI8 with specific lytic activity against Klebsiella michiganensis and its biofilms

Lytic bacteriophage vB_KmiS-Kmi2C disrupts biofilms formed by members of the Klebsiella oxytoca complex, and represents a novel virus family and genus

AIMS

This study aimed to characterize the lytic phage vB_KmiS-Kmi2C, isolated from sewage water on a GES-positive strain of Klebsiella michiganensis.

METHODS AND RESULTS

Comparative phylogenetic and network-based analyses were used to characterize the genome of phage vB_KmiS-Kmi2C (circular genome of 42 234 bp predicted to encode 55 genes), demonstrating it shared little similarity with other known phages. The phage was lytic on clinical strains of K. oxytoca (n = 2) and K. michiganensis (n = 4), and was found to both prevent biofilm formation and disrupt established biofilms produced by these strains.

CONCLUSIONS

We have identified a phage capable of killing clinically relevant members of the K. oxytoca complex (KoC). The phage represents a novel virus family (proposed name Dilsviridae) and genus (proposed name Dilsvirus).

Alterations in the gut virome in patients with ankylosing spondylitis

Introduction

Ankylosing spondylitis (AS), a chronic autoimmune disease, has been linked to the gut bacteriome.

Methods

To investigate the characteristics of the gut virome in AS, we profiled the gut viral community of 193 AS patients and 59 healthy subjects based on a metagenome-wide analysis of fecal metagenomes from two publicly available datasets.

Results

AS patients revealed a significant decrease in gut viral richness and a considerable alteration of the overall viral structure. At the family level, AS patients had an increased abundance of Gratiaviridae and Quimbyviridae and a decreased abundance of Drexlerviridae and Schitoviridae. We identified 1,004 differentially abundant viral operational taxonomic units (vOTUs) between patients and controls, including a higher proportion of AS-enriched Myoviridae viruses and control-enriched Siphoviridae viruses. Moreover, the AS-enriched vOTUs were more likely to infect bacteria such as Flavonifractor, Achromobacter, and Eggerthellaceae, whereas the control-enriched vOTUs were more likely to be Blautia, Ruminococcus, Collinsella, Prevotella, and Faecalibacterium bacteriophages. Additionally, some viral functional orthologs differed significantly in frequency between the AS-enriched and control-enriched vOTUs, suggesting the functional role of these AS-associated viruses. Moreover, we trained classification models based on gut viral signatures to discriminate AS patients from healthy controls, with an optimal area under the receiver operator characteristic curve (AUC) up to 0.936, suggesting the clinical potential of the gut virome for diagnosing AS.

Discussion

This work provides novel insight into the AS gut virome, and the findings may guide future mechanistic and therapeutic studies for other autoimmune diseases.

Expansion of Kuravirus-like Phage Sequences within the Past Decade, including Escherichia Phage YF01 from Japan, Prompt the Creation of Three New Genera

Bacteriophages, viruses that infect bacteria, are currently receiving significant attention amid an ever-growing global antibiotic resistance crisis. In tandem, a surge in the availability and affordability of next-generation and third-generation sequencing technologies has driven the deposition of a wealth of phage sequence data. Here, we have isolated a novel Escherichia phage, YF01, from a municipal wastewater treatment plant in Yokohama, Japan. We demonstrate that the YF01 phage shares a high similarity to a collection of thirty-five Escherichia and Shigella phages found in public databases, six of which have been previously classified into the Kuravirus genus by the International Committee on Taxonomy of Viruses (ICTV). Using modern phylogenetic approaches, we demonstrate that an expansion and reshaping of the current six-membered Kuravirus genus is required to accommodate all thirty-six member phages. Ultimately, we propose the creation of three additional genera, Vellorevirus, Jinjuvirus, and Yesanvirus, which will allow a more organized approach to the addition of future Kuravirus-like phages.

Alterations of the gut virome in patients with systemic lupus erythematosus

Background

Systemic lupus erythematosus (SLE) is a systemic autoimmune disease that has been linked to the dysbiosis of the gut microbiome and virome. However, the potential characterization of the gut virome in SLE patients needs to be explored more extensively.

Methods

Herein, we analyzed the gut viral community of 16 SLE patients and 31 healthy controls using both bulk and virus-like particle (VLP)-based metagenomic sequencing of their fecal samples. A total of 15,999 non-redundant viral operational taxonomic units (vOTUs) were identified from the metagenomic assembled contigs and used for gut virome profiling.

Results

SLE patients exhibited a significant decrease in gut viral diversity in the bulk metagenome dataset, but this change was not significant in the VLP metagenome dataset. Also, considerable alterations of the overall gut virome composition and remarkable changes in the viral family compositions were observed in SLE patients compared with healthy controls, as observed in both two technologies. We identified 408 vOTUs (177 SLE-enriched and 231 control-enriched) with significantly different relative abundances between patients and controls in the bulk virome, and 18 vOTUs (17 SLE-enriched in 1 control-enriched) in the VLP virome. The SLE-enriched vOTUs included numerous Siphoviridae, Microviridae, and crAss-like viruses and were frequently predicted to infect Bacteroides, Parabacteroides, and Ruminococcus_E, while the control-enriched contained numerous members of Siphoviridae and Myoviridae and were predicted to infect Prevotella and Lachnospirales_CAG-274. We explored the correlations between gut viruses and bacteria and found that some Lachnospirales_CAG-274 and Hungatella_A phages may play key roles in the virus-bacterium network. Furthermore, we explored the gut viral signatures for disease discrimination and achieved an area under the receiver operator characteristic curve (AUC) of above 0.95, suggesting the potential of the gut virome in the prediction of SLE.

Conclusion

Our findings demonstrated the alterations in viral diversity and taxonomic composition of the gut virome of SLE patients. Further research into the etiology of SLE and the gut viral community will open up new avenues for treating and preventing SLE and other autoimmune diseases.

Extended genomic analyses of the broad-host-range phages vB_KmiM-2Di and vB_KmiM-4Dii reveal slopekviruses have highly conserved genomes

High levels of antimicrobial resistance among members of the Klebsiella oxytoca complex (KoC) have led to renewed interest in the use of bacteriophage (phage) therapy to tackle infections caused by these bacteria. In this study we characterized two lytic phages, vB_KmiM-2Di and vB_KmiM-4Dii, that were isolated from sewage water against two GES-5-positive Klebsiella michiganensis strains (PS_Koxy2 and PS_Koxy4, respectively). ViPTree analysis showed both phages belonged to the genus Slopekvirus. rpoB gene-based sequence analysis of 108 presumptive K. oxytoca isolates (n=59 clinical, n=49 veterinary) found K. michiganensis to be more prevalent (46 % clinical and 43 % veterinary, respectively) than K. oxytoca (40 % clinical and 6 % veterinary, respectively). Host range analysis against these 108 isolates found both vB_KmiM-2Di and vB_KmiM-4Dii showed broad lytic activity against KoC species. Several hypothetical homing endonuclease genes were encoded within the genomes of both phages, which may contribute to their broad host range. Differences in the tail fibre protein may explain the non-identical host range of the two phages. Pangenome analysis of 24 slopekviruses found that genomes within this genus are highly conserved, with more than 50 % of all predicted coding sequences representing core genes at ≥95 % identity and ≥70 % coverage. Given their broad host ranges, our results suggest vB_KmiM-2Di and vB_KmiM-4Dii represent attractive potential therapeutics. In addition, current recommendations for phage-based pangenome analyses may require revision.

Bacteriophage-Mediated Control of Biofilm: A Promising New Dawn for the Future

Biofilms are complex microbial microcolonies consisting of planktonic and dormant bacteria bound to a surface. The bacterial cells within the biofilm are embedded within the extracellular polymeric substance (EPS) consisting mainly of exopolysaccharides, secreted proteins, lipids, and extracellular DNA. This structural matrix poses a major challenge against common treatment options due to its extensive antibiotic-resistant properties. Because biofilms are so recalcitrant to antibiotics, they pose a unique challenge to patients in a nosocomial setting, mainly linked to lower respiratory, urinary tract, and surgical wound infections as well as the medical devices used during treatment. Another unique property of biofilm is its ability to adhere to both biological and man-made surfaces, allowing growth on human tissues and organs, hospital tools, and medical devices, etc. Based on prior understanding of bacteriophage structure, mechanisms, and its effects on bacteria eradication, leading research has been conducted on the effects of phages and its individual proteins on biofilm and its role in overall biofilm removal while also revealing the obstacles this form of treatment currently have. The expansion in the phage host-species range is one that urges for improvement and is the focus for future studies. This review aims to demonstrate the advantages and challenges of bacteriophage and its components on biofilm removal, as well as potential usage of phage cocktail, combination therapy, and genetically modified phages in a clinical setting.