#Virus-host #interactions on #volcanic #ash from Mount #Etna

 

Abstract

Volcanic ash represents an extreme and dynamic habitat, yet it hosts diverse microbial communities with largely unexplored viral diversity. This study investigated bacterial and viral populations in volcanic ash from Mount Etna (Italy) collected during the eruption, focusing on microbial novelty, activity, and virus-host interactions. Taxonomic profiling revealed that Pseudomonas and Telluria were the dominant bacterial genera, both frequently detected in airborne environments. In contrast, enrichment cultures with volcanic ash were dominated by spore-forming members of the phylum Bacillota, highlighting their resilience under harsh conditions. Metagenomic analysis recovered 19 high-quality metagenome-assembled genomes, including four previously undescribed bacterial species. Replication rate estimates showed that certain taxa were metabolically active, particularly at one sampling site. The presence of Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR) systems with spacers matching viral sequences suggested viral predation pressure on volcanic ash. A total of 1139 viral operational taxonomic units (vOTUs) were identified, of only around half (660 vOTUs) showed similarities to known phages, underscoring the presence of novel viruses. Shared vOTUs across sites revealed the presence of both a core virome and site-specific viral populations. Virus-host predictions indicated frequent interactions with hosts from multiple Gammaproteobacterial genera. Additionally, a 336 kb jumbo phage genome exhibited extensive metabolic capabilities and genetic autonomy. Experimental work identified a unique lytic Bacillus-infecting phage (″Phoenix″) with limited propagation capacity. Furthermore, prophage induction experiments revealed active, morphologically diverse temperate phages across multiple bacterial host strains. Overall, these findings highlight volcanic ash as a reservoir of microbial and viral diversity, shaped by environmental extremes and dynamic ecological interactions.

Competing Interest Statement

The authors have declared no competing interest.

Funder Information Declared

Swedish Research Council, https://ror.org/03zttf063, 2023-03310_VR, 2022-06725

Source: 

Link: https://www.biorxiv.org/content/10.64898/2026.06.17.732739v1?rss=1

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#Phage-induced #protection against lethal #bacterial #reinfection

Significance

In 2021, antimicrobial-resistant bacteria were responsible for 1.14 million deaths and associated with 4.71 million deaths globally. Patients who experience sepsis often face a higher risk of reinfections and hospital readmissions. To combat this crisis, bacteriophages—viruses that infect and kill bacteria—are regaining interest as a potential solution. Here, we show that mice infected with extraintestinal pathogenic Escherichia coli and treated with phage HP3 not only recover from the initial infection but also gain protection against a secondary challenge with the same bacterial strain. The protective effect is dependent on the bacteriolytic action of the phage. These findings shift phages from being solely therapeutic antimicrobials to dual-action immunotherapeutics capable of both clearing and preventing bacterial infections.

Abstract

Bacteriophages, or phages, are viruses that target and infect bacteria. Due to a worldwide rise in antimicrobial resistance (AMR), phages have been proposed as a promising alternative to antibiotics for the treatment of resistant bacterial infections. Up to this point in history, phage use in preclinical animal studies, clinical trials, and emergency-use compassionate care cases has centered around the original observation from 1915 showing phage as lytic agent, and thus a treatment that kills bacteria. Here, we describe an activity associated with phage therapy that extends beyond lytic activity that results in long-term protection against reinfection. This activity is potent, providing almost complete protection against a second lethal infection for animals treated with phage therapy. The activity also reduced infection burden an astounding billion-fold over the control. Reinfection protection requires phage lytic killing of its target bacterium but is independent of additional phage therapy. The effect is not driven by phage alone, lingering phage resistors, or a sublethal inoculum. In vitro phage-lysed bacteria provide partial protection, suggesting a combination of phage-induced lytic activity and immune stimulation by phage treatment is responsible for the effect. These observations imply certain phages may induce host adaptive responses following the lysis of the infecting bacteria. This work suggests phage therapy may contain a dual-action effect, an initial treatment efficacy followed by a long-term protection against reoccurring infection, a therapeutic-vaccination mechanism of action.

Source: Proceedings of the National Academy of Sciences of the United States of America, https://www.pnas.org/doi/abs/10.1073/pnas.2423286122?af=R

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