We previously showed that each dog with chronic non-invasive sino-nasal aspergillosis (SNA) was infected with a single genotype of Aspergillus fumigatus. Here, we studied the transcriptome of this fungal pathogen and the canine host within the biofilm resulting from the infection. We describe here transcriptomes resulting from natural infections in animal species with A. fumigatus. The host transcriptome showed high expression of IL-8 and alarmins, uncontrolled inflammatory reaction and dysregulation of the Th17 response. The fungal transcriptome showed in particular expression of genes involved in secondary metabolites and nutrient acquisition. Single-nucleotide polymorphism analysis of fungal isolates from the biofilms showed large genetic variability and changes related with adaptation to host environmental factors. This was accompanied with large phenotypic variability in in vitro stress assays, even between isolates from the same canine patient. Our analysis provides insights in genetic and phenotypic variability of Aspergillus fumigatus in biofilms of naturally infected dogs reflecting in-host adaptation. Absence of a Th17 response and dampening of the Th1 response contributes to the formation of a chronic sino-nasal warzone.
Actinobacteriophages of a wide range of genome sizes continue to be isolated and characterized, but only a handful of these have atypically small genomes, defined in this work as genome sizes under 20,000 bp. These small phages are relatively rare and have received minimal study thus far. Small phages have been isolated on Arthrobacter, Gordonia, Rhodococcus, and Microbacterium hosts. A previous study by Pope et al. showed that Gordonia small phages have similar gene products and amino acid sequences. Here, we set out to further examine relationships between small Gordonia phages as well as small phages that infect other hosts. Of the 3222 sequenced phages listed on PhagesDB, we identified 109 distinctly small phages with genome sizes under 20,000 bp. The majority of the small phages were isolated on Arthrobacter or Microbacterium hosts. Using comparative genomics, we searched for patterns of similarity among 34 cluster-representative small phages. Dot plot comparisons showed that there was more amino acid conservation than nucleotide identity amongst small phages. Gene content similarity (GCS) analysis revealed that the temperate Gordonia phages in Cluster CW share significant GCS values (over 35%) with the lytic Arthrobacter phages in Cluster AN, suggesting that some small phages have a considerable degree of genomic similarity with each other. SplitsTree analyses of shared phams (genes with substantial amino acid identity) supported the complexity of clustering criteria in small phages, given shuffling of genes across phages of different clusters and close relationships despite varied cluster membership. We observed this continuum of phage diversity through Rhodococcus the closer similarity of phage RRH1 to phages in Gordonia subcluster CW1 than CW1 is to Gordonia subcluster CW3. Finally, we were able to confirm the presence of conserved phams across not only small Gordonia phages but also within small phages from different clusters and hosts. Studying these genomic trends hidden in small phages allows us to better understand and appreciate the overall diversity of phages.
Bacteriophages exhibit a vast spectrum of relatedness and there is increasing evidence of close genomic relationships independent of host genus. The variability in phage similarity at the nucleotide, amino acid, and gene content levels confounds attempts at quantifying phage relatedness, especially as more novel phages are isolated. This study describes three highly similar novel Arthrobacter globiformis phages–Powerpuff, Lego, and YesChef–which were assigned to Cluster AZ using a nucleotide-based clustering parameter. Phages in Cluster AZ, Microbacterium Cluster EH, and the former Microbacterium singleton Zeta1847 exhibited low nucleotide similarity. However, their gene content similarity was in excess of the recently adopted Microbacterium clustering parameter, which ultimately resulted in the reassignment of Zeta1847 to Cluster EH. This finding further highlights the importance of using multiple metrics to capture phage relatedness. Additionally, Clusters AZ and EH phages encode a shared integrase indicative of a lysogenic life cycle. In the first experimental verification of a Cluster AZ phage’s life cycle, we show that phage Powerpuff is a true temperate phage. It forms stable lysogens that exhibit immunity to superinfection by related phages, despite lacking identifiable repressors typically required for lysogenic maintenance and superinfection immunity. The ability of phage Powerpuff to undergo and maintain lysogeny suggests that other closely related phages may be temperate as well. Our findings provide additional evidence of significant shared phage genomic content spanning multiple actinobacterial host genera and demonstrate the continued need for verification and characterization of life cycles in newly isolated phages.
Bacteriophages exhibit a vast spectrum of relatedness and there is increasing evidence of close genomic relationships independent of host genus. The variability in phage similarity at the nucleotide, amino acid, and gene content levels confounds attempts at quantifying phage relatedness, especially as more novel phages are isolated. This study describes three highly similar novel Arthrobacter globiformis phages–Powerpuff, Lego, and YesChef–which were assigned to Cluster AZ using a nucleotide-based clustering parameter. Phages in Cluster AZ and Microbacterium Cluster EH, as well as the former Microbacterium singleton Zeta1847, exhibited low nucleotide similarity but gene content similarity in excess of the recently adopted Microbacterium clustering parameter, which resulted in the reassignment of Zeta1847 to Cluster EH. Additionally, while Clusters AZ and EH phages lack identifiable repressors or partitioning systems typically required for lysogeny, they encode a shared integrase indicative of a lysogenic life cycle. In the first experimental verification of a Cluster AZ phage’s life cycle, we show that phage Powerpuff is a true temperate phage and forms stable lysogens. Moreover, we provide evidence that Clusters AZ and EH phages exhibit similar genome architectures in addition to their shared integrases, suggesting that these phages may all be temperate and undergo an unknown lysogeny mechanism. Our findings further highlight the importance of using multiple metrics to capture phage relatedness and provide additional evidence of significant shared phage genomic content spanning multiple actinobacterial host genera.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.