Miro, J. M. | Search bioRxiv

bioRxiv2025

Comparative mortality of dominant Staphylococcus aureus lineages in human bacteremia and animal infection models

Staphylococcus aureus is a major cause of severe infections including infective endocarditis, but lineage-specific virulence determinants remain unclear. We analyzed 77 S. aureus bacteremic isolates from major lineages using phenotypic assays, infection models, and transcriptomics. Our results revealed significant heterogeneity in S. aureus pathogenicity. ST398 isolates exhibited heightened virulence, characterized by increased hemolysin production, whereas CC30 strains showed reduced growth, biofilm formation, and infectivity. Notably, the ST398 agrC mutant Sau7 exhibited unique phenotypic behavior, with high biofilm production and decreased virulence in Galleria mellonella larvae model. Infection studies in the rabbit experimental endocarditis model showed increased vegetation size and bacterial load in Sau7-infected animals, highlighting the role of agr system in S. aureus colonization and biofilm formation. Transcriptomic analysis identified key pathways, including quorum sensing systems and hemolysins, driving virulence in ST398 strains. These findings provide insights into the lineage-specific virulence mechanisms and the multifaceted nature of S. aureus pathogenicity.

microbiology↗

bioRxiv2021

Gut Microbiome Signatures Linked to HIV-1 Reservoir Size and Viremia Control

BackgroundThe potential role of the gut microbiome as a predictor of immune-mediated HIV-1 control in the absence of antiretroviral therapy (ART) is still unknown. In the BCN02 clinical trial, which combined the MVA.HIVconsv immunogen with the latency-reversing agent romidepsin in early-ART treated HIV-1 infected individuals, 23% (3/13) of participants showed sustained low-levels of plasma viremia during 32 weeks of a monitored ART pause (MAP). Here, we present a multi-omics analysis to identify compositional and functional gut microbiome patterns associated with HIV-1 control in the BCN02 trial. ResultsViremic controllers during the MAP (controllers) exhibited higher Bacteroidales/Clostridiales ratio and lower microbial gene richness before vaccination and throughout the study intervention when compared to non-controllers. Longitudinal assessment indicated that the gut microbiome of controllers was enriched in pro-inflammatory bacteria and depleted in butyrate-producing bacteria and methanogenic archaea. Functional profiling also showed that metabolic pathways, including methanogenesis and carbohydrate biosynthesis, were significantly decreased in controllers. Fecal metaproteome analyses confirmed that baseline functional differences were mainly driven by Clostridiales. Participants with high baseline Bacteroidales/Clostridiales ratio had increased pre-existing immune activation-related transcripts. The Bacteroidales/Clostridiales ratio as well as host immune-activation signatures inversely correlated with HIV-1 reservoir size. ConclusionsThis proof-of-concept study suggests the Bacteroidales/Clostridiales ratio as a novel gut microbiome signature associated with HIV-1 reservoir size and immune-mediated viral control after ART interruption.

immunology↗