Gut Microbiota-Derived Bacterial Extracellular Vesicles in COVID-19: Their Signature and Immunological Impact

Why clinicians should know about it

• Picked for Microbiology (medical) (paper of the day, 24 July 2026).

Abstract

Gut microbial dysbiosis has been observed in several diseases. Although causal links and direct effects on host cells remain unclear, bacteria-derived extracellular vesicles (BEVs) from the gut microbiota may regulate the host immune response. We examined the impact of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection on the gut microbiome and BEVs release, and the effects of released BEVs on cytokine responses in monocyte-derived cell lines. Fecal samples from 17 patients with coronavirus disease 2019 (COVID-19) and 20 healthy individuals were collected to isolate bacterial and BEV fractions. Parental BEV-releasing bacteria were identified from vesicle-encapsulated bacterial DNA by 16S rRNA gene sequencing. Patients with COVID-19 exhibited altered gut microbiota composition and the profile of bacterial DNA-containing BEVs (dcBEVs) release compared to healthy controls. BEVs from patients, but not from healthy individuals, significantly changed cytokine levels in U937 monocyte cells. Following COVID-19 recovery, dcBEV profiles diverged into two distinct groups: those that retained the capacity to induce cytokines in monocytes and those that lost this functionality. BEVs from single bacterial cultures within families altered after COVID-19 onset affected the expression of genes in monocytes, primarily immune-response genes, notably chemokine ligands and G protein-coupled receptors. SARS-CoV-2-induced dysbiosis alters the profile of dcBEVs release, thereby modulating the host immune response and potentially contributing to COVID-19 pathogenesis.

Abstract as published, via PubMed.