AUTHOR=Liu Guoxing , Zhu Chenxi , Gao Xiaojian , Zheng You , Zhu Xinhai , Jiang Hucheng , Wei Wanhong , Jiang Qichen , Zhang Xiaojun 

TITLE=Single-cell transcriptome analysis reveals a cellular immune response in freshwater dark sleeper (Odontobutis potamophila) after infection with Aeromonas veronii

JOURNAL=Frontiers in Physiology

VOLUME=14

YEAR=2023

URL=https://www.frontiersin.org/journals/physiology/articles/10.3389/fphys.2023.1201914

DOI=10.3389/fphys.2023.1201914

ISSN=1664-042X

ABSTRACT=<p>The bacterium <italic>Aeromonas veronii</italic> is a co-pathogenic species that can negatively impact the health of both humans and aquatic animals. In this study, we used single-cell transcriptome analysis (scRNA-seq) to investigate the effects of infection with <italic>A. veronii</italic> on head kidney cells and the regulation of gene expression in the dark sleeper (<italic>Odontobutis potamophila</italic>). scRNA-seq was used to assess the effects of infection with <italic>A. veronii</italic> in <italic>O. potamophila</italic> B cells, endothelial cells, macrophages, and granulocytes, and differential enrichment analysis of gene expression in B cells and granulocytes was performed. The analyses revealed a significant increase in neutrophils and decrease in eosinophils in granulocytes infected with <italic>A. veronii</italic>. Activation of neutrophils enhanced ribosome biogenesis by up-regulating the expression of <italic>RPS12</italic> and <italic>RPL12</italic> to fight against invading pathogens. Crucial pro-inflammatory mediators <italic>IL1B, IGHV1-4</italic>, and the major histocompatibility class II genes <italic>MHC2A</italic> and <italic>MHC2DAB</italic>, which are involved in virulence processes, were upregulated, suggesting that <italic>A. veronii</italic> activates an immune response that presents antigens and activates immunoglobulin receptors in B cells. These cellular immune responses triggered by infection with <italic>A. veronii</italic> enriched the available scRNA-seq data for teleosts, and these results are important for understanding the evolution of cellular immune defense and functional differentiation of head kidney cells.</p>