Transcriptome Analysis of Plectropomus leopardus Erythrocytes Reveals Transcriptional Immune Suppression Induced by Vibrio harveyi Infection

Unlike mammalian erythrocytes, teleost erythrocytes are nucleated and transcriptionally active, yet their immune functions remain not fully understood. The leopard coral grouper (Plectropomus leopardus) is an economically important marine fish and is highly susceptible to Vibrio harveyi infection. In this study, we aim to investigate the immune role of erythrocytes during V. harveyi infection. Flow cytometry analysis showed that erythrocytes actively internalize V. harveyi in a dose-dependent manner. Transcriptome profiling of erythrocytes from control and V. harveyi-infected groups was performed to reveal the host immune responses after bacterial internalization. A total of 5995 differentially expressed genes (DEGs) were identified and significantly enriched in immune-related pathways, with the MAPK signaling pathway, apoptosis, and NF-κB signaling pathway as the three core pathways. Heatmap analysis further revealed transcriptional downregulation of MAPK kinases, apoptotic components, and cytokines (interleukins, chemokines, TNFs, and interferons). These findings provide transcriptional evidence for the immune involvement of teleost erythrocytes and offer insights into host–pathogen interactions during V. harveyi infection.