LMBV-ICP46通过激活cGAS-STING-p53轴抑制病毒复制OA

Largemouth bass virus(LMBV)causes significant economic losses to the Micropterus salmoides aquaculture industry;however,the functions of many ranavirus immediate-early genes remain poorly understood.Cytosolic DNA sensing via the cGAS-STING axis is a key antiviral pathway that can also engage apoptosis to limit DNA virus replication.Defining how LMBV proteins interface with these defenses is important for understanding pathogenesis and control.This study aimed to characterize the immediate-early gene ICP46 of LMBV,determine its temporal expression and subcellular localization,and evaluate whether ICP46 modulates viral replication by regulating host cGAS-STING signaling and apoptosis-related responses in MSSC cells.MSSC cells were infected with LMBV and treated with cycloheximide(CHX)and cytosine arabinoside(Ara)to classify ICP46 as an immediate-early transcript by PCR-based temporal analysis.An EGFP-tagged expression plasmid(pEGFP-ICP46)was constructed to assess intracellular localization by confocal microscopy at different post-transfection times.ICP46 function was examined by(i)ectopic overexpression and(ii)siRNA-mediated knockdown followed by LMBV challenge.Viral replication was quantified by qPCR targeting the major capsid protein gene(MCP)and by viral copy-number calculation.Host responses were evaluated by qPCR of cGAS-STING pathway markers(STING,IRF3)and apoptosis-associated genes(p53,caspase-8,bcl-2,bcl-xL).These results identify LMBV ICP46 as an immediate-early protein that restricts,rather than enhances,viral replication.This contrasts with the reported pro-replication role of ICP46 previously reported in SGIV,highlighting functional diversification among ranavirus homologs.The reciprocal outcomes of overexpression and knockdown support a specific,gene-dependent phenotype.Mechanistically,ICP46 is associated with enhanced cGAS-STING-IRF3 signaling and a shift toward apoptosis,which potentially creates an antiviral cellular environment unfavorable for LMBV propagation.These findings provide novel insights into LMBV-host interactions and highlight ICP46 and its downstream pathways as potential targets for the development of antiviral strategies and rational disease control in largemouth bass aquaculture.