Berberine, a Natural Compound That Demonstrates Antiviral Effects Against Ostreid Herpesvirus 1 Infection in Anadara broughtonii

Ostreid herpesvirus 1 (OsHV-1) infection is the primary viral disease responsible for large-scale mortality in bivalve mollusks worldwide, and effective strategies to control the outbreaks of this disease are still lacking. Berberine (BBR), a plant-derived alkaloid, has demonstrated antiviral activity against various vertebrate viruses, while its potential antiviral effects on molluscan herpesviruses remain to be fully elucidated. Therefore, the present study sought to investigate the potential of berberine hydrochloride (BBH) against OsHV-1 infection in blood clams (<i>Anadara broughtonii</i>). The most optimal BBH concentration was figured out according to virus replication and mortality rates during in vivo experimental infection. Quantitative PCR and reverse transcription quantitative PCR were utilized to monitor the OsHV-1 genomic copy numbers and viral gene transcription levels during the development of OsHV-1 infection in the BBH-treated and control groups. The results demonstrated that a 3 mg/L BBH bath immersion significantly suppressed OsHV-1 replication in blood clams. During the early stage of infection (24 h), BBH treatment significantly reduced the expression of OsHV-1 open reading frames (ORFs) related to early enzymes, putative membrane proteins, and nucleocapsid proteins. At 96 h post-infection, all untreated blood clams died, whereas the survival rate of BBH-treated individuals increased to 46.67%. This study provides preliminary evidence for the inhibitory effects of BBH on OsHV-1, paving the way for the development of pharmacological control technologies for OsHV-1 infections.