Antiviral activity of berbamine dihydrochloride against Chikungunya virus

Arboviruses are viruses transmitted by the bite of haematophagous arthropods, with Aedes mosquitoes as the primary vectors. Among the ∼500 known arboviruses, chikungunya virus (CHIKV) is a major human pathogen responsible for Chikungunya fever. Currently, no approved treatment exists for CHIKV infection. This study aimed to evaluate the antiviral potential of berbamine (BBM) against CHIKV and its effect on the viral replication cycle. BHK-21 and Huh-7 cells were infected with CHIKV-CMV-NLuc, a viral construct containing a nanoluciferase reporter gene. Dose-dependent antiviral, time-of-addition, and virucidal assays were performed, as well as Western blotting to analyze the compound in relation to viral proteins. The maximum non-toxic concentration (MNTC) of BBM was 6.25 μM in BHK-21 cells and 12.5 μM in Huh-7 cells. At these concentrations, BBM reduced the replication of recombinant CHIKV harbouring a nanoluciferase reporter by 77.3% in BHK-21 cells and 94.6% in Huh7.0 cells. A time-of-addition assay demonstrated that BBM significantly inhibited both CHIKV entry and post-entry steps in both cell lines. Additionally, BBM exhibited a strong virucidal effect. Western blot analysis showed a marked reduction in viral nsP2 and nsP3 protein levels upon BBM treatment, while capsid protein levels remained unchanged. These findings highlight BBM as a promising antiviral candidate against CHIKV, warranting further investigation.