White spot syndrome virus (WSSV) is a fatal pathogen threatening global crustacean industry with no commercially available drugs to control WSSV. To address the urgent need for finding effective antiviral agents against WSSV, we examined the anti-WSSV activities of 11 common antiviral agents in crayfish Procambarus clarkia. The results showed that acyclovir displayed the highest inhibition on WSSV replication in vivo (92.59%, 50 mg/kg). Acyclovir repressed WSSV proliferation followed a dose-dependent fashion and pre- or post-treatment of acyclovir exerted strong inhibition on the viral loads. Further, we observed a markedly reduced expression levels of WSSV genes (immediate-early IE gene ie1, DNA polymerase gene DNApol and envelope protein gene Vp28) that are crucial in viral life cycle with the acyclovir treatment during the early infection. Meantime, we also found a significantly increased expressions of anti-oxidative as well as apoptosis related genes, suggesting that acyclovir could effectively suppress WSSV replication in vivo. Finally, acyclovir treatment could significantly improve the survival rate of WSSV-challenged crayfish by 56%. Taken together, acyclovir has the potential to be developed as a promising preventive or therapeutic agent against WSSV infection, and this finding may provide a reference for rapid discovery anti-WSSV agent in crustacean aquaculture.

白斑综合征病毒 (WSSV) 是一种致命的病原体，威胁着全球甲壳类动物产业，目前还没有商业上可用的药物来控制 WSSV。为了解决寻找针对 WSSV 的有效抗病毒药物的迫切需求，我们检测了小龙虾Procambarus clarkia中 11 种常见抗病毒药物的抗 WSSV 活性。结果表明，阿昔洛韦在体内对WSSV复制的抑制作用最高（92.59%，50 mg/kg）。阿昔洛韦抑制 WSSV 增殖遵循剂量依赖性方式，阿昔洛韦治疗前或治疗后对病毒载量产生强烈抑制作用。此外，我们观察到 WSSV 基因（即早 IE 基因ie1、DNA 聚合酶基因DNApol和包膜蛋白基因Vp28）在早期感染期间用阿昔洛韦治疗对病毒生命周期至关重要。同时，我们还发现抗氧化和凋亡相关基因的表达显着增加，表明阿昔洛韦可以有效抑制体内WSSV复制。最后，阿昔洛韦治疗可以显着提高 WSSV 攻击小龙虾的存活率 56%。综上所述，阿昔洛韦有可能被开发为一种很有前景的预防或治疗 WSSV 感染的药物，这一发现可为甲壳类水产养殖中快速发现抗 WSSV 药物提供参考。