Viral diseases cause serious economic loss in farmed animals industry.However,the efficacy of remedies for viral infection in farmed animals is limited,and treatment strategies are generally lacking for aquatic animals.Interactions of commensal microbiota and viral infection have been studied in recent years,demonstrating a third player in the interaction between hosts and viruses.Here,we discuss recent developments in the research of interactions between commensal bacteria and viral infection,including both promotion and inhibition effect of commensal bacteria on viral pathogenesis,as well as the impact of viral infection on commensal microbiota.The antiviral effect of commensal bacteria is mostly achieved through priming or regulation of the host immune responses,involving differential microbial components and host signaling pathways,and gives rise to various antiviral probiotics.Moreover,we summarize studies related to the interaction between commensal bacteria and viral infection in farmed animals,including pigs,chickens,fish and invertebrate species.Further studies in this area will deepen our understanding of antiviral immunity of farmed animals in the context of commensal microbiota,and promote the development of novel strategies for treatment of viral diseases in farmed animals.