Influenza B virus (IBV) belongs to the Orthomyxoviridae family and generally causes sporadic epidemics but is occasionally deadly to individuals. The current research mainly focuses on clinical and pathological characteristics of IBV. However, to better prevent or treat the disease, one must determine the strategies developed by IBV to invade and disrupt cellular proteins and approach to replicate itself, to suppress antiviral innate immunity, and understand how the host responds to IBV infection. The B/Shanghai/PD114/2018 virus was able to infect alveolar epithelial cells (A549) cells, with good potential for replication. To identify host cellular responses against IBV infection, differentially expressed genes (DEGs) were obtained using RNA sequencing. The GO and KEGG pathway term enrichment analyses with the DEGs were performed, and we found that the DEGs were primary involved in metabolic processes and cellular function, which may be related to the host response, including the innate immune response against the virus. Our transcriptome analysis results demonstrated robust induction of interferon and interferon-stimulated gene expression by IBV in human cells during the early stages of infection, providing a foundation for further studies focused on antiviral drug development and interactions between the virus and host. OPEN ACCESS Citation: Jiao P, Fan W, Cao Y, Zhang H, Tian L, Sun L, et al. (2020) Robust induction of interferon and interferon-stimulated gene expression by influenza B/Yamagata lineage virus infection of A549 cells. PLoS ONE 15(4): e0231039. https://rate is slower compared with influenza A viruses [4]. IBV is a pathogen with very limited host range, and its natural host is mainly humans with fever and cold symptoms. However, seasonal pandemics can break out, such as from the winter of 2017 to the spring of 2018, when the Yamagata lineage strain became the dominant pandemic strain alongside IAV (H1N1 and H3N2) [5].When influenza virus invades a host cell, the innate immune system is activated against the virus. During the infection, viruses are recognized by pattern recognition receptors, the innate response is triggered, and interferons (IFNs) are secreted to limit early viral proliferation [6]. This identification leads to an appropriate antiviral response and to the activation of inflammatory response and adaptive immune responses [7]. While the reasons for the limited host range of IBV remain unclear, one of explanations is that the interaction between IBV and the innate immune system imbues the virus with distinct characteristics, such as the role of ISG15, a typical interferon-induced antiviral gene for the innate immune response [8,9]. Existing studies describe the production of host cytokines, including IFNs, IFN-stimulated genes (ISGs), and proinflammatory cytokines against influenza virus infection, as integral parts of the process of the cellular antiviral response [10][11][12][13]. We have also reported that type I IFNs, ISGs, and proinflammatory cytokines can be induced by IBV viri...