Robust Lys63-Linked Ubiquitination of RIG-I Promotes Cytokine Eruption in Early Influenza B Virus Infection.
Influenza A and B virus infections both cause a host innate immunity response. Here, we report that the robust production of type I and III interferons (IFNs), IFN-stimulated genes, and proinflammatory factors can be induced by influenza B virus rather than influenza A virus infection in alveolar epithelial (A549) cells during early infection. This response is mainly dependent on the retinoic acid-inducible gene I (RIG-I)-mediated signaling pathway. Infection by influenza B virus promotes intense Lys63-linked ubiquitination of RIG-I, resulting in cytokine eruption. It is known that the influenza A virus NS1 protein (NS1-A) interacts with RIG-I and TRIM25 to suppress the activation of RIG-I-mediated signaling. However, the present results indicate that the influenza B virus NS1 protein (NS1-B) is unable to interact with RIG-I but engages in the formation of a RIG-I/TRIM25/NS1-B ternary complex. Furthermore, we demonstrate that the N-terminal RNA-binding domain (RBD) of NS1-B is responsible for interaction with TRIM25 and that this interaction blocks the inhibitory effect of the NS1-B C-terminal effector domain (TED) on RIG-I ubiquitination. Our findings reveal a novel mechanism for the host cytokine response to influenza B virus infection through regulatory interplay between host and viral proteins.



Influenza B virus generally causes local mild epidemics but is occasionally lethal to individuals. Existing studies describe the broad characteristics of influenza B virus epidemiology and pathology. However, to develop better prevention and treatments for the disease, determining the concrete molecular mechanisms of pathogenesis becomes pivotal to understand how the host reacts to the challenge of influenza B virus. Thus, we aimed to characterize the host innate immune response to influenza B virus infection. Here, we show that vigorous Lys63-linked ubiquitination of RIG-I and cytokine eruption dependent on RIG-I-mediated signal transduction are induced by virus infection. Additionally, TRIM25 positively regulates RIG-I-mediated signaling by ablating the inhibitory function of NS1-B on RIG-I ubiquitination.
School of Life Sciences, University of Science and Technology of China, Hefei, China.|CAS Key Laboratory of Pathogenic Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China.
Jingwen
J
Jiang
CAS Key Laboratory of Pathogenic Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China liuwj@im.ac.cn lj418@163.com.
Jing
J
Li
CAS Key Laboratory of Pathogenic Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China.
Wenhui
W
Fan
CAS Key Laboratory of Pathogenic Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China.
Weinan
W
Zheng
CAS Key Laboratory of Pathogenic Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China.
Meng
M
Yu
CAS Key Laboratory of Pathogenic Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China.
Can
C
Chen
CAS Key Laboratory of Pathogenic Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China.
Lei
L
Sun
CAS Key Laboratory of Pathogenic Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China.
Yuhai
Y
Bi
Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Shanghai, China.
Chan
C
Ding
School of Life Sciences, University of Science and Technology of China, Hefei, China.|CAS Key Laboratory of Pathogenic Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China.|University of Chinese Academy of Sciences, Beijing, China.
George F
GF
Gao
School of Life Sciences, University of Science and Technology of China, Hefei, China liuwj@im.ac.cn lj418@163.com.|CAS Key Laboratory of Pathogenic Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China.|University of Chinese Academy of Sciences, Beijing, China.
Wenjun
W
Liu
D000072283:A549 Cells; D016207:Cytokines / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D007113:Immunity, Innate / Q000276:immunology; D018836:Inflammation Mediators / Q000378:metabolism; D009980:Influenza A virus / Q000472:pathogenicity*; D009981:Influenza B virus / Q000472:pathogenicity*; D007251:Influenza, Human / Q000276:immunology* / Q000378:metabolism / Q000821:virology; D050835:Interferon Regulatory Factors / Q000235:genetics / Q000378:metabolism; D007372:Interferons / Q000235:genetics / Q000378:metabolism; D008239:Lysine / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D016297:Mutagenesis, Site-Directed; D009154:Mutation / Q000235:genetics; D011499:Protein Processing, Post-Translational; D018168:Receptors, Retinoic Acid / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism; D000070584:Tripartite Motif Proteins / Q000235:genetics / Q000378:metabolism; D025801:Ubiquitin / Q000378:metabolism*; D044767:Ubiquitin-Protein Ligases / Q000235:genetics / Q000378:metabolism; D054875:Ubiquitination; D017361:Viral Nonstructural Proteins / Q000235:genetics / Q000378:metabolism
D016207:Cytokines; C085820:INS1 protein, influenza virus; D018836:Inflammation Mediators; D050835:Interferon Regulatory Factors; C437968:PLAAT4 protein, human; D018168:Receptors, Retinoic Acid; D014157:Transcription Factors; D000070584:Tripartite Motif Proteins; D025801:Ubiquitin; D017361:Viral Nonstructural Proteins; D007372:Interferons; C084523:TRIM25 protein, human; D044767:Ubiquitin-Protein Ligases; D008239:Lysine