title: Differential nucleocytoplasmic shuttling of the nucleoprotein of influenza a viruses and association with host tropism.
abstract: The nucleoprotein (NP) of influenza A virus plays a crucial role in virus replication, infectivity, and host adaptation. As a major component of the viral ribonucleoprotein complexes (vRNP), NP initiates vRNP shuttling between the nucleus and cytoplasm in the host cell. However, the characteristics of the nucleocytoplasmic shuttling of NP from H1N1 influenza A virus still remain unclear. In the present study, the subcellular localization and the related key residues of the H1N1 influenza virus NP were identified and evaluated. The NP of influenza virus A/WSN/33 (H1N1; WSN) displayed a more obvious nuclear accumulation than A/Anhui/1/2013 (H7N9; AH) and A/chicken/Shandong/lx1023/2007 (H9N2; SD). NP residue K4, located in NLS1, and residue F253, located in NES3, from WSN NP are not conserved in H7N9 and H9N2, which instead encode Q4 and I253, respectively. Crucially, these residues are involved in the regulation of NP nucleocytoplasmic shuttling through interactions with CRM1 and importin-α. Moreover, residues at position 253 also play important roles in the replication of the virus, resulting in an increase in vRNP polymerase activity and an alteration of the cell tropism and pathogenicity in mice. The present data revealed a pivotal role of the Q4 and I253 residues of NP from H7N9 in enhancing the cytoplasmic accumulation of NP and vRNP activity compared to the K4 and F253 residues in WSN-NP. In addition, an F253I substitution in the NP of WSN altered the survival ratio of infected mice and the growth curve in infected avian-origin cells (DF-1). The current data indicate that the F253I mutation results in attenuated pathogenicity of the virus in mice and altered cell tropism. The present study demonstrated the dissimilarity in subcellular NP transport processes between H1N1 virus WSN and other influenza A virus strains, as well as uncovered the mechanism responsible for this difference.
authors.affiliation: CAS Key Laboratory of Pathogenic Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China.
authors.forename: Jing
authors.initials: J
authors.lastname: Li
authors.affiliation: CAS Key Laboratory of Pathogenic Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China.
authors.forename: Weinan
authors.initials: W
authors.lastname: Zheng
authors.affiliation: CAS Key Laboratory of Pathogenic Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China.|China Institute of Veterinary Drug Control, Beijing, China.
authors.forename: Lidan
authors.initials: L
authors.lastname: Hou
authors.affiliation: 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.
authors.forename: Can
authors.initials: C
authors.lastname: Chen
authors.affiliation: CAS Key Laboratory of Pathogenic Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China.
authors.forename: Wenhui
authors.initials: W
authors.lastname: Fan
authors.affiliation: CAS Key Laboratory of Pathogenic Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China.
authors.forename: Hongren
authors.initials: H
authors.lastname: Qu
authors.affiliation: CAS Key Laboratory of Pathogenic Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China.|School of Life Sciences, University of Science and Technology of China, Hefei, China.
authors.forename: Jingwen
authors.initials: J
authors.lastname: Jiang
authors.affiliation: Key Laboratory of Zoonosis of Ministry of Agriculture, College of Veterinary Medicine, China Agricultural University, Beijing, China.
authors.forename: Jinhua
authors.initials: J
authors.lastname: Liu
authors.affiliation: 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.|Beijing Institutes of Life Science, Chinese Academy of Sciences, Beijing, China.|Office of Director-General, Chinese Center for Disease Control and Prevention, Beijing, China.
authors.forename: George F
authors.initials: GF
authors.lastname: Gao
authors.affiliation: College of Veterinary Medicine, Nanjing Agricultural University, Nanjing, China.
authors.forename: Jiyong
authors.initials: J
authors.lastname: Zhou
authors.affiliation: 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.
authors.forename: Lei
authors.initials: L
authors.lastname: Sun
authors.affiliation: 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.
authors.forename: Wenjun
authors.initials: W
authors.lastname: Liu
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002467:Cell Nucleus / Q000378:metabolism* / Q000821:virology; D003593:Cytoplasm / Q000378:metabolism* / Q000821:virology; D004285:Dogs; D005260:Female; D057809:HEK293 Cells; D054884:Host-Pathogen Interactions; D006801:Humans; D009980:Influenza A virus / Q000502:physiology*; D007251:Influenza, Human / Q000821:virology*; D061985:Madin Darby Canine Kidney Cells; D008807:Mice, Inbred BALB C; D009698:Nucleoproteins / Q000378:metabolism*; D011485:Protein Binding; D021381:Protein Transport; D014764:Viral Proteins / Q000378:metabolism*; D056189:Viral Tropism; D014779:Virus Replication
chemical_list: D009698:Nucleoproteins; D014764:Viral Proteins
keywords: H1N1 influenza A virus; nucleocytoplasmic shuttling; nucleoprotein; virus replication