title: Characterization of a novel mutation in NS1 protein of influenza A virus induced by a chemical substance for the attenuation of pathogenicity.
abstract: It is generally accepted that live attenuated influenza vaccine (LAIV) has the potential for use as a vaccination against flu. In this study, we demonstrated the nature of an influenza A virus (IAV) mutant induced by treating the IAV with a stable furan derivative, (1R,2R)-1-(5'-methylfur-3'-yl)propane-1,2,3-triol (MFPT), which had been isolated from Streptomyces sp. strain FV60 with the objective of it being an LAIV candidate. The resulting MFPT-resistant (MFPTr) IAVs possessed attenuated pathogenicity in vitro and in vivo when compared with that of the parent virus (H1N1 subtype, NWS strain). Sequencing analysis revealed that a novel mutation, C490U in ns gene (P164S in NS1), was detected in all MFPTr virus clones tested. Therefore, NS1 might be a main target of MFPT, and it was suggested that the P164S mutation contributed to the attenuated pathogenicity of the mutants. Although the phosphatidylinositol 3-kinase (PI3K)/Akt signaling pathway is one of the targets of NS1, the MFPTr virus suppressed the phosphorylation of Akt when compared with the wild-type (WT) virus. It was suggested that this might lead to the subsequent inhibition of the cleavage of PARP-1 and caspase-3, which is important for the progression of apoptosis. At the same time, nucleoprotein (NP) was found to be retained in the nuclei in MFPTr virus-infected cells while nuclear export of NP was detected in WT virus-infected cells. In addition, the expression levels of interferon-β transcripts were significantly decreased in MFPTr virus-infected cells. From these results it can be shown that the mutation, NS1P164S, might be one of the key residues to control NS1 function concerning the induction of apoptosis. In conclusion, MFPT induced favorable mutation in the ns gene for the attenuation of IAV, and therefore might provide the novel methodology for preparing LAIVs.
authors: Graduate School of Medicine and Pharmaceutical Sciences for Research, University of Toyama, Toyama, Toyama, 930-0194, Japan.
authors: Kohei
authors: K
authors: Sasaki
authors: Research Institute of Life and Health Sciences, Chubu University, Kasugai, Aichi, 487-8501, Japan.
authors: Kyoko
authors: K
authors: Hayashi
authors: Graduate School of Medicine and Pharmaceutical Sciences for Research, University of Toyama, Toyama, Toyama, 930-0194, Japan.
authors: Jung-Bum
authors: JB
authors: Lee
authors: Graduate School of Medicine and Pharmaceutical Sciences for Research, University of Toyama, Toyama, Toyama, 930-0194, Japan.
authors: Fumiya
authors: F
authors: Kurosaki
authors: Research Institute of Life and Health Sciences, Chubu University, Kasugai, Aichi, 487-8501, Japan.
authors: Toshimitsu
authors: T
authors: Hayashi
mesh_terms: D000818:Animals; D004285:Dogs; D005260:Female; D005663:Furans / Q000737:chemistry / Q000494:pharmacology*; D005990:Glycerol / Q000031:analogs & derivatives* / Q000737:chemistry / Q000494:pharmacology; D006801:Humans; D009980:Influenza A virus / Q000187:drug effects / Q000235:genetics* / Q000254:growth & development / Q000472:pathogenicity*; D016899:Interferon-beta / Q000235:genetics / Q000378:metabolism; D007700:Kinetics; D061985:Madin Darby Canine Kidney Cells; D008807:Mice, Inbred BALB C; D008969:Molecular Sequence Data; D009154:Mutation / Q000235:genetics*; D009976:Orthomyxoviridae Infections / Q000821:virology; D010641:Phenotype; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D014613:Vaccines, Attenuated / Q000276:immunology; D017361:Viral Nonstructural Proteins / Q000235:genetics*
chemical_list: C414401:1-(5'-methylfur-3'-yl)propane-1,2,3-triol; D005663:Furans; C085820:INS1 protein, influenza virus; D012333:RNA, Messenger; D014613:Vaccines, Attenuated; D017361:Viral Nonstructural Proteins; D016899:Interferon-beta; D005990:Glycerol