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Serum-dependent expression of promyelocytic leukemia protein suppresses propagation of influenza virus

Journal Article · · Virology
 [1];  [1];  [1];  [1];  [2];  [1]
  1. Department of Microbiology, Sapporo Medical University School of Medicine, Chuo-ku, Sapporo 060-8556 (Japan)
  2. Department of Infection Biology, Graduate School of Comprehensive Human Sciences and Institute of Basic Medical Sciences, University of Tsukuba, Tsukuba 305-8575 (Japan)
The rate of propagation of influenza virus in human adenocarcinoma Caco-2 cells was found to negatively correlate with the concentration of fetal bovine serum (FBS) in the culture medium. Virus replicated more rapidly at lower FBS concentrations (0 or 2%) than at higher concentrations (10 or 20%) during an early stage of infection. Basal and interferon (IFN)-induced levels of typical IFN-inducible anti-viral proteins, such as 2',5'-oligoadenylate synthetase, dsRNA-activated protein kinase and MxA, were unaffected by variation in FBS concentrations. But promyelocytic leukemia protein (PML) was expressed in a serum-dependent manner. In particular, the 65 to 70 kDa isoform of PML was markedly upregulated following the addition of serum. In contrast, other isoforms were induced by IFN treatment, and weakly induced by FBS concentrations. Immunofluorescence microscopy indicated that PML was mainly formed nuclear bodies in Caco-2 cells at various FBS concentrations, and the levels of the PML-nuclear bodies were upregulated by FBS. Overexpression of PML isoform consisting of 560 or 633 amino acid residues by transfection of expression plasmid results in significantly delayed viral replication rate in Caco-2 cells. On the other hand, downregulation of PML expression by RNAi enhanced viral replication. These results indicate that PML isoforms which are expressed in a serum-dependent manner suppress the propagation of influenza virus at an early stage of infection.
OSTI ID:
20779438
Journal Information:
Virology, Journal Name: Virology Journal Issue: 1 Vol. 343; ISSN VIRLAX; ISSN 0042-6822
Country of Publication:
United States
Language:
English