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Asian Pac J Allergy Immunol. 2017 Aug 8. doi: 10.12932/AP0870. [Epub ahead of print]
H5N1 NS genomic segment distinctly governs the influenza virus infectivity and cytokine induction in monocytic cells.
Lamichhane PP1, Boonnak K2, Changsom D1,3, Noisumdaeng P4, Sangsiriwut K5, Pattanakitsakul SN6, Puthavathana P1,3.
Author information
Abstract
BACKGROUND:
The level of virulence of H5N1 highly pathogenic avian influenza (HPAI) virus was higher than those of the other virus subtypes. It has been suggested that the nonstructural (NS) gene might be a factor contributing to H5N1 HPAI virulence.
OBJECTIVES:
To determine the efficiency of the NS genomic segment of H5N1 HPAI virus on governing viral infectivity and cytokine induction in monocytic cells compared to other virus strain/subtypes.
METHODS:
By reverse genetics, five reassortant influenza viruses carrying the NS genomic segment derived from seasonal influenza A(H1N1), 2009 pandemic A(H1N1), A(H3N2) or H5N1 HPAI virus in the backbone of A/Puerto Rico/8/34 H1N1 (PR8) virus were constructed together with the reassorted PR8 virus control, i.e., rgH1N1sea-NS, rgH1N1pdm-NS, rgH3N2-NS, rgH5N1-NS and rgPR8 viruses, respectively. These reverse genetics-derived viruses (rg-viruses) were used to infect monocytic cells for 24 hours prior to determining intracellular influenza nucleoprotein (NP) levels and cytokine induction by flow cytometry.
RESULTS:
U937 cells were significantly more susceptible to rgPR8 control virus than THP-1 cells; thus, U937 cells were chosen for further study. The number of U937-infected cells (NP+ cells) and the numbers of infected cells that expressed IFN-α (NP+IFN-α+ cell) obtained with rgH5N1-NS virus infection were significantly higher than the others, except for cells infected with the rgH1N1pdm-NS virus. Nevertheless, the numbers of U937 cells that expressed NP+IL-1β+ were comparable upon infection with any of the rg-viruses; almost none expressed TNF-α.
CONCLUSIONS:
The H5N1 NS genomic segment distinctly up-regulated the viral infectivity and induction of IFN-α compared to the rgPR8, rgH1N1sea-NS and rgH3N2-NS viruses.
PMID: 28802028 DOI: 10.12932/AP0870
H5N1 NS genomic segment distinctly governs the influenza virus infectivity and cytokine induction in monocytic cells.
Lamichhane PP1, Boonnak K2, Changsom D1,3, Noisumdaeng P4, Sangsiriwut K5, Pattanakitsakul SN6, Puthavathana P1,3.
Author information
Abstract
BACKGROUND:
The level of virulence of H5N1 highly pathogenic avian influenza (HPAI) virus was higher than those of the other virus subtypes. It has been suggested that the nonstructural (NS) gene might be a factor contributing to H5N1 HPAI virulence.
OBJECTIVES:
To determine the efficiency of the NS genomic segment of H5N1 HPAI virus on governing viral infectivity and cytokine induction in monocytic cells compared to other virus strain/subtypes.
METHODS:
By reverse genetics, five reassortant influenza viruses carrying the NS genomic segment derived from seasonal influenza A(H1N1), 2009 pandemic A(H1N1), A(H3N2) or H5N1 HPAI virus in the backbone of A/Puerto Rico/8/34 H1N1 (PR8) virus were constructed together with the reassorted PR8 virus control, i.e., rgH1N1sea-NS, rgH1N1pdm-NS, rgH3N2-NS, rgH5N1-NS and rgPR8 viruses, respectively. These reverse genetics-derived viruses (rg-viruses) were used to infect monocytic cells for 24 hours prior to determining intracellular influenza nucleoprotein (NP) levels and cytokine induction by flow cytometry.
RESULTS:
U937 cells were significantly more susceptible to rgPR8 control virus than THP-1 cells; thus, U937 cells were chosen for further study. The number of U937-infected cells (NP+ cells) and the numbers of infected cells that expressed IFN-α (NP+IFN-α+ cell) obtained with rgH5N1-NS virus infection were significantly higher than the others, except for cells infected with the rgH1N1pdm-NS virus. Nevertheless, the numbers of U937 cells that expressed NP+IL-1β+ were comparable upon infection with any of the rg-viruses; almost none expressed TNF-α.
CONCLUSIONS:
The H5N1 NS genomic segment distinctly up-regulated the viral infectivity and induction of IFN-α compared to the rgPR8, rgH1N1sea-NS and rgH3N2-NS viruses.
PMID: 28802028 DOI: 10.12932/AP0870