H5N1 NS genomic segment distinctly governs the influenza virus infectivity and cytokine induction in monocytic cells

作者：Lamichhane Prem Prasad; Boonnak Kob****; Changsom Don; Noisumdaeng Pirom; Sangsiriwut Kantima; Pattanakitsakul Sa-nga; Puthavathana Pilaipan^*

来源：Asian Pacific Journal of Allergy and Immunology, 2018, 36(1): 58-68.

DOI：10.12932/AP0870

• Influenza nonstructural genomic segment
• virus infectivity
• cytokines
• monocytic cells
• reverse genetics
• flow cytometry

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.& para;& para;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.& para;& para;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., rgH1N1 sea-NS, rgH1N1 pdm-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.& para;& para;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 (NI)* cells) and the numbers of infected cells that expressed IFN-alpha (NP IFN-alpha(+)-cell) obtained with rgH5N1-NS virus infection were significantly higher than the others, except for cells infected with the rgH1N1 pdm-NS virus. Nevertheless, the numbers of U937 cells that expressed NP IL-beta(+) were comparable upon infection with any of the rg-viruses; almost none expressed TNF-alpha.& para;& para;Conclusions: The H5N1 NS genomic segment distinctly up-regulated the viral infectivity and induction of IFN-alpha compared to the rgPR8, rgH1N1-NS and rgH3N2-NS viruses.

• 出版日期2018-3