The difference in IL-1β, MIP-1α, IL-8 and IL-18 production between the infection of PMA activated U937 cells with recombinant vaccinia viruses inserted 2004 H5N1 influenza HA genes and NS genes

Abstract

Background: The severity of avian influenza H5N1 disease is correlated with the ability of the virus to induce an over production of pro-inflammatory cytokines from innate immune cells. However, the role of each virus gene is unknown. To elaborate the function of each virus gene, the recombinant vaccinia virus inserted HA and NS gene from the 2004 H5N1 virus were used in the study. Methods: U937 cells and PMA activated U937 cells were infected with recombinant vaccinia virus inserted with HA or NS gene. The expressions of HA and NS proteins in cells were detected on immunofluorescence stained slides using a confocal microscope. The cytokine productions in the cell supernatant were quantitated by ELISA. Results: The recombinant vaccinia virus inserted with HA genes induces the production of IL-1β, MIP-1α, IL-8 and IL-18 cytokines from PMA activated U937 cells significantly more than cells infected with wild type vaccinia, whereas the recombinant vaccinia virus inserted with NS genes it was similar to that with the wild type vaccinia virus. However, there was no synergistic nor antagonistic effect of HA genes and NS genes in relation to cytokines production. Conclusion: Only the HA gene from the 2004 H5N1 virus induces IL-1β, MIP-1α, IL-8 and IL-18 cytokine productions from activated U937 cells. The same HA gene effect may or may not be the same in respiratory epithelial cells and this needs to be explored.