Figure 1.

Cytokine production in human macrophages. Human monocyte–derived macrophages were infected with a series of reassortants between IDN3006 and VN3028IIcl2 at a multiplicity of infection of 2. At 12 hours after infection, the supernatants of the infected cells were collected, and the concentrations of 7 cytokines (interleukin-6 [IL-6], CXCL10 [IP-10], CCL3 [MIP-1α], CCL4 [MIP-1β], CCL5 [RANTES], tumor necrosis factor α [TNF-α], and CXCL9 [MIG]) were measured. All values were normalized to the value of IDN3006. A, Contributions of a set of 4 viral genes to the cytokine production were evaluated. B, Single viral gene segments responsible for the cytokine induction were determined. The values are means ± SD (n = 3). *P < .05, compared with the IDN3006 group (1-way analysis of variance with the post hoc Tukey honestly significant difference test). Abbreviations: HA, hemagglutinin; M, matrix; NA, neuraminidase; NP, nucleoprotein; NS, nonstructural.