Figure 5.

Serum HMGB1 levels in cotton rats immunized with FluLaval and challenged with A/California. Young and aged animals were immunized with the indicated doses of FluLaval 2016–2017 (FluL) twice with an interval of 3 weeks and infected with influenza A/Cal 3 weeks after the second immunization. Control animals were infected with A/Cal and re-infected 6 weeks later (secondary infection, °2) or mock immunized and infected with A/Cal (primary infection, °1). Serum from a group of young animals immunized in a similar manner with FluLaval 2012–2013 (FluL 12/13) and challenged with A/Cal was included in the analysis. Serum was obtained on day 4 post-challenge. Results represent GMT±SE for 5–6 animals per group. *p < .05 when compared to HMGB1 levels in serum of the same-age animals with primary infection