Figure 1.

Experimental design schematic. Mice were randomly divided into four groups. Mice under chronic heat stress (CHS) were exposed to 38 ± 1°C for 4 h per day from day 0 to day 21, meanwhile mice of thermally neutral (TN) groups were maintained at 24 ± 1°C. Mice were immunized with 50 μL formalin-inactivated H5N1 virus or PBS on day 0 and boosted on day 14, and all the mice were challenged with PBS-diluted H5N1 virus (50 PFU) on day 21. The mortality of virus-infected mice was observed for 14 days after the viral challenge. Three mice from each group were sacrificed on days 7, 14, 21, 24, and 27; serum, lung, and spleen tissues were collected.