FIG 4.

Abilities of the different DENV serotypes to undergo structural changes at elevated temperatures. Cryo-EM images of DENV4 strain SG/06K2270DK1/2005 (A), DENV1 strain PVP159 (B), and DENV2 strain NGC (C) after incubation at 37°C for 30 min are shown. The sizes of the DENV1 and DENV4 particles remained the same, and their surfaces appeared to be smooth, whereas DENV2 had expanded particles with a rough appearance. (D) DENV4 incubated at 40°C for 30 min. DENV4 particles aggregated together; however, the surfaces are not as bumpy as those of DENV2 at 37°C.