Various cytopathic effects observed in DENV-1-infected Vero E6 cells after 7 days post infection. (A) The monolayer sheet of cells at 100× magnification appeared to be congested and haphazard. (B) A typical syncythial giant cell formation or syncytia resulting from the fusion of a few cells infected with DENV-1 viewed at 200× magnification. The morphological changes appeared to be group of cells without a clear white demarcation of cell membrane. The cells located at the perimeter of the syncytia were observed clearly. (C) Areas of cell death or lysis are pointed out by the arrows. These small areas were clear of any cells and reflected the colour of the pink medium. (D) A higher magnification image (400×) showing white dots called blebs.