Replication of CHIKV (IMT isolate) in C6/36 cells. (a) Ultrastructural analysis of mock-infected C6/36 cells. At higher magnification, Golgi apparatus (GA), endoplasmic reticulum (ER) and mitochondria (M), can be observed. The bar corresponds to 0.5 μm. (b) Presence of Cytopathic Vacuoles (CPV) I in early infection (8 h post-infection). A typical CPV I complex (appx 800 nm) can be observed. CPV I is characterized by membranous spherules (arrows) regularly arranged from the interior surface of the complex. The bar corresponds to 0.2 μm. (c) Virus release by budding at the plasma membrane during early infection. CHIKV particle are observed to be budding from the plasma membrane (Pm). The bar corresponds to 0.2 μm. (c) i Enlarged of (c) showing the lining of the nucleocapsids (arrowheads) underneath the plasma membrane (Pm) of the cell. Matured virus (arrow) is observed to be budding from the peripheral of cells membrane. (d) Budding of CHIKV occurred extensively at the plasma membrane of the cells. The bar corresponds to 0.2 μm. (d) i Enlarged of (d) monitored the different stages of budding of CHIKV particles from the plasma membrane (arrows). (e) Ultrastructural analysis of late infection with CHIKV in C6/36 cells (Day 1 post infection). CPV II formations are observed. The viral nucleocapsids (arrowheads) are present at the cytoplasmic surface of CPV II complexes. The bar corresponds to 0.2 μm. (f) Several CPV II complexes are found in cluster near the plasma membrane (Pm) with the noticed of mature virus (arrows) in the complex. (g) and (h) At the late stage, CHIKV can be seen to be released from cells via exocytosis (arrows). Both the bar of g and h correspond to 0.2 μm.