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Fig. 6 | Virology Journal

Fig. 6

From: Dengue virus 3 genotype I (GI) lineage 1 (L1) isolates elicit differential cytopathic effect with syncytium formation in human glioblastoma cells (U251)

Fig. 6

Transmission electron microscopy (TEM) analysis. Human glioblastoma cells (U251) infected with DENV3 GIL1 isolates was observed at 1 MOI on the 4th day. Cell morphology and visualization of membranes (2 μM scale bar) (6A–C) showed a constriction in the nucleus, the presence of a pair of centrioles, an intact cell membrane (CM), and a healthy-looking cell structure in the mock-infected cell (6A). DENV3 PV_BR (6B) was observed to have integral membranes, while DENV3 MG-20 (6C) was found to have multiple membranous compartmentalization indicating a possible process of cell death by apoptosis (Ap. B – Apoptotic bodies) and damaged CM. At 500 nm scale bar, the transmission electron microscopy (TEM) analysis of the mock-infected cell (6D), DENV3 PV_BR (6E), and DENV3 MG-20 (6F) revealed a regular morphology of ribosomes (RER) with small electrodense particles adhered to the reticles; mild rough RE hyperplasia in DENV3 PV_BR; and a region of intense RER hyperplasia in DENV3 MG-20. At 500 nm scale bars, the visualization of vesicles with proteins showed regular size of vesicles in the mock-infected cell (6G), turgid vesicles with organic molecules in DENV3 PV_BR (6H), and a large flow of dilated vesicles with large amounts of organic molecules in DENV3 MG-20 (6I). These suggested potential virus morphogenesis regions. At 500 nm scale bars, the intense activity due to the high presence of organelles and reticulum in the mock-infected cell (6J); intense metabolic activity with excess organelles and membranes indicating a putative region of viral synthesis in DENV3 PV_BR (6K); and high metabolic activity with excess of organelles, membranes, vesicles and Golgi complex in DENV3 MG-20 (6L), suggesting that this area is a more intense region of viral synthesis than that of DENV3 PV_BR. At 500 nm scale bars, observation of vesicle structures revealed misshapen and disorganized filling in the mock-infected cell (6M), vesicles with electron-dense particles, circular, with an icosahedral core suggestive of DENV3 viral particles in DENV3 PV_BR (6N), and multi-membranous vesicles containing electron-dense particles Dengue virus-like in DENV3 MG-20 (6O). The geometries and sizes were compatible with those described for the DENV (at 200 nm scale bar), yellow asterisk indicates virus

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Virology Journal

ISSN: 1743-422X